src/util/half_float.h

   1 /*
   2  * Mesa 3-D graphics library
   3  *
   4  * Copyright (C) 1999-2007  Brian Paul   All Rights Reserved.
   5  * Copyright (C) 2018-2019 Intel Corporation
   6  *
   7  * Permission is hereby granted, free of charge, to any person obtaining a
   8  * copy of this software and associated documentation files (the "Software"),
   9  * to deal in the Software without restriction, including without limitation
  10  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  11  * and/or sell copies of the Software, and to permit persons to whom the
  12  * Software is furnished to do so, subject to the following conditions:
  13  *
  14  * The above copyright notice and this permission notice shall be included
  15  * in all copies or substantial portions of the Software.
  16  *
  17  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  18  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  20  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
  21  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  22  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  23  * OTHER DEALINGS IN THE SOFTWARE.
  24  */
  25
  26 #ifndef _HALF_FLOAT_H_
  27 #define _HALF_FLOAT_H_
  28
  29 #include <stdbool.h>
  30 #include <stdint.h>
  31
  32 #ifdef __cplusplus
  33 extern "C" {
  34 #endif
  35
  36 #define FP16_ONE     ((uint16_t) 0x3c00)
  37 #define FP16_ZERO    ((uint16_t) 0)
  38
  39 uint16_t _mesa_float_to_half(float val);
  40 float _mesa_half_to_float(uint16_t val);
  41 uint8_t _mesa_half_to_unorm8(uint16_t v);
  42 uint16_t _mesa_uint16_div_64k_to_half(uint16_t v);
  43
  44 /*
  45  * _mesa_float_to_float16_rtz is no more than a wrapper to the counterpart
  46  * softfloat.h call. Still, softfloat.h conversion API is meant to be kept
  47  * private. In other words, only use the API published here, instead of
  48  * calling directly the softfloat.h one.
  49  */
  50 uint16_t _mesa_float_to_float16_rtz(float val);
  51
  52 static inline uint16_t
  53 _mesa_float_to_float16_rtne(float val)
  54 {
  55    return _mesa_float_to_half(val);
  56 }
  57
  58 static inline bool
  59 _mesa_half_is_negative(uint16_t h)
  60 {
  61    return !!(h & 0x8000);
  62 }
  63
  64
  65 #ifdef __cplusplus
  66
  67 /* Helper class for disambiguating fp16 from uint16_t in C++ overloads */
  68
  69 struct float16_t {
  70    uint16_t bits;
  71    float16_t(float f) : bits(_mesa_float_to_half(f)) {}
  72    float16_t(double d) : bits(_mesa_float_to_half(d)) {}
  73    float16_t(uint16_t bits) : bits(bits) {}
  74    static float16_t one() { return float16_t(FP16_ONE); }
  75    static float16_t zero() { return float16_t(FP16_ZERO); }
  76 };
  77
  78 #endif
  79
  80
  81 #ifdef __cplusplus
  82 } /* extern C */
  83 #endif
  84
  85 #endif /* _HALF_FLOAT_H_ */