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// Copyright 2017 The Dawn Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include "common/Math.h"
#include "common/Assert.h"
#include <algorithm>
#include <cmath>
#if defined(DAWN_COMPILER_MSVC)
# include <intrin.h>
#endif
uint32_t ScanForward(uint32_t bits) {
ASSERT(bits != 0);
#if defined(DAWN_COMPILER_MSVC)
unsigned long firstBitIndex = 0ul;
unsigned char ret = _BitScanForward(&firstBitIndex, bits);
ASSERT(ret != 0);
return firstBitIndex;
#else
return static_cast<uint32_t>(__builtin_ctz(bits));
#endif
}
uint32_t Log2(uint32_t value) {
ASSERT(value != 0);
#if defined(DAWN_COMPILER_MSVC)
unsigned long firstBitIndex = 0ul;
unsigned char ret = _BitScanReverse(&firstBitIndex, value);
ASSERT(ret != 0);
return firstBitIndex;
#else
return 31 - static_cast<uint32_t>(__builtin_clz(value));
#endif
}
uint32_t Log2(uint64_t value) {
ASSERT(value != 0);
#if defined(DAWN_COMPILER_MSVC)
unsigned long firstBitIndex = 0ul;
unsigned char ret = _BitScanReverse64(&firstBitIndex, value);
ASSERT(ret != 0);
return firstBitIndex;
#else
return 63 - static_cast<uint32_t>(__builtin_clzll(value));
#endif
}
uint64_t NextPowerOfTwo(uint64_t n) {
#if defined(DAWN_COMPILER_MSVC)
if (n <= 1) {
return 1;
}
unsigned long firstBitIndex = 0ul;
unsigned char ret = _BitScanReverse64(&firstBitIndex, n - 1);
ASSERT(ret != 0);
return 1ull << (firstBitIndex + 1);
#else
return n <= 1 ? 1 : 1ull << (64 - __builtin_clzll(n - 1));
#endif
}
bool IsPowerOfTwo(uint64_t n) {
ASSERT(n != 0);
return (n & (n - 1)) == 0;
}
bool IsPtrAligned(const void* ptr, size_t alignment) {
ASSERT(IsPowerOfTwo(alignment));
ASSERT(alignment != 0);
return (reinterpret_cast<size_t>(ptr) & (alignment - 1)) == 0;
}
void* AlignVoidPtr(void* ptr, size_t alignment) {
ASSERT(IsPowerOfTwo(alignment));
ASSERT(alignment != 0);
return reinterpret_cast<void*>((reinterpret_cast<size_t>(ptr) + (alignment - 1)) &
~(alignment - 1));
}
bool IsAligned(uint32_t value, size_t alignment) {
ASSERT(alignment <= UINT32_MAX);
ASSERT(IsPowerOfTwo(alignment));
ASSERT(alignment != 0);
uint32_t alignment32 = static_cast<uint32_t>(alignment);
return (value & (alignment32 - 1)) == 0;
}
uint32_t Align(uint32_t value, size_t alignment) {
ASSERT(alignment <= UINT32_MAX);
ASSERT(IsPowerOfTwo(alignment));
ASSERT(alignment != 0);
uint32_t alignment32 = static_cast<uint32_t>(alignment);
return (value + (alignment32 - 1)) & ~(alignment32 - 1);
}
uint16_t Float32ToFloat16(float fp32) {
uint32_t fp32i = BitCast<uint32_t>(fp32);
uint32_t sign16 = (fp32i & 0x80000000) >> 16;
uint32_t mantissaAndExponent = fp32i & 0x7FFFFFFF;
if (mantissaAndExponent > 0x7F800000) { // NaN
return 0x7FFF;
} else if (mantissaAndExponent > 0x47FFEFFF) { // Infinity
return static_cast<uint16_t>(sign16 | 0x7C00);
} else if (mantissaAndExponent < 0x38800000) { // Denormal
uint32_t mantissa = (mantissaAndExponent & 0x007FFFFF) | 0x00800000;
int32_t exponent = 113 - (mantissaAndExponent >> 23);
if (exponent < 24) {
mantissaAndExponent = mantissa >> exponent;
} else {
mantissaAndExponent = 0;
}
return static_cast<uint16_t>(
sign16 | (mantissaAndExponent + 0x00000FFF + ((mantissaAndExponent >> 13) & 1)) >> 13);
} else {
return static_cast<uint16_t>(sign16 | (mantissaAndExponent + 0xC8000000 + 0x00000FFF +
((mantissaAndExponent >> 13) & 1)) >>
13);
}
}
bool IsFloat16NaN(uint16_t fp16) {
return (fp16 & 0x7FFF) > 0x7C00;
}
// Based on the Khronos Data Format Specification 1.2 Section 13.3 sRGB transfer functions
float SRGBToLinear(float srgb) {
// sRGB is always used in unsigned normalized formats so clamp to [0.0, 1.0]
if (srgb <= 0.0f) {
return 0.0f;
} else if (srgb > 1.0f) {
return 1.0f;
}
if (srgb < 0.04045f) {
return srgb / 12.92f;
} else {
return std::pow((srgb + 0.055f) / 1.055f, 2.4f);
}
}
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