0,0 → 1,123 |
/************************************************************************** |
* |
* Copyright 2010 Luca Barbieri |
* |
* Permission is hereby granted, free of charge, to any person obtaining |
* a copy of this software and associated documentation files (the |
* "Software"), to deal in the Software without restriction, including |
* without limitation the rights to use, copy, modify, merge, publish, |
* distribute, sublicense, and/or sell copies of the Software, and to |
* permit persons to whom the Software is furnished to do so, subject to |
* the following conditions: |
* |
* The above copyright notice and this permission notice (including the |
* next paragraph) shall be included in all copies or substantial |
* portions of the Software. |
* |
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, |
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF |
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. |
* IN NO EVENT SHALL THE COPYRIGHT OWNER(S) AND/OR ITS SUPPLIERS BE |
* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION |
* OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION |
* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. |
* |
**************************************************************************/ |
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#ifndef U_HALF_H |
#define U_HALF_H |
|
#include "pipe/p_compiler.h" |
#include "util/u_math.h" |
|
#ifdef __cplusplus |
extern "C" { |
#endif |
|
/* |
* References for float <-> half conversions |
* |
* http://fgiesen.wordpress.com/2012/03/28/half-to-float-done-quic/ |
* https://gist.github.com/2156668 |
* https://gist.github.com/2144712 |
*/ |
|
static INLINE uint16_t |
util_float_to_half(float f) |
{ |
uint32_t sign_mask = 0x80000000; |
uint32_t round_mask = ~0xfff; |
uint32_t f32inf = 0xff << 23; |
uint32_t f16inf = 0x1f << 23; |
uint32_t sign; |
union fi magic; |
union fi f32; |
uint16_t f16; |
|
magic.ui = 0xf << 23; |
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f32.f = f; |
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/* Sign */ |
sign = f32.ui & sign_mask; |
f32.ui ^= sign; |
|
if (f32.ui == f32inf) { |
/* Inf */ |
f16 = 0x7c00; |
} else if (f32.ui > f32inf) { |
/* NaN */ |
f16 = 0x7e00; |
} else { |
/* Number */ |
f32.ui &= round_mask; |
f32.f *= magic.f; |
f32.ui -= round_mask; |
|
/* Clamp to infinity if overflowed */ |
if (f32.ui > f16inf) |
f32.ui = f16inf; |
|
f16 = f32.ui >> 13; |
} |
|
/* Sign */ |
f16 |= sign >> 16; |
|
return f16; |
} |
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static INLINE float |
util_half_to_float(uint16_t f16) |
{ |
union fi infnan; |
union fi magic; |
union fi f32; |
|
infnan.ui = 0x8f << 23; |
infnan.f = 65536.0f; |
magic.ui = 0xef << 23; |
|
/* Exponent / Mantissa */ |
f32.ui = (f16 & 0x7fff) << 13; |
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/* Adjust */ |
f32.f *= magic.f; |
|
/* Inf / NaN */ |
if (f32.f >= infnan.f) |
f32.ui |= 0xff << 23; |
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/* Sign */ |
f32.ui |= (f16 & 0x8000) << 16; |
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return f32.f; |
} |
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#ifdef __cplusplus |
} |
#endif |
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#endif /* U_HALF_H */ |
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