File size: 1,729 Bytes
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* SPDX-FileCopyrightText: Copyright (c) 1993-2024 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
* SPDX-License-Identifier: Apache-2.0
*
* 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 "bfloat16.h"
#include <cstring>
namespace sample
{
BFloat16::operator float() const
{
static_assert(sizeof(uint32_t) == sizeof(float), "");
float val{0.F};
auto bits = static_cast<uint32_t>(mRep) << 16;
std::memcpy(&val, &bits, sizeof(uint32_t));
return val;
}
BFloat16::BFloat16(float x)
{
static_assert(sizeof(uint32_t) == sizeof(float), "");
uint32_t bits{0};
std::memcpy(&bits, &x, sizeof(float));
// FP32 format: 1 sign bit, 8 bit exponent, 23 bit mantissa
// BF16 format: 1 sign bit, 8 bit exponent, 7 bit mantissa
// Mask for exponent
constexpr uint32_t exponent = 0xFFU << 23;
// Check if exponent is all 1s (NaN or infinite)
if ((bits & exponent) != exponent)
{
// x is finite - round to even
bits += 0x7FFFU + (bits >> 16 & 1);
}
mRep = static_cast<uint16_t>(bits >> 16);
}
BFloat16 operator+(BFloat16 x, BFloat16 y)
{
return BFloat16(static_cast<float>(x) + static_cast<float>(y));
}
} // namespace sample
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