workbench/libs/mesa/src/gallium/auxiliary/util/u_half.h

   1 /**************************************************************************
   2  *
   3  * Copyright 2010 Luca Barbieri
   4  *
   5  * Permission is hereby granted, free of charge, to any person obtaining
   6  * a copy of this software and associated documentation files (the
   7  * "Software"), to deal in the Software without restriction, including
   8  * without limitation the rights to use, copy, modify, merge, publish,
   9  * distribute, sublicense, and/or sell copies of the Software, and to
  10  * permit persons to whom the Software is furnished to do so, subject to
  11  * the following conditions:
  12  *
  13  * The above copyright notice and this permission notice (including the
  14  * next paragraph) shall be included in all copies or substantial
  15  * portions of the Software.
  16  *
  17  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  18  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  19  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
  20  * IN NO EVENT SHALL THE COPYRIGHT OWNER(S) AND/OR ITS SUPPLIERS BE
  21  * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  22  * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  23  * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  24  *
  25  **************************************************************************/
  26
  27
  28 #ifndef U_HALF_H
  29 #define U_HALF_H
  30
  31 #include "pipe/p_compiler.h"
  32 #include "util/u_math.h"
  33
  34 #ifdef __cplusplus
  35 extern "C" {
  36 #endif
  37
  38 extern const uint32_t util_half_to_float_mantissa_table[2048];
  39 extern const uint32_t util_half_to_float_exponent_table[64];
  40 extern const uint32_t util_half_to_float_offset_table[64];
  41 extern const uint16_t util_float_to_half_base_table[512];
  42 extern const uint8_t util_float_to_half_shift_table[512];
  43
  44 /*
  45  * Note that if the half float is a signaling NaN, the x87 FPU will turn
  46  * it into a quiet NaN immediately upon loading into a float.
  47  *
  48  * Additionally, denormals may be flushed to zero.
  49  *
  50  * To avoid this, use the floatui functions instead of the float ones
  51  * when just doing conversion rather than computation on the resulting
  52  * floats.
  53  */
  54
  55 static INLINE uint32_t
  56 util_half_to_floatui(uint16_t h)
  57 {
  58    unsigned exp = h >> 10;
  59    return util_half_to_float_mantissa_table[util_half_to_float_offset_table[exp] + (h & 0x3ff)] + util_half_to_float_exponent_table[exp];
  60 }
  61
  62 static INLINE float
  63 util_half_to_float(uint16_t h)
  64 {
  65    union fi r;
  66    r.ui = util_half_to_floatui(h);
  67    return r.f;
  68 }
  69
  70 static INLINE uint16_t
  71 util_floatui_to_half(uint32_t v)
  72 {
  73    unsigned signexp = v >> 23;
  74    return util_float_to_half_base_table[signexp] + ((v & 0x007fffff) >> util_float_to_half_shift_table[signexp]);
  75 }
  76
  77 static INLINE uint16_t
  78 util_float_to_half(float f)
  79 {
  80    union fi i;
  81    i.f = f;
  82    return util_floatui_to_half(i.ui);
  83 }
  84
  85 #ifdef __cplusplus
  86 }
  87 #endif
  88
  89 #endif /* U_HALF_H */
  90