Maneesh Gupta
a0b5dfd625
* Merge master-next changes in master (include vdi development in master branch)
71 wiersze
3.0 KiB
C++
71 wiersze
3.0 KiB
C++
/*
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Copyright (c) 2018 - present Advanced Micro Devices, Inc. All rights reserved.
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in
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all copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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THE SOFTWARE.
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*/
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#include <cstdint>
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#include <algorithm>
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// conversion routines between float and half precision
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static inline std::uint32_t f32_as_u32(float f) { union { float f; std::uint32_t u; } v; v.f = f; return v.u; }
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static inline float u32_as_f32(std::uint32_t u) { union { float f; std::uint32_t u; } v; v.u = u; return v.f; }
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static inline int clamp_int(int i, int l, int h) { return std::min(std::max(i, l), h); }
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// half to float, the f16 is in the low 16 bits of the input argument a
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static inline float __convert_half_to_float(std::uint32_t a) noexcept {
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std::uint32_t u = ((a << 13) + 0x70000000U) & 0x8fffe000U;
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std::uint32_t v = f32_as_u32(u32_as_f32(u) * 0x1.0p+112f) + 0x38000000U;
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u = (a & 0x7fff) != 0 ? v : u;
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return u32_as_f32(u) * 0x1.0p-112f;
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}
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// float to half with nearest even rounding
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// The lower 16 bits of the result is the bit pattern for the f16
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static inline std::uint32_t __convert_float_to_half(float a) noexcept {
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std::uint32_t u = f32_as_u32(a);
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int e = static_cast<int>((u >> 23) & 0xff) - 127 + 15;
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std::uint32_t m = ((u >> 11) & 0xffe) | ((u & 0xfff) != 0);
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std::uint32_t i = 0x7c00 | (m != 0 ? 0x0200 : 0);
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std::uint32_t n = ((std::uint32_t)e << 12) | m;
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std::uint32_t s = (u >> 16) & 0x8000;
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int b = clamp_int(1-e, 0, 13);
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std::uint32_t d = (0x1000 | m) >> b;
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d |= (d << b) != (0x1000 | m);
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std::uint32_t v = e < 1 ? d : n;
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v = (v >> 2) + (((v & 0x7) == 3) | ((v & 0x7) > 5));
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v = e > 30 ? 0x7c00 : v;
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v = e == 143 ? i : v;
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return s | v;
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}
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// On machines without fp16 instructions, clang lowers llvm.convert.from.fp16
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// to call of this function.
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extern "C" __attribute__((visibility("default")))
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float __gnu_h2f_ieee(unsigned short h){
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return __convert_half_to_float((std::uint32_t) h);
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}
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// On machines without fp16 instructions, clang lowers llvm.convert.to.fp16
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// to call of this function.
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extern "C" __attribute__((visibility("default")))
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unsigned short __gnu_f2h_ieee(float f){
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return (unsigned short)__convert_float_to_half(f);
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}
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