1/*
2 * Copyright © 2014 Intel Corporation
3 *
4 * Permission is hereby granted, free of charge, to any person obtaining a
5 * copy of this software and associated documentation files (the "Software"),
6 * to deal in the Software without restriction, including without limitation
7 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
8 * and/or sell copies of the Software, and to permit persons to whom the
9 * Software is furnished to do so, subject to the following conditions:
10 *
11 * The above copyright notice and this permission notice (including the next
12 * paragraph) shall be included in all copies or substantial portions of the
13 * Software.
14 *
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
18 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
20 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
21 * IN THE SOFTWARE.
22 */
23#include "brw_reg.h"
24
25union fu {
26   float f;
27   unsigned u;
28   struct {
29      unsigned mantissa:23;
30      unsigned exponent:8;
31      unsigned sign:1;
32   } s;
33};
34
35int
36brw_float_to_vf(float f)
37{
38   union fu fu = { .f = f };
39
40   /* ±0.0f is special cased. */
41   if (f == 0.0f)
42      return fu.s.sign << 7;
43
44   unsigned mantissa = fu.s.mantissa >> (23 - 4);
45   unsigned exponent = fu.s.exponent - (127 - 3);
46   unsigned vf = (fu.s.sign << 7) | (exponent << 4) | mantissa;
47
48   /* 0.125 would have had the same representation as 0.0, so reject it. */
49   if ((vf & 0x7f) == 0)
50      return -1;
51
52   /* Make sure the mantissa fits in 4-bits and the exponent in 3-bits. */
53   if (fu.u & 0x7ffff || exponent > 7)
54      return -1;
55
56   return vf;
57}
58
59float
60brw_vf_to_float(unsigned char vf)
61{
62   union fu fu;
63
64   /* ±0.0f is special cased. */
65   if (vf == 0x00 || vf == 0x80) {
66      fu.u = vf << 24;
67      return fu.f;
68   }
69
70   fu.s.sign = vf >> 7;
71   fu.s.exponent = ((vf & 0x70) >> 4) + (127 - 3);
72   fu.s.mantissa = (vf & 0xf) << (23 - 4);
73
74   return fu.f;
75}
76