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// Copyright 2016 The SwiftShader Authors. All Rights Reserved.
//
// 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 "Half.hpp"
namespace sw {
half::half(float fp32)
{
unsigned int fp32i = *(unsigned int*)&fp32;
unsigned int sign = (fp32i & 0x80000000) >> 16;
unsigned int abs = fp32i & 0x7FFFFFFF;
if(abs > 0x47FFEFFF) // Infinity
{
fp16i = sign | 0x7FFF;
}
else if(abs < 0x38800000) // Denormal
{
unsigned int mantissa = (abs & 0x007FFFFF) | 0x00800000;
int e = 113 - (abs >> 23);
if(e < 24)
{
abs = mantissa >> e;
}
else
{
abs = 0;
}
fp16i = sign | (abs + 0x00000FFF + ((abs >> 13) & 1)) >> 13;
}
else
{
fp16i = sign | (abs + 0xC8000000 + 0x00000FFF + ((abs >> 13) & 1)) >> 13;
}
}
half::operator float() const
{
unsigned int fp32i;
int s = (fp16i >> 15) & 0x00000001;
int e = (fp16i >> 10) & 0x0000001F;
int m = fp16i & 0x000003FF;
if(e == 0)
{
if(m == 0)
{
fp32i = s << 31;
return (float&)fp32i;
}
else
{
while(!(m & 0x00000400))
{
m <<= 1;
e -= 1;
}
e += 1;
m &= ~0x00000400;
}
}
e = e + (127 - 15);
m = m << 13;
fp32i = (s << 31) | (e << 23) | m;
return (float&)fp32i;
}
half &half::operator=(half h)
{
fp16i = h.fp16i;
return *this;
}
half &half::operator=(float f)
{
*this = half(f);
return *this;
}
} // namespace sw