ClangPlatformMath.h

Go to the documentation of this file.

// Copyright Epic Games, Inc. All Rights Reserved.
 
/*=============================================================================================
    ClangPlatformMath.h: Clang intrinsic implementations of some platform Math functions
==============================================================================================*/
 
#pragma once
 
#ifdef __clang__
 
#include "Concepts/Integral.h"
#include "GenericPlatform/GenericPlatformMath.h"
 
// HEADER_UNIT_UNSUPPORTED - Clang not supporting header units
 
struct FClangPlatformMath : public FGenericPlatformMath
{
    static UE_FORCEINLINE_HINT constexpr uint8 CountLeadingZeros8(uint8 Value)
    {
        return uint8(__builtin_clz((uint32(Value) << 1) | 1) - 23);
    }
 
    static UE_FORCEINLINE_HINT constexpr uint32 CountLeadingZeros(uint32 Value)
    {
        return __builtin_clzll((uint64(Value) << 1) | 1) - 31;
    }
 
    static inline constexpr uint64 CountLeadingZeros64(uint64 Value)
    {
        if (Value == 0)
        {
            return 64;
        }
 
        return __builtin_clzll(Value);
    }
 
    static inline constexpr uint32 CountTrailingZeros(uint32 Value)
    {
        if (Value == 0)
        {
            return 32;
        }
    
        return (uint32)__builtin_ctz(Value);
    }
    
    static inline constexpr uint64 CountTrailingZeros64(uint64 Value)
    {
        if (Value == 0)
        {
            return 64;
        }
    
        return (uint64)__builtin_ctzll(Value);
    }
 
    static UE_FORCEINLINE_HINT constexpr uint32 FloorLog2(uint32 Value)
    {
        return 31 - __builtin_clz(Value | 1);
    }
 
    static UE_FORCEINLINE_HINT constexpr uint32 FloorLog2NonZero(uint32 Value)
    {
        return 31 - __builtin_clz(Value);
    }
 
    static UE_FORCEINLINE_HINT constexpr uint64 FloorLog2_64(uint64 Value)
    {
        return 63 - __builtin_clzll(Value | 1);
    }
 
    static UE_FORCEINLINE_HINT constexpr uint64 FloorLog2NonZero_64(uint64 Value)
    {
        return 63 - __builtin_clzll(Value);
    }
 
    template <UE::CIntegral IntType>
    static UE_FORCEINLINE_HINT bool AddAndCheckForOverflow(IntType A, IntType B, IntType& OutResult)
    {
        return !__builtin_add_overflow(A, B, &OutResult);
    }
 
    template <UE::CIntegral IntType>
    static UE_FORCEINLINE_HINT bool SubtractAndCheckForOverflow(IntType A, IntType B, IntType& OutResult)
    {
        return !__builtin_sub_overflow(A, B, &OutResult);
    }
 
    template <UE::CIntegral IntType>
    static UE_FORCEINLINE_HINT bool MultiplyAndCheckForOverflow(IntType A, IntType B, IntType& OutResult)
    {
        return !__builtin_mul_overflow(A, B, &OutResult);
    }
};
 
#endif //~__clang__