fp16_emu.cuh

/**
 * Copyright (c) 2015-present, Facebook, Inc.
 * All rights reserved.
 *
 * This source code is licensed under the CC-by-NC license found in the
 * LICENSE file in the root directory of this source tree.
 */

// from Nvidia cuDNN library samples; modified to compile within faiss

#pragma once

namespace faiss { namespace gpu {

/*
 * Copyright 1993-2014 NVIDIA Corporation.  All rights reserved.
 *
 * NOTICE TO LICENSEE:
 *
 * This source code and/or documentation ("Licensed Deliverables") are
 * subject to NVIDIA intellectual property rights under U.S. and
 * international Copyright laws.
 *
 * These Licensed Deliverables contained herein is PROPRIETARY and
 * CONFIDENTIAL to NVIDIA and is being provided under the terms and
 * conditions of a form of NVIDIA software license agreement by and
 * between NVIDIA and Licensee ("License Agreement") or electronically
 * accepted by Licensee.  Notwithstanding any terms or conditions to
 * the contrary in the License Agreement, reproduction or disclosure
 * of the Licensed Deliverables to any third party without the express
 * written consent of NVIDIA is prohibited.
 *
 * NOTWITHSTANDING ANY TERMS OR CONDITIONS TO THE CONTRARY IN THE
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 * OF THESE LICENSED DELIVERABLES.
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 * U.S. Government End Users.  These Licensed Deliverables are a
 * "commercial item" as that term is defined at 48 C.F.R. 2.101 (OCT
 * 1995), consisting of "commercial computer software" and "commercial
 * computer software documentation" as such terms are used in 48
 * C.F.R. 12.212 (SEPT 1995) and is provided to the U.S. Government
 * only as a commercial end item.  Consistent with 48 C.F.R.12.212 and
 * 48 C.F.R. 227.7202-1 through 227.7202-4 (JUNE 1995), all
 * U.S. Government End Users acquire the Licensed Deliverables with
 * only those rights set forth herein.
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 * Any use of the Licensed Deliverables in individual and commercial
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 */

// Conversion from/to 16-bit floating point (half-precision).

#define HLF_EPSILON 4.887581E-04

typedef struct __align__(2) {
   unsigned short x;
} half1;

half1 cpu_float2half_rn(float f);

float cpu_half2float(half1 h);

static __inline__ __device__ __host__ half1 habs(half1 h)
{
    h.x &= 0x7fffU;
    return h;
}

static __inline__ __device__ __host__ half1 hneg(half1 h)
{
    h.x ^= 0x8000U;
    return h;
}

static __inline__ __device__ __host__ int ishnan(half1 h)
{
    // When input is NaN, exponent is all ones and mantissa is non-zero.
    return (h.x & 0x7c00U) == 0x7c00U && (h.x & 0x03ffU) != 0;
}

static __inline__ __device__ __host__ int ishinf(half1 h)
{
    // When input is +/- inf, exponent is all ones and mantissa is zero.
    return (h.x & 0x7c00U) == 0x7c00U && (h.x & 0x03ffU) == 0;
}

static __inline__ __device__ __host__ int ishequ(half1 x, half1 y)
{
    return ishnan(x) == 0 && ishnan(y) == 0 && x.x == y.x;
}

static __inline__ __device__ __host__ half1 hzero()
{
    half1 ret;
    ret.x = 0x0000U;
    return ret;
}

static __inline__ __device__ __host__ half1 hone()
{
    half1 ret;
    ret.x = 0x3c00U;
    return ret;
}

} } // namespace