core/num/uint_macros.rs
1macro_rules! uint_impl {
2 (
3 Self = $SelfT:ty,
4 ActualT = $ActualT:ident,
5 SignedT = $SignedT:ident,
6
7 // These are all for use *only* in doc comments.
8 // As such, they're all passed as literals -- passing them as a string
9 // literal is fine if they need to be multiple code tokens.
10 // In non-comments, use the associated constants rather than these.
11 BITS = $BITS:literal,
12 BITS_MINUS_ONE = $BITS_MINUS_ONE:literal,
13 MAX = $MaxV:literal,
14 rot = $rot:literal,
15 rot_op = $rot_op:literal,
16 rot_result = $rot_result:literal,
17 fsh_op = $fsh_op:literal,
18 fshl_result = $fshl_result:literal,
19 fshr_result = $fshr_result:literal,
20 clmul_lhs = $clmul_lhs:literal,
21 clmul_rhs = $clmul_rhs:literal,
22 clmul_result = $clmul_result:literal,
23 swap_op = $swap_op:literal,
24 swapped = $swapped:literal,
25 reversed = $reversed:literal,
26 le_bytes = $le_bytes:literal,
27 be_bytes = $be_bytes:literal,
28 to_xe_bytes_doc = $to_xe_bytes_doc:expr,
29 from_xe_bytes_doc = $from_xe_bytes_doc:expr,
30 bound_condition = $bound_condition:literal,
31 ) => {
32 /// The smallest value that can be represented by this integer type.
33 ///
34 /// # Examples
35 ///
36 /// ```
37 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MIN, 0);")]
38 /// ```
39 #[stable(feature = "assoc_int_consts", since = "1.43.0")]
40 pub const MIN: Self = 0;
41
42 /// The largest value that can be represented by this integer type
43 #[doc = concat!("(2<sup>", $BITS, "</sup> − 1", $bound_condition, ").")]
44 ///
45 /// # Examples
46 ///
47 /// ```
48 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX, ", stringify!($MaxV), ");")]
49 /// ```
50 #[stable(feature = "assoc_int_consts", since = "1.43.0")]
51 pub const MAX: Self = !0;
52
53 /// The size of this integer type in bits.
54 ///
55 /// # Examples
56 ///
57 /// ```
58 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::BITS, ", stringify!($BITS), ");")]
59 /// ```
60 #[stable(feature = "int_bits_const", since = "1.53.0")]
61 pub const BITS: u32 = Self::MAX.count_ones();
62
63 /// Returns the number of ones in the binary representation of `self`.
64 ///
65 /// # Examples
66 ///
67 /// ```
68 #[doc = concat!("let n = 0b01001100", stringify!($SelfT), ";")]
69 /// assert_eq!(n.count_ones(), 3);
70 ///
71 #[doc = concat!("let max = ", stringify!($SelfT),"::MAX;")]
72 #[doc = concat!("assert_eq!(max.count_ones(), ", stringify!($BITS), ");")]
73 ///
74 #[doc = concat!("let zero = 0", stringify!($SelfT), ";")]
75 /// assert_eq!(zero.count_ones(), 0);
76 /// ```
77 #[stable(feature = "rust1", since = "1.0.0")]
78 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
79 #[doc(alias = "popcount")]
80 #[doc(alias = "popcnt")]
81 #[must_use = "this returns the result of the operation, \
82 without modifying the original"]
83 #[inline(always)]
84 pub const fn count_ones(self) -> u32 {
85 return intrinsics::ctpop(self);
86 }
87
88 /// Returns the number of zeros in the binary representation of `self`.
89 ///
90 /// # Examples
91 ///
92 /// ```
93 #[doc = concat!("let zero = 0", stringify!($SelfT), ";")]
94 #[doc = concat!("assert_eq!(zero.count_zeros(), ", stringify!($BITS), ");")]
95 ///
96 #[doc = concat!("let max = ", stringify!($SelfT),"::MAX;")]
97 /// assert_eq!(max.count_zeros(), 0);
98 /// ```
99 ///
100 /// This is heavily dependent on the width of the type, and thus
101 /// might give surprising results depending on type inference:
102 /// ```
103 /// # fn foo(_: u8) {}
104 /// # fn bar(_: u16) {}
105 /// let lucky = 7;
106 /// foo(lucky);
107 /// assert_eq!(lucky.count_zeros(), 5);
108 /// assert_eq!(lucky.count_ones(), 3);
109 ///
110 /// let lucky = 7;
111 /// bar(lucky);
112 /// assert_eq!(lucky.count_zeros(), 13);
113 /// assert_eq!(lucky.count_ones(), 3);
114 /// ```
115 /// You might want to use [`Self::count_ones`] instead, or emphasize
116 /// the type you're using in the call rather than method syntax:
117 /// ```
118 /// let small = 1;
119 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::count_zeros(small), ", stringify!($BITS_MINUS_ONE) ,");")]
120 /// ```
121 #[stable(feature = "rust1", since = "1.0.0")]
122 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
123 #[must_use = "this returns the result of the operation, \
124 without modifying the original"]
125 #[inline(always)]
126 pub const fn count_zeros(self) -> u32 {
127 (!self).count_ones()
128 }
129
130 /// Returns the number of leading zeros in the binary representation of `self`.
131 ///
132 /// Depending on what you're doing with the value, you might also be interested in the
133 /// [`ilog2`] function which returns a consistent number, even if the type widens.
134 ///
135 /// # Examples
136 ///
137 /// ```
138 #[doc = concat!("let n = ", stringify!($SelfT), "::MAX >> 2;")]
139 /// assert_eq!(n.leading_zeros(), 2);
140 ///
141 #[doc = concat!("let zero = 0", stringify!($SelfT), ";")]
142 #[doc = concat!("assert_eq!(zero.leading_zeros(), ", stringify!($BITS), ");")]
143 ///
144 #[doc = concat!("let max = ", stringify!($SelfT),"::MAX;")]
145 /// assert_eq!(max.leading_zeros(), 0);
146 /// ```
147 #[doc = concat!("[`ilog2`]: ", stringify!($SelfT), "::ilog2")]
148 #[stable(feature = "rust1", since = "1.0.0")]
149 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
150 #[must_use = "this returns the result of the operation, \
151 without modifying the original"]
152 #[inline(always)]
153 pub const fn leading_zeros(self) -> u32 {
154 return intrinsics::ctlz(self as $ActualT);
155 }
156
157 /// Returns the number of trailing zeros in the binary representation
158 /// of `self`.
159 ///
160 /// # Examples
161 ///
162 /// ```
163 #[doc = concat!("let n = 0b0101000", stringify!($SelfT), ";")]
164 /// assert_eq!(n.trailing_zeros(), 3);
165 ///
166 #[doc = concat!("let zero = 0", stringify!($SelfT), ";")]
167 #[doc = concat!("assert_eq!(zero.trailing_zeros(), ", stringify!($BITS), ");")]
168 ///
169 #[doc = concat!("let max = ", stringify!($SelfT),"::MAX;")]
170 #[doc = concat!("assert_eq!(max.trailing_zeros(), 0);")]
171 /// ```
172 #[stable(feature = "rust1", since = "1.0.0")]
173 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
174 #[must_use = "this returns the result of the operation, \
175 without modifying the original"]
176 #[inline(always)]
177 pub const fn trailing_zeros(self) -> u32 {
178 return intrinsics::cttz(self);
179 }
180
181 /// Returns the number of leading ones in the binary representation of `self`.
182 ///
183 /// # Examples
184 ///
185 /// ```
186 #[doc = concat!("let n = !(", stringify!($SelfT), "::MAX >> 2);")]
187 /// assert_eq!(n.leading_ones(), 2);
188 ///
189 #[doc = concat!("let zero = 0", stringify!($SelfT), ";")]
190 /// assert_eq!(zero.leading_ones(), 0);
191 ///
192 #[doc = concat!("let max = ", stringify!($SelfT),"::MAX;")]
193 #[doc = concat!("assert_eq!(max.leading_ones(), ", stringify!($BITS), ");")]
194 /// ```
195 #[stable(feature = "leading_trailing_ones", since = "1.46.0")]
196 #[rustc_const_stable(feature = "leading_trailing_ones", since = "1.46.0")]
197 #[must_use = "this returns the result of the operation, \
198 without modifying the original"]
199 #[inline(always)]
200 pub const fn leading_ones(self) -> u32 {
201 (!self).leading_zeros()
202 }
203
204 /// Returns the number of trailing ones in the binary representation
205 /// of `self`.
206 ///
207 /// # Examples
208 ///
209 /// ```
210 #[doc = concat!("let n = 0b1010111", stringify!($SelfT), ";")]
211 /// assert_eq!(n.trailing_ones(), 3);
212 ///
213 #[doc = concat!("let zero = 0", stringify!($SelfT), ";")]
214 /// assert_eq!(zero.trailing_ones(), 0);
215 ///
216 #[doc = concat!("let max = ", stringify!($SelfT),"::MAX;")]
217 #[doc = concat!("assert_eq!(max.trailing_ones(), ", stringify!($BITS), ");")]
218 /// ```
219 #[stable(feature = "leading_trailing_ones", since = "1.46.0")]
220 #[rustc_const_stable(feature = "leading_trailing_ones", since = "1.46.0")]
221 #[must_use = "this returns the result of the operation, \
222 without modifying the original"]
223 #[inline(always)]
224 pub const fn trailing_ones(self) -> u32 {
225 (!self).trailing_zeros()
226 }
227
228 /// Returns the minimum number of bits required to represent `self`.
229 ///
230 /// This method returns zero if `self` is zero.
231 ///
232 /// # Examples
233 ///
234 /// ```
235 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".bit_width(), 0);")]
236 #[doc = concat!("assert_eq!(0b111_", stringify!($SelfT), ".bit_width(), 3);")]
237 #[doc = concat!("assert_eq!(0b1110_", stringify!($SelfT), ".bit_width(), 4);")]
238 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.bit_width(), ", stringify!($BITS), ");")]
239 /// ```
240 #[stable(feature = "uint_bit_width", since = "CURRENT_RUSTC_VERSION")]
241 #[rustc_const_stable(feature = "uint_bit_width", since = "CURRENT_RUSTC_VERSION")]
242 #[must_use = "this returns the result of the operation, \
243 without modifying the original"]
244 #[inline(always)]
245 pub const fn bit_width(self) -> u32 {
246 Self::BITS - self.leading_zeros()
247 }
248
249 /// Returns `self` with only the most significant bit set, or `0` if
250 /// the input is `0`.
251 ///
252 /// # Examples
253 ///
254 /// ```
255 #[doc = concat!("let n: ", stringify!($SelfT), " = 0b_01100100;")]
256 ///
257 /// assert_eq!(n.isolate_highest_one(), 0b_01000000);
258 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".isolate_highest_one(), 0);")]
259 /// ```
260 #[stable(feature = "isolate_most_least_significant_one", since = "CURRENT_RUSTC_VERSION")]
261 #[rustc_const_stable(feature = "isolate_most_least_significant_one", since = "CURRENT_RUSTC_VERSION")]
262 #[must_use = "this returns the result of the operation, \
263 without modifying the original"]
264 #[inline(always)]
265 pub const fn isolate_highest_one(self) -> Self {
266 self & (((1 as $SelfT) << (<$SelfT>::BITS - 1)).wrapping_shr(self.leading_zeros()))
267 }
268
269 /// Returns `self` with only the least significant bit set, or `0` if
270 /// the input is `0`.
271 ///
272 /// # Examples
273 ///
274 /// ```
275 #[doc = concat!("let n: ", stringify!($SelfT), " = 0b_01100100;")]
276 ///
277 /// assert_eq!(n.isolate_lowest_one(), 0b_00000100);
278 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".isolate_lowest_one(), 0);")]
279 /// ```
280 #[stable(feature = "isolate_most_least_significant_one", since = "CURRENT_RUSTC_VERSION")]
281 #[rustc_const_stable(feature = "isolate_most_least_significant_one", since = "CURRENT_RUSTC_VERSION")]
282 #[must_use = "this returns the result of the operation, \
283 without modifying the original"]
284 #[inline(always)]
285 pub const fn isolate_lowest_one(self) -> Self {
286 self & self.wrapping_neg()
287 }
288
289 /// Returns the index of the highest bit set to one in `self`, or `None`
290 /// if `self` is `0`.
291 ///
292 /// # Examples
293 ///
294 /// ```
295 #[doc = concat!("assert_eq!(0b0_", stringify!($SelfT), ".highest_one(), None);")]
296 #[doc = concat!("assert_eq!(0b1_", stringify!($SelfT), ".highest_one(), Some(0));")]
297 #[doc = concat!("assert_eq!(0b1_0000_", stringify!($SelfT), ".highest_one(), Some(4));")]
298 #[doc = concat!("assert_eq!(0b1_1111_", stringify!($SelfT), ".highest_one(), Some(4));")]
299 /// ```
300 #[stable(feature = "int_lowest_highest_one", since = "CURRENT_RUSTC_VERSION")]
301 #[rustc_const_stable(feature = "int_lowest_highest_one", since = "CURRENT_RUSTC_VERSION")]
302 #[must_use = "this returns the result of the operation, \
303 without modifying the original"]
304 #[inline(always)]
305 pub const fn highest_one(self) -> Option<u32> {
306 match NonZero::new(self) {
307 Some(v) => Some(v.highest_one()),
308 None => None,
309 }
310 }
311
312 /// Returns the index of the lowest bit set to one in `self`, or `None`
313 /// if `self` is `0`.
314 ///
315 /// # Examples
316 ///
317 /// ```
318 #[doc = concat!("assert_eq!(0b0_", stringify!($SelfT), ".lowest_one(), None);")]
319 #[doc = concat!("assert_eq!(0b1_", stringify!($SelfT), ".lowest_one(), Some(0));")]
320 #[doc = concat!("assert_eq!(0b1_0000_", stringify!($SelfT), ".lowest_one(), Some(4));")]
321 #[doc = concat!("assert_eq!(0b1_1111_", stringify!($SelfT), ".lowest_one(), Some(0));")]
322 /// ```
323 #[stable(feature = "int_lowest_highest_one", since = "CURRENT_RUSTC_VERSION")]
324 #[rustc_const_stable(feature = "int_lowest_highest_one", since = "CURRENT_RUSTC_VERSION")]
325 #[must_use = "this returns the result of the operation, \
326 without modifying the original"]
327 #[inline(always)]
328 pub const fn lowest_one(self) -> Option<u32> {
329 match NonZero::new(self) {
330 Some(v) => Some(v.lowest_one()),
331 None => None,
332 }
333 }
334
335 /// Returns the bit pattern of `self` reinterpreted as a signed integer of the same size.
336 ///
337 /// This produces the same result as an `as` cast, but ensures that the bit-width remains
338 /// the same.
339 ///
340 /// # Examples
341 ///
342 /// ```
343 #[doc = concat!("let n = ", stringify!($SelfT), "::MAX;")]
344 ///
345 #[doc = concat!("assert_eq!(n.cast_signed(), -1", stringify!($SignedT), ");")]
346 /// ```
347 #[stable(feature = "integer_sign_cast", since = "1.87.0")]
348 #[rustc_const_stable(feature = "integer_sign_cast", since = "1.87.0")]
349 #[must_use = "this returns the result of the operation, \
350 without modifying the original"]
351 #[inline(always)]
352 pub const fn cast_signed(self) -> $SignedT {
353 self as $SignedT
354 }
355
356 /// Saturating conversion of `self` to a signed integer of the same size.
357 ///
358 /// The signed integer's maximum value is returned if `self` is larger
359 /// than the maximum positive value representable by the signed integer.
360 ///
361 /// For other kinds of signed integer casts, see
362 /// [`cast_signed`](Self::cast_signed),
363 /// [`checked_cast_signed`](Self::checked_cast_signed),
364 /// or [`strict_cast_signed`](Self::strict_cast_signed).
365 ///
366 /// # Examples
367 ///
368 /// ```
369 /// #![feature(integer_cast_extras)]
370 #[doc = concat!("let n = ", stringify!($SelfT), "::MAX;")]
371 ///
372 #[doc = concat!("assert_eq!(n.saturating_cast_signed(), ", stringify!($SignedT), "::MAX);")]
373 #[doc = concat!("assert_eq!(64", stringify!($SelfT), ".saturating_cast_signed(), 64", stringify!($SignedT), ");")]
374 /// ```
375 #[rustc_const_unstable(feature = "integer_cast_extras", issue = "154650")]
376 #[unstable(feature = "integer_cast_extras", issue = "154650")]
377 #[must_use = "this returns the result of the operation, \
378 without modifying the original"]
379 #[inline(always)]
380 pub const fn saturating_cast_signed(self) -> $SignedT {
381 // Clamp to the signed integer max size, which is ActualT::MAX >> 1.
382 if self <= <$SignedT>::MAX.cast_unsigned() {
383 self.cast_signed()
384 } else {
385 <$SignedT>::MAX
386 }
387 }
388
389 /// Checked conversion of `self` to a signed integer of the same size,
390 /// returning `None` if `self` is larger than the signed integer's
391 /// maximum value.
392 ///
393 /// For other kinds of signed integer casts, see
394 /// [`cast_signed`](Self::cast_signed),
395 /// [`saturating_cast_signed`](Self::saturating_cast_signed),
396 /// or [`strict_cast_signed`](Self::strict_cast_signed).
397 ///
398 /// # Examples
399 ///
400 /// ```
401 /// #![feature(integer_cast_extras)]
402 #[doc = concat!("let n = ", stringify!($SelfT), "::MAX;")]
403 ///
404 #[doc = concat!("assert_eq!(n.checked_cast_signed(), None);")]
405 #[doc = concat!("assert_eq!(64", stringify!($SelfT), ".checked_cast_signed(), Some(64", stringify!($SignedT), "));")]
406 /// ```
407 #[rustc_const_unstable(feature = "integer_cast_extras", issue = "154650")]
408 #[unstable(feature = "integer_cast_extras", issue = "154650")]
409 #[must_use = "this returns the result of the operation, \
410 without modifying the original"]
411 #[inline(always)]
412 pub const fn checked_cast_signed(self) -> Option<$SignedT> {
413 if self <= <$SignedT>::MAX.cast_unsigned() {
414 Some(self.cast_signed())
415 } else {
416 None
417 }
418 }
419
420 /// Strict conversion of `self` to a signed integer of the same size,
421 /// which panics if `self` is larger than the signed integer's maximum
422 /// value.
423 ///
424 /// For other kinds of signed integer casts, see
425 /// [`cast_signed`](Self::cast_signed),
426 /// [`checked_cast_signed`](Self::checked_cast_signed),
427 /// or [`saturating_cast_signed`](Self::saturating_cast_signed).
428 ///
429 /// # Examples
430 ///
431 /// ```should_panic
432 /// #![feature(integer_cast_extras)]
433 #[doc = concat!("let _ = ", stringify!($SelfT), "::MAX.strict_cast_signed();")]
434 /// ```
435 #[rustc_const_unstable(feature = "integer_cast_extras", issue = "154650")]
436 #[unstable(feature = "integer_cast_extras", issue = "154650")]
437 #[must_use = "this returns the result of the operation, \
438 without modifying the original"]
439 #[inline]
440 #[track_caller]
441 pub const fn strict_cast_signed(self) -> $SignedT {
442 match self.checked_cast_signed() {
443 Some(n) => n,
444 None => imp::overflow_panic::cast_integer(),
445 }
446 }
447
448 /// Shifts the bits to the left by a specified amount, `n`,
449 /// wrapping the truncated bits to the end of the resulting integer.
450 ///
451 /// `rotate_left(n)` is equivalent to applying `rotate_left(1)` a total of `n` times. In
452 /// particular, a rotation by the number of bits in `self` returns the input value
453 /// unchanged.
454 ///
455 /// Please note this isn't the same operation as the `<<` shifting operator!
456 ///
457 /// # Examples
458 ///
459 /// ```
460 #[doc = concat!("let n = ", $rot_op, stringify!($SelfT), ";")]
461 #[doc = concat!("let m = ", $rot_result, ";")]
462 ///
463 #[doc = concat!("assert_eq!(n.rotate_left(", $rot, "), m);")]
464 #[doc = concat!("assert_eq!(n.rotate_left(1024), n);")]
465 /// ```
466 #[stable(feature = "rust1", since = "1.0.0")]
467 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
468 #[must_use = "this returns the result of the operation, \
469 without modifying the original"]
470 #[inline(always)]
471 #[rustc_allow_const_fn_unstable(const_trait_impl)] // for the intrinsic fallback
472 pub const fn rotate_left(self, n: u32) -> Self {
473 return intrinsics::rotate_left(self, n);
474 }
475
476 /// Shifts the bits to the right by a specified amount, `n`,
477 /// wrapping the truncated bits to the beginning of the resulting
478 /// integer.
479 ///
480 /// `rotate_right(n)` is equivalent to applying `rotate_right(1)` a total of `n` times. In
481 /// particular, a rotation by the number of bits in `self` returns the input value
482 /// unchanged.
483 ///
484 /// Please note this isn't the same operation as the `>>` shifting operator!
485 ///
486 /// # Examples
487 ///
488 /// ```
489 #[doc = concat!("let n = ", $rot_result, stringify!($SelfT), ";")]
490 #[doc = concat!("let m = ", $rot_op, ";")]
491 ///
492 #[doc = concat!("assert_eq!(n.rotate_right(", $rot, "), m);")]
493 #[doc = concat!("assert_eq!(n.rotate_right(1024), n);")]
494 /// ```
495 #[stable(feature = "rust1", since = "1.0.0")]
496 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
497 #[must_use = "this returns the result of the operation, \
498 without modifying the original"]
499 #[inline(always)]
500 #[rustc_allow_const_fn_unstable(const_trait_impl)] // for the intrinsic fallback
501 pub const fn rotate_right(self, n: u32) -> Self {
502 return intrinsics::rotate_right(self, n);
503 }
504
505 /// Performs a left funnel shift (concatenates `self` with `rhs`, with `self`
506 /// making up the most significant half, then shifts the combined value left
507 /// by `n`, and most significant half is extracted to produce the result).
508 ///
509 /// Please note this isn't the same operation as the `<<` shifting operator or
510 /// [`rotate_left`](Self::rotate_left), although `a.funnel_shl(a, n)` is *equivalent*
511 /// to `a.rotate_left(n)`.
512 ///
513 /// # Panics
514 ///
515 /// If `n` is greater than or equal to the number of bits in `self`
516 ///
517 /// # Examples
518 ///
519 /// Basic usage:
520 ///
521 /// ```
522 /// #![feature(funnel_shifts)]
523 #[doc = concat!("let a = ", $rot_op, stringify!($SelfT), ";")]
524 #[doc = concat!("let b = ", $fsh_op, stringify!($SelfT), ";")]
525 #[doc = concat!("let m = ", $fshl_result, ";")]
526 ///
527 #[doc = concat!("assert_eq!(a.funnel_shl(b, ", $rot, "), m);")]
528 /// ```
529 #[rustc_const_unstable(feature = "funnel_shifts", issue = "145686")]
530 #[unstable(feature = "funnel_shifts", issue = "145686")]
531 #[must_use = "this returns the result of the operation, \
532 without modifying the original"]
533 #[inline(always)]
534 pub const fn funnel_shl(self, rhs: Self, n: u32) -> Self {
535 assert!(n < Self::BITS, "attempt to funnel shift left with overflow");
536 // SAFETY: just checked that `shift` is in-range
537 unsafe { self.unchecked_funnel_shl(rhs, n) }
538 }
539
540 /// Performs a right funnel shift (concatenates `self` and `rhs`, with `self`
541 /// making up the most significant half, then shifts the combined value right
542 /// by `n`, and least significant half is extracted to produce the result).
543 ///
544 /// Please note this isn't the same operation as the `>>` shifting operator or
545 /// [`rotate_right`](Self::rotate_right), although `a.funnel_shr(a, n)` is *equivalent*
546 /// to `a.rotate_right(n)`.
547 ///
548 /// # Panics
549 ///
550 /// If `n` is greater than or equal to the number of bits in `self`
551 ///
552 /// # Examples
553 ///
554 /// Basic usage:
555 ///
556 /// ```
557 /// #![feature(funnel_shifts)]
558 #[doc = concat!("let a = ", $rot_op, stringify!($SelfT), ";")]
559 #[doc = concat!("let b = ", $fsh_op, stringify!($SelfT), ";")]
560 #[doc = concat!("let m = ", $fshr_result, ";")]
561 ///
562 #[doc = concat!("assert_eq!(a.funnel_shr(b, ", $rot, "), m);")]
563 /// ```
564 #[rustc_const_unstable(feature = "funnel_shifts", issue = "145686")]
565 #[unstable(feature = "funnel_shifts", issue = "145686")]
566 #[must_use = "this returns the result of the operation, \
567 without modifying the original"]
568 #[inline(always)]
569 pub const fn funnel_shr(self, rhs: Self, n: u32) -> Self {
570 assert!(n < Self::BITS, "attempt to funnel shift right with overflow");
571 // SAFETY: just checked that `shift` is in-range
572 unsafe { self.unchecked_funnel_shr(rhs, n) }
573 }
574
575 /// Unchecked funnel shift left.
576 ///
577 /// # Safety
578 ///
579 /// This results in undefined behavior if `n` is greater than or equal to
580 #[doc = concat!("`", stringify!($SelfT) , "::BITS`,")]
581 /// i.e. when [`funnel_shl`](Self::funnel_shl) would panic.
582 ///
583 #[rustc_const_unstable(feature = "funnel_shifts", issue = "145686")]
584 #[unstable(feature = "funnel_shifts", issue = "145686")]
585 #[must_use = "this returns the result of the operation, \
586 without modifying the original"]
587 #[inline(always)]
588 #[track_caller]
589 pub const unsafe fn unchecked_funnel_shl(self, low: Self, n: u32) -> Self {
590 assert_unsafe_precondition!(
591 check_language_ub,
592 concat!(stringify!($SelfT), "::unchecked_funnel_shl cannot overflow"),
593 (n: u32 = n) => n < <$ActualT>::BITS,
594 );
595
596 // SAFETY: this is guaranteed to be safe by the caller.
597 unsafe {
598 intrinsics::unchecked_funnel_shl(self, low, n)
599 }
600 }
601
602 /// Unchecked funnel shift right.
603 ///
604 /// # Safety
605 ///
606 /// This results in undefined behavior if `n` is greater than or equal to
607 #[doc = concat!("`", stringify!($SelfT) , "::BITS`,")]
608 /// i.e. when [`funnel_shr`](Self::funnel_shr) would panic.
609 ///
610 #[rustc_const_unstable(feature = "funnel_shifts", issue = "145686")]
611 #[unstable(feature = "funnel_shifts", issue = "145686")]
612 #[must_use = "this returns the result of the operation, \
613 without modifying the original"]
614 #[inline(always)]
615 #[track_caller]
616 pub const unsafe fn unchecked_funnel_shr(self, low: Self, n: u32) -> Self {
617 assert_unsafe_precondition!(
618 check_language_ub,
619 concat!(stringify!($SelfT), "::unchecked_funnel_shr cannot overflow"),
620 (n: u32 = n) => n < <$ActualT>::BITS,
621 );
622
623 // SAFETY: this is guaranteed to be safe by the caller.
624 unsafe {
625 intrinsics::unchecked_funnel_shr(self, low, n)
626 }
627 }
628
629 /// Performs a carry-less multiplication, returning the lower bits.
630 ///
631 /// This operation is similar to long multiplication in base 2, except that exclusive or is
632 /// used instead of addition. The implementation is equivalent to:
633 ///
634 /// ```no_run
635 #[doc = concat!("pub fn carryless_mul(lhs: ", stringify!($SelfT), ", rhs: ", stringify!($SelfT), ") -> ", stringify!($SelfT), "{")]
636 /// let mut retval = 0;
637 #[doc = concat!(" for i in 0..", stringify!($SelfT), "::BITS {")]
638 /// if (rhs >> i) & 1 != 0 {
639 /// // long multiplication would use +=
640 /// retval ^= lhs << i;
641 /// }
642 /// }
643 /// retval
644 /// }
645 /// ```
646 ///
647 /// The actual implementation is more efficient, and on some platforms lowers directly to a
648 /// dedicated instruction.
649 ///
650 /// # Uses
651 ///
652 /// Carryless multiplication can be used to turn a bitmask of quote characters into a
653 /// bit mask of characters surrounded by quotes:
654 ///
655 /// ```no_run
656 /// r#"abc xxx "foobar" zzz "a"!"#; // input string
657 /// 0b0000000010000001000001010; // quote_mask
658 /// 0b0000000001111110000000100; // quote_mask.carryless_mul(!0) & !quote_mask
659 /// ```
660 ///
661 /// Another use is in cryptography, where carryless multiplication allows for efficient
662 /// implementations of polynomial multiplication in `GF(2)[X]`, the polynomial ring
663 /// over `GF(2)`.
664 ///
665 /// # Examples
666 ///
667 /// ```
668 /// #![feature(uint_carryless_mul)]
669 ///
670 #[doc = concat!("let a = ", $clmul_lhs, stringify!($SelfT), ";")]
671 #[doc = concat!("let b = ", $clmul_rhs, stringify!($SelfT), ";")]
672 ///
673 #[doc = concat!("assert_eq!(a.carryless_mul(b), ", $clmul_result, ");")]
674 /// ```
675 #[rustc_const_unstable(feature = "uint_carryless_mul", issue = "152080")]
676 #[doc(alias = "clmul")]
677 #[unstable(feature = "uint_carryless_mul", issue = "152080")]
678 #[must_use = "this returns the result of the operation, \
679 without modifying the original"]
680 #[inline(always)]
681 pub const fn carryless_mul(self, rhs: Self) -> Self {
682 intrinsics::carryless_mul(self, rhs)
683 }
684
685 /// Reverses the byte order of the integer.
686 ///
687 /// # Examples
688 ///
689 /// ```
690 #[doc = concat!("let n = ", $swap_op, stringify!($SelfT), ";")]
691 /// let m = n.swap_bytes();
692 ///
693 #[doc = concat!("assert_eq!(m, ", $swapped, ");")]
694 /// ```
695 #[stable(feature = "rust1", since = "1.0.0")]
696 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
697 #[must_use = "this returns the result of the operation, \
698 without modifying the original"]
699 #[inline(always)]
700 pub const fn swap_bytes(self) -> Self {
701 intrinsics::bswap(self as $ActualT) as Self
702 }
703
704 /// Returns an integer with the bit locations specified by `mask` packed
705 /// contiguously into the least significant bits of the result.
706 /// ```
707 /// #![feature(uint_gather_scatter_bits)]
708 #[doc = concat!("let n: ", stringify!($SelfT), " = 0b1011_1100;")]
709 ///
710 /// assert_eq!(n.extract_bits(0b0010_0100), 0b0000_0011);
711 /// assert_eq!(n.extract_bits(0xF0), 0b0000_1011);
712 /// ```
713 #[doc(alias = "pext")]
714 #[unstable(feature = "uint_gather_scatter_bits", issue = "149069")]
715 #[must_use = "this returns the result of the operation, \
716 without modifying the original"]
717 #[inline]
718 pub const fn extract_bits(self, mask: Self) -> Self {
719 imp::int_bits::$ActualT::extract_impl(self as $ActualT, mask as $ActualT) as $SelfT
720 }
721
722 /// Returns an integer with the least significant bits of `self`
723 /// distributed to the bit locations specified by `mask`.
724 /// ```
725 /// #![feature(uint_gather_scatter_bits)]
726 #[doc = concat!("let n: ", stringify!($SelfT), " = 0b1010_1101;")]
727 ///
728 /// assert_eq!(n.deposit_bits(0b0101_0101), 0b0101_0001);
729 /// assert_eq!(n.deposit_bits(0xF0), 0b1101_0000);
730 /// ```
731 #[doc(alias = "pdep")]
732 #[unstable(feature = "uint_gather_scatter_bits", issue = "149069")]
733 #[must_use = "this returns the result of the operation, \
734 without modifying the original"]
735 #[inline]
736 pub const fn deposit_bits(self, mask: Self) -> Self {
737 imp::int_bits::$ActualT::deposit_impl(self as $ActualT, mask as $ActualT) as $SelfT
738 }
739
740 /// Reverses the order of bits in the integer. The least significant bit becomes the most significant bit,
741 /// second least-significant bit becomes second most-significant bit, etc.
742 ///
743 /// # Examples
744 ///
745 /// ```
746 #[doc = concat!("let n = ", $swap_op, stringify!($SelfT), ";")]
747 /// let m = n.reverse_bits();
748 ///
749 #[doc = concat!("assert_eq!(m, ", $reversed, ");")]
750 #[doc = concat!("assert_eq!(0, 0", stringify!($SelfT), ".reverse_bits());")]
751 /// ```
752 #[stable(feature = "reverse_bits", since = "1.37.0")]
753 #[rustc_const_stable(feature = "reverse_bits", since = "1.37.0")]
754 #[must_use = "this returns the result of the operation, \
755 without modifying the original"]
756 #[inline(always)]
757 pub const fn reverse_bits(self) -> Self {
758 intrinsics::bitreverse(self as $ActualT) as Self
759 }
760
761 /// Converts an integer from big endian to the target's endianness.
762 ///
763 /// On big endian this is a no-op. On little endian the bytes are
764 /// swapped.
765 ///
766 /// # Examples
767 ///
768 /// ```
769 #[doc = concat!("let n = 0x1A", stringify!($SelfT), ";")]
770 ///
771 /// if cfg!(target_endian = "big") {
772 #[doc = concat!(" assert_eq!(", stringify!($SelfT), "::from_be(n), n)")]
773 /// } else {
774 #[doc = concat!(" assert_eq!(", stringify!($SelfT), "::from_be(n), n.swap_bytes())")]
775 /// }
776 /// ```
777 #[stable(feature = "rust1", since = "1.0.0")]
778 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
779 #[must_use]
780 #[inline(always)]
781 pub const fn from_be(x: Self) -> Self {
782 cfg_select! {
783 target_endian = "big" => x,
784 _ => x.swap_bytes(),
785 }
786 }
787
788 /// Converts an integer from little endian to the target's endianness.
789 ///
790 /// On little endian this is a no-op. On big endian the bytes are
791 /// swapped.
792 ///
793 /// # Examples
794 ///
795 /// ```
796 #[doc = concat!("let n = 0x1A", stringify!($SelfT), ";")]
797 ///
798 /// if cfg!(target_endian = "little") {
799 #[doc = concat!(" assert_eq!(", stringify!($SelfT), "::from_le(n), n)")]
800 /// } else {
801 #[doc = concat!(" assert_eq!(", stringify!($SelfT), "::from_le(n), n.swap_bytes())")]
802 /// }
803 /// ```
804 #[stable(feature = "rust1", since = "1.0.0")]
805 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
806 #[must_use]
807 #[inline(always)]
808 pub const fn from_le(x: Self) -> Self {
809 cfg_select! {
810 target_endian = "little" => x,
811 _ => x.swap_bytes(),
812 }
813 }
814
815 /// Converts `self` to big endian from the target's endianness.
816 ///
817 /// On big endian this is a no-op. On little endian the bytes are
818 /// swapped.
819 ///
820 /// # Examples
821 ///
822 /// ```
823 #[doc = concat!("let n = 0x1A", stringify!($SelfT), ";")]
824 ///
825 /// if cfg!(target_endian = "big") {
826 /// assert_eq!(n.to_be(), n)
827 /// } else {
828 /// assert_eq!(n.to_be(), n.swap_bytes())
829 /// }
830 /// ```
831 #[stable(feature = "rust1", since = "1.0.0")]
832 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
833 #[must_use = "this returns the result of the operation, \
834 without modifying the original"]
835 #[inline(always)]
836 pub const fn to_be(self) -> Self { // or not to be?
837 cfg_select! {
838 target_endian = "big" => self,
839 _ => self.swap_bytes(),
840 }
841 }
842
843 /// Converts `self` to little endian from the target's endianness.
844 ///
845 /// On little endian this is a no-op. On big endian the bytes are
846 /// swapped.
847 ///
848 /// # Examples
849 ///
850 /// ```
851 #[doc = concat!("let n = 0x1A", stringify!($SelfT), ";")]
852 ///
853 /// if cfg!(target_endian = "little") {
854 /// assert_eq!(n.to_le(), n)
855 /// } else {
856 /// assert_eq!(n.to_le(), n.swap_bytes())
857 /// }
858 /// ```
859 #[stable(feature = "rust1", since = "1.0.0")]
860 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
861 #[must_use = "this returns the result of the operation, \
862 without modifying the original"]
863 #[inline(always)]
864 pub const fn to_le(self) -> Self {
865 cfg_select! {
866 target_endian = "little" => self,
867 _ => self.swap_bytes(),
868 }
869 }
870
871 /// Checked integer addition. Computes `self + rhs`, returning `None`
872 /// if overflow occurred.
873 ///
874 /// # Examples
875 ///
876 /// ```
877 #[doc = concat!(
878 "assert_eq!((", stringify!($SelfT), "::MAX - 2).checked_add(1), ",
879 "Some(", stringify!($SelfT), "::MAX - 1));"
880 )]
881 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).checked_add(3), None);")]
882 /// ```
883 #[stable(feature = "rust1", since = "1.0.0")]
884 #[rustc_const_stable(feature = "const_checked_int_methods", since = "1.47.0")]
885 #[must_use = "this returns the result of the operation, \
886 without modifying the original"]
887 #[inline]
888 pub const fn checked_add(self, rhs: Self) -> Option<Self> {
889 // This used to use `overflowing_add`, but that means it ends up being
890 // a `wrapping_add`, losing some optimization opportunities. Notably,
891 // phrasing it this way helps `.checked_add(1)` optimize to a check
892 // against `MAX` and a `add nuw`.
893 // Per <https://github.com/rust-lang/rust/pull/124114#issuecomment-2066173305>,
894 // LLVM is happy to re-form the intrinsic later if useful.
895
896 if intrinsics::unlikely(intrinsics::add_with_overflow(self, rhs).1) {
897 None
898 } else {
899 // SAFETY: Just checked it doesn't overflow
900 Some(unsafe { intrinsics::unchecked_add(self, rhs) })
901 }
902 }
903
904 /// Strict integer addition. Computes `self + rhs`, panicking
905 /// if overflow occurred.
906 ///
907 /// # Panics
908 ///
909 /// ## Overflow behavior
910 ///
911 /// This function will always panic on overflow, regardless of whether overflow checks are enabled.
912 ///
913 /// # Examples
914 ///
915 /// ```
916 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).strict_add(1), ", stringify!($SelfT), "::MAX - 1);")]
917 /// ```
918 ///
919 /// The following panics because of overflow:
920 ///
921 /// ```should_panic
922 #[doc = concat!("let _ = (", stringify!($SelfT), "::MAX - 2).strict_add(3);")]
923 /// ```
924 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
925 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
926 #[must_use = "this returns the result of the operation, \
927 without modifying the original"]
928 #[inline]
929 #[track_caller]
930 pub const fn strict_add(self, rhs: Self) -> Self {
931 let (a, b) = self.overflowing_add(rhs);
932 if b { imp::overflow_panic::add() } else { a }
933 }
934
935 /// Unchecked integer addition. Computes `self + rhs`, assuming overflow
936 /// cannot occur.
937 ///
938 /// Calling `x.unchecked_add(y)` is semantically equivalent to calling
939 /// `x.`[`checked_add`]`(y).`[`unwrap_unchecked`]`()`.
940 ///
941 /// If you're just trying to avoid the panic in debug mode, then **do not**
942 /// use this. Instead, you're looking for [`wrapping_add`].
943 ///
944 /// # Safety
945 ///
946 /// This results in undefined behavior when
947 #[doc = concat!("`self + rhs > ", stringify!($SelfT), "::MAX`,")]
948 /// i.e. when [`checked_add`] would return `None`.
949 ///
950 /// [`unwrap_unchecked`]: option/enum.Option.html#method.unwrap_unchecked
951 #[doc = concat!("[`checked_add`]: ", stringify!($SelfT), "::checked_add")]
952 #[doc = concat!("[`wrapping_add`]: ", stringify!($SelfT), "::wrapping_add")]
953 #[stable(feature = "unchecked_math", since = "1.79.0")]
954 #[rustc_const_stable(feature = "unchecked_math", since = "1.79.0")]
955 #[must_use = "this returns the result of the operation, \
956 without modifying the original"]
957 #[inline(always)]
958 #[track_caller]
959 pub const unsafe fn unchecked_add(self, rhs: Self) -> Self {
960 assert_unsafe_precondition!(
961 check_language_ub,
962 concat!(stringify!($SelfT), "::unchecked_add cannot overflow"),
963 (
964 lhs: $SelfT = self,
965 rhs: $SelfT = rhs,
966 ) => !lhs.overflowing_add(rhs).1,
967 );
968
969 // SAFETY: this is guaranteed to be safe by the caller.
970 unsafe {
971 intrinsics::unchecked_add(self, rhs)
972 }
973 }
974
975 /// Checked addition with a signed integer. Computes `self + rhs`,
976 /// returning `None` if overflow occurred.
977 ///
978 /// # Examples
979 ///
980 /// ```
981 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".checked_add_signed(2), Some(3));")]
982 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".checked_add_signed(-2), None);")]
983 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).checked_add_signed(3), None);")]
984 /// ```
985 #[stable(feature = "mixed_integer_ops", since = "1.66.0")]
986 #[rustc_const_stable(feature = "mixed_integer_ops", since = "1.66.0")]
987 #[must_use = "this returns the result of the operation, \
988 without modifying the original"]
989 #[inline]
990 pub const fn checked_add_signed(self, rhs: $SignedT) -> Option<Self> {
991 let (a, b) = self.overflowing_add_signed(rhs);
992 if intrinsics::unlikely(b) { None } else { Some(a) }
993 }
994
995 /// Strict addition with a signed integer. Computes `self + rhs`,
996 /// panicking if overflow occurred.
997 ///
998 /// # Panics
999 ///
1000 /// ## Overflow behavior
1001 ///
1002 /// This function will always panic on overflow, regardless of whether overflow checks are enabled.
1003 ///
1004 /// # Examples
1005 ///
1006 /// ```
1007 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".strict_add_signed(2), 3);")]
1008 /// ```
1009 ///
1010 /// The following panic because of overflow:
1011 ///
1012 /// ```should_panic
1013 #[doc = concat!("let _ = 1", stringify!($SelfT), ".strict_add_signed(-2);")]
1014 /// ```
1015 ///
1016 /// ```should_panic
1017 #[doc = concat!("let _ = (", stringify!($SelfT), "::MAX - 2).strict_add_signed(3);")]
1018 /// ```
1019 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
1020 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
1021 #[must_use = "this returns the result of the operation, \
1022 without modifying the original"]
1023 #[inline]
1024 #[track_caller]
1025 pub const fn strict_add_signed(self, rhs: $SignedT) -> Self {
1026 let (a, b) = self.overflowing_add_signed(rhs);
1027 if b { imp::overflow_panic::add() } else { a }
1028 }
1029
1030 /// Checked integer subtraction. Computes `self - rhs`, returning
1031 /// `None` if overflow occurred.
1032 ///
1033 /// # Examples
1034 ///
1035 /// ```
1036 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".checked_sub(1), Some(0));")]
1037 #[doc = concat!("assert_eq!(0", stringify!($SelfT), ".checked_sub(1), None);")]
1038 /// ```
1039 #[stable(feature = "rust1", since = "1.0.0")]
1040 #[rustc_const_stable(feature = "const_checked_int_methods", since = "1.47.0")]
1041 #[must_use = "this returns the result of the operation, \
1042 without modifying the original"]
1043 #[inline]
1044 pub const fn checked_sub(self, rhs: Self) -> Option<Self> {
1045 // Per PR#103299, there's no advantage to the `overflowing` intrinsic
1046 // for *unsigned* subtraction and we just emit the manual check anyway.
1047 // Thus, rather than using `overflowing_sub` that produces a wrapping
1048 // subtraction, check it ourself so we can use an unchecked one.
1049
1050 if self < rhs {
1051 None
1052 } else {
1053 // SAFETY: just checked this can't overflow
1054 Some(unsafe { intrinsics::unchecked_sub(self, rhs) })
1055 }
1056 }
1057
1058 /// Strict integer subtraction. Computes `self - rhs`, panicking if
1059 /// overflow occurred.
1060 ///
1061 /// # Panics
1062 ///
1063 /// ## Overflow behavior
1064 ///
1065 /// This function will always panic on overflow, regardless of whether overflow checks are enabled.
1066 ///
1067 /// # Examples
1068 ///
1069 /// ```
1070 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".strict_sub(1), 0);")]
1071 /// ```
1072 ///
1073 /// The following panics because of overflow:
1074 ///
1075 /// ```should_panic
1076 #[doc = concat!("let _ = 0", stringify!($SelfT), ".strict_sub(1);")]
1077 /// ```
1078 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
1079 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
1080 #[must_use = "this returns the result of the operation, \
1081 without modifying the original"]
1082 #[inline]
1083 #[track_caller]
1084 pub const fn strict_sub(self, rhs: Self) -> Self {
1085 let (a, b) = self.overflowing_sub(rhs);
1086 if b { imp::overflow_panic::sub() } else { a }
1087 }
1088
1089 /// Unchecked integer subtraction. Computes `self - rhs`, assuming overflow
1090 /// cannot occur.
1091 ///
1092 /// Calling `x.unchecked_sub(y)` is semantically equivalent to calling
1093 /// `x.`[`checked_sub`]`(y).`[`unwrap_unchecked`]`()`.
1094 ///
1095 /// If you're just trying to avoid the panic in debug mode, then **do not**
1096 /// use this. Instead, you're looking for [`wrapping_sub`].
1097 ///
1098 /// If you find yourself writing code like this:
1099 ///
1100 /// ```
1101 /// # let foo = 30_u32;
1102 /// # let bar = 20;
1103 /// if foo >= bar {
1104 /// // SAFETY: just checked it will not overflow
1105 /// let diff = unsafe { foo.unchecked_sub(bar) };
1106 /// // ... use diff ...
1107 /// }
1108 /// ```
1109 ///
1110 /// Consider changing it to
1111 ///
1112 /// ```
1113 /// # let foo = 30_u32;
1114 /// # let bar = 20;
1115 /// if let Some(diff) = foo.checked_sub(bar) {
1116 /// // ... use diff ...
1117 /// }
1118 /// ```
1119 ///
1120 /// As that does exactly the same thing -- including telling the optimizer
1121 /// that the subtraction cannot overflow -- but avoids needing `unsafe`.
1122 ///
1123 /// # Safety
1124 ///
1125 /// This results in undefined behavior when
1126 #[doc = concat!("`self - rhs < ", stringify!($SelfT), "::MIN`,")]
1127 /// i.e. when [`checked_sub`] would return `None`.
1128 ///
1129 /// [`unwrap_unchecked`]: option/enum.Option.html#method.unwrap_unchecked
1130 #[doc = concat!("[`checked_sub`]: ", stringify!($SelfT), "::checked_sub")]
1131 #[doc = concat!("[`wrapping_sub`]: ", stringify!($SelfT), "::wrapping_sub")]
1132 #[stable(feature = "unchecked_math", since = "1.79.0")]
1133 #[rustc_const_stable(feature = "unchecked_math", since = "1.79.0")]
1134 #[must_use = "this returns the result of the operation, \
1135 without modifying the original"]
1136 #[inline(always)]
1137 #[track_caller]
1138 pub const unsafe fn unchecked_sub(self, rhs: Self) -> Self {
1139 assert_unsafe_precondition!(
1140 check_language_ub,
1141 concat!(stringify!($SelfT), "::unchecked_sub cannot overflow"),
1142 (
1143 lhs: $SelfT = self,
1144 rhs: $SelfT = rhs,
1145 ) => !lhs.overflowing_sub(rhs).1,
1146 );
1147
1148 // SAFETY: this is guaranteed to be safe by the caller.
1149 unsafe {
1150 intrinsics::unchecked_sub(self, rhs)
1151 }
1152 }
1153
1154 /// Checked subtraction with a signed integer. Computes `self - rhs`,
1155 /// returning `None` if overflow occurred.
1156 ///
1157 /// # Examples
1158 ///
1159 /// ```
1160 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".checked_sub_signed(2), None);")]
1161 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".checked_sub_signed(-2), Some(3));")]
1162 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).checked_sub_signed(-4), None);")]
1163 /// ```
1164 #[stable(feature = "mixed_integer_ops_unsigned_sub", since = "1.90.0")]
1165 #[rustc_const_stable(feature = "mixed_integer_ops_unsigned_sub", since = "1.90.0")]
1166 #[must_use = "this returns the result of the operation, \
1167 without modifying the original"]
1168 #[inline]
1169 pub const fn checked_sub_signed(self, rhs: $SignedT) -> Option<Self> {
1170 let (res, overflow) = self.overflowing_sub_signed(rhs);
1171
1172 if !overflow {
1173 Some(res)
1174 } else {
1175 None
1176 }
1177 }
1178
1179 /// Strict subtraction with a signed integer. Computes `self - rhs`,
1180 /// panicking if overflow occurred.
1181 ///
1182 /// # Panics
1183 ///
1184 /// ## Overflow behavior
1185 ///
1186 /// This function will always panic on overflow, regardless of whether overflow checks are enabled.
1187 ///
1188 /// # Examples
1189 ///
1190 /// ```
1191 #[doc = concat!("assert_eq!(3", stringify!($SelfT), ".strict_sub_signed(2), 1);")]
1192 /// ```
1193 ///
1194 /// The following panic because of overflow:
1195 ///
1196 /// ```should_panic
1197 #[doc = concat!("let _ = 1", stringify!($SelfT), ".strict_sub_signed(2);")]
1198 /// ```
1199 ///
1200 /// ```should_panic
1201 #[doc = concat!("let _ = (", stringify!($SelfT), "::MAX).strict_sub_signed(-1);")]
1202 /// ```
1203 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
1204 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
1205 #[must_use = "this returns the result of the operation, \
1206 without modifying the original"]
1207 #[inline]
1208 #[track_caller]
1209 pub const fn strict_sub_signed(self, rhs: $SignedT) -> Self {
1210 let (a, b) = self.overflowing_sub_signed(rhs);
1211 if b { imp::overflow_panic::sub() } else { a }
1212 }
1213
1214 #[doc = concat!(
1215 "Checked integer subtraction. Computes `self - rhs` and checks if the result fits into an [`",
1216 stringify!($SignedT), "`], returning `None` if overflow occurred."
1217 )]
1218 ///
1219 /// # Examples
1220 ///
1221 /// ```
1222 #[doc = concat!("assert_eq!(10", stringify!($SelfT), ".checked_signed_diff(2), Some(8));")]
1223 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".checked_signed_diff(10), Some(-8));")]
1224 #[doc = concat!(
1225 "assert_eq!(",
1226 stringify!($SelfT),
1227 "::MAX.checked_signed_diff(",
1228 stringify!($SignedT),
1229 "::MAX as ",
1230 stringify!($SelfT),
1231 "), None);"
1232 )]
1233 #[doc = concat!(
1234 "assert_eq!((",
1235 stringify!($SignedT),
1236 "::MAX as ",
1237 stringify!($SelfT),
1238 ").checked_signed_diff(",
1239 stringify!($SelfT),
1240 "::MAX), Some(",
1241 stringify!($SignedT),
1242 "::MIN));"
1243 )]
1244 #[doc = concat!(
1245 "assert_eq!((",
1246 stringify!($SignedT),
1247 "::MAX as ",
1248 stringify!($SelfT),
1249 " + 1).checked_signed_diff(0), None);"
1250 )]
1251 #[doc = concat!(
1252 "assert_eq!(",
1253 stringify!($SelfT),
1254 "::MAX.checked_signed_diff(",
1255 stringify!($SelfT),
1256 "::MAX), Some(0));"
1257 )]
1258 /// ```
1259 #[stable(feature = "unsigned_signed_diff", since = "1.91.0")]
1260 #[rustc_const_stable(feature = "unsigned_signed_diff", since = "1.91.0")]
1261 #[inline]
1262 pub const fn checked_signed_diff(self, rhs: Self) -> Option<$SignedT> {
1263 let res = self.wrapping_sub(rhs) as $SignedT;
1264 let overflow = (self >= rhs) == (res < 0);
1265
1266 if !overflow {
1267 Some(res)
1268 } else {
1269 None
1270 }
1271 }
1272
1273 /// Checked integer multiplication. Computes `self * rhs`, returning
1274 /// `None` if overflow occurred.
1275 ///
1276 /// # Examples
1277 ///
1278 /// ```
1279 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".checked_mul(1), Some(5));")]
1280 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.checked_mul(2), None);")]
1281 /// ```
1282 #[stable(feature = "rust1", since = "1.0.0")]
1283 #[rustc_const_stable(feature = "const_checked_int_methods", since = "1.47.0")]
1284 #[must_use = "this returns the result of the operation, \
1285 without modifying the original"]
1286 #[inline]
1287 pub const fn checked_mul(self, rhs: Self) -> Option<Self> {
1288 let (a, b) = self.overflowing_mul(rhs);
1289 if intrinsics::unlikely(b) { None } else { Some(a) }
1290 }
1291
1292 /// Strict integer multiplication. Computes `self * rhs`, panicking if
1293 /// overflow occurred.
1294 ///
1295 /// # Panics
1296 ///
1297 /// ## Overflow behavior
1298 ///
1299 /// This function will always panic on overflow, regardless of whether overflow checks are enabled.
1300 ///
1301 /// # Examples
1302 ///
1303 /// ```
1304 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".strict_mul(1), 5);")]
1305 /// ```
1306 ///
1307 /// The following panics because of overflow:
1308 ///
1309 /// ``` should_panic
1310 #[doc = concat!("let _ = ", stringify!($SelfT), "::MAX.strict_mul(2);")]
1311 /// ```
1312 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
1313 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
1314 #[must_use = "this returns the result of the operation, \
1315 without modifying the original"]
1316 #[inline]
1317 #[track_caller]
1318 pub const fn strict_mul(self, rhs: Self) -> Self {
1319 let (a, b) = self.overflowing_mul(rhs);
1320 if b { imp::overflow_panic::mul() } else { a }
1321 }
1322
1323 /// Unchecked integer multiplication. Computes `self * rhs`, assuming overflow
1324 /// cannot occur.
1325 ///
1326 /// Calling `x.unchecked_mul(y)` is semantically equivalent to calling
1327 /// `x.`[`checked_mul`]`(y).`[`unwrap_unchecked`]`()`.
1328 ///
1329 /// If you're just trying to avoid the panic in debug mode, then **do not**
1330 /// use this. Instead, you're looking for [`wrapping_mul`].
1331 ///
1332 /// # Safety
1333 ///
1334 /// This results in undefined behavior when
1335 #[doc = concat!("`self * rhs > ", stringify!($SelfT), "::MAX`,")]
1336 /// i.e. when [`checked_mul`] would return `None`.
1337 ///
1338 /// [`unwrap_unchecked`]: option/enum.Option.html#method.unwrap_unchecked
1339 #[doc = concat!("[`checked_mul`]: ", stringify!($SelfT), "::checked_mul")]
1340 #[doc = concat!("[`wrapping_mul`]: ", stringify!($SelfT), "::wrapping_mul")]
1341 #[stable(feature = "unchecked_math", since = "1.79.0")]
1342 #[rustc_const_stable(feature = "unchecked_math", since = "1.79.0")]
1343 #[must_use = "this returns the result of the operation, \
1344 without modifying the original"]
1345 #[inline(always)]
1346 #[track_caller]
1347 pub const unsafe fn unchecked_mul(self, rhs: Self) -> Self {
1348 assert_unsafe_precondition!(
1349 check_language_ub,
1350 concat!(stringify!($SelfT), "::unchecked_mul cannot overflow"),
1351 (
1352 lhs: $SelfT = self,
1353 rhs: $SelfT = rhs,
1354 ) => !lhs.overflowing_mul(rhs).1,
1355 );
1356
1357 // SAFETY: this is guaranteed to be safe by the caller.
1358 unsafe {
1359 intrinsics::unchecked_mul(self, rhs)
1360 }
1361 }
1362
1363 /// Checked integer division. Computes `self / rhs`, returning `None`
1364 /// if `rhs == 0`.
1365 ///
1366 /// # Examples
1367 ///
1368 /// ```
1369 #[doc = concat!("assert_eq!(128", stringify!($SelfT), ".checked_div(2), Some(64));")]
1370 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".checked_div(0), None);")]
1371 /// ```
1372 #[stable(feature = "rust1", since = "1.0.0")]
1373 #[rustc_const_stable(feature = "const_checked_int_div", since = "1.52.0")]
1374 #[must_use = "this returns the result of the operation, \
1375 without modifying the original"]
1376 #[inline]
1377 pub const fn checked_div(self, rhs: Self) -> Option<Self> {
1378 if intrinsics::unlikely(rhs == 0) {
1379 None
1380 } else {
1381 // SAFETY: div by zero has been checked above and unsigned types have no other
1382 // failure modes for division
1383 Some(unsafe { intrinsics::unchecked_div(self, rhs) })
1384 }
1385 }
1386
1387 /// Strict integer division. Computes `self / rhs`.
1388 ///
1389 /// Strict division on unsigned types is just normal division. There's no
1390 /// way overflow could ever happen. This function exists so that all
1391 /// operations are accounted for in the strict operations.
1392 ///
1393 /// # Panics
1394 ///
1395 /// This function will panic if `rhs` is zero.
1396 ///
1397 /// # Examples
1398 ///
1399 /// ```
1400 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".strict_div(10), 10);")]
1401 /// ```
1402 ///
1403 /// The following panics because of division by zero:
1404 ///
1405 /// ```should_panic
1406 #[doc = concat!("let _ = (1", stringify!($SelfT), ").strict_div(0);")]
1407 /// ```
1408 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
1409 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
1410 #[must_use = "this returns the result of the operation, \
1411 without modifying the original"]
1412 #[inline(always)]
1413 #[track_caller]
1414 pub const fn strict_div(self, rhs: Self) -> Self {
1415 self / rhs
1416 }
1417
1418 /// Checked Euclidean division. Computes `self.div_euclid(rhs)`, returning `None`
1419 /// if `rhs == 0`.
1420 ///
1421 /// # Examples
1422 ///
1423 /// ```
1424 #[doc = concat!("assert_eq!(128", stringify!($SelfT), ".checked_div_euclid(2), Some(64));")]
1425 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".checked_div_euclid(0), None);")]
1426 /// ```
1427 #[stable(feature = "euclidean_division", since = "1.38.0")]
1428 #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.52.0")]
1429 #[must_use = "this returns the result of the operation, \
1430 without modifying the original"]
1431 #[inline]
1432 pub const fn checked_div_euclid(self, rhs: Self) -> Option<Self> {
1433 if intrinsics::unlikely(rhs == 0) {
1434 None
1435 } else {
1436 Some(self.div_euclid(rhs))
1437 }
1438 }
1439
1440 /// Strict Euclidean division. Computes `self.div_euclid(rhs)`.
1441 ///
1442 /// Strict division on unsigned types is just normal division. There's no
1443 /// way overflow could ever happen. This function exists so that all
1444 /// operations are accounted for in the strict operations. Since, for the
1445 /// positive integers, all common definitions of division are equal, this
1446 /// is exactly equal to `self.strict_div(rhs)`.
1447 ///
1448 /// # Panics
1449 ///
1450 /// This function will panic if `rhs` is zero.
1451 ///
1452 /// # Examples
1453 ///
1454 /// ```
1455 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".strict_div_euclid(10), 10);")]
1456 /// ```
1457 /// The following panics because of division by zero:
1458 ///
1459 /// ```should_panic
1460 #[doc = concat!("let _ = (1", stringify!($SelfT), ").strict_div_euclid(0);")]
1461 /// ```
1462 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
1463 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
1464 #[must_use = "this returns the result of the operation, \
1465 without modifying the original"]
1466 #[inline(always)]
1467 #[track_caller]
1468 pub const fn strict_div_euclid(self, rhs: Self) -> Self {
1469 self / rhs
1470 }
1471
1472 /// Checked integer division without remainder. Computes `self / rhs`,
1473 /// returning `None` if `rhs == 0` or if `self % rhs != 0`.
1474 ///
1475 /// # Examples
1476 ///
1477 /// ```
1478 /// #![feature(exact_div)]
1479 #[doc = concat!("assert_eq!(64", stringify!($SelfT), ".checked_div_exact(2), Some(32));")]
1480 #[doc = concat!("assert_eq!(64", stringify!($SelfT), ".checked_div_exact(32), Some(2));")]
1481 #[doc = concat!("assert_eq!(64", stringify!($SelfT), ".checked_div_exact(0), None);")]
1482 #[doc = concat!("assert_eq!(65", stringify!($SelfT), ".checked_div_exact(2), None);")]
1483 /// ```
1484 #[unstable(
1485 feature = "exact_div",
1486 issue = "139911",
1487 )]
1488 #[must_use = "this returns the result of the operation, \
1489 without modifying the original"]
1490 #[inline]
1491 pub const fn checked_div_exact(self, rhs: Self) -> Option<Self> {
1492 if intrinsics::unlikely(rhs == 0) {
1493 None
1494 } else {
1495 // SAFETY: division by zero is checked above
1496 unsafe {
1497 if intrinsics::unlikely(intrinsics::unchecked_rem(self, rhs) != 0) {
1498 None
1499 } else {
1500 Some(intrinsics::exact_div(self, rhs))
1501 }
1502 }
1503 }
1504 }
1505
1506 /// Integer division without remainder. Computes `self / rhs`, returning `None` if `self % rhs != 0`.
1507 ///
1508 /// # Panics
1509 ///
1510 /// This function will panic if `rhs == 0`.
1511 ///
1512 /// # Examples
1513 ///
1514 /// ```
1515 /// #![feature(exact_div)]
1516 #[doc = concat!("assert_eq!(64", stringify!($SelfT), ".div_exact(2), Some(32));")]
1517 #[doc = concat!("assert_eq!(64", stringify!($SelfT), ".div_exact(32), Some(2));")]
1518 #[doc = concat!("assert_eq!(65", stringify!($SelfT), ".div_exact(2), None);")]
1519 /// ```
1520 #[unstable(
1521 feature = "exact_div",
1522 issue = "139911",
1523 )]
1524 #[must_use = "this returns the result of the operation, \
1525 without modifying the original"]
1526 #[inline]
1527 #[rustc_inherit_overflow_checks]
1528 pub const fn div_exact(self, rhs: Self) -> Option<Self> {
1529 if self % rhs != 0 {
1530 None
1531 } else {
1532 Some(self / rhs)
1533 }
1534 }
1535
1536 /// Unchecked integer division without remainder. Computes `self / rhs`.
1537 ///
1538 /// # Safety
1539 ///
1540 /// This results in undefined behavior when `rhs == 0` or `self % rhs != 0`,
1541 /// i.e. when [`checked_div_exact`](Self::checked_div_exact) would return `None`.
1542 #[unstable(
1543 feature = "exact_div",
1544 issue = "139911",
1545 )]
1546 #[must_use = "this returns the result of the operation, \
1547 without modifying the original"]
1548 #[inline]
1549 pub const unsafe fn unchecked_div_exact(self, rhs: Self) -> Self {
1550 assert_unsafe_precondition!(
1551 check_language_ub,
1552 concat!(stringify!($SelfT), "::unchecked_div_exact divide by zero or leave a remainder"),
1553 (
1554 lhs: $SelfT = self,
1555 rhs: $SelfT = rhs,
1556 ) => rhs > 0 && lhs % rhs == 0,
1557 );
1558 // SAFETY: Same precondition
1559 unsafe { intrinsics::exact_div(self, rhs) }
1560 }
1561
1562 /// Checked integer remainder. Computes `self % rhs`, returning `None`
1563 /// if `rhs == 0`.
1564 ///
1565 /// # Examples
1566 ///
1567 /// ```
1568 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".checked_rem(2), Some(1));")]
1569 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".checked_rem(0), None);")]
1570 /// ```
1571 #[stable(feature = "wrapping", since = "1.7.0")]
1572 #[rustc_const_stable(feature = "const_checked_int_div", since = "1.52.0")]
1573 #[must_use = "this returns the result of the operation, \
1574 without modifying the original"]
1575 #[inline]
1576 pub const fn checked_rem(self, rhs: Self) -> Option<Self> {
1577 if intrinsics::unlikely(rhs == 0) {
1578 None
1579 } else {
1580 // SAFETY: div by zero has been checked above and unsigned types have no other
1581 // failure modes for division
1582 Some(unsafe { intrinsics::unchecked_rem(self, rhs) })
1583 }
1584 }
1585
1586 /// Strict integer remainder. Computes `self % rhs`.
1587 ///
1588 /// Strict remainder calculation on unsigned types is just the regular
1589 /// remainder calculation. There's no way overflow could ever happen.
1590 /// This function exists so that all operations are accounted for in the
1591 /// strict operations.
1592 ///
1593 /// # Panics
1594 ///
1595 /// This function will panic if `rhs` is zero.
1596 ///
1597 /// # Examples
1598 ///
1599 /// ```
1600 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".strict_rem(10), 0);")]
1601 /// ```
1602 ///
1603 /// The following panics because of division by zero:
1604 ///
1605 /// ```should_panic
1606 #[doc = concat!("let _ = 5", stringify!($SelfT), ".strict_rem(0);")]
1607 /// ```
1608 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
1609 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
1610 #[must_use = "this returns the result of the operation, \
1611 without modifying the original"]
1612 #[inline(always)]
1613 #[track_caller]
1614 pub const fn strict_rem(self, rhs: Self) -> Self {
1615 self % rhs
1616 }
1617
1618 /// Checked Euclidean modulo. Computes `self.rem_euclid(rhs)`, returning `None`
1619 /// if `rhs == 0`.
1620 ///
1621 /// # Examples
1622 ///
1623 /// ```
1624 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".checked_rem_euclid(2), Some(1));")]
1625 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".checked_rem_euclid(0), None);")]
1626 /// ```
1627 #[stable(feature = "euclidean_division", since = "1.38.0")]
1628 #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.52.0")]
1629 #[must_use = "this returns the result of the operation, \
1630 without modifying the original"]
1631 #[inline]
1632 pub const fn checked_rem_euclid(self, rhs: Self) -> Option<Self> {
1633 if intrinsics::unlikely(rhs == 0) {
1634 None
1635 } else {
1636 Some(self.rem_euclid(rhs))
1637 }
1638 }
1639
1640 /// Strict Euclidean modulo. Computes `self.rem_euclid(rhs)`.
1641 ///
1642 /// Strict modulo calculation on unsigned types is just the regular
1643 /// remainder calculation. There's no way overflow could ever happen.
1644 /// This function exists so that all operations are accounted for in the
1645 /// strict operations. Since, for the positive integers, all common
1646 /// definitions of division are equal, this is exactly equal to
1647 /// `self.strict_rem(rhs)`.
1648 ///
1649 /// # Panics
1650 ///
1651 /// This function will panic if `rhs` is zero.
1652 ///
1653 /// # Examples
1654 ///
1655 /// ```
1656 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".strict_rem_euclid(10), 0);")]
1657 /// ```
1658 ///
1659 /// The following panics because of division by zero:
1660 ///
1661 /// ```should_panic
1662 #[doc = concat!("let _ = 5", stringify!($SelfT), ".strict_rem_euclid(0);")]
1663 /// ```
1664 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
1665 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
1666 #[must_use = "this returns the result of the operation, \
1667 without modifying the original"]
1668 #[inline(always)]
1669 #[track_caller]
1670 pub const fn strict_rem_euclid(self, rhs: Self) -> Self {
1671 self % rhs
1672 }
1673
1674 /// Same value as `self | other`, but UB if any bit position is set in both inputs.
1675 ///
1676 /// This is a situational micro-optimization for places where you'd rather
1677 /// use addition on some platforms and bitwise or on other platforms, based
1678 /// on exactly which instructions combine better with whatever else you're
1679 /// doing. Note that there's no reason to bother using this for places
1680 /// where it's clear from the operations involved that they can't overlap.
1681 /// For example, if you're combining `u16`s into a `u32` with
1682 /// `((a as u32) << 16) | (b as u32)`, that's fine, as the backend will
1683 /// know those sides of the `|` are disjoint without needing help.
1684 ///
1685 /// # Examples
1686 ///
1687 /// ```
1688 /// #![feature(disjoint_bitor)]
1689 ///
1690 /// // SAFETY: `1` and `4` have no bits in common.
1691 /// unsafe {
1692 #[doc = concat!(" assert_eq!(1_", stringify!($SelfT), ".unchecked_disjoint_bitor(4), 5);")]
1693 /// }
1694 /// ```
1695 ///
1696 /// # Safety
1697 ///
1698 /// Requires that `(self & other) == 0`, otherwise it's immediate UB.
1699 ///
1700 /// Equivalently, requires that `(self | other) == (self + other)`.
1701 #[unstable(feature = "disjoint_bitor", issue = "135758")]
1702 #[rustc_const_unstable(feature = "disjoint_bitor", issue = "135758")]
1703 #[inline]
1704 pub const unsafe fn unchecked_disjoint_bitor(self, other: Self) -> Self {
1705 assert_unsafe_precondition!(
1706 check_language_ub,
1707 concat!(stringify!($SelfT), "::unchecked_disjoint_bitor cannot have overlapping bits"),
1708 (
1709 lhs: $SelfT = self,
1710 rhs: $SelfT = other,
1711 ) => (lhs & rhs) == 0,
1712 );
1713
1714 // SAFETY: Same precondition
1715 unsafe { intrinsics::disjoint_bitor(self, other) }
1716 }
1717
1718 /// Returns the logarithm of the number with respect to an arbitrary base,
1719 /// rounded down.
1720 ///
1721 /// This method might not be optimized owing to implementation details;
1722 /// `ilog2` can produce results more efficiently for base 2, and `ilog10`
1723 /// can produce results more efficiently for base 10.
1724 ///
1725 /// # Panics
1726 ///
1727 /// This function will panic if `self` is zero, or if `base` is less than 2.
1728 ///
1729 /// # Examples
1730 ///
1731 /// ```
1732 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".ilog(5), 1);")]
1733 /// ```
1734 #[stable(feature = "int_log", since = "1.67.0")]
1735 #[rustc_const_stable(feature = "int_log", since = "1.67.0")]
1736 #[must_use = "this returns the result of the operation, \
1737 without modifying the original"]
1738 #[inline]
1739 #[track_caller]
1740 pub const fn ilog(self, base: Self) -> u32 {
1741 assert!(base >= 2, "base of integer logarithm must be at least 2");
1742 if let Some(log) = self.checked_ilog(base) {
1743 log
1744 } else {
1745 imp::int_log10::panic_for_nonpositive_argument()
1746 }
1747 }
1748
1749 /// Returns the base 2 logarithm of the number, rounded down.
1750 ///
1751 /// # Panics
1752 ///
1753 /// This function will panic if `self` is zero.
1754 ///
1755 /// # Examples
1756 ///
1757 /// ```
1758 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".ilog2(), 1);")]
1759 /// ```
1760 #[stable(feature = "int_log", since = "1.67.0")]
1761 #[rustc_const_stable(feature = "int_log", since = "1.67.0")]
1762 #[must_use = "this returns the result of the operation, \
1763 without modifying the original"]
1764 #[inline]
1765 #[track_caller]
1766 pub const fn ilog2(self) -> u32 {
1767 if let Some(log) = self.checked_ilog2() {
1768 log
1769 } else {
1770 imp::int_log10::panic_for_nonpositive_argument()
1771 }
1772 }
1773
1774 /// Returns the base 10 logarithm of the number, rounded down.
1775 ///
1776 /// # Panics
1777 ///
1778 /// This function will panic if `self` is zero.
1779 ///
1780 /// # Example
1781 ///
1782 /// ```
1783 #[doc = concat!("assert_eq!(10", stringify!($SelfT), ".ilog10(), 1);")]
1784 /// ```
1785 #[stable(feature = "int_log", since = "1.67.0")]
1786 #[rustc_const_stable(feature = "int_log", since = "1.67.0")]
1787 #[must_use = "this returns the result of the operation, \
1788 without modifying the original"]
1789 #[inline]
1790 #[track_caller]
1791 pub const fn ilog10(self) -> u32 {
1792 if let Some(log) = self.checked_ilog10() {
1793 log
1794 } else {
1795 imp::int_log10::panic_for_nonpositive_argument()
1796 }
1797 }
1798
1799 /// Returns the logarithm of the number with respect to an arbitrary base,
1800 /// rounded down.
1801 ///
1802 /// Returns `None` if the number is zero, or if the base is not at least 2.
1803 ///
1804 /// This method might not be optimized owing to implementation details;
1805 /// `checked_ilog2` can produce results more efficiently for base 2, and
1806 /// `checked_ilog10` can produce results more efficiently for base 10.
1807 ///
1808 /// # Examples
1809 ///
1810 /// ```
1811 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".checked_ilog(5), Some(1));")]
1812 /// ```
1813 #[stable(feature = "int_log", since = "1.67.0")]
1814 #[rustc_const_stable(feature = "int_log", since = "1.67.0")]
1815 #[must_use = "this returns the result of the operation, \
1816 without modifying the original"]
1817 #[inline]
1818 pub const fn checked_ilog(self, base: Self) -> Option<u32> {
1819 // Inform compiler of optimizations when the base is known at
1820 // compile time and there's a cheaper method available.
1821 //
1822 // Note: Like all optimizations, this is not guaranteed to be
1823 // applied by the compiler. If you want those specific bases,
1824 // use `.checked_ilog2()` or `.checked_ilog10()` directly.
1825 if core::intrinsics::is_val_statically_known(base) {
1826 if base == 2 {
1827 return self.checked_ilog2();
1828 } else if base == 10 {
1829 return self.checked_ilog10();
1830 }
1831 }
1832
1833 if self <= 0 || base <= 1 {
1834 None
1835 } else if self < base {
1836 Some(0)
1837 } else {
1838 // Since base >= self, n >= 1
1839 let mut n = 1;
1840 let mut r = base;
1841
1842 // Optimization for 128 bit wide integers.
1843 if Self::BITS == 128 {
1844 // The following is a correct lower bound for ⌊log(base,self)⌋ because
1845 //
1846 // log(base,self) = log(2,self) / log(2,base)
1847 // ≥ ⌊log(2,self)⌋ / (⌊log(2,base)⌋ + 1)
1848 //
1849 // hence
1850 //
1851 // ⌊log(base,self)⌋ ≥ ⌊ ⌊log(2,self)⌋ / (⌊log(2,base)⌋ + 1) ⌋ .
1852 n = self.ilog2() / (base.ilog2() + 1);
1853 r = base.pow(n);
1854 }
1855
1856 while r <= self / base {
1857 n += 1;
1858 r *= base;
1859 }
1860 Some(n)
1861 }
1862 }
1863
1864 /// Returns the base 2 logarithm of the number, rounded down.
1865 ///
1866 /// Returns `None` if the number is zero.
1867 ///
1868 /// # Examples
1869 ///
1870 /// ```
1871 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".checked_ilog2(), Some(1));")]
1872 /// ```
1873 #[stable(feature = "int_log", since = "1.67.0")]
1874 #[rustc_const_stable(feature = "int_log", since = "1.67.0")]
1875 #[must_use = "this returns the result of the operation, \
1876 without modifying the original"]
1877 #[inline]
1878 pub const fn checked_ilog2(self) -> Option<u32> {
1879 match NonZero::new(self) {
1880 Some(x) => Some(x.ilog2()),
1881 None => None,
1882 }
1883 }
1884
1885 /// Returns the base 10 logarithm of the number, rounded down.
1886 ///
1887 /// Returns `None` if the number is zero.
1888 ///
1889 /// # Examples
1890 ///
1891 /// ```
1892 #[doc = concat!("assert_eq!(10", stringify!($SelfT), ".checked_ilog10(), Some(1));")]
1893 /// ```
1894 #[stable(feature = "int_log", since = "1.67.0")]
1895 #[rustc_const_stable(feature = "int_log", since = "1.67.0")]
1896 #[must_use = "this returns the result of the operation, \
1897 without modifying the original"]
1898 #[inline]
1899 pub const fn checked_ilog10(self) -> Option<u32> {
1900 match NonZero::new(self) {
1901 Some(x) => Some(x.ilog10()),
1902 None => None,
1903 }
1904 }
1905
1906 /// Checked negation. Computes `-self`, returning `None` unless `self ==
1907 /// 0`.
1908 ///
1909 /// Note that negating any positive integer will overflow.
1910 ///
1911 /// # Examples
1912 ///
1913 /// ```
1914 #[doc = concat!("assert_eq!(0", stringify!($SelfT), ".checked_neg(), Some(0));")]
1915 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".checked_neg(), None);")]
1916 /// ```
1917 #[stable(feature = "wrapping", since = "1.7.0")]
1918 #[rustc_const_stable(feature = "const_checked_int_methods", since = "1.47.0")]
1919 #[must_use = "this returns the result of the operation, \
1920 without modifying the original"]
1921 #[inline]
1922 pub const fn checked_neg(self) -> Option<Self> {
1923 let (a, b) = self.overflowing_neg();
1924 if intrinsics::unlikely(b) { None } else { Some(a) }
1925 }
1926
1927 /// Strict negation. Computes `-self`, panicking unless `self ==
1928 /// 0`.
1929 ///
1930 /// Note that negating any positive integer will overflow.
1931 ///
1932 /// # Panics
1933 ///
1934 /// ## Overflow behavior
1935 ///
1936 /// This function will always panic on overflow, regardless of whether overflow checks are enabled.
1937 ///
1938 /// # Examples
1939 ///
1940 /// ```
1941 #[doc = concat!("assert_eq!(0", stringify!($SelfT), ".strict_neg(), 0);")]
1942 /// ```
1943 ///
1944 /// The following panics because of overflow:
1945 ///
1946 /// ```should_panic
1947 #[doc = concat!("let _ = 1", stringify!($SelfT), ".strict_neg();")]
1948 /// ```
1949 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
1950 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
1951 #[must_use = "this returns the result of the operation, \
1952 without modifying the original"]
1953 #[inline]
1954 #[track_caller]
1955 pub const fn strict_neg(self) -> Self {
1956 let (a, b) = self.overflowing_neg();
1957 if b { imp::overflow_panic::neg() } else { a }
1958 }
1959
1960 /// Checked shift left. Computes `self << rhs`, returning `None`
1961 /// if `rhs` is larger than or equal to the number of bits in `self`.
1962 ///
1963 /// # Examples
1964 ///
1965 /// ```
1966 #[doc = concat!("assert_eq!(0x1", stringify!($SelfT), ".checked_shl(4), Some(0x10));")]
1967 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".checked_shl(129), None);")]
1968 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".checked_shl(", stringify!($BITS_MINUS_ONE), "), Some(0));")]
1969 /// ```
1970 #[stable(feature = "wrapping", since = "1.7.0")]
1971 #[rustc_const_stable(feature = "const_checked_int_methods", since = "1.47.0")]
1972 #[must_use = "this returns the result of the operation, \
1973 without modifying the original"]
1974 #[inline]
1975 pub const fn checked_shl(self, rhs: u32) -> Option<Self> {
1976 // Not using overflowing_shl as that's a wrapping shift
1977 if rhs < Self::BITS {
1978 // SAFETY: just checked the RHS is in-range
1979 Some(unsafe { self.unchecked_shl(rhs) })
1980 } else {
1981 None
1982 }
1983 }
1984
1985 /// Strict shift left. Computes `self << rhs`, panicking if `rhs` is larger
1986 /// than or equal to the number of bits in `self`.
1987 ///
1988 /// # Panics
1989 ///
1990 /// ## Overflow behavior
1991 ///
1992 /// This function will always panic on overflow, regardless of whether overflow checks are enabled.
1993 ///
1994 /// # Examples
1995 ///
1996 /// ```
1997 #[doc = concat!("assert_eq!(0x1", stringify!($SelfT), ".strict_shl(4), 0x10);")]
1998 /// ```
1999 ///
2000 /// The following panics because of overflow:
2001 ///
2002 /// ```should_panic
2003 #[doc = concat!("let _ = 0x10", stringify!($SelfT), ".strict_shl(129);")]
2004 /// ```
2005 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
2006 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
2007 #[must_use = "this returns the result of the operation, \
2008 without modifying the original"]
2009 #[inline]
2010 #[track_caller]
2011 pub const fn strict_shl(self, rhs: u32) -> Self {
2012 let (a, b) = self.overflowing_shl(rhs);
2013 if b { imp::overflow_panic::shl() } else { a }
2014 }
2015
2016 /// Unchecked shift left. Computes `self << rhs`, assuming that
2017 /// `rhs` is less than the number of bits in `self`.
2018 ///
2019 /// # Safety
2020 ///
2021 /// This results in undefined behavior if `rhs` is larger than
2022 /// or equal to the number of bits in `self`,
2023 /// i.e. when [`checked_shl`] would return `None`.
2024 ///
2025 #[doc = concat!("[`checked_shl`]: ", stringify!($SelfT), "::checked_shl")]
2026 #[stable(feature = "unchecked_shifts", since = "1.93.0")]
2027 #[rustc_const_stable(feature = "unchecked_shifts", since = "1.93.0")]
2028 #[must_use = "this returns the result of the operation, \
2029 without modifying the original"]
2030 #[inline(always)]
2031 #[track_caller]
2032 pub const unsafe fn unchecked_shl(self, rhs: u32) -> Self {
2033 assert_unsafe_precondition!(
2034 check_language_ub,
2035 concat!(stringify!($SelfT), "::unchecked_shl cannot overflow"),
2036 (
2037 rhs: u32 = rhs,
2038 ) => rhs < <$ActualT>::BITS,
2039 );
2040
2041 // SAFETY: this is guaranteed to be safe by the caller.
2042 unsafe {
2043 intrinsics::unchecked_shl(self, rhs)
2044 }
2045 }
2046
2047 /// Unbounded shift left. Computes `self << rhs`, without bounding the value of `rhs`.
2048 ///
2049 /// If `rhs` is larger or equal to the number of bits in `self`,
2050 /// the entire value is shifted out, and `0` is returned.
2051 ///
2052 /// # Examples
2053 ///
2054 /// ```
2055 #[doc = concat!("assert_eq!(0x1_", stringify!($SelfT), ".unbounded_shl(4), 0x10);")]
2056 #[doc = concat!("assert_eq!(0x1_", stringify!($SelfT), ".unbounded_shl(129), 0);")]
2057 #[doc = concat!("assert_eq!(0b101_", stringify!($SelfT), ".unbounded_shl(0), 0b101);")]
2058 #[doc = concat!("assert_eq!(0b101_", stringify!($SelfT), ".unbounded_shl(1), 0b1010);")]
2059 #[doc = concat!("assert_eq!(0b101_", stringify!($SelfT), ".unbounded_shl(2), 0b10100);")]
2060 #[doc = concat!("assert_eq!(42_", stringify!($SelfT), ".unbounded_shl(", stringify!($BITS), "), 0);")]
2061 #[doc = concat!("assert_eq!(42_", stringify!($SelfT), ".unbounded_shl(1).unbounded_shl(", stringify!($BITS_MINUS_ONE), "), 0);")]
2062 ///
2063 #[doc = concat!("let start : ", stringify!($SelfT), " = 13;")]
2064 /// let mut running = start;
2065 /// for i in 0..160 {
2066 /// // The unbounded shift left by i is the same as `<< 1` i times
2067 /// assert_eq!(running, start.unbounded_shl(i));
2068 /// // Which is not always the case for a wrapping shift
2069 #[doc = concat!(" assert_eq!(running == start.wrapping_shl(i), i < ", stringify!($BITS), ");")]
2070 ///
2071 /// running <<= 1;
2072 /// }
2073 /// ```
2074 #[stable(feature = "unbounded_shifts", since = "1.87.0")]
2075 #[rustc_const_stable(feature = "unbounded_shifts", since = "1.87.0")]
2076 #[must_use = "this returns the result of the operation, \
2077 without modifying the original"]
2078 #[inline]
2079 pub const fn unbounded_shl(self, rhs: u32) -> $SelfT{
2080 if rhs < Self::BITS {
2081 // SAFETY:
2082 // rhs is just checked to be in-range above
2083 unsafe { self.unchecked_shl(rhs) }
2084 } else {
2085 0
2086 }
2087 }
2088
2089 /// Exact shift left. Computes `self << rhs` as long as it can be reversed losslessly.
2090 ///
2091 /// Returns `None` if any non-zero bits would be shifted out or if `rhs` >=
2092 #[doc = concat!("`", stringify!($SelfT), "::BITS`.")]
2093 /// Otherwise, returns `Some(self << rhs)`.
2094 ///
2095 /// # Examples
2096 ///
2097 /// ```
2098 /// #![feature(exact_bitshifts)]
2099 ///
2100 #[doc = concat!("assert_eq!(0x1", stringify!($SelfT), ".shl_exact(4), Some(0x10));")]
2101 #[doc = concat!("assert_eq!(0x1", stringify!($SelfT), ".shl_exact(129), None);")]
2102 /// ```
2103 #[unstable(feature = "exact_bitshifts", issue = "144336")]
2104 #[must_use = "this returns the result of the operation, \
2105 without modifying the original"]
2106 #[inline]
2107 pub const fn shl_exact(self, rhs: u32) -> Option<$SelfT> {
2108 if rhs <= self.leading_zeros() && rhs < <$SelfT>::BITS {
2109 // SAFETY: rhs is checked above
2110 Some(unsafe { self.unchecked_shl(rhs) })
2111 } else {
2112 None
2113 }
2114 }
2115
2116 /// Unchecked exact shift left. Computes `self << rhs`, assuming the operation can be
2117 /// losslessly reversed `rhs` cannot be larger than
2118 #[doc = concat!("`", stringify!($SelfT), "::BITS`.")]
2119 ///
2120 /// # Safety
2121 ///
2122 /// This results in undefined behavior when `rhs > self.leading_zeros() || rhs >=
2123 #[doc = concat!(stringify!($SelfT), "::BITS`")]
2124 /// i.e. when
2125 #[doc = concat!("[`", stringify!($SelfT), "::shl_exact`]")]
2126 /// would return `None`.
2127 #[unstable(feature = "exact_bitshifts", issue = "144336")]
2128 #[must_use = "this returns the result of the operation, \
2129 without modifying the original"]
2130 #[inline]
2131 pub const unsafe fn unchecked_shl_exact(self, rhs: u32) -> $SelfT {
2132 assert_unsafe_precondition!(
2133 check_library_ub,
2134 concat!(stringify!($SelfT), "::unchecked_shl_exact cannot shift out non-zero bits"),
2135 (
2136 zeros: u32 = self.leading_zeros(),
2137 bits: u32 = <$SelfT>::BITS,
2138 rhs: u32 = rhs,
2139 ) => rhs <= zeros && rhs < bits,
2140 );
2141
2142 // SAFETY: this is guaranteed to be safe by the caller
2143 unsafe { self.unchecked_shl(rhs) }
2144 }
2145
2146 /// Checked shift right. Computes `self >> rhs`, returning `None`
2147 /// if `rhs` is larger than or equal to the number of bits in `self`.
2148 ///
2149 /// # Examples
2150 ///
2151 /// ```
2152 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".checked_shr(4), Some(0x1));")]
2153 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".checked_shr(129), None);")]
2154 /// ```
2155 #[stable(feature = "wrapping", since = "1.7.0")]
2156 #[rustc_const_stable(feature = "const_checked_int_methods", since = "1.47.0")]
2157 #[must_use = "this returns the result of the operation, \
2158 without modifying the original"]
2159 #[inline]
2160 pub const fn checked_shr(self, rhs: u32) -> Option<Self> {
2161 // Not using overflowing_shr as that's a wrapping shift
2162 if rhs < Self::BITS {
2163 // SAFETY: just checked the RHS is in-range
2164 Some(unsafe { self.unchecked_shr(rhs) })
2165 } else {
2166 None
2167 }
2168 }
2169
2170 /// Strict shift right. Computes `self >> rhs`, panicking if `rhs` is
2171 /// larger than or equal to the number of bits in `self`.
2172 ///
2173 /// # Panics
2174 ///
2175 /// ## Overflow behavior
2176 ///
2177 /// This function will always panic on overflow, regardless of whether overflow checks are enabled.
2178 ///
2179 /// # Examples
2180 ///
2181 /// ```
2182 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".strict_shr(4), 0x1);")]
2183 /// ```
2184 ///
2185 /// The following panics because of overflow:
2186 ///
2187 /// ```should_panic
2188 #[doc = concat!("let _ = 0x10", stringify!($SelfT), ".strict_shr(129);")]
2189 /// ```
2190 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
2191 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
2192 #[must_use = "this returns the result of the operation, \
2193 without modifying the original"]
2194 #[inline]
2195 #[track_caller]
2196 pub const fn strict_shr(self, rhs: u32) -> Self {
2197 let (a, b) = self.overflowing_shr(rhs);
2198 if b { imp::overflow_panic::shr() } else { a }
2199 }
2200
2201 /// Unchecked shift right. Computes `self >> rhs`, assuming that
2202 /// `rhs` is less than the number of bits in `self`.
2203 ///
2204 /// # Safety
2205 ///
2206 /// This results in undefined behavior if `rhs` is larger than
2207 /// or equal to the number of bits in `self`,
2208 /// i.e. when [`checked_shr`] would return `None`.
2209 ///
2210 #[doc = concat!("[`checked_shr`]: ", stringify!($SelfT), "::checked_shr")]
2211 #[stable(feature = "unchecked_shifts", since = "1.93.0")]
2212 #[rustc_const_stable(feature = "unchecked_shifts", since = "1.93.0")]
2213 #[must_use = "this returns the result of the operation, \
2214 without modifying the original"]
2215 #[inline(always)]
2216 #[track_caller]
2217 pub const unsafe fn unchecked_shr(self, rhs: u32) -> Self {
2218 assert_unsafe_precondition!(
2219 check_language_ub,
2220 concat!(stringify!($SelfT), "::unchecked_shr cannot overflow"),
2221 (
2222 rhs: u32 = rhs,
2223 ) => rhs < <$ActualT>::BITS,
2224 );
2225
2226 // SAFETY: this is guaranteed to be safe by the caller.
2227 unsafe {
2228 intrinsics::unchecked_shr(self, rhs)
2229 }
2230 }
2231
2232 /// Unbounded shift right. Computes `self >> rhs`, without bounding the value of `rhs`.
2233 ///
2234 /// If `rhs` is larger or equal to the number of bits in `self`,
2235 /// the entire value is shifted out, and `0` is returned.
2236 ///
2237 /// # Examples
2238 ///
2239 /// ```
2240 #[doc = concat!("assert_eq!(0x10_", stringify!($SelfT), ".unbounded_shr(4), 0x1);")]
2241 #[doc = concat!("assert_eq!(0x10_", stringify!($SelfT), ".unbounded_shr(129), 0);")]
2242 #[doc = concat!("assert_eq!(0b1010_", stringify!($SelfT), ".unbounded_shr(0), 0b1010);")]
2243 #[doc = concat!("assert_eq!(0b1010_", stringify!($SelfT), ".unbounded_shr(1), 0b101);")]
2244 #[doc = concat!("assert_eq!(0b1010_", stringify!($SelfT), ".unbounded_shr(2), 0b10);")]
2245 #[doc = concat!("assert_eq!(42_", stringify!($SelfT), ".unbounded_shr(", stringify!($BITS), "), 0);")]
2246 #[doc = concat!("assert_eq!(42_", stringify!($SelfT), ".unbounded_shr(1).unbounded_shr(", stringify!($BITS_MINUS_ONE), "), 0);")]
2247 ///
2248 #[doc = concat!("let start = ", stringify!($SelfT), "::rotate_right(13, 4);")]
2249 /// let mut running = start;
2250 /// for i in 0..160 {
2251 /// // The unbounded shift right by i is the same as `>> 1` i times
2252 /// assert_eq!(running, start.unbounded_shr(i));
2253 /// // Which is not always the case for a wrapping shift
2254 #[doc = concat!(" assert_eq!(running == start.wrapping_shr(i), i < ", stringify!($BITS), ");")]
2255 ///
2256 /// running >>= 1;
2257 /// }
2258 /// ```
2259 #[stable(feature = "unbounded_shifts", since = "1.87.0")]
2260 #[rustc_const_stable(feature = "unbounded_shifts", since = "1.87.0")]
2261 #[must_use = "this returns the result of the operation, \
2262 without modifying the original"]
2263 #[inline]
2264 pub const fn unbounded_shr(self, rhs: u32) -> $SelfT{
2265 if rhs < Self::BITS {
2266 // SAFETY:
2267 // rhs is just checked to be in-range above
2268 unsafe { self.unchecked_shr(rhs) }
2269 } else {
2270 0
2271 }
2272 }
2273
2274 /// Exact shift right. Computes `self >> rhs` as long as it can be reversed losslessly.
2275 ///
2276 /// Returns `None` if any non-zero bits would be shifted out or if `rhs` >=
2277 #[doc = concat!("`", stringify!($SelfT), "::BITS`.")]
2278 /// Otherwise, returns `Some(self >> rhs)`.
2279 ///
2280 /// # Examples
2281 ///
2282 /// ```
2283 /// #![feature(exact_bitshifts)]
2284 ///
2285 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".shr_exact(4), Some(0x1));")]
2286 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".shr_exact(5), None);")]
2287 /// ```
2288 #[unstable(feature = "exact_bitshifts", issue = "144336")]
2289 #[must_use = "this returns the result of the operation, \
2290 without modifying the original"]
2291 #[inline]
2292 pub const fn shr_exact(self, rhs: u32) -> Option<$SelfT> {
2293 if rhs <= self.trailing_zeros() && rhs < <$SelfT>::BITS {
2294 // SAFETY: rhs is checked above
2295 Some(unsafe { self.unchecked_shr(rhs) })
2296 } else {
2297 None
2298 }
2299 }
2300
2301 /// Unchecked exact shift right. Computes `self >> rhs`, assuming the operation can be
2302 /// losslessly reversed and `rhs` cannot be larger than
2303 #[doc = concat!("`", stringify!($SelfT), "::BITS`.")]
2304 ///
2305 /// # Safety
2306 ///
2307 /// This results in undefined behavior when `rhs > self.trailing_zeros() || rhs >=
2308 #[doc = concat!(stringify!($SelfT), "::BITS`")]
2309 /// i.e. when
2310 #[doc = concat!("[`", stringify!($SelfT), "::shr_exact`]")]
2311 /// would return `None`.
2312 #[unstable(feature = "exact_bitshifts", issue = "144336")]
2313 #[must_use = "this returns the result of the operation, \
2314 without modifying the original"]
2315 #[inline]
2316 pub const unsafe fn unchecked_shr_exact(self, rhs: u32) -> $SelfT {
2317 assert_unsafe_precondition!(
2318 check_library_ub,
2319 concat!(stringify!($SelfT), "::unchecked_shr_exact cannot shift out non-zero bits"),
2320 (
2321 zeros: u32 = self.trailing_zeros(),
2322 bits: u32 = <$SelfT>::BITS,
2323 rhs: u32 = rhs,
2324 ) => rhs <= zeros && rhs < bits,
2325 );
2326
2327 // SAFETY: this is guaranteed to be safe by the caller
2328 unsafe { self.unchecked_shr(rhs) }
2329 }
2330
2331 /// Checked exponentiation. Computes `self.pow(exp)`, returning `None` if
2332 /// overflow occurred.
2333 ///
2334 /// # Examples
2335 ///
2336 /// ```
2337 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".checked_pow(5), Some(32));")]
2338 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".checked_pow(0), Some(1));")]
2339 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.checked_pow(2), None);")]
2340 /// ```
2341 #[stable(feature = "no_panic_pow", since = "1.34.0")]
2342 #[rustc_const_stable(feature = "const_int_pow", since = "1.50.0")]
2343 #[must_use = "this returns the result of the operation, \
2344 without modifying the original"]
2345 #[inline]
2346 pub const fn checked_pow(self, mut exp: u32) -> Option<Self> {
2347 if exp == 0 {
2348 return Some(1);
2349 }
2350 let mut base = self;
2351 let mut acc: Self = 1;
2352
2353 loop {
2354 if (exp & 1) == 1 {
2355 acc = try_opt!(acc.checked_mul(base));
2356 // since exp!=0, finally the exp must be 1.
2357 if exp == 1 {
2358 return Some(acc);
2359 }
2360 }
2361 exp /= 2;
2362 base = try_opt!(base.checked_mul(base));
2363 }
2364 }
2365
2366 /// Strict exponentiation. Computes `self.pow(exp)`, panicking if
2367 /// overflow occurred.
2368 ///
2369 /// # Panics
2370 ///
2371 /// ## Overflow behavior
2372 ///
2373 /// This function will always panic on overflow, regardless of whether overflow checks are enabled.
2374 ///
2375 /// # Examples
2376 ///
2377 /// ```
2378 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".strict_pow(5), 32);")]
2379 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".strict_pow(0), 1);")]
2380 /// ```
2381 ///
2382 /// The following panics because of overflow:
2383 ///
2384 /// ```should_panic
2385 #[doc = concat!("let _ = ", stringify!($SelfT), "::MAX.strict_pow(2);")]
2386 /// ```
2387 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
2388 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
2389 #[must_use = "this returns the result of the operation, \
2390 without modifying the original"]
2391 #[inline]
2392 #[track_caller]
2393 pub const fn strict_pow(self, mut exp: u32) -> Self {
2394 if exp == 0 {
2395 return 1;
2396 }
2397 let mut base = self;
2398 let mut acc: Self = 1;
2399
2400 loop {
2401 if (exp & 1) == 1 {
2402 acc = acc.strict_mul(base);
2403 // since exp!=0, finally the exp must be 1.
2404 if exp == 1 {
2405 return acc;
2406 }
2407 }
2408 exp /= 2;
2409 base = base.strict_mul(base);
2410 }
2411 }
2412
2413 /// Saturating integer addition. Computes `self + rhs`, saturating at
2414 /// the numeric bounds instead of overflowing.
2415 ///
2416 /// # Examples
2417 ///
2418 /// ```
2419 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".saturating_add(1), 101);")]
2420 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.saturating_add(127), ", stringify!($SelfT), "::MAX);")]
2421 /// ```
2422 #[stable(feature = "rust1", since = "1.0.0")]
2423 #[must_use = "this returns the result of the operation, \
2424 without modifying the original"]
2425 #[rustc_const_stable(feature = "const_saturating_int_methods", since = "1.47.0")]
2426 #[inline(always)]
2427 pub const fn saturating_add(self, rhs: Self) -> Self {
2428 intrinsics::saturating_add(self, rhs)
2429 }
2430
2431 /// Saturating addition with a signed integer. Computes `self + rhs`,
2432 /// saturating at the numeric bounds instead of overflowing.
2433 ///
2434 /// # Examples
2435 ///
2436 /// ```
2437 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".saturating_add_signed(2), 3);")]
2438 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".saturating_add_signed(-2), 0);")]
2439 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).saturating_add_signed(4), ", stringify!($SelfT), "::MAX);")]
2440 /// ```
2441 #[stable(feature = "mixed_integer_ops", since = "1.66.0")]
2442 #[rustc_const_stable(feature = "mixed_integer_ops", since = "1.66.0")]
2443 #[must_use = "this returns the result of the operation, \
2444 without modifying the original"]
2445 #[inline]
2446 pub const fn saturating_add_signed(self, rhs: $SignedT) -> Self {
2447 let (res, overflow) = self.overflowing_add(rhs as Self);
2448 if overflow == (rhs < 0) {
2449 res
2450 } else if overflow {
2451 Self::MAX
2452 } else {
2453 0
2454 }
2455 }
2456
2457 /// Saturating integer subtraction. Computes `self - rhs`, saturating
2458 /// at the numeric bounds instead of overflowing.
2459 ///
2460 /// # Examples
2461 ///
2462 /// ```
2463 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".saturating_sub(27), 73);")]
2464 #[doc = concat!("assert_eq!(13", stringify!($SelfT), ".saturating_sub(127), 0);")]
2465 /// ```
2466 #[stable(feature = "rust1", since = "1.0.0")]
2467 #[must_use = "this returns the result of the operation, \
2468 without modifying the original"]
2469 #[rustc_const_stable(feature = "const_saturating_int_methods", since = "1.47.0")]
2470 #[inline(always)]
2471 pub const fn saturating_sub(self, rhs: Self) -> Self {
2472 intrinsics::saturating_sub(self, rhs)
2473 }
2474
2475 /// Saturating integer subtraction. Computes `self` - `rhs`, saturating at
2476 /// the numeric bounds instead of overflowing.
2477 ///
2478 /// # Examples
2479 ///
2480 /// ```
2481 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".saturating_sub_signed(2), 0);")]
2482 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".saturating_sub_signed(-2), 3);")]
2483 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).saturating_sub_signed(-4), ", stringify!($SelfT), "::MAX);")]
2484 /// ```
2485 #[stable(feature = "mixed_integer_ops_unsigned_sub", since = "1.90.0")]
2486 #[rustc_const_stable(feature = "mixed_integer_ops_unsigned_sub", since = "1.90.0")]
2487 #[must_use = "this returns the result of the operation, \
2488 without modifying the original"]
2489 #[inline]
2490 pub const fn saturating_sub_signed(self, rhs: $SignedT) -> Self {
2491 let (res, overflow) = self.overflowing_sub_signed(rhs);
2492
2493 if !overflow {
2494 res
2495 } else if rhs < 0 {
2496 Self::MAX
2497 } else {
2498 0
2499 }
2500 }
2501
2502 /// Saturating integer multiplication. Computes `self * rhs`,
2503 /// saturating at the numeric bounds instead of overflowing.
2504 ///
2505 /// # Examples
2506 ///
2507 /// ```
2508 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".saturating_mul(10), 20);")]
2509 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX).saturating_mul(10), ", stringify!($SelfT),"::MAX);")]
2510 /// ```
2511 #[stable(feature = "wrapping", since = "1.7.0")]
2512 #[rustc_const_stable(feature = "const_saturating_int_methods", since = "1.47.0")]
2513 #[must_use = "this returns the result of the operation, \
2514 without modifying the original"]
2515 #[inline]
2516 pub const fn saturating_mul(self, rhs: Self) -> Self {
2517 match self.checked_mul(rhs) {
2518 Some(x) => x,
2519 None => Self::MAX,
2520 }
2521 }
2522
2523 /// Saturating integer division. Computes `self / rhs`, saturating at the
2524 /// numeric bounds instead of overflowing.
2525 ///
2526 /// # Panics
2527 ///
2528 /// This function will panic if `rhs` is zero.
2529 ///
2530 /// # Examples
2531 ///
2532 /// ```
2533 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".saturating_div(2), 2);")]
2534 ///
2535 /// ```
2536 #[stable(feature = "saturating_div", since = "1.58.0")]
2537 #[rustc_const_stable(feature = "saturating_div", since = "1.58.0")]
2538 #[must_use = "this returns the result of the operation, \
2539 without modifying the original"]
2540 #[inline]
2541 #[track_caller]
2542 pub const fn saturating_div(self, rhs: Self) -> Self {
2543 // on unsigned types, there is no overflow in integer division
2544 self.wrapping_div(rhs)
2545 }
2546
2547 /// Saturating integer exponentiation. Computes `self.pow(exp)`,
2548 /// saturating at the numeric bounds instead of overflowing.
2549 ///
2550 /// # Examples
2551 ///
2552 /// ```
2553 #[doc = concat!("assert_eq!(4", stringify!($SelfT), ".saturating_pow(3), 64);")]
2554 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".saturating_pow(0), 1);")]
2555 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.saturating_pow(2), ", stringify!($SelfT), "::MAX);")]
2556 /// ```
2557 #[stable(feature = "no_panic_pow", since = "1.34.0")]
2558 #[rustc_const_stable(feature = "const_int_pow", since = "1.50.0")]
2559 #[must_use = "this returns the result of the operation, \
2560 without modifying the original"]
2561 #[inline]
2562 pub const fn saturating_pow(self, exp: u32) -> Self {
2563 match self.checked_pow(exp) {
2564 Some(x) => x,
2565 None => Self::MAX,
2566 }
2567 }
2568
2569 /// Wrapping (modular) addition. Computes `self + rhs`,
2570 /// wrapping around at the boundary of the type.
2571 ///
2572 /// # Examples
2573 ///
2574 /// ```
2575 #[doc = concat!("assert_eq!(200", stringify!($SelfT), ".wrapping_add(55), 255);")]
2576 #[doc = concat!("assert_eq!(200", stringify!($SelfT), ".wrapping_add(", stringify!($SelfT), "::MAX), 199);")]
2577 /// ```
2578 #[stable(feature = "rust1", since = "1.0.0")]
2579 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
2580 #[must_use = "this returns the result of the operation, \
2581 without modifying the original"]
2582 #[inline(always)]
2583 pub const fn wrapping_add(self, rhs: Self) -> Self {
2584 intrinsics::wrapping_add(self, rhs)
2585 }
2586
2587 /// Wrapping (modular) addition with a signed integer. Computes
2588 /// `self + rhs`, wrapping around at the boundary of the type.
2589 ///
2590 /// # Examples
2591 ///
2592 /// ```
2593 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".wrapping_add_signed(2), 3);")]
2594 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".wrapping_add_signed(-2), ", stringify!($SelfT), "::MAX);")]
2595 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).wrapping_add_signed(4), 1);")]
2596 /// ```
2597 #[stable(feature = "mixed_integer_ops", since = "1.66.0")]
2598 #[rustc_const_stable(feature = "mixed_integer_ops", since = "1.66.0")]
2599 #[must_use = "this returns the result of the operation, \
2600 without modifying the original"]
2601 #[inline]
2602 pub const fn wrapping_add_signed(self, rhs: $SignedT) -> Self {
2603 self.wrapping_add(rhs as Self)
2604 }
2605
2606 /// Wrapping (modular) subtraction. Computes `self - rhs`,
2607 /// wrapping around at the boundary of the type.
2608 ///
2609 /// # Examples
2610 ///
2611 /// ```
2612 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".wrapping_sub(100), 0);")]
2613 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".wrapping_sub(", stringify!($SelfT), "::MAX), 101);")]
2614 /// ```
2615 #[stable(feature = "rust1", since = "1.0.0")]
2616 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
2617 #[must_use = "this returns the result of the operation, \
2618 without modifying the original"]
2619 #[inline(always)]
2620 pub const fn wrapping_sub(self, rhs: Self) -> Self {
2621 intrinsics::wrapping_sub(self, rhs)
2622 }
2623
2624 /// Wrapping (modular) subtraction with a signed integer. Computes
2625 /// `self - rhs`, wrapping around at the boundary of the type.
2626 ///
2627 /// # Examples
2628 ///
2629 /// ```
2630 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".wrapping_sub_signed(2), ", stringify!($SelfT), "::MAX);")]
2631 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".wrapping_sub_signed(-2), 3);")]
2632 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).wrapping_sub_signed(-4), 1);")]
2633 /// ```
2634 #[stable(feature = "mixed_integer_ops_unsigned_sub", since = "1.90.0")]
2635 #[rustc_const_stable(feature = "mixed_integer_ops_unsigned_sub", since = "1.90.0")]
2636 #[must_use = "this returns the result of the operation, \
2637 without modifying the original"]
2638 #[inline]
2639 pub const fn wrapping_sub_signed(self, rhs: $SignedT) -> Self {
2640 self.wrapping_sub(rhs as Self)
2641 }
2642
2643 /// Wrapping (modular) multiplication. Computes `self *
2644 /// rhs`, wrapping around at the boundary of the type.
2645 ///
2646 /// # Examples
2647 ///
2648 /// Please note that this example is shared among integer types, which is why `u8` is used.
2649 ///
2650 /// ```
2651 /// assert_eq!(10u8.wrapping_mul(12), 120);
2652 /// assert_eq!(25u8.wrapping_mul(12), 44);
2653 /// ```
2654 #[stable(feature = "rust1", since = "1.0.0")]
2655 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
2656 #[must_use = "this returns the result of the operation, \
2657 without modifying the original"]
2658 #[inline(always)]
2659 pub const fn wrapping_mul(self, rhs: Self) -> Self {
2660 intrinsics::wrapping_mul(self, rhs)
2661 }
2662
2663 /// Wrapping (modular) division. Computes `self / rhs`.
2664 ///
2665 /// Wrapped division on unsigned types is just normal division. There's
2666 /// no way wrapping could ever happen. This function exists so that all
2667 /// operations are accounted for in the wrapping operations.
2668 ///
2669 /// # Panics
2670 ///
2671 /// This function will panic if `rhs` is zero.
2672 ///
2673 /// # Examples
2674 ///
2675 /// ```
2676 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".wrapping_div(10), 10);")]
2677 /// ```
2678 #[stable(feature = "num_wrapping", since = "1.2.0")]
2679 #[rustc_const_stable(feature = "const_wrapping_int_methods", since = "1.52.0")]
2680 #[must_use = "this returns the result of the operation, \
2681 without modifying the original"]
2682 #[inline(always)]
2683 #[track_caller]
2684 pub const fn wrapping_div(self, rhs: Self) -> Self {
2685 self / rhs
2686 }
2687
2688 /// Wrapping Euclidean division. Computes `self.div_euclid(rhs)`.
2689 ///
2690 /// Wrapped division on unsigned types is just normal division. There's
2691 /// no way wrapping could ever happen. This function exists so that all
2692 /// operations are accounted for in the wrapping operations. Since, for
2693 /// the positive integers, all common definitions of division are equal,
2694 /// this is exactly equal to `self.wrapping_div(rhs)`.
2695 ///
2696 /// # Panics
2697 ///
2698 /// This function will panic if `rhs` is zero.
2699 ///
2700 /// # Examples
2701 ///
2702 /// ```
2703 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".wrapping_div_euclid(10), 10);")]
2704 /// ```
2705 #[stable(feature = "euclidean_division", since = "1.38.0")]
2706 #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.52.0")]
2707 #[must_use = "this returns the result of the operation, \
2708 without modifying the original"]
2709 #[inline(always)]
2710 #[track_caller]
2711 pub const fn wrapping_div_euclid(self, rhs: Self) -> Self {
2712 self / rhs
2713 }
2714
2715 /// Wrapping (modular) remainder. Computes `self % rhs`.
2716 ///
2717 /// Wrapped remainder calculation on unsigned types is just the regular
2718 /// remainder calculation. There's no way wrapping could ever happen.
2719 /// This function exists so that all operations are accounted for in the
2720 /// wrapping operations.
2721 ///
2722 /// # Panics
2723 ///
2724 /// This function will panic if `rhs` is zero.
2725 ///
2726 /// # Examples
2727 ///
2728 /// ```
2729 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".wrapping_rem(10), 0);")]
2730 /// ```
2731 #[stable(feature = "num_wrapping", since = "1.2.0")]
2732 #[rustc_const_stable(feature = "const_wrapping_int_methods", since = "1.52.0")]
2733 #[must_use = "this returns the result of the operation, \
2734 without modifying the original"]
2735 #[inline(always)]
2736 #[track_caller]
2737 pub const fn wrapping_rem(self, rhs: Self) -> Self {
2738 self % rhs
2739 }
2740
2741 /// Wrapping Euclidean modulo. Computes `self.rem_euclid(rhs)`.
2742 ///
2743 /// Wrapped modulo calculation on unsigned types is just the regular
2744 /// remainder calculation. There's no way wrapping could ever happen.
2745 /// This function exists so that all operations are accounted for in the
2746 /// wrapping operations. Since, for the positive integers, all common
2747 /// definitions of division are equal, this is exactly equal to
2748 /// `self.wrapping_rem(rhs)`.
2749 ///
2750 /// # Panics
2751 ///
2752 /// This function will panic if `rhs` is zero.
2753 ///
2754 /// # Examples
2755 ///
2756 /// ```
2757 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".wrapping_rem_euclid(10), 0);")]
2758 /// ```
2759 #[stable(feature = "euclidean_division", since = "1.38.0")]
2760 #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.52.0")]
2761 #[must_use = "this returns the result of the operation, \
2762 without modifying the original"]
2763 #[inline(always)]
2764 #[track_caller]
2765 pub const fn wrapping_rem_euclid(self, rhs: Self) -> Self {
2766 self % rhs
2767 }
2768
2769 /// Wrapping (modular) negation. Computes `-self`,
2770 /// wrapping around at the boundary of the type.
2771 ///
2772 /// Since unsigned types do not have negative equivalents
2773 /// all applications of this function will wrap (except for `-0`).
2774 /// For values smaller than the corresponding signed type's maximum
2775 /// the result is the same as casting the corresponding signed value.
2776 /// Any larger values are equivalent to `MAX + 1 - (val - MAX - 1)` where
2777 /// `MAX` is the corresponding signed type's maximum.
2778 ///
2779 /// # Examples
2780 ///
2781 /// ```
2782 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".wrapping_neg(), 0);")]
2783 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.wrapping_neg(), 1);")]
2784 #[doc = concat!("assert_eq!(13_", stringify!($SelfT), ".wrapping_neg(), (!13) + 1);")]
2785 #[doc = concat!("assert_eq!(42_", stringify!($SelfT), ".wrapping_neg(), !(42 - 1));")]
2786 /// ```
2787 #[stable(feature = "num_wrapping", since = "1.2.0")]
2788 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
2789 #[must_use = "this returns the result of the operation, \
2790 without modifying the original"]
2791 #[inline(always)]
2792 pub const fn wrapping_neg(self) -> Self {
2793 (0 as $SelfT).wrapping_sub(self)
2794 }
2795
2796 /// Panic-free bitwise shift-left; yields `self << mask(rhs)`,
2797 /// where `mask` removes any high-order bits of `rhs` that
2798 /// would cause the shift to exceed the bitwidth of the type.
2799 ///
2800 /// Beware that, unlike most other `wrapping_*` methods on integers, this
2801 /// does *not* give the same result as doing the shift in infinite precision
2802 /// then truncating as needed. The behaviour matches what shift instructions
2803 /// do on many processors, and is what the `<<` operator does when overflow
2804 /// checks are disabled, but numerically it's weird. Consider, instead,
2805 /// using [`Self::unbounded_shl`] which has nicer behaviour.
2806 ///
2807 /// Note that this is *not* the same as a rotate-left; the
2808 /// RHS of a wrapping shift-left is restricted to the range
2809 /// of the type, rather than the bits shifted out of the LHS
2810 /// being returned to the other end. The primitive integer
2811 /// types all implement a [`rotate_left`](Self::rotate_left) function,
2812 /// which may be what you want instead.
2813 ///
2814 /// # Examples
2815 ///
2816 /// ```
2817 #[doc = concat!("assert_eq!(1_", stringify!($SelfT), ".wrapping_shl(7), 128);")]
2818 #[doc = concat!("assert_eq!(0b101_", stringify!($SelfT), ".wrapping_shl(0), 0b101);")]
2819 #[doc = concat!("assert_eq!(0b101_", stringify!($SelfT), ".wrapping_shl(1), 0b1010);")]
2820 #[doc = concat!("assert_eq!(0b101_", stringify!($SelfT), ".wrapping_shl(2), 0b10100);")]
2821 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.wrapping_shl(2), ", stringify!($SelfT), "::MAX - 3);")]
2822 #[doc = concat!("assert_eq!(42_", stringify!($SelfT), ".wrapping_shl(", stringify!($BITS), "), 42);")]
2823 #[doc = concat!("assert_eq!(42_", stringify!($SelfT), ".wrapping_shl(1).wrapping_shl(", stringify!($BITS_MINUS_ONE), "), 0);")]
2824 #[doc = concat!("assert_eq!(1_", stringify!($SelfT), ".wrapping_shl(128), 1);")]
2825 #[doc = concat!("assert_eq!(5_", stringify!($SelfT), ".wrapping_shl(1025), 10);")]
2826 /// ```
2827 #[stable(feature = "num_wrapping", since = "1.2.0")]
2828 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
2829 #[must_use = "this returns the result of the operation, \
2830 without modifying the original"]
2831 #[inline(always)]
2832 pub const fn wrapping_shl(self, rhs: u32) -> Self {
2833 // SAFETY: the masking by the bitsize of the type ensures that we do not shift
2834 // out of bounds
2835 unsafe {
2836 self.unchecked_shl(rhs & (Self::BITS - 1))
2837 }
2838 }
2839
2840 /// Panic-free bitwise shift-right; yields `self >> mask(rhs)`,
2841 /// where `mask` removes any high-order bits of `rhs` that
2842 /// would cause the shift to exceed the bitwidth of the type.
2843 ///
2844 /// Beware that, unlike most other `wrapping_*` methods on integers, this
2845 /// does *not* give the same result as doing the shift in infinite precision
2846 /// then truncating as needed. The behaviour matches what shift instructions
2847 /// do on many processors, and is what the `>>` operator does when overflow
2848 /// checks are disabled, but numerically it's weird. Consider, instead,
2849 /// using [`Self::unbounded_shr`] which has nicer behaviour.
2850 ///
2851 /// Note that this is *not* the same as a rotate-right; the
2852 /// RHS of a wrapping shift-right is restricted to the range
2853 /// of the type, rather than the bits shifted out of the LHS
2854 /// being returned to the other end. The primitive integer
2855 /// types all implement a [`rotate_right`](Self::rotate_right) function,
2856 /// which may be what you want instead.
2857 ///
2858 /// # Examples
2859 ///
2860 /// ```
2861 #[doc = concat!("assert_eq!(128_", stringify!($SelfT), ".wrapping_shr(7), 1);")]
2862 #[doc = concat!("assert_eq!(0b1010_", stringify!($SelfT), ".wrapping_shr(0), 0b1010);")]
2863 #[doc = concat!("assert_eq!(0b1010_", stringify!($SelfT), ".wrapping_shr(1), 0b101);")]
2864 #[doc = concat!("assert_eq!(0b1010_", stringify!($SelfT), ".wrapping_shr(2), 0b10);")]
2865 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.wrapping_shr(1), ", stringify!($SignedT), "::MAX.cast_unsigned());")]
2866 #[doc = concat!("assert_eq!(42_", stringify!($SelfT), ".wrapping_shr(", stringify!($BITS), "), 42);")]
2867 #[doc = concat!("assert_eq!(42_", stringify!($SelfT), ".wrapping_shr(1).wrapping_shr(", stringify!($BITS_MINUS_ONE), "), 0);")]
2868 #[doc = concat!("assert_eq!(128_", stringify!($SelfT), ".wrapping_shr(128), 128);")]
2869 #[doc = concat!("assert_eq!(10_", stringify!($SelfT), ".wrapping_shr(1025), 5);")]
2870 /// ```
2871 #[stable(feature = "num_wrapping", since = "1.2.0")]
2872 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
2873 #[must_use = "this returns the result of the operation, \
2874 without modifying the original"]
2875 #[inline(always)]
2876 pub const fn wrapping_shr(self, rhs: u32) -> Self {
2877 // SAFETY: the masking by the bitsize of the type ensures that we do not shift
2878 // out of bounds
2879 unsafe {
2880 self.unchecked_shr(rhs & (Self::BITS - 1))
2881 }
2882 }
2883
2884 /// Wrapping (modular) exponentiation. Computes `self.pow(exp)`,
2885 /// wrapping around at the boundary of the type.
2886 ///
2887 /// # Examples
2888 ///
2889 /// ```
2890 #[doc = concat!("assert_eq!(3", stringify!($SelfT), ".wrapping_pow(5), 243);")]
2891 /// assert_eq!(3u8.wrapping_pow(6), 217);
2892 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".wrapping_pow(0), 1);")]
2893 /// ```
2894 #[stable(feature = "no_panic_pow", since = "1.34.0")]
2895 #[rustc_const_stable(feature = "const_int_pow", since = "1.50.0")]
2896 #[must_use = "this returns the result of the operation, \
2897 without modifying the original"]
2898 #[inline]
2899 pub const fn wrapping_pow(self, mut exp: u32) -> Self {
2900 if exp == 0 {
2901 return 1;
2902 }
2903 let mut base = self;
2904 let mut acc: Self = 1;
2905
2906 if intrinsics::is_val_statically_known(exp) {
2907 while exp > 1 {
2908 if (exp & 1) == 1 {
2909 acc = acc.wrapping_mul(base);
2910 }
2911 exp /= 2;
2912 base = base.wrapping_mul(base);
2913 }
2914
2915 // since exp!=0, finally the exp must be 1.
2916 // Deal with the final bit of the exponent separately, since
2917 // squaring the base afterwards is not necessary.
2918 acc.wrapping_mul(base)
2919 } else {
2920 // This is faster than the above when the exponent is not known
2921 // at compile time. We can't use the same code for the constant
2922 // exponent case because LLVM is currently unable to unroll
2923 // this loop.
2924 loop {
2925 if (exp & 1) == 1 {
2926 acc = acc.wrapping_mul(base);
2927 // since exp!=0, finally the exp must be 1.
2928 if exp == 1 {
2929 return acc;
2930 }
2931 }
2932 exp /= 2;
2933 base = base.wrapping_mul(base);
2934 }
2935 }
2936 }
2937
2938 /// Calculates `self` + `rhs`.
2939 ///
2940 /// Returns a tuple of the addition along with a boolean indicating
2941 /// whether an arithmetic overflow would occur. If an overflow would
2942 /// have occurred then the wrapped value is returned.
2943 ///
2944 /// # Examples
2945 ///
2946 /// ```
2947 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".overflowing_add(2), (7, false));")]
2948 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.overflowing_add(1), (0, true));")]
2949 /// ```
2950 #[stable(feature = "wrapping", since = "1.7.0")]
2951 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
2952 #[must_use = "this returns the result of the operation, \
2953 without modifying the original"]
2954 #[inline(always)]
2955 pub const fn overflowing_add(self, rhs: Self) -> (Self, bool) {
2956 let (a, b) = intrinsics::add_with_overflow(self as $ActualT, rhs as $ActualT);
2957 (a as Self, b)
2958 }
2959
2960 /// Calculates `self` + `rhs` + `carry` and returns a tuple containing
2961 /// the sum and the output carry (in that order).
2962 ///
2963 /// Performs "ternary addition" of two integer operands and a carry-in
2964 /// bit, and returns an output integer and a carry-out bit. This allows
2965 /// chaining together multiple additions to create a wider addition, and
2966 /// can be useful for bignum addition.
2967 ///
2968 #[doc = concat!("This can be thought of as a ", stringify!($BITS), "-bit \"full adder\", in the electronics sense.")]
2969 ///
2970 /// If the input carry is false, this method is equivalent to
2971 /// [`overflowing_add`](Self::overflowing_add), and the output carry is
2972 /// equal to the overflow flag. Note that although carry and overflow
2973 /// flags are similar for unsigned integers, they are different for
2974 /// signed integers.
2975 ///
2976 /// # Examples
2977 ///
2978 /// ```
2979 #[doc = concat!("// 3 MAX (a = 3 × 2^", stringify!($BITS), " + 2^", stringify!($BITS), " - 1)")]
2980 #[doc = concat!("// + 5 7 (b = 5 × 2^", stringify!($BITS), " + 7)")]
2981 /// // ---------
2982 #[doc = concat!("// 9 6 (sum = 9 × 2^", stringify!($BITS), " + 6)")]
2983 ///
2984 #[doc = concat!("let (a1, a0): (", stringify!($SelfT), ", ", stringify!($SelfT), ") = (3, ", stringify!($SelfT), "::MAX);")]
2985 #[doc = concat!("let (b1, b0): (", stringify!($SelfT), ", ", stringify!($SelfT), ") = (5, 7);")]
2986 /// let carry0 = false;
2987 ///
2988 /// let (sum0, carry1) = a0.carrying_add(b0, carry0);
2989 /// assert_eq!(carry1, true);
2990 /// let (sum1, carry2) = a1.carrying_add(b1, carry1);
2991 /// assert_eq!(carry2, false);
2992 ///
2993 /// assert_eq!((sum1, sum0), (9, 6));
2994 /// ```
2995 #[stable(feature = "unsigned_bigint_helpers", since = "1.91.0")]
2996 #[rustc_const_unstable(feature = "const_unsigned_bigint_helpers", issue = "152015")]
2997 #[must_use = "this returns the result of the operation, \
2998 without modifying the original"]
2999 #[inline]
3000 pub const fn carrying_add(self, rhs: Self, carry: bool) -> (Self, bool) {
3001 // note: longer-term this should be done via an intrinsic, but this has been shown
3002 // to generate optimal code for now, and LLVM doesn't have an equivalent intrinsic
3003 let (a, c1) = self.overflowing_add(rhs);
3004 let (b, c2) = a.overflowing_add(carry as $SelfT);
3005 // Ideally LLVM would know this is disjoint without us telling them,
3006 // but it doesn't <https://github.com/llvm/llvm-project/issues/118162>
3007 // SAFETY: Only one of `c1` and `c2` can be set.
3008 // For c1 to be set we need to have overflowed, but if we did then
3009 // `a` is at most `MAX-1`, which means that `c2` cannot possibly
3010 // overflow because it's adding at most `1` (since it came from `bool`)
3011 (b, unsafe { intrinsics::disjoint_bitor(c1, c2) })
3012 }
3013
3014 /// Calculates `self` + `rhs` with a signed `rhs`.
3015 ///
3016 /// Returns a tuple of the addition along with a boolean indicating
3017 /// whether an arithmetic overflow would occur. If an overflow would
3018 /// have occurred then the wrapped value is returned.
3019 ///
3020 /// # Examples
3021 ///
3022 /// ```
3023 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".overflowing_add_signed(2), (3, false));")]
3024 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".overflowing_add_signed(-2), (", stringify!($SelfT), "::MAX, true));")]
3025 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).overflowing_add_signed(4), (1, true));")]
3026 /// ```
3027 #[stable(feature = "mixed_integer_ops", since = "1.66.0")]
3028 #[rustc_const_stable(feature = "mixed_integer_ops", since = "1.66.0")]
3029 #[must_use = "this returns the result of the operation, \
3030 without modifying the original"]
3031 #[inline]
3032 pub const fn overflowing_add_signed(self, rhs: $SignedT) -> (Self, bool) {
3033 let (res, overflowed) = self.overflowing_add(rhs as Self);
3034 (res, overflowed ^ (rhs < 0))
3035 }
3036
3037 /// Calculates `self` - `rhs`.
3038 ///
3039 /// Returns a tuple of the subtraction along with a boolean indicating
3040 /// whether an arithmetic overflow would occur. If an overflow would
3041 /// have occurred then the wrapped value is returned.
3042 ///
3043 /// # Examples
3044 ///
3045 /// ```
3046 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".overflowing_sub(2), (3, false));")]
3047 #[doc = concat!("assert_eq!(0", stringify!($SelfT), ".overflowing_sub(1), (", stringify!($SelfT), "::MAX, true));")]
3048 /// ```
3049 #[stable(feature = "wrapping", since = "1.7.0")]
3050 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
3051 #[must_use = "this returns the result of the operation, \
3052 without modifying the original"]
3053 #[inline(always)]
3054 pub const fn overflowing_sub(self, rhs: Self) -> (Self, bool) {
3055 let (a, b) = intrinsics::sub_with_overflow(self as $ActualT, rhs as $ActualT);
3056 (a as Self, b)
3057 }
3058
3059 /// Calculates `self` − `rhs` − `borrow` and returns a tuple
3060 /// containing the difference and the output borrow.
3061 ///
3062 /// Performs "ternary subtraction" by subtracting both an integer
3063 /// operand and a borrow-in bit from `self`, and returns an output
3064 /// integer and a borrow-out bit. This allows chaining together multiple
3065 /// subtractions to create a wider subtraction, and can be useful for
3066 /// bignum subtraction.
3067 ///
3068 /// # Examples
3069 ///
3070 /// ```
3071 #[doc = concat!("// 9 6 (a = 9 × 2^", stringify!($BITS), " + 6)")]
3072 #[doc = concat!("// - 5 7 (b = 5 × 2^", stringify!($BITS), " + 7)")]
3073 /// // ---------
3074 #[doc = concat!("// 3 MAX (diff = 3 × 2^", stringify!($BITS), " + 2^", stringify!($BITS), " - 1)")]
3075 ///
3076 #[doc = concat!("let (a1, a0): (", stringify!($SelfT), ", ", stringify!($SelfT), ") = (9, 6);")]
3077 #[doc = concat!("let (b1, b0): (", stringify!($SelfT), ", ", stringify!($SelfT), ") = (5, 7);")]
3078 /// let borrow0 = false;
3079 ///
3080 /// let (diff0, borrow1) = a0.borrowing_sub(b0, borrow0);
3081 /// assert_eq!(borrow1, true);
3082 /// let (diff1, borrow2) = a1.borrowing_sub(b1, borrow1);
3083 /// assert_eq!(borrow2, false);
3084 ///
3085 #[doc = concat!("assert_eq!((diff1, diff0), (3, ", stringify!($SelfT), "::MAX));")]
3086 /// ```
3087 #[stable(feature = "unsigned_bigint_helpers", since = "1.91.0")]
3088 #[rustc_const_unstable(feature = "const_unsigned_bigint_helpers", issue = "152015")]
3089 #[must_use = "this returns the result of the operation, \
3090 without modifying the original"]
3091 #[inline]
3092 pub const fn borrowing_sub(self, rhs: Self, borrow: bool) -> (Self, bool) {
3093 // note: longer-term this should be done via an intrinsic, but this has been shown
3094 // to generate optimal code for now, and LLVM doesn't have an equivalent intrinsic
3095 let (a, c1) = self.overflowing_sub(rhs);
3096 let (b, c2) = a.overflowing_sub(borrow as $SelfT);
3097 // SAFETY: Only one of `c1` and `c2` can be set.
3098 // For c1 to be set we need to have underflowed, but if we did then
3099 // `a` is nonzero, which means that `c2` cannot possibly
3100 // underflow because it's subtracting at most `1` (since it came from `bool`)
3101 (b, unsafe { intrinsics::disjoint_bitor(c1, c2) })
3102 }
3103
3104 /// Calculates `self` - `rhs` with a signed `rhs`
3105 ///
3106 /// Returns a tuple of the subtraction along with a boolean indicating
3107 /// whether an arithmetic overflow would occur. If an overflow would
3108 /// have occurred then the wrapped value is returned.
3109 ///
3110 /// # Examples
3111 ///
3112 /// ```
3113 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".overflowing_sub_signed(2), (", stringify!($SelfT), "::MAX, true));")]
3114 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".overflowing_sub_signed(-2), (3, false));")]
3115 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).overflowing_sub_signed(-4), (1, true));")]
3116 /// ```
3117 #[stable(feature = "mixed_integer_ops_unsigned_sub", since = "1.90.0")]
3118 #[rustc_const_stable(feature = "mixed_integer_ops_unsigned_sub", since = "1.90.0")]
3119 #[must_use = "this returns the result of the operation, \
3120 without modifying the original"]
3121 #[inline]
3122 pub const fn overflowing_sub_signed(self, rhs: $SignedT) -> (Self, bool) {
3123 let (res, overflow) = self.overflowing_sub(rhs as Self);
3124
3125 (res, overflow ^ (rhs < 0))
3126 }
3127
3128 /// Computes the absolute difference between `self` and `other`.
3129 ///
3130 /// # Examples
3131 ///
3132 /// ```
3133 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".abs_diff(80), 20", stringify!($SelfT), ");")]
3134 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".abs_diff(110), 10", stringify!($SelfT), ");")]
3135 /// ```
3136 #[stable(feature = "int_abs_diff", since = "1.60.0")]
3137 #[rustc_const_stable(feature = "int_abs_diff", since = "1.60.0")]
3138 #[must_use = "this returns the result of the operation, \
3139 without modifying the original"]
3140 #[inline]
3141 pub const fn abs_diff(self, other: Self) -> Self {
3142 if size_of::<Self>() == 1 {
3143 // Trick LLVM into generating the psadbw instruction when SSE2
3144 // is available and this function is autovectorized for u8's.
3145 (self as i32).wrapping_sub(other as i32).unsigned_abs() as Self
3146 } else {
3147 if self < other {
3148 other - self
3149 } else {
3150 self - other
3151 }
3152 }
3153 }
3154
3155 /// Calculates the multiplication of `self` and `rhs`.
3156 ///
3157 /// Returns a tuple of the multiplication along with a boolean
3158 /// indicating whether an arithmetic overflow would occur. If an
3159 /// overflow would have occurred then the wrapped value is returned.
3160 ///
3161 /// If you want the *value* of the overflow, rather than just *whether*
3162 /// an overflow occurred, see [`Self::carrying_mul`].
3163 ///
3164 /// # Examples
3165 ///
3166 /// Please note that this example is shared among integer types, which is why `u32` is used.
3167 ///
3168 /// ```
3169 /// assert_eq!(5u32.overflowing_mul(2), (10, false));
3170 /// assert_eq!(1_000_000_000u32.overflowing_mul(10), (1410065408, true));
3171 /// ```
3172 #[stable(feature = "wrapping", since = "1.7.0")]
3173 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
3174 #[must_use = "this returns the result of the operation, \
3175 without modifying the original"]
3176 #[inline(always)]
3177 pub const fn overflowing_mul(self, rhs: Self) -> (Self, bool) {
3178 let (a, b) = intrinsics::mul_with_overflow(self as $ActualT, rhs as $ActualT);
3179 (a as Self, b)
3180 }
3181
3182 /// Calculates the "full multiplication" `self * rhs + carry`
3183 /// without the possibility to overflow.
3184 ///
3185 /// This returns the low-order (wrapping) bits and the high-order (overflow) bits
3186 /// of the result as two separate values, in that order.
3187 ///
3188 /// Performs "long multiplication" which takes in an extra amount to add, and may return an
3189 /// additional amount of overflow. This allows for chaining together multiple
3190 /// multiplications to create "big integers" which represent larger values.
3191 ///
3192 /// If you also need to add a value, then use [`Self::carrying_mul_add`].
3193 ///
3194 /// # Examples
3195 ///
3196 /// Please note that this example is shared among integer types, which is why `u32` is used.
3197 ///
3198 /// ```
3199 /// assert_eq!(5u32.carrying_mul(2, 0), (10, 0));
3200 /// assert_eq!(5u32.carrying_mul(2, 10), (20, 0));
3201 /// assert_eq!(1_000_000_000u32.carrying_mul(10, 0), (1410065408, 2));
3202 /// assert_eq!(1_000_000_000u32.carrying_mul(10, 10), (1410065418, 2));
3203 #[doc = concat!("assert_eq!(",
3204 stringify!($SelfT), "::MAX.carrying_mul(", stringify!($SelfT), "::MAX, ", stringify!($SelfT), "::MAX), ",
3205 "(0, ", stringify!($SelfT), "::MAX));"
3206 )]
3207 /// ```
3208 ///
3209 /// This is the core operation needed for scalar multiplication when
3210 /// implementing it for wider-than-native types.
3211 ///
3212 /// ```
3213 /// fn scalar_mul_eq(little_endian_digits: &mut Vec<u16>, multiplicand: u16) {
3214 /// let mut carry = 0;
3215 /// for d in little_endian_digits.iter_mut() {
3216 /// (*d, carry) = d.carrying_mul(multiplicand, carry);
3217 /// }
3218 /// if carry != 0 {
3219 /// little_endian_digits.push(carry);
3220 /// }
3221 /// }
3222 ///
3223 /// let mut v = vec![10, 20];
3224 /// scalar_mul_eq(&mut v, 3);
3225 /// assert_eq!(v, [30, 60]);
3226 ///
3227 /// assert_eq!(0x87654321_u64 * 0xFEED, 0x86D3D159E38D);
3228 /// let mut v = vec![0x4321, 0x8765];
3229 /// scalar_mul_eq(&mut v, 0xFEED);
3230 /// assert_eq!(v, [0xE38D, 0xD159, 0x86D3]);
3231 /// ```
3232 ///
3233 /// If `carry` is zero, this is similar to [`overflowing_mul`](Self::overflowing_mul),
3234 /// except that it gives the value of the overflow instead of just whether one happened:
3235 ///
3236 /// ```
3237 /// # #![allow(unused_features)]
3238 /// #![feature(const_unsigned_bigint_helpers)]
3239 /// let r = u8::carrying_mul(7, 13, 0);
3240 /// assert_eq!((r.0, r.1 != 0), u8::overflowing_mul(7, 13));
3241 /// let r = u8::carrying_mul(13, 42, 0);
3242 /// assert_eq!((r.0, r.1 != 0), u8::overflowing_mul(13, 42));
3243 /// ```
3244 ///
3245 /// The value of the first field in the returned tuple matches what you'd get
3246 /// by combining the [`wrapping_mul`](Self::wrapping_mul) and
3247 /// [`wrapping_add`](Self::wrapping_add) methods:
3248 ///
3249 /// ```
3250 /// # #![allow(unused_features)]
3251 /// #![feature(const_unsigned_bigint_helpers)]
3252 /// assert_eq!(
3253 /// 789_u16.carrying_mul(456, 123).0,
3254 /// 789_u16.wrapping_mul(456).wrapping_add(123),
3255 /// );
3256 /// ```
3257 #[stable(feature = "unsigned_bigint_helpers", since = "1.91.0")]
3258 #[rustc_const_unstable(feature = "const_unsigned_bigint_helpers", issue = "152015")]
3259 #[must_use = "this returns the result of the operation, \
3260 without modifying the original"]
3261 #[inline]
3262 pub const fn carrying_mul(self, rhs: Self, carry: Self) -> (Self, Self) {
3263 Self::carrying_mul_add(self, rhs, carry, 0)
3264 }
3265
3266 /// Calculates the "full multiplication" `self * rhs + carry + add`.
3267 ///
3268 /// This returns the low-order (wrapping) bits and the high-order (overflow) bits
3269 /// of the result as two separate values, in that order.
3270 ///
3271 /// This cannot overflow, as the double-width result has exactly enough
3272 /// space for the largest possible result. This is equivalent to how, in
3273 /// decimal, 9 × 9 + 9 + 9 = 81 + 18 = 99 = 9×10⁰ + 9×10¹ = 10² - 1.
3274 ///
3275 /// Performs "long multiplication" which takes in an extra amount to add, and may return an
3276 /// additional amount of overflow. This allows for chaining together multiple
3277 /// multiplications to create "big integers" which represent larger values.
3278 ///
3279 /// If you don't need the `add` part, then you can use [`Self::carrying_mul`] instead.
3280 ///
3281 /// # Examples
3282 ///
3283 /// Please note that this example is shared between integer types,
3284 /// which explains why `u32` is used here.
3285 ///
3286 /// ```
3287 /// assert_eq!(5u32.carrying_mul_add(2, 0, 0), (10, 0));
3288 /// assert_eq!(5u32.carrying_mul_add(2, 10, 10), (30, 0));
3289 /// assert_eq!(1_000_000_000u32.carrying_mul_add(10, 0, 0), (1410065408, 2));
3290 /// assert_eq!(1_000_000_000u32.carrying_mul_add(10, 10, 10), (1410065428, 2));
3291 #[doc = concat!("assert_eq!(",
3292 stringify!($SelfT), "::MAX.carrying_mul_add(", stringify!($SelfT), "::MAX, ", stringify!($SelfT), "::MAX, ", stringify!($SelfT), "::MAX), ",
3293 "(", stringify!($SelfT), "::MAX, ", stringify!($SelfT), "::MAX));"
3294 )]
3295 /// ```
3296 ///
3297 /// This is the core per-digit operation for "grade school" O(n²) multiplication.
3298 ///
3299 /// Please note that this example is shared between integer types,
3300 /// using `u8` for simplicity of the demonstration.
3301 ///
3302 /// ```
3303 /// fn quadratic_mul<const N: usize>(a: [u8; N], b: [u8; N]) -> [u8; N] {
3304 /// let mut out = [0; N];
3305 /// for j in 0..N {
3306 /// let mut carry = 0;
3307 /// for i in 0..(N - j) {
3308 /// (out[j + i], carry) = u8::carrying_mul_add(a[i], b[j], out[j + i], carry);
3309 /// }
3310 /// }
3311 /// out
3312 /// }
3313 ///
3314 /// // -1 * -1 == 1
3315 /// assert_eq!(quadratic_mul([0xFF; 3], [0xFF; 3]), [1, 0, 0]);
3316 ///
3317 /// assert_eq!(u32::wrapping_mul(0x9e3779b9, 0x7f4a7c15), 0xcffc982d);
3318 /// assert_eq!(
3319 /// quadratic_mul(u32::to_le_bytes(0x9e3779b9), u32::to_le_bytes(0x7f4a7c15)),
3320 /// u32::to_le_bytes(0xcffc982d)
3321 /// );
3322 /// ```
3323 #[stable(feature = "unsigned_bigint_helpers", since = "1.91.0")]
3324 #[rustc_const_unstable(feature = "const_unsigned_bigint_helpers", issue = "152015")]
3325 #[must_use = "this returns the result of the operation, \
3326 without modifying the original"]
3327 #[inline]
3328 pub const fn carrying_mul_add(self, rhs: Self, carry: Self, add: Self) -> (Self, Self) {
3329 intrinsics::carrying_mul_add(self, rhs, carry, add)
3330 }
3331
3332 /// Calculates the divisor when `self` is divided by `rhs`.
3333 ///
3334 /// Returns a tuple of the divisor along with a boolean indicating
3335 /// whether an arithmetic overflow would occur. Note that for unsigned
3336 /// integers overflow never occurs, so the second value is always
3337 /// `false`.
3338 ///
3339 /// # Panics
3340 ///
3341 /// This function will panic if `rhs` is zero.
3342 ///
3343 /// # Examples
3344 ///
3345 /// ```
3346 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".overflowing_div(2), (2, false));")]
3347 /// ```
3348 #[inline(always)]
3349 #[stable(feature = "wrapping", since = "1.7.0")]
3350 #[rustc_const_stable(feature = "const_overflowing_int_methods", since = "1.52.0")]
3351 #[must_use = "this returns the result of the operation, \
3352 without modifying the original"]
3353 #[track_caller]
3354 pub const fn overflowing_div(self, rhs: Self) -> (Self, bool) {
3355 (self / rhs, false)
3356 }
3357
3358 /// Calculates the quotient of Euclidean division `self.div_euclid(rhs)`.
3359 ///
3360 /// Returns a tuple of the divisor along with a boolean indicating
3361 /// whether an arithmetic overflow would occur. Note that for unsigned
3362 /// integers overflow never occurs, so the second value is always
3363 /// `false`.
3364 /// Since, for the positive integers, all common
3365 /// definitions of division are equal, this
3366 /// is exactly equal to `self.overflowing_div(rhs)`.
3367 ///
3368 /// # Panics
3369 ///
3370 /// This function will panic if `rhs` is zero.
3371 ///
3372 /// # Examples
3373 ///
3374 /// ```
3375 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".overflowing_div_euclid(2), (2, false));")]
3376 /// ```
3377 #[inline(always)]
3378 #[stable(feature = "euclidean_division", since = "1.38.0")]
3379 #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.52.0")]
3380 #[must_use = "this returns the result of the operation, \
3381 without modifying the original"]
3382 #[track_caller]
3383 pub const fn overflowing_div_euclid(self, rhs: Self) -> (Self, bool) {
3384 (self / rhs, false)
3385 }
3386
3387 /// Calculates the remainder when `self` is divided by `rhs`.
3388 ///
3389 /// Returns a tuple of the remainder after dividing along with a boolean
3390 /// indicating whether an arithmetic overflow would occur. Note that for
3391 /// unsigned integers overflow never occurs, so the second value is
3392 /// always `false`.
3393 ///
3394 /// # Panics
3395 ///
3396 /// This function will panic if `rhs` is zero.
3397 ///
3398 /// # Examples
3399 ///
3400 /// ```
3401 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".overflowing_rem(2), (1, false));")]
3402 /// ```
3403 #[inline(always)]
3404 #[stable(feature = "wrapping", since = "1.7.0")]
3405 #[rustc_const_stable(feature = "const_overflowing_int_methods", since = "1.52.0")]
3406 #[must_use = "this returns the result of the operation, \
3407 without modifying the original"]
3408 #[track_caller]
3409 pub const fn overflowing_rem(self, rhs: Self) -> (Self, bool) {
3410 (self % rhs, false)
3411 }
3412
3413 /// Calculates the remainder `self.rem_euclid(rhs)` as if by Euclidean division.
3414 ///
3415 /// Returns a tuple of the modulo after dividing along with a boolean
3416 /// indicating whether an arithmetic overflow would occur. Note that for
3417 /// unsigned integers overflow never occurs, so the second value is
3418 /// always `false`.
3419 /// Since, for the positive integers, all common
3420 /// definitions of division are equal, this operation
3421 /// is exactly equal to `self.overflowing_rem(rhs)`.
3422 ///
3423 /// # Panics
3424 ///
3425 /// This function will panic if `rhs` is zero.
3426 ///
3427 /// # Examples
3428 ///
3429 /// ```
3430 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".overflowing_rem_euclid(2), (1, false));")]
3431 /// ```
3432 #[inline(always)]
3433 #[stable(feature = "euclidean_division", since = "1.38.0")]
3434 #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.52.0")]
3435 #[must_use = "this returns the result of the operation, \
3436 without modifying the original"]
3437 #[track_caller]
3438 pub const fn overflowing_rem_euclid(self, rhs: Self) -> (Self, bool) {
3439 (self % rhs, false)
3440 }
3441
3442 /// Negates self in an overflowing fashion.
3443 ///
3444 /// Returns `!self + 1` using wrapping operations to return the value
3445 /// that represents the negation of this unsigned value. Note that for
3446 /// positive unsigned values overflow always occurs, but negating 0 does
3447 /// not overflow.
3448 ///
3449 /// # Examples
3450 ///
3451 /// ```
3452 #[doc = concat!("assert_eq!(0", stringify!($SelfT), ".overflowing_neg(), (0, false));")]
3453 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".overflowing_neg(), (-2i32 as ", stringify!($SelfT), ", true));")]
3454 /// ```
3455 #[inline(always)]
3456 #[stable(feature = "wrapping", since = "1.7.0")]
3457 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
3458 #[must_use = "this returns the result of the operation, \
3459 without modifying the original"]
3460 pub const fn overflowing_neg(self) -> (Self, bool) {
3461 ((!self).wrapping_add(1), self != 0)
3462 }
3463
3464 /// Shifts self left by `rhs` bits.
3465 ///
3466 /// Returns a tuple of the shifted version of self along with a boolean
3467 /// indicating whether the shift value was larger than or equal to the
3468 /// number of bits. If the shift value is too large, then value is
3469 /// masked (N-1) where N is the number of bits, and this value is then
3470 /// used to perform the shift.
3471 ///
3472 /// # Examples
3473 ///
3474 /// ```
3475 #[doc = concat!("assert_eq!(0x1", stringify!($SelfT), ".overflowing_shl(4), (0x10, false));")]
3476 #[doc = concat!("assert_eq!(0x1", stringify!($SelfT), ".overflowing_shl(132), (0x10, true));")]
3477 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".overflowing_shl(", stringify!($BITS_MINUS_ONE), "), (0, false));")]
3478 /// ```
3479 #[stable(feature = "wrapping", since = "1.7.0")]
3480 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
3481 #[must_use = "this returns the result of the operation, \
3482 without modifying the original"]
3483 #[inline(always)]
3484 pub const fn overflowing_shl(self, rhs: u32) -> (Self, bool) {
3485 (self.wrapping_shl(rhs), rhs >= Self::BITS)
3486 }
3487
3488 /// Shifts self right by `rhs` bits.
3489 ///
3490 /// Returns a tuple of the shifted version of self along with a boolean
3491 /// indicating whether the shift value was larger than or equal to the
3492 /// number of bits. If the shift value is too large, then value is
3493 /// masked (N-1) where N is the number of bits, and this value is then
3494 /// used to perform the shift.
3495 ///
3496 /// # Examples
3497 ///
3498 /// ```
3499 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".overflowing_shr(4), (0x1, false));")]
3500 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".overflowing_shr(132), (0x1, true));")]
3501 /// ```
3502 #[stable(feature = "wrapping", since = "1.7.0")]
3503 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
3504 #[must_use = "this returns the result of the operation, \
3505 without modifying the original"]
3506 #[inline(always)]
3507 pub const fn overflowing_shr(self, rhs: u32) -> (Self, bool) {
3508 (self.wrapping_shr(rhs), rhs >= Self::BITS)
3509 }
3510
3511 /// Raises self to the power of `exp`, using exponentiation by squaring.
3512 ///
3513 /// Returns a tuple of the exponentiation along with a bool indicating
3514 /// whether an overflow happened.
3515 ///
3516 /// # Examples
3517 ///
3518 /// ```
3519 #[doc = concat!("assert_eq!(3", stringify!($SelfT), ".overflowing_pow(5), (243, false));")]
3520 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".overflowing_pow(0), (1, false));")]
3521 /// assert_eq!(3u8.overflowing_pow(6), (217, true));
3522 /// ```
3523 #[stable(feature = "no_panic_pow", since = "1.34.0")]
3524 #[rustc_const_stable(feature = "const_int_pow", since = "1.50.0")]
3525 #[must_use = "this returns the result of the operation, \
3526 without modifying the original"]
3527 #[inline]
3528 pub const fn overflowing_pow(self, mut exp: u32) -> (Self, bool) {
3529 if exp == 0{
3530 return (1,false);
3531 }
3532 let mut base = self;
3533 let mut acc: Self = 1;
3534 let mut overflown = false;
3535 // Scratch space for storing results of overflowing_mul.
3536 let mut r;
3537
3538 loop {
3539 if (exp & 1) == 1 {
3540 r = acc.overflowing_mul(base);
3541 // since exp!=0, finally the exp must be 1.
3542 if exp == 1 {
3543 r.1 |= overflown;
3544 return r;
3545 }
3546 acc = r.0;
3547 overflown |= r.1;
3548 }
3549 exp /= 2;
3550 r = base.overflowing_mul(base);
3551 base = r.0;
3552 overflown |= r.1;
3553 }
3554 }
3555
3556 /// Raises self to the power of `exp`, using exponentiation by squaring.
3557 ///
3558 /// # Examples
3559 ///
3560 /// ```
3561 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".pow(5), 32);")]
3562 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".pow(0), 1);")]
3563 /// ```
3564 #[stable(feature = "rust1", since = "1.0.0")]
3565 #[rustc_const_stable(feature = "const_int_pow", since = "1.50.0")]
3566 #[must_use = "this returns the result of the operation, \
3567 without modifying the original"]
3568 #[inline]
3569 #[rustc_inherit_overflow_checks]
3570 pub const fn pow(self, mut exp: u32) -> Self {
3571 if exp == 0 {
3572 return 1;
3573 }
3574 let mut base = self;
3575 let mut acc = 1;
3576
3577 if intrinsics::is_val_statically_known(exp) {
3578 while exp > 1 {
3579 if (exp & 1) == 1 {
3580 acc = acc * base;
3581 }
3582 exp /= 2;
3583 base = base * base;
3584 }
3585
3586 // since exp!=0, finally the exp must be 1.
3587 // Deal with the final bit of the exponent separately, since
3588 // squaring the base afterwards is not necessary and may cause a
3589 // needless overflow.
3590 acc * base
3591 } else {
3592 // This is faster than the above when the exponent is not known
3593 // at compile time. We can't use the same code for the constant
3594 // exponent case because LLVM is currently unable to unroll
3595 // this loop.
3596 loop {
3597 if (exp & 1) == 1 {
3598 acc = acc * base;
3599 // since exp!=0, finally the exp must be 1.
3600 if exp == 1 {
3601 return acc;
3602 }
3603 }
3604 exp /= 2;
3605 base = base * base;
3606 }
3607 }
3608 }
3609
3610 /// Returns the square root of the number, rounded down.
3611 ///
3612 /// # Examples
3613 ///
3614 /// ```
3615 #[doc = concat!("assert_eq!(10", stringify!($SelfT), ".isqrt(), 3);")]
3616 /// ```
3617 #[stable(feature = "isqrt", since = "1.84.0")]
3618 #[rustc_const_stable(feature = "isqrt", since = "1.84.0")]
3619 #[must_use = "this returns the result of the operation, \
3620 without modifying the original"]
3621 #[inline]
3622 pub const fn isqrt(self) -> Self {
3623 let result = imp::int_sqrt::$ActualT(self as $ActualT) as Self;
3624
3625 // Inform the optimizer what the range of outputs is. If testing
3626 // `core` crashes with no panic message and a `num::int_sqrt::u*`
3627 // test failed, it's because your edits caused these assertions or
3628 // the assertions in `fn isqrt` of `nonzero.rs` to become false.
3629 //
3630 // SAFETY: Integer square root is a monotonically nondecreasing
3631 // function, which means that increasing the input will never
3632 // cause the output to decrease. Thus, since the input for unsigned
3633 // integers is bounded by `[0, <$ActualT>::MAX]`, sqrt(n) will be
3634 // bounded by `[sqrt(0), sqrt(<$ActualT>::MAX)]` and bounding the
3635 // input by `[1, <$ActualT>::MAX]` bounds sqrt(n) by
3636 // `[sqrt(1), sqrt(<$ActualT>::MAX)]`.
3637 unsafe {
3638 const MAX_RESULT: $SelfT = imp::int_sqrt::$ActualT(<$ActualT>::MAX) as $SelfT;
3639 crate::hint::assert_unchecked(result <= MAX_RESULT)
3640 }
3641
3642 if self >= 1 {
3643 // SAFETY: The above statements about monotonicity also apply here.
3644 // Since the input in this branch is bounded by `[1, <$ActualT>::MAX]`,
3645 // sqrt(n) is bounded by `[sqrt(1), sqrt(<$ActualT>::MAX)]`, and
3646 // `sqrt(1) == 1`.
3647 unsafe { crate::hint::assert_unchecked(result >= 1) }
3648 }
3649
3650 // SAFETY: the isqrt implementation returns the square root and rounds down,
3651 // meaning `result * result <= self`. This implies `result <= self`.
3652 // The compiler needs both to optimize for both.
3653 // `result * result <= self` implies the multiplication will not overflow.
3654 unsafe {
3655 crate::hint::assert_unchecked(result.unchecked_mul(result) <= self);
3656 crate::hint::assert_unchecked(result <= self);
3657 }
3658
3659 result
3660 }
3661
3662 /// Performs Euclidean division.
3663 ///
3664 /// Since, for the positive integers, all common
3665 /// definitions of division are equal, this
3666 /// is exactly equal to `self / rhs`.
3667 ///
3668 /// # Panics
3669 ///
3670 /// This function will panic if `rhs` is zero.
3671 ///
3672 /// # Examples
3673 ///
3674 /// ```
3675 #[doc = concat!("assert_eq!(7", stringify!($SelfT), ".div_euclid(4), 1); // or any other integer type")]
3676 /// ```
3677 #[stable(feature = "euclidean_division", since = "1.38.0")]
3678 #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.52.0")]
3679 #[must_use = "this returns the result of the operation, \
3680 without modifying the original"]
3681 #[inline(always)]
3682 #[track_caller]
3683 pub const fn div_euclid(self, rhs: Self) -> Self {
3684 self / rhs
3685 }
3686
3687
3688 /// Calculates the least remainder of `self` when divided by
3689 /// `rhs`.
3690 ///
3691 /// Since, for the positive integers, all common
3692 /// definitions of division are equal, this
3693 /// is exactly equal to `self % rhs`.
3694 ///
3695 /// # Panics
3696 ///
3697 /// This function will panic if `rhs` is zero.
3698 ///
3699 /// # Examples
3700 ///
3701 /// ```
3702 #[doc = concat!("assert_eq!(7", stringify!($SelfT), ".rem_euclid(4), 3); // or any other integer type")]
3703 /// ```
3704 #[doc(alias = "modulo", alias = "mod")]
3705 #[stable(feature = "euclidean_division", since = "1.38.0")]
3706 #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.52.0")]
3707 #[must_use = "this returns the result of the operation, \
3708 without modifying the original"]
3709 #[inline(always)]
3710 #[track_caller]
3711 pub const fn rem_euclid(self, rhs: Self) -> Self {
3712 self % rhs
3713 }
3714
3715 /// Calculates the quotient of `self` and `rhs`, rounding the result towards negative infinity.
3716 ///
3717 /// This is the same as performing `self / rhs` for all unsigned integers.
3718 ///
3719 /// # Panics
3720 ///
3721 /// This function will panic if `rhs` is zero.
3722 ///
3723 /// # Examples
3724 ///
3725 /// ```
3726 /// #![feature(int_roundings)]
3727 #[doc = concat!("assert_eq!(7_", stringify!($SelfT), ".div_floor(4), 1);")]
3728 /// ```
3729 #[unstable(feature = "int_roundings", issue = "88581")]
3730 #[must_use = "this returns the result of the operation, \
3731 without modifying the original"]
3732 #[inline(always)]
3733 #[track_caller]
3734 pub const fn div_floor(self, rhs: Self) -> Self {
3735 self / rhs
3736 }
3737
3738 /// Calculates the quotient of `self` and `rhs`, rounding the result towards positive infinity.
3739 ///
3740 /// # Panics
3741 ///
3742 /// This function will panic if `rhs` is zero.
3743 ///
3744 /// # Examples
3745 ///
3746 /// ```
3747 #[doc = concat!("assert_eq!(7_", stringify!($SelfT), ".div_ceil(4), 2);")]
3748 /// ```
3749 #[stable(feature = "int_roundings1", since = "1.73.0")]
3750 #[rustc_const_stable(feature = "int_roundings1", since = "1.73.0")]
3751 #[must_use = "this returns the result of the operation, \
3752 without modifying the original"]
3753 #[inline]
3754 #[track_caller]
3755 pub const fn div_ceil(self, rhs: Self) -> Self {
3756 let d = self / rhs;
3757 let r = self % rhs;
3758 if r > 0 {
3759 d + 1
3760 } else {
3761 d
3762 }
3763 }
3764
3765 /// Calculates the smallest value greater than or equal to `self` that
3766 /// is a multiple of `rhs`.
3767 ///
3768 /// # Panics
3769 ///
3770 /// This function will panic if `rhs` is zero.
3771 ///
3772 /// ## Overflow behavior
3773 ///
3774 /// On overflow, this function will panic if overflow checks are enabled (default in debug
3775 /// mode) and wrap if overflow checks are disabled (default in release mode).
3776 ///
3777 /// # Examples
3778 ///
3779 /// ```
3780 #[doc = concat!("assert_eq!(16_", stringify!($SelfT), ".next_multiple_of(8), 16);")]
3781 #[doc = concat!("assert_eq!(23_", stringify!($SelfT), ".next_multiple_of(8), 24);")]
3782 /// ```
3783 #[stable(feature = "int_roundings1", since = "1.73.0")]
3784 #[rustc_const_stable(feature = "int_roundings1", since = "1.73.0")]
3785 #[must_use = "this returns the result of the operation, \
3786 without modifying the original"]
3787 #[inline]
3788 #[rustc_inherit_overflow_checks]
3789 pub const fn next_multiple_of(self, rhs: Self) -> Self {
3790 match self % rhs {
3791 0 => self,
3792 r => self + (rhs - r)
3793 }
3794 }
3795
3796 /// Calculates the smallest value greater than or equal to `self` that
3797 /// is a multiple of `rhs`. Returns `None` if `rhs` is zero or the
3798 /// operation would result in overflow.
3799 ///
3800 /// # Examples
3801 ///
3802 /// ```
3803 #[doc = concat!("assert_eq!(16_", stringify!($SelfT), ".checked_next_multiple_of(8), Some(16));")]
3804 #[doc = concat!("assert_eq!(23_", stringify!($SelfT), ".checked_next_multiple_of(8), Some(24));")]
3805 #[doc = concat!("assert_eq!(1_", stringify!($SelfT), ".checked_next_multiple_of(0), None);")]
3806 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.checked_next_multiple_of(2), None);")]
3807 /// ```
3808 #[stable(feature = "int_roundings1", since = "1.73.0")]
3809 #[rustc_const_stable(feature = "int_roundings1", since = "1.73.0")]
3810 #[must_use = "this returns the result of the operation, \
3811 without modifying the original"]
3812 #[inline]
3813 pub const fn checked_next_multiple_of(self, rhs: Self) -> Option<Self> {
3814 match try_opt!(self.checked_rem(rhs)) {
3815 0 => Some(self),
3816 // rhs - r cannot overflow because r is smaller than rhs
3817 r => self.checked_add(rhs - r)
3818 }
3819 }
3820
3821 /// Returns `true` if `self` is an integer multiple of `rhs`, and false otherwise.
3822 ///
3823 /// This function is equivalent to `self % rhs == 0`, except that it will not panic
3824 /// for `rhs == 0`. Instead, `0.is_multiple_of(0) == true`, and for any non-zero `n`,
3825 /// `n.is_multiple_of(0) == false`.
3826 ///
3827 /// # Examples
3828 ///
3829 /// ```
3830 #[doc = concat!("assert!(6_", stringify!($SelfT), ".is_multiple_of(2));")]
3831 #[doc = concat!("assert!(!5_", stringify!($SelfT), ".is_multiple_of(2));")]
3832 ///
3833 #[doc = concat!("assert!(0_", stringify!($SelfT), ".is_multiple_of(0));")]
3834 #[doc = concat!("assert!(!6_", stringify!($SelfT), ".is_multiple_of(0));")]
3835 /// ```
3836 #[stable(feature = "unsigned_is_multiple_of", since = "1.87.0")]
3837 #[rustc_const_stable(feature = "unsigned_is_multiple_of", since = "1.87.0")]
3838 #[must_use]
3839 #[inline]
3840 pub const fn is_multiple_of(self, rhs: Self) -> bool {
3841 match rhs {
3842 0 => self == 0,
3843 _ => self % rhs == 0,
3844 }
3845 }
3846
3847 /// Returns `true` if and only if `self == 2^k` for some unsigned integer `k`.
3848 ///
3849 /// # Examples
3850 ///
3851 /// ```
3852 #[doc = concat!("assert!(16", stringify!($SelfT), ".is_power_of_two());")]
3853 #[doc = concat!("assert!(!10", stringify!($SelfT), ".is_power_of_two());")]
3854 /// ```
3855 #[must_use]
3856 #[stable(feature = "rust1", since = "1.0.0")]
3857 #[rustc_const_stable(feature = "const_is_power_of_two", since = "1.32.0")]
3858 #[inline(always)]
3859 pub const fn is_power_of_two(self) -> bool {
3860 self.count_ones() == 1
3861 }
3862
3863 // Returns one less than next power of two.
3864 // (For 8u8 next power of two is 8u8 and for 6u8 it is 8u8)
3865 //
3866 // 8u8.one_less_than_next_power_of_two() == 7
3867 // 6u8.one_less_than_next_power_of_two() == 7
3868 //
3869 // This method cannot overflow, as in the `next_power_of_two`
3870 // overflow cases it instead ends up returning the maximum value
3871 // of the type, and can return 0 for 0.
3872 #[inline]
3873 const fn one_less_than_next_power_of_two(self) -> Self {
3874 if self <= 1 { return 0; }
3875
3876 let p = self - 1;
3877 // SAFETY: Because `p > 0`, it cannot consist entirely of leading zeros.
3878 // That means the shift is always in-bounds, and some processors
3879 // (such as intel pre-haswell) have more efficient ctlz
3880 // intrinsics when the argument is non-zero.
3881 let z = unsafe { intrinsics::ctlz_nonzero(p) };
3882 <$SelfT>::MAX >> z
3883 }
3884
3885 /// Returns the smallest power of two greater than or equal to `self`.
3886 ///
3887 /// When return value overflows (i.e., `self > (1 << (N-1))` for type
3888 /// `uN`), it panics in debug mode and the return value is wrapped to 0 in
3889 /// release mode (the only situation in which this method can return 0).
3890 ///
3891 /// # Examples
3892 ///
3893 /// ```
3894 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".next_power_of_two(), 2);")]
3895 #[doc = concat!("assert_eq!(3", stringify!($SelfT), ".next_power_of_two(), 4);")]
3896 #[doc = concat!("assert_eq!(0", stringify!($SelfT), ".next_power_of_two(), 1);")]
3897 /// ```
3898 #[stable(feature = "rust1", since = "1.0.0")]
3899 #[rustc_const_stable(feature = "const_int_pow", since = "1.50.0")]
3900 #[must_use = "this returns the result of the operation, \
3901 without modifying the original"]
3902 #[inline]
3903 #[rustc_inherit_overflow_checks]
3904 pub const fn next_power_of_two(self) -> Self {
3905 self.one_less_than_next_power_of_two() + 1
3906 }
3907
3908 /// Returns the smallest power of two greater than or equal to `self`. If
3909 /// the next power of two is greater than the type's maximum value,
3910 /// `None` is returned, otherwise the power of two is wrapped in `Some`.
3911 ///
3912 /// # Examples
3913 ///
3914 /// ```
3915 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".checked_next_power_of_two(), Some(2));")]
3916 #[doc = concat!("assert_eq!(3", stringify!($SelfT), ".checked_next_power_of_two(), Some(4));")]
3917 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.checked_next_power_of_two(), None);")]
3918 /// ```
3919 #[inline]
3920 #[stable(feature = "rust1", since = "1.0.0")]
3921 #[rustc_const_stable(feature = "const_int_pow", since = "1.50.0")]
3922 #[must_use = "this returns the result of the operation, \
3923 without modifying the original"]
3924 pub const fn checked_next_power_of_two(self) -> Option<Self> {
3925 self.one_less_than_next_power_of_two().checked_add(1)
3926 }
3927
3928 /// Returns the smallest power of two greater than or equal to `n`. If
3929 /// the next power of two is greater than the type's maximum value,
3930 /// the return value is wrapped to `0`.
3931 ///
3932 /// # Examples
3933 ///
3934 /// ```
3935 /// #![feature(wrapping_next_power_of_two)]
3936 ///
3937 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".wrapping_next_power_of_two(), 2);")]
3938 #[doc = concat!("assert_eq!(3", stringify!($SelfT), ".wrapping_next_power_of_two(), 4);")]
3939 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.wrapping_next_power_of_two(), 0);")]
3940 /// ```
3941 #[inline]
3942 #[unstable(feature = "wrapping_next_power_of_two", issue = "32463",
3943 reason = "needs decision on wrapping behavior")]
3944 #[must_use = "this returns the result of the operation, \
3945 without modifying the original"]
3946 pub const fn wrapping_next_power_of_two(self) -> Self {
3947 self.one_less_than_next_power_of_two().wrapping_add(1)
3948 }
3949
3950 /// Returns the memory representation of this integer as a byte array in
3951 /// big-endian (network) byte order.
3952 ///
3953 #[doc = $to_xe_bytes_doc]
3954 ///
3955 /// # Examples
3956 ///
3957 /// ```
3958 #[doc = concat!("let bytes = ", $swap_op, stringify!($SelfT), ".to_be_bytes();")]
3959 #[doc = concat!("assert_eq!(bytes, ", $be_bytes, ");")]
3960 /// ```
3961 #[stable(feature = "int_to_from_bytes", since = "1.32.0")]
3962 #[rustc_const_stable(feature = "const_int_conversion", since = "1.44.0")]
3963 #[must_use = "this returns the result of the operation, \
3964 without modifying the original"]
3965 #[inline]
3966 pub const fn to_be_bytes(self) -> [u8; size_of::<Self>()] {
3967 self.to_be().to_ne_bytes()
3968 }
3969
3970 /// Returns the memory representation of this integer as a byte array in
3971 /// little-endian byte order.
3972 ///
3973 #[doc = $to_xe_bytes_doc]
3974 ///
3975 /// # Examples
3976 ///
3977 /// ```
3978 #[doc = concat!("let bytes = ", $swap_op, stringify!($SelfT), ".to_le_bytes();")]
3979 #[doc = concat!("assert_eq!(bytes, ", $le_bytes, ");")]
3980 /// ```
3981 #[stable(feature = "int_to_from_bytes", since = "1.32.0")]
3982 #[rustc_const_stable(feature = "const_int_conversion", since = "1.44.0")]
3983 #[must_use = "this returns the result of the operation, \
3984 without modifying the original"]
3985 #[inline]
3986 pub const fn to_le_bytes(self) -> [u8; size_of::<Self>()] {
3987 self.to_le().to_ne_bytes()
3988 }
3989
3990 /// Returns the memory representation of this integer as a byte array in
3991 /// native byte order.
3992 ///
3993 /// As the target platform's native endianness is used, portable code
3994 /// should use [`to_be_bytes`] or [`to_le_bytes`], as appropriate,
3995 /// instead.
3996 ///
3997 #[doc = $to_xe_bytes_doc]
3998 ///
3999 /// [`to_be_bytes`]: Self::to_be_bytes
4000 /// [`to_le_bytes`]: Self::to_le_bytes
4001 ///
4002 /// # Examples
4003 ///
4004 /// ```
4005 #[doc = concat!("let bytes = ", $swap_op, stringify!($SelfT), ".to_ne_bytes();")]
4006 /// assert_eq!(
4007 /// bytes,
4008 /// if cfg!(target_endian = "big") {
4009 #[doc = concat!(" ", $be_bytes)]
4010 /// } else {
4011 #[doc = concat!(" ", $le_bytes)]
4012 /// }
4013 /// );
4014 /// ```
4015 #[stable(feature = "int_to_from_bytes", since = "1.32.0")]
4016 #[rustc_const_stable(feature = "const_int_conversion", since = "1.44.0")]
4017 #[must_use = "this returns the result of the operation, \
4018 without modifying the original"]
4019 #[allow(unnecessary_transmutes)]
4020 // SAFETY: const sound because integers are plain old datatypes so we can always
4021 // transmute them to arrays of bytes
4022 #[inline]
4023 pub const fn to_ne_bytes(self) -> [u8; size_of::<Self>()] {
4024 // SAFETY: integers are plain old datatypes so we can always transmute them to
4025 // arrays of bytes
4026 unsafe { mem::transmute(self) }
4027 }
4028
4029 /// Creates a native endian integer value from its representation
4030 /// as a byte array in big endian.
4031 ///
4032 #[doc = $from_xe_bytes_doc]
4033 ///
4034 /// # Examples
4035 ///
4036 /// ```
4037 #[doc = concat!("let value = ", stringify!($SelfT), "::from_be_bytes(", $be_bytes, ");")]
4038 #[doc = concat!("assert_eq!(value, ", $swap_op, ");")]
4039 /// ```
4040 ///
4041 /// When starting from a slice rather than an array, fallible conversion APIs can be used:
4042 ///
4043 /// ```
4044 #[doc = concat!("fn read_be_", stringify!($SelfT), "(input: &mut &[u8]) -> ", stringify!($SelfT), " {")]
4045 #[doc = concat!(" let (int_bytes, rest) = input.split_at(size_of::<", stringify!($SelfT), ">());")]
4046 /// *input = rest;
4047 #[doc = concat!(" ", stringify!($SelfT), "::from_be_bytes(int_bytes.try_into().unwrap())")]
4048 /// }
4049 /// ```
4050 #[stable(feature = "int_to_from_bytes", since = "1.32.0")]
4051 #[rustc_const_stable(feature = "const_int_conversion", since = "1.44.0")]
4052 #[must_use]
4053 #[inline]
4054 pub const fn from_be_bytes(bytes: [u8; size_of::<Self>()]) -> Self {
4055 Self::from_be(Self::from_ne_bytes(bytes))
4056 }
4057
4058 /// Creates a native endian integer value from its representation
4059 /// as a byte array in little endian.
4060 ///
4061 #[doc = $from_xe_bytes_doc]
4062 ///
4063 /// # Examples
4064 ///
4065 /// ```
4066 #[doc = concat!("let value = ", stringify!($SelfT), "::from_le_bytes(", $le_bytes, ");")]
4067 #[doc = concat!("assert_eq!(value, ", $swap_op, ");")]
4068 /// ```
4069 ///
4070 /// When starting from a slice rather than an array, fallible conversion APIs can be used:
4071 ///
4072 /// ```
4073 #[doc = concat!("fn read_le_", stringify!($SelfT), "(input: &mut &[u8]) -> ", stringify!($SelfT), " {")]
4074 #[doc = concat!(" let (int_bytes, rest) = input.split_at(size_of::<", stringify!($SelfT), ">());")]
4075 /// *input = rest;
4076 #[doc = concat!(" ", stringify!($SelfT), "::from_le_bytes(int_bytes.try_into().unwrap())")]
4077 /// }
4078 /// ```
4079 #[stable(feature = "int_to_from_bytes", since = "1.32.0")]
4080 #[rustc_const_stable(feature = "const_int_conversion", since = "1.44.0")]
4081 #[must_use]
4082 #[inline]
4083 pub const fn from_le_bytes(bytes: [u8; size_of::<Self>()]) -> Self {
4084 Self::from_le(Self::from_ne_bytes(bytes))
4085 }
4086
4087 /// Creates a native endian integer value from its memory representation
4088 /// as a byte array in native endianness.
4089 ///
4090 /// As the target platform's native endianness is used, portable code
4091 /// likely wants to use [`from_be_bytes`] or [`from_le_bytes`], as
4092 /// appropriate instead.
4093 ///
4094 /// [`from_be_bytes`]: Self::from_be_bytes
4095 /// [`from_le_bytes`]: Self::from_le_bytes
4096 ///
4097 #[doc = $from_xe_bytes_doc]
4098 ///
4099 /// # Examples
4100 ///
4101 /// ```
4102 #[doc = concat!("let value = ", stringify!($SelfT), "::from_ne_bytes(if cfg!(target_endian = \"big\") {")]
4103 #[doc = concat!(" ", $be_bytes, "")]
4104 /// } else {
4105 #[doc = concat!(" ", $le_bytes, "")]
4106 /// });
4107 #[doc = concat!("assert_eq!(value, ", $swap_op, ");")]
4108 /// ```
4109 ///
4110 /// When starting from a slice rather than an array, fallible conversion APIs can be used:
4111 ///
4112 /// ```
4113 #[doc = concat!("fn read_ne_", stringify!($SelfT), "(input: &mut &[u8]) -> ", stringify!($SelfT), " {")]
4114 #[doc = concat!(" let (int_bytes, rest) = input.split_at(size_of::<", stringify!($SelfT), ">());")]
4115 /// *input = rest;
4116 #[doc = concat!(" ", stringify!($SelfT), "::from_ne_bytes(int_bytes.try_into().unwrap())")]
4117 /// }
4118 /// ```
4119 #[stable(feature = "int_to_from_bytes", since = "1.32.0")]
4120 #[rustc_const_stable(feature = "const_int_conversion", since = "1.44.0")]
4121 #[allow(unnecessary_transmutes)]
4122 #[must_use]
4123 // SAFETY: const sound because integers are plain old datatypes so we can always
4124 // transmute to them
4125 #[inline]
4126 pub const fn from_ne_bytes(bytes: [u8; size_of::<Self>()]) -> Self {
4127 // SAFETY: integers are plain old datatypes so we can always transmute to them
4128 unsafe { mem::transmute(bytes) }
4129 }
4130
4131 /// New code should prefer to use
4132 #[doc = concat!("[`", stringify!($SelfT), "::MIN", "`] instead.")]
4133 ///
4134 /// Returns the smallest value that can be represented by this integer type.
4135 #[stable(feature = "rust1", since = "1.0.0")]
4136 #[rustc_promotable]
4137 #[inline(always)]
4138 #[rustc_const_stable(feature = "const_max_value", since = "1.32.0")]
4139 #[deprecated(since = "TBD", note = "replaced by the `MIN` associated constant on this type")]
4140 #[rustc_diagnostic_item = concat!(stringify!($SelfT), "_legacy_fn_min_value")]
4141 pub const fn min_value() -> Self { Self::MIN }
4142
4143 /// New code should prefer to use
4144 #[doc = concat!("[`", stringify!($SelfT), "::MAX", "`] instead.")]
4145 ///
4146 /// Returns the largest value that can be represented by this integer type.
4147 #[stable(feature = "rust1", since = "1.0.0")]
4148 #[rustc_promotable]
4149 #[inline(always)]
4150 #[rustc_const_stable(feature = "const_max_value", since = "1.32.0")]
4151 #[deprecated(since = "TBD", note = "replaced by the `MAX` associated constant on this type")]
4152 #[rustc_diagnostic_item = concat!(stringify!($SelfT), "_legacy_fn_max_value")]
4153 pub const fn max_value() -> Self { Self::MAX }
4154
4155 /// Truncate an integer to an integer of the same size or smaller, preserving the least
4156 /// significant bits.
4157 ///
4158 /// # Examples
4159 ///
4160 /// ```
4161 /// #![feature(integer_widen_truncate)]
4162 #[doc = concat!("assert_eq!(120u8, 120", stringify!($SelfT), ".truncate());")]
4163 /// assert_eq!(120u8, 376u32.truncate());
4164 /// ```
4165 #[must_use = "this returns the truncated value and does not modify the original"]
4166 #[unstable(feature = "integer_widen_truncate", issue = "154330")]
4167 #[rustc_const_unstable(feature = "integer_widen_truncate", issue = "154330")]
4168 #[inline]
4169 pub const fn truncate<Target>(self) -> Target
4170 where Self: [const] traits::TruncateTarget<Target>
4171 {
4172 traits::TruncateTarget::internal_truncate(self)
4173 }
4174
4175 /// Truncate an integer to an integer of the same size or smaller, saturating at numeric bounds
4176 /// instead of truncating.
4177 ///
4178 /// # Examples
4179 ///
4180 /// ```
4181 /// #![feature(integer_widen_truncate)]
4182 #[doc = concat!("assert_eq!(120u8, 120", stringify!($SelfT), ".saturating_truncate());")]
4183 /// assert_eq!(255u8, 376u32.saturating_truncate());
4184 /// ```
4185 #[must_use = "this returns the truncated value and does not modify the original"]
4186 #[unstable(feature = "integer_widen_truncate", issue = "154330")]
4187 #[rustc_const_unstable(feature = "integer_widen_truncate", issue = "154330")]
4188 #[inline]
4189 pub const fn saturating_truncate<Target>(self) -> Target
4190 where Self: [const] traits::TruncateTarget<Target>
4191 {
4192 traits::TruncateTarget::internal_saturating_truncate(self)
4193 }
4194
4195 /// Truncate an integer to an integer of the same size or smaller, returning `None` if the value
4196 /// is outside the bounds of the smaller type.
4197 ///
4198 /// # Examples
4199 ///
4200 /// ```
4201 /// #![feature(integer_widen_truncate)]
4202 #[doc = concat!("assert_eq!(Some(120u8), 120", stringify!($SelfT), ".checked_truncate());")]
4203 /// assert_eq!(None, 376u32.checked_truncate::<u8>());
4204 /// ```
4205 #[must_use = "this returns the truncated value and does not modify the original"]
4206 #[unstable(feature = "integer_widen_truncate", issue = "154330")]
4207 #[rustc_const_unstable(feature = "integer_widen_truncate", issue = "154330")]
4208 #[inline]
4209 pub const fn checked_truncate<Target>(self) -> Option<Target>
4210 where Self: [const] traits::TruncateTarget<Target>
4211 {
4212 traits::TruncateTarget::internal_checked_truncate(self)
4213 }
4214
4215 /// Widen to an integer of the same size or larger, preserving its value.
4216 ///
4217 /// # Examples
4218 ///
4219 /// ```
4220 /// #![feature(integer_widen_truncate)]
4221 #[doc = concat!("assert_eq!(120u128, 120u8.widen());")]
4222 /// ```
4223 #[must_use = "this returns the widened value and does not modify the original"]
4224 #[unstable(feature = "integer_widen_truncate", issue = "154330")]
4225 #[rustc_const_unstable(feature = "integer_widen_truncate", issue = "154330")]
4226 #[inline]
4227 pub const fn widen<Target>(self) -> Target
4228 where Self: [const] traits::WidenTarget<Target>
4229 {
4230 traits::WidenTarget::internal_widen(self)
4231 }
4232 }
4233}