src/common/Math.h

// 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.

#ifndef COMMON_MATH_H_
#define COMMON_MATH_H_

#include <cstddef>
#include <cstdint>
#include <cstring>

#include <limits>
#include <type_traits>

#include "common/Assert.h"

// The following are not valid for 0
uint32_t ScanForward(uint32_t bits);
uint32_t Log2(uint32_t value);
uint32_t Log2(uint64_t value);

uint64_t NextPowerOfTwo(uint64_t n);

// bool IsPowerOfTwo(size_t n);

inline bool IsPowerOfTwo(uint64_t n) {
    ASSERT(n != 0);
    return (n & (n - 1)) == 0;
}

inline bool IsPtrAligned(const void* ptr, size_t alignment) {
    ASSERT(IsPowerOfTwo(alignment));
    ASSERT(alignment != 0);
    return (reinterpret_cast<size_t>(ptr) & (alignment - 1)) == 0;
}

inline 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));
}

inline 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;
}

inline 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);
}

// bool IsPtrAligned(const void* ptr, size_t alignment);
// void* AlignVoidPtr(void* ptr, size_t alignment);
// bool IsAligned(uint32_t value, size_t alignment);
// uint32_t Align(uint32_t value, size_t alignment);

template <typename T>
T* AlignPtr(T* ptr, size_t alignment) {
    return static_cast<T*>(AlignVoidPtr(ptr, alignment));
}

template <typename T>
const T* AlignPtr(const T* ptr, size_t alignment) {
    return static_cast<const T*>(AlignVoidPtr(const_cast<T*>(ptr), alignment));
}

template <typename destType, typename sourceType>
destType BitCast(const sourceType& source) {
    static_assert(sizeof(destType) == sizeof(sourceType), "BitCast: cannot lose precision.");
    destType output;
    std::memcpy(&output, &source, sizeof(destType));
    return output;
}

uint16_t Float32ToFloat16(float fp32);
bool IsFloat16NaN(uint16_t fp16);

float SRGBToLinear(float srgb);

#endif  // COMMON_MATH_H_