Directory: | ../../../ffmpeg/ |
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File: | src/libavcodec/half2float.h |
Date: | 2022-07-04 19:11:22 |
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Lines: | 31 | 31 | 100.0% |
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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_HALF2FLOAT_H | ||
20 | #define AVCODEC_HALF2FLOAT_H | ||
21 | |||
22 | #include <stdint.h> | ||
23 | |||
24 | 175956 | static uint32_t convertmantissa(uint32_t i) | |
25 | { | ||
26 | 175956 | int32_t m = i << 13; // Zero pad mantissa bits | |
27 | 175956 | int32_t e = 0; // Zero exponent | |
28 | |||
29 |
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526148 | while (!(m & 0x00800000)) { // While not normalized |
30 | 350192 | e -= 0x00800000; // Decrement exponent (1<<23) | |
31 | 350192 | m <<= 1; // Shift mantissa | |
32 | } | ||
33 | |||
34 | 175956 | m &= ~0x00800000; // Clear leading 1 bit | |
35 | 175956 | e += 0x38800000; // Adjust bias ((127-14)<<23) | |
36 | |||
37 | 175956 | return m | e; // Return combined number | |
38 | } | ||
39 | |||
40 | 172 | static void half2float_table(uint32_t *mantissatable, uint32_t *exponenttable, | |
41 | uint16_t *offsettable) | ||
42 | { | ||
43 | 172 | mantissatable[0] = 0; | |
44 |
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176128 | for (int i = 1; i < 1024; i++) |
45 | 175956 | mantissatable[i] = convertmantissa(i); | |
46 |
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176300 | for (int i = 1024; i < 2048; i++) |
47 | 176128 | mantissatable[i] = 0x38000000UL + ((i - 1024) << 13UL); | |
48 | |||
49 | 172 | exponenttable[0] = 0; | |
50 |
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5332 | for (int i = 1; i < 31; i++) |
51 | 5160 | exponenttable[i] = i << 23; | |
52 |
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5332 | for (int i = 33; i < 63; i++) |
53 | 5160 | exponenttable[i] = 0x80000000UL + ((i - 32) << 23UL); | |
54 | 172 | exponenttable[31]= 0x47800000UL; | |
55 | 172 | exponenttable[32]= 0x80000000UL; | |
56 | 172 | exponenttable[63]= 0xC7800000UL; | |
57 | |||
58 | 172 | offsettable[0] = 0; | |
59 |
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11008 | for (int i = 1; i < 64; i++) |
60 | 10836 | offsettable[i] = 1024; | |
61 | 172 | offsettable[32] = 0; | |
62 | 172 | } | |
63 | |||
64 | 11272192 | static uint32_t half2float(uint16_t h, uint32_t *mantissatable, uint32_t *exponenttable, | |
65 | uint16_t *offsettable) | ||
66 | { | ||
67 | uint32_t f; | ||
68 | |||
69 | 11272192 | f = mantissatable[offsettable[h >> 10] + (h & 0x3ff)] + exponenttable[h >> 10]; | |
70 | |||
71 | 11272192 | return f; | |
72 | } | ||
73 | |||
74 | #endif /* AVCODEC_HALF2FLOAT_H */ | ||
75 |