1/*
2 * Copyright (C) 2006-2018 Apple Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
14 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
17 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
18 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
19 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
20 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
21 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
23 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26#pragma once
27
28#include <algorithm>
29#include <climits>
30#include <cmath>
31#include <float.h>
32#include <limits>
33#include <stdint.h>
34#include <stdlib.h>
35#include <wtf/StdLibExtras.h>
36
37#if OS(OPENBSD)
38#include <sys/types.h>
39#include <machine/ieee.h>
40#endif
41
42#ifndef M_PI
43const double piDouble = 3.14159265358979323846;
44const float piFloat = 3.14159265358979323846f;
45#else
46const double piDouble = M_PI;
47const float piFloat = static_cast<float>(M_PI);
48#endif
49
50#ifndef M_PI_2
51const double piOverTwoDouble = 1.57079632679489661923;
52const float piOverTwoFloat = 1.57079632679489661923f;
53#else
54const double piOverTwoDouble = M_PI_2;
55const float piOverTwoFloat = static_cast<float>(M_PI_2);
56#endif
57
58#ifndef M_PI_4
59const double piOverFourDouble = 0.785398163397448309616;
60const float piOverFourFloat = 0.785398163397448309616f;
61#else
62const double piOverFourDouble = M_PI_4;
63const float piOverFourFloat = static_cast<float>(M_PI_4);
64#endif
65
66#ifndef M_SQRT2
67const double sqrtOfTwoDouble = 1.41421356237309504880;
68const float sqrtOfTwoFloat = 1.41421356237309504880f;
69#else
70const double sqrtOfTwoDouble = M_SQRT2;
71const float sqrtOfTwoFloat = static_cast<float>(M_SQRT2);
72#endif
73
74#if COMPILER(MSVC)
75
76// Work around a bug in Win, where atan2(+-infinity, +-infinity) yields NaN instead of specific values.
77extern "C" inline double wtf_atan2(double x, double y)
78{
79 double posInf = std::numeric_limits<double>::infinity();
80 double negInf = -std::numeric_limits<double>::infinity();
81 double nan = std::numeric_limits<double>::quiet_NaN();
82
83 double result = nan;
84
85 if (x == posInf && y == posInf)
86 result = piOverFourDouble;
87 else if (x == posInf && y == negInf)
88 result = 3 * piOverFourDouble;
89 else if (x == negInf && y == posInf)
90 result = -piOverFourDouble;
91 else if (x == negInf && y == negInf)
92 result = -3 * piOverFourDouble;
93 else
94 result = ::atan2(x, y);
95
96 return result;
97}
98
99#define atan2(x, y) wtf_atan2(x, y)
100
101#endif // COMPILER(MSVC)
102
103inline double deg2rad(double d) { return d * piDouble / 180.0; }
104inline double rad2deg(double r) { return r * 180.0 / piDouble; }
105inline double deg2grad(double d) { return d * 400.0 / 360.0; }
106inline double grad2deg(double g) { return g * 360.0 / 400.0; }
107inline double turn2deg(double t) { return t * 360.0; }
108inline double deg2turn(double d) { return d / 360.0; }
109inline double rad2grad(double r) { return r * 200.0 / piDouble; }
110inline double grad2rad(double g) { return g * piDouble / 200.0; }
111
112inline float deg2rad(float d) { return d * piFloat / 180.0f; }
113inline float rad2deg(float r) { return r * 180.0f / piFloat; }
114inline float deg2grad(float d) { return d * 400.0f / 360.0f; }
115inline float grad2deg(float g) { return g * 360.0f / 400.0f; }
116inline float turn2deg(float t) { return t * 360.0f; }
117inline float deg2turn(float d) { return d / 360.0f; }
118inline float rad2grad(float r) { return r * 200.0f / piFloat; }
119inline float grad2rad(float g) { return g * piFloat / 200.0f; }
120
121// std::numeric_limits<T>::min() returns the smallest positive value for floating point types
122template<typename T> constexpr T defaultMinimumForClamp() { return std::numeric_limits<T>::min(); }
123template<> constexpr float defaultMinimumForClamp() { return -std::numeric_limits<float>::max(); }
124template<> constexpr double defaultMinimumForClamp() { return -std::numeric_limits<double>::max(); }
125template<typename T> constexpr T defaultMaximumForClamp() { return std::numeric_limits<T>::max(); }
126
127// Same type in and out.
128template<typename TargetType, typename SourceType>
129typename std::enable_if<std::is_same<TargetType, SourceType>::value, TargetType>::type
130clampTo(SourceType value, TargetType min = defaultMinimumForClamp<TargetType>(), TargetType max = defaultMaximumForClamp<TargetType>())
131{
132 if (value >= max)
133 return max;
134 if (value <= min)
135 return min;
136 return value;
137}
138
139// Floating point source.
140template<typename TargetType, typename SourceType>
141typename std::enable_if<!std::is_same<TargetType, SourceType>::value
142 && std::is_floating_point<SourceType>::value
143 && !(std::is_floating_point<TargetType>::value && sizeof(TargetType) > sizeof(SourceType)), TargetType>::type
144clampTo(SourceType value, TargetType min = defaultMinimumForClamp<TargetType>(), TargetType max = defaultMaximumForClamp<TargetType>())
145{
146 if (value >= static_cast<SourceType>(max))
147 return max;
148 if (value <= static_cast<SourceType>(min))
149 return min;
150 return static_cast<TargetType>(value);
151}
152
153template<typename TargetType, typename SourceType>
154typename std::enable_if<!std::is_same<TargetType, SourceType>::value
155 && std::is_floating_point<SourceType>::value
156 && std::is_floating_point<TargetType>::value
157 && (sizeof(TargetType) > sizeof(SourceType)), TargetType>::type
158clampTo(SourceType value, TargetType min = defaultMinimumForClamp<TargetType>(), TargetType max = defaultMaximumForClamp<TargetType>())
159{
160 TargetType convertedValue = static_cast<TargetType>(value);
161 if (convertedValue >= max)
162 return max;
163 if (convertedValue <= min)
164 return min;
165 return convertedValue;
166}
167
168// Source and Target have the same sign and Source is larger or equal to Target
169template<typename TargetType, typename SourceType>
170typename std::enable_if<!std::is_same<TargetType, SourceType>::value
171 && std::numeric_limits<SourceType>::is_integer
172 && std::numeric_limits<TargetType>::is_integer
173 && std::numeric_limits<TargetType>::is_signed == std::numeric_limits<SourceType>::is_signed
174 && sizeof(SourceType) >= sizeof(TargetType), TargetType>::type
175clampTo(SourceType value, TargetType min = defaultMinimumForClamp<TargetType>(), TargetType max = defaultMaximumForClamp<TargetType>())
176{
177 if (value >= static_cast<SourceType>(max))
178 return max;
179 if (value <= static_cast<SourceType>(min))
180 return min;
181 return static_cast<TargetType>(value);
182}
183
184// Clamping a unsigned integer to the max signed value.
185template<typename TargetType, typename SourceType>
186typename std::enable_if<!std::is_same<TargetType, SourceType>::value
187 && std::numeric_limits<SourceType>::is_integer
188 && std::numeric_limits<TargetType>::is_integer
189 && std::numeric_limits<TargetType>::is_signed
190 && !std::numeric_limits<SourceType>::is_signed
191 && sizeof(SourceType) >= sizeof(TargetType), TargetType>::type
192clampTo(SourceType value)
193{
194 TargetType max = std::numeric_limits<TargetType>::max();
195 if (value >= static_cast<SourceType>(max))
196 return max;
197 return static_cast<TargetType>(value);
198}
199
200// Clamping a signed integer into a valid unsigned integer.
201template<typename TargetType, typename SourceType>
202typename std::enable_if<!std::is_same<TargetType, SourceType>::value
203 && std::numeric_limits<SourceType>::is_integer
204 && std::numeric_limits<TargetType>::is_integer
205 && !std::numeric_limits<TargetType>::is_signed
206 && std::numeric_limits<SourceType>::is_signed
207 && sizeof(SourceType) == sizeof(TargetType), TargetType>::type
208clampTo(SourceType value)
209{
210 if (value < 0)
211 return 0;
212 return static_cast<TargetType>(value);
213}
214
215template<typename TargetType, typename SourceType>
216typename std::enable_if<!std::is_same<TargetType, SourceType>::value
217 && std::numeric_limits<SourceType>::is_integer
218 && std::numeric_limits<TargetType>::is_integer
219 && !std::numeric_limits<TargetType>::is_signed
220 && std::numeric_limits<SourceType>::is_signed
221 && (sizeof(SourceType) > sizeof(TargetType)), TargetType>::type
222clampTo(SourceType value)
223{
224 if (value < 0)
225 return 0;
226 TargetType max = std::numeric_limits<TargetType>::max();
227 if (value >= static_cast<SourceType>(max))
228 return max;
229 return static_cast<TargetType>(value);
230}
231
232inline int clampToInteger(double value)
233{
234 return clampTo<int>(value);
235}
236
237inline unsigned clampToUnsigned(double value)
238{
239 return clampTo<unsigned>(value);
240}
241
242inline float clampToFloat(double value)
243{
244 return clampTo<float>(value);
245}
246
247inline int clampToPositiveInteger(double value)
248{
249 return clampTo<int>(value, 0);
250}
251
252inline int clampToInteger(float value)
253{
254 return clampTo<int>(value);
255}
256
257template<typename T>
258inline int clampToInteger(T x)
259{
260 static_assert(std::numeric_limits<T>::is_integer, "T must be an integer.");
261
262 const T intMax = static_cast<unsigned>(std::numeric_limits<int>::max());
263
264 if (x >= intMax)
265 return std::numeric_limits<int>::max();
266 return static_cast<int>(x);
267}
268
269// Explicitly accept 64bit result when clamping double value.
270// Keep in mind that double can only represent 53bit integer precisely.
271template<typename T> constexpr T clampToAccepting64(double value, T min = defaultMinimumForClamp<T>(), T max = defaultMaximumForClamp<T>())
272{
273 return (value >= static_cast<double>(max)) ? max : ((value <= static_cast<double>(min)) ? min : static_cast<T>(value));
274}
275
276inline bool isWithinIntRange(float x)
277{
278 return x > static_cast<float>(std::numeric_limits<int>::min()) && x < static_cast<float>(std::numeric_limits<int>::max());
279}
280
281inline float normalizedFloat(float value)
282{
283 if (value > 0 && value < std::numeric_limits<float>::min())
284 return std::numeric_limits<float>::min();
285 if (value < 0 && value > -std::numeric_limits<float>::min())
286 return -std::numeric_limits<float>::min();
287 return value;
288}
289
290template<typename T> constexpr bool hasOneBitSet(T value)
291{
292 return !((value - 1) & value) && value;
293}
294
295template<typename T> constexpr bool hasZeroOrOneBitsSet(T value)
296{
297 return !((value - 1) & value);
298}
299
300template<typename T> constexpr bool hasTwoOrMoreBitsSet(T value)
301{
302 return !hasZeroOrOneBitsSet(value);
303}
304
305template<typename T> inline T divideRoundedUp(T a, T b)
306{
307 return (a + b - 1) / b;
308}
309
310template<typename T> inline T timesThreePlusOneDividedByTwo(T value)
311{
312 // Mathematically equivalent to:
313 // (value * 3 + 1) / 2;
314 // or:
315 // (unsigned)ceil(value * 1.5));
316 // This form is not prone to internal overflow.
317 return value + (value >> 1) + (value & 1);
318}
319
320template<typename T> inline bool isNotZeroAndOrdered(T value)
321{
322 return value > 0.0 || value < 0.0;
323}
324
325template<typename T> inline bool isZeroOrUnordered(T value)
326{
327 return !isNotZeroAndOrdered(value);
328}
329
330template<typename T> inline bool isGreaterThanNonZeroPowerOfTwo(T value, unsigned power)
331{
332 // The crazy way of testing of index >= 2 ** power
333 // (where I use ** to denote pow()).
334 return !!((value >> 1) >> (power - 1));
335}
336
337template<typename T> constexpr bool isLessThan(const T& a, const T& b) { return a < b; }
338template<typename T> constexpr bool isLessThanEqual(const T& a, const T& b) { return a <= b; }
339template<typename T> constexpr bool isGreaterThan(const T& a, const T& b) { return a > b; }
340template<typename T> constexpr bool isGreaterThanEqual(const T& a, const T& b) { return a >= b; }
341
342#ifndef UINT64_C
343#if COMPILER(MSVC)
344#define UINT64_C(c) c ## ui64
345#else
346#define UINT64_C(c) c ## ull
347#endif
348#endif
349
350#if COMPILER(MINGW64) && (!defined(__MINGW64_VERSION_RC) || __MINGW64_VERSION_RC < 1)
351inline double wtf_pow(double x, double y)
352{
353 // MinGW-w64 has a custom implementation for pow.
354 // This handles certain special cases that are different.
355 if ((x == 0.0 || std::isinf(x)) && std::isfinite(y)) {
356 double f;
357 if (modf(y, &f) != 0.0)
358 return ((x == 0.0) ^ (y > 0.0)) ? std::numeric_limits<double>::infinity() : 0.0;
359 }
360
361 if (x == 2.0) {
362 int yInt = static_cast<int>(y);
363 if (y == yInt)
364 return ldexp(1.0, yInt);
365 }
366
367 return pow(x, y);
368}
369#define pow(x, y) wtf_pow(x, y)
370#endif // COMPILER(MINGW64) && (!defined(__MINGW64_VERSION_RC) || __MINGW64_VERSION_RC < 1)
371
372
373// decompose 'number' to its sign, exponent, and mantissa components.
374// The result is interpreted as:
375// (sign ? -1 : 1) * pow(2, exponent) * (mantissa / (1 << 52))
376inline void decomposeDouble(double number, bool& sign, int32_t& exponent, uint64_t& mantissa)
377{
378 ASSERT(std::isfinite(number));
379
380 sign = std::signbit(number);
381
382 uint64_t bits = WTF::bitwise_cast<uint64_t>(number);
383 exponent = (static_cast<int32_t>(bits >> 52) & 0x7ff) - 0x3ff;
384 mantissa = bits & 0xFFFFFFFFFFFFFull;
385
386 // Check for zero/denormal values; if so, adjust the exponent,
387 // if not insert the implicit, omitted leading 1 bit.
388 if (exponent == -0x3ff)
389 exponent = mantissa ? -0x3fe : 0;
390 else
391 mantissa |= 0x10000000000000ull;
392}
393
394// Calculate d % 2^{64}.
395inline void doubleToInteger(double d, unsigned long long& value)
396{
397 if (std::isnan(d) || std::isinf(d))
398 value = 0;
399 else {
400 // -2^{64} < fmodValue < 2^{64}.
401 double fmodValue = fmod(trunc(d), std::numeric_limits<unsigned long long>::max() + 1.0);
402 if (fmodValue >= 0) {
403 // 0 <= fmodValue < 2^{64}.
404 // 0 <= value < 2^{64}. This cast causes no loss.
405 value = static_cast<unsigned long long>(fmodValue);
406 } else {
407 // -2^{64} < fmodValue < 0.
408 // 0 < fmodValueInUnsignedLongLong < 2^{64}. This cast causes no loss.
409 unsigned long long fmodValueInUnsignedLongLong = static_cast<unsigned long long>(-fmodValue);
410 // -1 < (std::numeric_limits<unsigned long long>::max() - fmodValueInUnsignedLongLong) < 2^{64} - 1.
411 // 0 < value < 2^{64}.
412 value = std::numeric_limits<unsigned long long>::max() - fmodValueInUnsignedLongLong + 1;
413 }
414 }
415}
416
417namespace WTF {
418
419// From http://graphics.stanford.edu/~seander/bithacks.html#RoundUpPowerOf2
420constexpr uint32_t roundUpToPowerOfTwo(uint32_t v)
421{
422 v--;
423 v |= v >> 1;
424 v |= v >> 2;
425 v |= v >> 4;
426 v |= v >> 8;
427 v |= v >> 16;
428 v++;
429 return v;
430}
431
432constexpr unsigned maskForSize(unsigned size)
433{
434 if (!size)
435 return 0;
436 return roundUpToPowerOfTwo(size) - 1;
437}
438
439inline unsigned fastLog2(unsigned i)
440{
441 unsigned log2 = 0;
442 if (i & (i - 1))
443 log2 += 1;
444 if (i >> 16) {
445 log2 += 16;
446 i >>= 16;
447 }
448 if (i >> 8) {
449 log2 += 8;
450 i >>= 8;
451 }
452 if (i >> 4) {
453 log2 += 4;
454 i >>= 4;
455 }
456 if (i >> 2) {
457 log2 += 2;
458 i >>= 2;
459 }
460 if (i >> 1)
461 log2 += 1;
462 return log2;
463}
464
465inline unsigned fastLog2(uint64_t value)
466{
467 unsigned high = static_cast<unsigned>(value >> 32);
468 if (high)
469 return fastLog2(high) + 32;
470 return fastLog2(static_cast<unsigned>(value));
471}
472
473template <typename T>
474inline typename std::enable_if<std::is_floating_point<T>::value, T>::type safeFPDivision(T u, T v)
475{
476 // Protect against overflow / underflow.
477 if (v < 1 && u > v * std::numeric_limits<T>::max())
478 return std::numeric_limits<T>::max();
479 if (v > 1 && u < v * std::numeric_limits<T>::min())
480 return 0;
481 return u / v;
482}
483
484// Floating point numbers comparison:
485// u is "essentially equal" [1][2] to v if: | u - v | / |u| <= e and | u - v | / |v| <= e
486//
487// [1] Knuth, D. E. "Accuracy of Floating Point Arithmetic." The Art of Computer Programming. 3rd ed. Vol. 2.
488// Boston: Addison-Wesley, 1998. 229-45.
489// [2] http://www.boost.org/doc/libs/1_34_0/libs/test/doc/components/test_tools/floating_point_comparison.html
490template <typename T>
491inline typename std::enable_if<std::is_floating_point<T>::value, bool>::type areEssentiallyEqual(T u, T v, T epsilon = std::numeric_limits<T>::epsilon())
492{
493 if (u == v)
494 return true;
495
496 const T delta = std::abs(u - v);
497 return safeFPDivision(delta, std::abs(u)) <= epsilon && safeFPDivision(delta, std::abs(v)) <= epsilon;
498}
499
500// Match behavior of Math.min, where NaN is returned if either argument is NaN.
501template <typename T>
502inline typename std::enable_if<std::is_floating_point<T>::value, T>::type nanPropagatingMin(T a, T b)
503{
504 return std::isnan(a) || std::isnan(b) ? std::numeric_limits<T>::quiet_NaN() : std::min(a, b);
505}
506
507// Match behavior of Math.max, where NaN is returned if either argument is NaN.
508template <typename T>
509inline typename std::enable_if<std::is_floating_point<T>::value, T>::type nanPropagatingMax(T a, T b)
510{
511 return std::isnan(a) || std::isnan(b) ? std::numeric_limits<T>::quiet_NaN() : std::max(a, b);
512}
513
514inline bool isIntegral(float value)
515{
516 return static_cast<int>(value) == value;
517}
518
519template<typename T>
520inline void incrementWithSaturation(T& value)
521{
522 if (value != std::numeric_limits<T>::max())
523 value++;
524}
525
526template<typename T>
527inline T leftShiftWithSaturation(T value, unsigned shiftAmount, T max = std::numeric_limits<T>::max())
528{
529 T result = value << shiftAmount;
530 // We will have saturated if shifting right doesn't recover the original value.
531 if (result >> shiftAmount != value)
532 return max;
533 if (result > max)
534 return max;
535 return result;
536}
537
538// Check if two ranges overlap assuming that neither range is empty.
539template<typename T>
540inline bool nonEmptyRangesOverlap(T leftMin, T leftMax, T rightMin, T rightMax)
541{
542 ASSERT(leftMin < leftMax);
543 ASSERT(rightMin < rightMax);
544
545 return leftMax > rightMin && rightMax > leftMin;
546}
547
548// Pass ranges with the min being inclusive and the max being exclusive. For example, this should
549// return false:
550//
551// rangesOverlap(0, 8, 8, 16)
552template<typename T>
553inline bool rangesOverlap(T leftMin, T leftMax, T rightMin, T rightMax)
554{
555 ASSERT(leftMin <= leftMax);
556 ASSERT(rightMin <= rightMax);
557
558 // Empty ranges interfere with nothing.
559 if (leftMin == leftMax)
560 return false;
561 if (rightMin == rightMax)
562 return false;
563
564 return nonEmptyRangesOverlap(leftMin, leftMax, rightMin, rightMax);
565}
566
567template<typename VectorType, typename RandomFunc>
568void shuffleVector(VectorType& vector, size_t size, const RandomFunc& randomFunc)
569{
570 for (size_t i = 0; i + 1 < size; ++i)
571 std::swap(vector[i], vector[i + randomFunc(size - i)]);
572}
573
574template<typename VectorType, typename RandomFunc>
575void shuffleVector(VectorType& vector, const RandomFunc& randomFunc)
576{
577 shuffleVector(vector, vector.size(), randomFunc);
578}
579
580template <typename T>
581constexpr unsigned clzConstexpr(T value)
582{
583 constexpr unsigned bitSize = sizeof(T) * CHAR_BIT;
584
585 using UT = typename std::make_unsigned<T>::type;
586 UT uValue = value;
587
588 unsigned zeroCount = 0;
589 for (int i = bitSize - 1; i >= 0; i--) {
590 if (uValue >> i)
591 break;
592 zeroCount++;
593 }
594 return zeroCount;
595}
596
597template<typename T>
598inline unsigned clz(T value)
599{
600 constexpr unsigned bitSize = sizeof(T) * CHAR_BIT;
601
602 using UT = typename std::make_unsigned<T>::type;
603 UT uValue = value;
604
605#if COMPILER(GCC_COMPATIBLE)
606 constexpr unsigned bitSize64 = sizeof(uint64_t) * CHAR_BIT;
607 if (uValue)
608 return __builtin_clzll(uValue) - (bitSize64 - bitSize);
609 return bitSize;
610#elif COMPILER(MSVC) && !CPU(X86)
611 // Visual Studio 2008 or upper have __lzcnt, but we can't detect Intel AVX at compile time.
612 // So we use bit-scan-reverse operation to calculate clz.
613 // _BitScanReverse64 is defined in X86_64 and ARM in MSVC supported environments.
614 unsigned long ret = 0;
615 if (_BitScanReverse64(&ret, uValue))
616 return bitSize - 1 - ret;
617 return bitSize;
618#else
619 UNUSED_PARAM(bitSize);
620 UNUSED_PARAM(uValue);
621 return clzConstexpr(value);
622#endif
623}
624
625template <typename T>
626constexpr unsigned ctzConstexpr(T value)
627{
628 constexpr unsigned bitSize = sizeof(T) * CHAR_BIT;
629
630 using UT = typename std::make_unsigned<T>::type;
631 UT uValue = value;
632
633 unsigned zeroCount = 0;
634 for (unsigned i = 0; i < bitSize; i++) {
635 if (uValue & 1)
636 break;
637
638 zeroCount++;
639 uValue >>= 1;
640 }
641 return zeroCount;
642}
643
644template<typename T>
645inline unsigned ctz(T value)
646{
647 constexpr unsigned bitSize = sizeof(T) * CHAR_BIT;
648
649 using UT = typename std::make_unsigned<T>::type;
650 UT uValue = value;
651
652#if COMPILER(GCC_COMPATIBLE)
653 if (uValue)
654 return __builtin_ctzll(uValue);
655 return bitSize;
656#elif COMPILER(MSVC) && !CPU(X86)
657 unsigned long ret = 0;
658 if (_BitScanForward64(&ret, uValue))
659 return ret;
660 return bitSize;
661#else
662 UNUSED_PARAM(bitSize);
663 UNUSED_PARAM(uValue);
664 return ctzConstexpr(value);
665#endif
666}
667
668template<typename T>
669inline unsigned getLSBSet(T t)
670{
671 ASSERT(t);
672 return ctz(t);
673}
674
675template<typename T>
676constexpr unsigned getLSBSetConstexpr(T t)
677{
678 ASSERT_UNDER_CONSTEXPR_CONTEXT(t);
679 return ctzConstexpr(t);
680}
681
682template<typename T>
683inline unsigned getMSBSet(T t)
684{
685 constexpr unsigned bitSize = sizeof(T) * CHAR_BIT;
686 ASSERT(t);
687 return bitSize - 1 - clz(t);
688}
689
690template<typename T>
691constexpr unsigned getMSBSetConstexpr(T t)
692{
693 constexpr unsigned bitSize = sizeof(T) * CHAR_BIT;
694 ASSERT_UNDER_CONSTEXPR_CONTEXT(t);
695 return bitSize - 1 - clzConstexpr(t);
696}
697
698} // namespace WTF
699
700using WTF::shuffleVector;
701using WTF::clz;
702using WTF::ctz;
703using WTF::getLSBSet;
704using WTF::getMSBSet;
705