wehub-resource-sync
61 lines
1.7 KiB
C++
61 lines
1.7 KiB
C++
/*
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* SPDX-FileCopyrightText: Copyright (c) 1993-2024 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
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* SPDX-License-Identifier: Apache-2.0
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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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*/
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#include "bfloat16.h"
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#include <cstring>
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namespace sample
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{
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BFloat16::operator float() const
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{
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static_assert(sizeof(uint32_t) == sizeof(float), "");
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float val{0.F};
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auto bits = static_cast<uint32_t>(mRep) << 16;
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std::memcpy(&val, &bits, sizeof(uint32_t));
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return val;
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}
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BFloat16::BFloat16(float x)
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{
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static_assert(sizeof(uint32_t) == sizeof(float), "");
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uint32_t bits{0};
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std::memcpy(&bits, &x, sizeof(float));
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// FP32 format: 1 sign bit, 8 bit exponent, 23 bit mantissa
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// BF16 format: 1 sign bit, 8 bit exponent, 7 bit mantissa
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// Mask for exponent
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constexpr uint32_t exponent = 0xFFU << 23;
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// Check if exponent is all 1s (NaN or infinite)
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if ((bits & exponent) != exponent)
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{
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// x is finite - round to even
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bits += 0x7FFFU + (bits >> 16 & 1);
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}
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mRep = static_cast<uint16_t>(bits >> 16);
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}
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BFloat16 operator+(BFloat16 x, BFloat16 y)
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{
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return BFloat16(static_cast<float>(x) + static_cast<float>(y));
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}
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} // namespace sample
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