IABSD.fr/xenocara/lib/mesa/src/intel/compiler/brw_packed_float.c

Branch : - branch - master - tag -

• Show log

  Commit

• Author : jsg
  Date : 2020-08-26 06:02:31
  Hash : 6cd42bcb
  Message : Merge Mesa 20.1.6

• lib/mesa/src/intel/compiler/brw_packed_float.c

• /*
   * Copyright © 2014 Intel Corporation
   *
   * 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 AUTHORS OR COPYRIGHT HOLDERS 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.
   */
  #include "brw_reg.h"
  
  union fu {
     float f;
     unsigned u;
     struct {
        unsigned mantissa:23;
        unsigned exponent:8;
        unsigned sign:1;
     } s;
  };
  
  int
  brw_float_to_vf(float f)
  {
     union fu fu = { .f = f };
  
     /* ±0.0f is special cased. */
     if (f == 0.0f)
        return fu.s.sign << 7;
  
     unsigned mantissa = fu.s.mantissa >> (23 - 4);
     unsigned exponent = fu.s.exponent - (127 - 3);
     unsigned vf = (fu.s.sign << 7) | (exponent << 4) | mantissa;
  
     /* 0.125 would have had the same representation as 0.0, so reject it. */
     if ((vf & 0x7f) == 0)
        return -1;
  
     /* Make sure the mantissa fits in 4-bits and the exponent in 3-bits. */
     if (fu.u & 0x7ffff || exponent > 7)
        return -1;
  
     return vf;
  }
  
  float
  brw_vf_to_float(unsigned char vf)
  {
     union fu fu;
  
     /* ±0.0f is special cased. */
     if (vf == 0x00 || vf == 0x80) {
        fu.u = (unsigned)vf << 24;
        return fu.f;
     }
  
     fu.s.sign = vf >> 7;
     fu.s.exponent = ((vf & 0x70) >> 4) + (127 - 3);
     fu.s.mantissa = (vf & 0xf) << (23 - 4);
  
     return fu.f;
  }