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660c6c8d6f
Similar to the previous commit, to avoid undefined behaviour we need to avoid evaluating out-of-bounds shifts, even if their result is going to ignored by being multiplied by 0 later. Detected by running a subset of the test suite with -Dsanitize=address,undefined on x86_64. Signed-off-by: Simon McVittie <smcv@debian.org>
126 lines
3.3 KiB
C
126 lines
3.3 KiB
C
/* fp16private.h
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*
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* Copyright 2021 Red Hat, Inc.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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* SPDX-License-Identifier: LGPL-2.1-or-later
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*/
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#pragma once
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#include <glib.h>
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G_BEGIN_DECLS
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#define FP16_ZERO ((guint16)0)
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#define FP16_ONE ((guint16)15360)
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#define FP16_MINUS_ONE ((guint16)48128)
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static inline guint
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as_uint (const float x)
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{
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return *(guint*)&x;
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}
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static inline float
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as_float (const guint x)
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{
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return *(float*)&x;
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}
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// IEEE-754 16-bit floating-point format (without infinity): 1-5-10
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static inline float
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half_to_float_one (const guint16 x)
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{
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const guint e = (x & 0x7C00) >> 10; // exponent
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const guint m = (x & 0x03FF) << 13; // mantissa
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const guint v = as_uint ((float) m) >> 23;
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guint normalized = 0;
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guint denormalized = 0;
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if (e != 0)
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normalized = (e + 112) << 23 | m;
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if (e == 0 && m != 0)
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denormalized = (v - 37) << 23 | ((m << (150 - v)) & 0x007FE000);
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return as_float ((x & 0x8000u) << 16 | normalized | denormalized);
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}
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static inline guint16
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float_to_half_one (const float x)
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{
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const guint b = *(guint*)&x+0x00001000; // round-to-nearest-even
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const guint e = (b&0x7F800000)>>23; // exponent
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const guint m = b&0x007FFFFF; // mantissa
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guint n0 = 0;
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guint n1 = 0;
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guint n2 = 0;
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if (e > 112)
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n0 = (((e - 112) << 10) & 0x7C00) | m >> 13;
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if (e < 113 && e > 101)
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n1 = (((0x007FF000 + m) >> (125- e)) + 1) >> 1;
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if (e > 143)
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n2 = 0x7FFF;
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return (b & 0x80000000) >> 16 | n0 | n1 | n2; // sign : normalized : denormalized : saturate
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}
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void float_to_half4 (const float f[4],
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guint16 h[4]);
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void half_to_float4 (const guint16 h[4],
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float f[4]);
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void float_to_half (const float *f,
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guint16 *h,
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int n);
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void half_to_float (const guint16 *h,
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float *f,
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int n);
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void float_to_half4_f16c (const float f[4],
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guint16 h[4]);
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void half_to_float4_f16c (const guint16 h[4],
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float f[4]);
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void float_to_half_f16c (const float *f,
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guint16 *h,
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int n);
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void half_to_float_f16c (const guint16 *h,
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float *f,
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int n);
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void float_to_half4_c (const float f[4],
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guint16 h[4]);
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void half_to_float4_c (const guint16 h[4],
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float f[4]);
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void float_to_half_c (const float *f,
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guint16 *h,
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int n);
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void half_to_float_c (const guint16 *h,
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float *f,
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int n);
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G_END_DECLS
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