// Copyright 2016 The SwiftShader Authors. All Rights Reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include "Half.hpp"
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namespace sw
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{
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half::half(float fp32)
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{
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unsigned int fp32i = *(unsigned int*)&fp32;
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unsigned int sign = (fp32i & 0x80000000) >> 16;
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unsigned int abs = fp32i & 0x7FFFFFFF;
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if(abs > 0x47FFEFFF) // Infinity
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{
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fp16i = sign | 0x7FFF;
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}
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else if(abs < 0x38800000) // Denormal
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{
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unsigned int mantissa = (abs & 0x007FFFFF) | 0x00800000;
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int e = 113 - (abs >> 23);
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if(e < 24)
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{
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abs = mantissa >> e;
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}
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else
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{
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abs = 0;
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}
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fp16i = sign | (abs + 0x00000FFF + ((abs >> 13) & 1)) >> 13;
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}
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else
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{
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fp16i = sign | (abs + 0xC8000000 + 0x00000FFF + ((abs >> 13) & 1)) >> 13;
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}
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}
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half::operator float() const
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{
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unsigned int fp32i;
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int s = (fp16i >> 15) & 0x00000001;
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int e = (fp16i >> 10) & 0x0000001F;
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int m = fp16i & 0x000003FF;
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if(e == 0)
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{
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if(m == 0)
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{
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fp32i = s << 31;
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return (float&)fp32i;
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}
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else
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{
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while(!(m & 0x00000400))
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{
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m <<= 1;
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e -= 1;
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}
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e += 1;
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m &= ~0x00000400;
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}
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}
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e = e + (127 - 15);
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m = m << 13;
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fp32i = (s << 31) | (e << 23) | m;
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return (float&)fp32i;
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}
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half &half::operator=(half h)
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{
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fp16i = h.fp16i;
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return *this;
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}
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half &half::operator=(float f)
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{
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*this = half(f);
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return *this;
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}
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}
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