o3de/Code/Legacy/CryCommon/CryHalf.inl

/*
 * Copyright (c) Contributors to the Open 3D Engine Project.
 * For complete copyright and license terms please see the LICENSE at the root of this distribution.
 *
 * SPDX-License-Identifier: Apache-2.0 OR MIT
 *
 */


#ifndef CRY_HALF_INL
#define CRY_HALF_INL

#pragma once



typedef uint16 CryHalf;

typedef union floatint_union
{
    float f;
    uint32 i;
} floatint_union;

__forceinline CryHalf CryConvertFloatToHalf(const float Value)
{
#if defined(LINUX) || defined(MAC)
    asm volatile("" ::: "memory");
#endif
    unsigned int Result;

    unsigned int IValue = ((unsigned int*)(&Value))[0];
    unsigned int Sign = (IValue & 0x80000000U) >> 16U;
    IValue = IValue & 0x7FFFFFFFU;      // Hack off the sign

    if (IValue > 0x47FFEFFFU)
    {
        // The number is too large to be represented as a half.  Saturate to infinity.
        Result = 0x7FFFU;
    }
    else
    {
        if (IValue < 0x38800000U)
        {
            // The number is too small to be represented as a normalized half.
            // Convert it to a denormalized value.
            unsigned int Shift = 113U - (IValue >> 23U);
            IValue = (0x800000U | (IValue & 0x7FFFFFU)) >> Shift;
        }
        else
        {
            // Rebias the exponent to represent the value as a normalized half.
            IValue += 0xC8000000U;
        }

        Result = ((IValue + 0x0FFFU + ((IValue >> 13U) & 1U)) >> 13U) & 0x7FFFU;
    }
    return (CryHalf)(Result | Sign);
}

__forceinline float CryConvertHalfToFloat(const CryHalf Value)
{
#if defined(LINUX) || defined(MAC)
    asm volatile("" ::: "memory");
#endif
    unsigned int Mantissa;
    unsigned int Exponent;
    unsigned int Result;

    Mantissa = (unsigned int)(Value & 0x03FF);

    if ((Value & 0x7C00) != 0)  // The value is normalized
    {
        Exponent = (unsigned int)((Value >> 10) & 0x1F);
    }
    else if (Mantissa != 0)     // The value is denormalized
    {
        // Normalize the value in the resulting float
        Exponent = 1;

        do
        {
            Exponent--;
            Mantissa <<= 1;
        } while ((Mantissa & 0x0400) == 0);

        Mantissa &= 0x03FF;
    }
    else                        // The value is zero
    {
        Exponent = (unsigned int)-112;
    }

    Result = ((Value & 0x8000) << 16) | // Sign
        ((Exponent + 112) << 23) | // Exponent
        (Mantissa << 13);          // Mantissa

    return *(float*)&Result;
}

struct CryHalf2
{
    CryHalf x;
    CryHalf y;

    CryHalf2()
    {
    }
    CryHalf2(CryHalf _x, CryHalf _y)
        : x(_x)
        , y(_y)
    {
    }
    CryHalf2(const CryHalf* const __restrict pArray)
    {
        x = pArray[0];
        y = pArray[1];
    }
    CryHalf2(float _x, float _y)
    {
        x = CryConvertFloatToHalf(_x);
        y = CryConvertFloatToHalf(_y);
    }
    CryHalf2(const float* const __restrict pArray)
    {
        x = CryConvertFloatToHalf(pArray[0]);
        y = CryConvertFloatToHalf(pArray[1]);
    }
    CryHalf2& operator= (const CryHalf2& Half2)
    {
        x = Half2.x;
        y = Half2.y;
        return *this;
    }

    bool operator !=(const CryHalf2& rhs) const
    {
        return x != rhs.x || y != rhs.y;
    }
};

struct CryHalf4
{
    CryHalf x;
    CryHalf y;
    CryHalf z;
    CryHalf w;

    CryHalf4()
    {
    }
    CryHalf4(CryHalf _x, CryHalf _y, CryHalf _z, CryHalf _w)
        : x(_x)
        , y(_y)
        , z(_z)
        , w(_w)
    {
    }
    CryHalf4(const CryHalf* const __restrict pArray)
    {
        x = pArray[0];
        y = pArray[1];
        z = pArray[2];
        w = pArray[3];
    }
    CryHalf4(float _x, float _y, float _z, float _w)
    {
        x = CryConvertFloatToHalf(_x);
        y = CryConvertFloatToHalf(_y);
        z = CryConvertFloatToHalf(_z);
        w = CryConvertFloatToHalf(_w);
    }
    CryHalf4(const float* const __restrict pArray)
    {
        x = CryConvertFloatToHalf(pArray[0]);
        y = CryConvertFloatToHalf(pArray[1]);
        z = CryConvertFloatToHalf(pArray[2]);
        w = CryConvertFloatToHalf(pArray[3]);
    }
    CryHalf4& operator= (const CryHalf4& Half4)
    {
        x = Half4.x;
        y = Half4.y;
        z = Half4.z;
        w = Half4.w;
        return *this;
    }
    bool operator !=(const CryHalf4& rhs) const
    {
        return x != rhs.x || y != rhs.y || z != rhs.z || w != rhs.w;
    }
};

#endif // #ifndef CRY_HALF_INL