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// Geometric Tools, LLC
// Copyright (c) 1998-2014
// Distributed under the Boost Software License, Version 1.0.
// http://www.boost.org/LICENSE_1_0.txt
// http://www.geometrictools.com/License/Boost/LICENSE_1_0.txt
//
// File Version: 5.0.0 (2010/01/01)
#include "Wm5GraphicsPCH.h"
#include "Wm5HalfFloat.h"
namespace Wm5
{
//----------------------------------------------------------------------------
HalfFloat ToHalf (float value)
{
unsigned int bits = *(unsigned int*)&value;
unsigned short biasExp = (unsigned short)((bits & 0x7F800000) >> 23);
if (biasExp >= 0x0071)
{
if (biasExp <= 0x008E)
{
if (biasExp != 0)
{
// Truncate 23-bit mantissa to 10 bits.
unsigned short signBit =
(unsigned short)((bits & 0x80000000) >> 16);
unsigned int mantissa = (bits & 0x007FFFFF) >> 13;
biasExp = (biasExp - 0x0070) << 10;
return (HalfFloat)(signBit | biasExp | mantissa);
}
else
{
// E = 0 (alternate encoding of zero, M does not matter)
return (unsigned short)0;
}
}
else
{
// E = 30, M = 1023 (largest magnitude half-float)
unsigned short signBit =
(unsigned short)((bits & 0x80000000) >> 16);
return signBit | (unsigned short)0x7BFF;
}
}
else
{
// E = 1, M = 0 (smallest magnitude half-float)
unsigned short signBit = (unsigned short)((bits & 0x80000000) >> 16);
return signBit | (unsigned short)0x0400;
}
}
//----------------------------------------------------------------------------
float ToFloat (HalfFloat value)
{
unsigned int biasExp = (unsigned int)(value & 0x7C00) >> 10;
if (biasExp != 0)
{
unsigned int signBit = (unsigned int)(value & 0x8000) << 16;
unsigned int mantissa = (unsigned int)(value & 0x03FF) << 13;
biasExp = (biasExp + 0x0070) << 23;
unsigned int result = signBit | biasExp | mantissa;
return *(float*)&result;
}
else
{
// E = 0 (alternate encoding of zero, M does not matter)
return 0.0f;
}
}
//----------------------------------------------------------------------------
}
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