FFmpeg coverage


Directory: ../../../ffmpeg/
File: src/libavcodec/float2half.h
Date: 2021-09-24 20:55:06
Exec Total Coverage
Lines: 0 30 0.0%
Branches: 0 10 0.0%

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1 /*
2 * This file is part of FFmpeg.
3 *
4 * FFmpeg is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU Lesser General Public
6 * License as published by the Free Software Foundation; either
7 * version 2.1 of the License, or (at your option) any later version.
8 *
9 * FFmpeg is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * Lesser General Public License for more details.
13 *
14 * You should have received a copy of the GNU Lesser General Public
15 * License along with FFmpeg; if not, write to the Free Software
16 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
17 */
18
19 #ifndef AVCODEC_FLOAT2HALF_H
20 #define AVCODEC_FLOAT2HALF_H
21
22 #include <stdint.h>
23
24 static void float2half_tables(uint16_t *basetable, uint8_t *shifttable)
25 {
26 for (int i = 0; i < 256; i++) {
27 int e = i - 127;
28
29 if (e < -24) { // Very small numbers map to zero
30 basetable[i|0x000] = 0x0000;
31 basetable[i|0x100] = 0x8000;
32 shifttable[i|0x000] = 24;
33 shifttable[i|0x100] = 24;
34 } else if (e < -14) { // Small numbers map to denorms
35 basetable[i|0x000] = (0x0400>>(-e-14));
36 basetable[i|0x100] = (0x0400>>(-e-14)) | 0x8000;
37 shifttable[i|0x000] = -e-1;
38 shifttable[i|0x100] = -e-1;
39 } else if (e <= 15) { // Normal numbers just lose precision
40 basetable[i|0x000] = ((e + 15) << 10);
41 basetable[i|0x100] = ((e + 15) << 10) | 0x8000;
42 shifttable[i|0x000] = 13;
43 shifttable[i|0x100] = 13;
44 } else if (e < 128) { // Large numbers map to Infinity
45 basetable[i|0x000] = 0x7C00;
46 basetable[i|0x100] = 0xFC00;
47 shifttable[i|0x000] = 24;
48 shifttable[i|0x100] = 24;
49 } else { // Infinity and NaN's stay Infinity and NaN's
50 basetable[i|0x000] = 0x7C00;
51 basetable[i|0x100] = 0xFC00;
52 shifttable[i|0x000] = 13;
53 shifttable[i|0x100] = 13;
54 }
55 }
56 }
57
58 static uint16_t float2half(uint32_t f, uint16_t *basetable, uint8_t *shifttable)
59 {
60 uint16_t h;
61
62 h = basetable[(f >> 23) & 0x1ff] + ((f & 0x007fffff) >> shifttable[(f >> 23) & 0x1ff]);
63
64 return h;
65 }
66
67 #endif /* AVCODEC_FLOAT2HALF_H */
68