124 lines
2.9 KiB
C
124 lines
2.9 KiB
C
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/**************************************************************************
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*
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* Copyright 2010 Luca Barbieri
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*
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* Permission is hereby granted, free of charge, to any person obtaining
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* a copy of this software and associated documentation files (the
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* "Software"), to deal in the Software without restriction, including
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* without limitation the rights to use, copy, modify, merge, publish,
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* distribute, sublicense, and/or sell copies of the Software, and to
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* permit persons to whom the Software is furnished to do so, subject to
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* the following conditions:
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*
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* The above copyright notice and this permission notice (including the
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* next paragraph) shall be included in all copies or substantial
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* portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
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* IN NO EVENT SHALL THE COPYRIGHT OWNER(S) AND/OR ITS SUPPLIERS BE
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* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
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* OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
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* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*
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**************************************************************************/
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#ifndef U_HALF_H
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#define U_HALF_H
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#include "pipe/p_compiler.h"
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#include "util/u_math.h"
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#ifdef __cplusplus
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extern "C" {
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#endif
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/*
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* References for float <-> half conversions
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*
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* http://fgiesen.wordpress.com/2012/03/28/half-to-float-done-quic/
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* https://gist.github.com/2156668
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* https://gist.github.com/2144712
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*/
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static INLINE uint16_t
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util_float_to_half(float f)
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{
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uint32_t sign_mask = 0x80000000;
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uint32_t round_mask = ~0xfff;
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uint32_t f32inf = 0xff << 23;
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uint32_t f16inf = 0x1f << 23;
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uint32_t sign;
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union fi magic;
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union fi f32;
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uint16_t f16;
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magic.ui = 0xf << 23;
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f32.f = f;
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/* Sign */
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sign = f32.ui & sign_mask;
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f32.ui ^= sign;
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if (f32.ui == f32inf) {
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/* Inf */
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f16 = 0x7c00;
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} else if (f32.ui > f32inf) {
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/* NaN */
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f16 = 0x7e00;
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} else {
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/* Number */
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f32.ui &= round_mask;
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f32.f *= magic.f;
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f32.ui -= round_mask;
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/* Clamp to infinity if overflowed */
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if (f32.ui > f16inf)
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f32.ui = f16inf;
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f16 = f32.ui >> 13;
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}
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/* Sign */
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f16 |= sign >> 16;
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return f16;
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}
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static INLINE float
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util_half_to_float(uint16_t f16)
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{
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union fi infnan;
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union fi magic;
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union fi f32;
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infnan.ui = 0x8f << 23;
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infnan.f = 65536.0f;
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magic.ui = 0xef << 23;
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/* Exponent / Mantissa */
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f32.ui = (f16 & 0x7fff) << 13;
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/* Adjust */
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f32.f *= magic.f;
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/* Inf / NaN */
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if (f32.f >= infnan.f)
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f32.ui |= 0xff << 23;
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/* Sign */
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f32.ui |= (f16 & 0x8000) << 16;
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return f32.f;
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}
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#ifdef __cplusplus
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}
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#endif
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#endif /* U_HALF_H */
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