8da8fc1be9
Change-Id: Ie327ec5eb3f3314b24aa512ce180760f18ee5348
284 строки
9.1 KiB
C++
284 строки
9.1 KiB
C++
/**
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* MIT License
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*
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* Copyright (c) 2019 - 2021 Advanced Micro Devices, Inc. All rights reserved.
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*
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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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*
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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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*
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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 THE
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* SOFTWARE.
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*/
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/*!\file
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* \brief hip_bfloat16.h provides struct for hip_bfloat16 typedef
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*/
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#ifndef _HIP_BFLOAT16_H_
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#define _HIP_BFLOAT16_H_
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#if __cplusplus < 201103L || !defined(__HIPCC__)
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// If this is a C compiler, C++ compiler below C++11, or a host-only compiler, we only
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// include a minimal definition of hip_bfloat16
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#include <stdint.h>
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/*! \brief Struct to represent a 16 bit brain floating point number. */
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typedef struct
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{
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uint16_t data;
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} hip_bfloat16;
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#else // __cplusplus < 201103L || !defined(__HIPCC__)
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#include <cmath>
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#include <cstddef>
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#include <cstdint>
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#include <hip/hip_runtime.h>
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#include <ostream>
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#include <type_traits>
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#pragma clang diagnostic push
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#pragma clang diagnostic ignored "-Wshadow"
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struct hip_bfloat16
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{
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uint16_t data;
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enum truncate_t
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{
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truncate
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};
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__host__ __device__ hip_bfloat16() = default;
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// round upper 16 bits of IEEE float to convert to bfloat16
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explicit __host__ __device__ hip_bfloat16(float f)
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: data(float_to_bfloat16(f))
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{
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}
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explicit __host__ __device__ hip_bfloat16(float f, truncate_t)
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: data(truncate_float_to_bfloat16(f))
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{
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}
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// zero extend lower 16 bits of bfloat16 to convert to IEEE float
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__host__ __device__ operator float() const
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{
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union
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{
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uint32_t int32;
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float fp32;
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} u = {uint32_t(data) << 16};
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return u.fp32;
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}
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static __host__ __device__ hip_bfloat16 round_to_bfloat16(float f)
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{
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hip_bfloat16 output;
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output.data = float_to_bfloat16(f);
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return output;
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}
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static __host__ __device__ hip_bfloat16 round_to_bfloat16(float f, truncate_t)
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{
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hip_bfloat16 output;
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output.data = truncate_float_to_bfloat16(f);
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return output;
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}
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private:
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static __host__ __device__ uint16_t float_to_bfloat16(float f)
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{
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union
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{
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float fp32;
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uint32_t int32;
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} u = {f};
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if(~u.int32 & 0x7f800000)
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{
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// When the exponent bits are not all 1s, then the value is zero, normal,
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// or subnormal. We round the bfloat16 mantissa up by adding 0x7FFF, plus
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// 1 if the least significant bit of the bfloat16 mantissa is 1 (odd).
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// This causes the bfloat16's mantissa to be incremented by 1 if the 16
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// least significant bits of the float mantissa are greater than 0x8000,
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// or if they are equal to 0x8000 and the least significant bit of the
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// bfloat16 mantissa is 1 (odd). This causes it to be rounded to even when
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// the lower 16 bits are exactly 0x8000. If the bfloat16 mantissa already
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// has the value 0x7f, then incrementing it causes it to become 0x00 and
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// the exponent is incremented by one, which is the next higher FP value
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// to the unrounded bfloat16 value. When the bfloat16 value is subnormal
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// with an exponent of 0x00 and a mantissa of 0x7F, it may be rounded up
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// to a normal value with an exponent of 0x01 and a mantissa of 0x00.
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// When the bfloat16 value has an exponent of 0xFE and a mantissa of 0x7F,
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// incrementing it causes it to become an exponent of 0xFF and a mantissa
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// of 0x00, which is Inf, the next higher value to the unrounded value.
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u.int32 += 0x7fff + ((u.int32 >> 16) & 1); // Round to nearest, round to even
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}
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else if(u.int32 & 0xffff)
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{
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// When all of the exponent bits are 1, the value is Inf or NaN.
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// Inf is indicated by a zero mantissa. NaN is indicated by any nonzero
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// mantissa bit. Quiet NaN is indicated by the most significant mantissa
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// bit being 1. Signaling NaN is indicated by the most significant
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// mantissa bit being 0 but some other bit(s) being 1. If any of the
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// lower 16 bits of the mantissa are 1, we set the least significant bit
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// of the bfloat16 mantissa, in order to preserve signaling NaN in case
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// the bloat16's mantissa bits are all 0.
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u.int32 |= 0x10000; // Preserve signaling NaN
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}
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return uint16_t(u.int32 >> 16);
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}
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// Truncate instead of rounding, preserving SNaN
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static __host__ __device__ uint16_t truncate_float_to_bfloat16(float f)
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{
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union
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{
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float fp32;
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uint32_t int32;
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} u = {f};
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return uint16_t(u.int32 >> 16) | (!(~u.int32 & 0x7f800000) && (u.int32 & 0xffff));
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}
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};
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#pragma clang diagnostic pop
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typedef struct
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{
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uint16_t data;
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} hip_bfloat16_public;
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static_assert(std::is_standard_layout<hip_bfloat16>{},
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"hip_bfloat16 is not a standard layout type, and thus is "
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"incompatible with C.");
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static_assert(std::is_trivial<hip_bfloat16>{},
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"hip_bfloat16 is not a trivial type, and thus is "
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"incompatible with C.");
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static_assert(sizeof(hip_bfloat16) == sizeof(hip_bfloat16_public)
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&& offsetof(hip_bfloat16, data) == offsetof(hip_bfloat16_public, data),
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"internal hip_bfloat16 does not match public hip_bfloat16");
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inline std::ostream& operator<<(std::ostream& os, const hip_bfloat16& bf16)
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{
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return os << float(bf16);
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}
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inline __host__ __device__ hip_bfloat16 operator+(hip_bfloat16 a)
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{
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return a;
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}
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inline __host__ __device__ hip_bfloat16 operator-(hip_bfloat16 a)
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{
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a.data ^= 0x8000;
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return a;
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}
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inline __host__ __device__ hip_bfloat16 operator+(hip_bfloat16 a, hip_bfloat16 b)
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{
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return hip_bfloat16(float(a) + float(b));
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}
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inline __host__ __device__ hip_bfloat16 operator-(hip_bfloat16 a, hip_bfloat16 b)
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{
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return hip_bfloat16(float(a) - float(b));
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}
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inline __host__ __device__ hip_bfloat16 operator*(hip_bfloat16 a, hip_bfloat16 b)
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{
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return hip_bfloat16(float(a) * float(b));
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}
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inline __host__ __device__ hip_bfloat16 operator/(hip_bfloat16 a, hip_bfloat16 b)
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{
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return hip_bfloat16(float(a) / float(b));
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}
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inline __host__ __device__ bool operator<(hip_bfloat16 a, hip_bfloat16 b)
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{
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return float(a) < float(b);
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}
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inline __host__ __device__ bool operator==(hip_bfloat16 a, hip_bfloat16 b)
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{
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return float(a) == float(b);
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}
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inline __host__ __device__ bool operator>(hip_bfloat16 a, hip_bfloat16 b)
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{
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return b < a;
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}
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inline __host__ __device__ bool operator<=(hip_bfloat16 a, hip_bfloat16 b)
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{
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return !(a > b);
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}
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inline __host__ __device__ bool operator!=(hip_bfloat16 a, hip_bfloat16 b)
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{
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return !(a == b);
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}
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inline __host__ __device__ bool operator>=(hip_bfloat16 a, hip_bfloat16 b)
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{
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return !(a < b);
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}
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inline __host__ __device__ hip_bfloat16& operator+=(hip_bfloat16& a, hip_bfloat16 b)
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{
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return a = a + b;
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}
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inline __host__ __device__ hip_bfloat16& operator-=(hip_bfloat16& a, hip_bfloat16 b)
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{
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return a = a - b;
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}
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inline __host__ __device__ hip_bfloat16& operator*=(hip_bfloat16& a, hip_bfloat16 b)
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{
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return a = a * b;
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}
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inline __host__ __device__ hip_bfloat16& operator/=(hip_bfloat16& a, hip_bfloat16 b)
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{
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return a = a / b;
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}
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inline __host__ __device__ hip_bfloat16& operator++(hip_bfloat16& a)
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{
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return a += hip_bfloat16(1.0f);
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}
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inline __host__ __device__ hip_bfloat16& operator--(hip_bfloat16& a)
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{
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return a -= hip_bfloat16(1.0f);
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}
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inline __host__ __device__ hip_bfloat16 operator++(hip_bfloat16& a, int)
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{
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hip_bfloat16 orig = a;
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++a;
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return orig;
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}
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inline __host__ __device__ hip_bfloat16 operator--(hip_bfloat16& a, int)
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{
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hip_bfloat16 orig = a;
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--a;
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return orig;
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}
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namespace std
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{
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constexpr __host__ __device__ bool isinf(hip_bfloat16 a)
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{
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return !(~a.data & 0x7f80) && !(a.data & 0x7f);
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}
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constexpr __host__ __device__ bool isnan(hip_bfloat16 a)
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{
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return !(~a.data & 0x7f80) && +(a.data & 0x7f);
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}
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constexpr __host__ __device__ bool iszero(hip_bfloat16 a)
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{
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return !(a.data & 0x7fff);
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}
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}
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#endif // __cplusplus < 201103L || !defined(__HIPCC__)
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#endif // _HIP_BFLOAT16_H_
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