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1 | /* | ||
2 | * Header file for hardcoded AAC cube-root table | ||
3 | * | ||
4 | * Copyright (c) 2010 Reimar Döffinger <Reimar.Doeffinger@gmx.de> | ||
5 | * | ||
6 | * This file is part of FFmpeg. | ||
7 | * | ||
8 | * FFmpeg is free software; you can redistribute it and/or | ||
9 | * modify it under the terms of the GNU Lesser General Public | ||
10 | * License as published by the Free Software Foundation; either | ||
11 | * version 2.1 of the License, or (at your option) any later version. | ||
12 | * | ||
13 | * FFmpeg is distributed in the hope that it will be useful, | ||
14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | ||
15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | ||
16 | * Lesser General Public License for more details. | ||
17 | * | ||
18 | * You should have received a copy of the GNU Lesser General Public | ||
19 | * License along with FFmpeg; if not, write to the Free Software | ||
20 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA | ||
21 | */ | ||
22 | |||
23 | #ifndef AVCODEC_CBRT_TABLEGEN_H | ||
24 | #define AVCODEC_CBRT_TABLEGEN_H | ||
25 | |||
26 | #include <assert.h> | ||
27 | #include <stdint.h> | ||
28 | #include <math.h> | ||
29 | #include "libavutil/attributes.h" | ||
30 | #include "libavutil/intfloat.h" | ||
31 | #include "libavcodec/aac_defines.h" | ||
32 | #include "cbrt_data.h" | ||
33 | |||
34 | #if USE_FIXED | ||
35 | #define CBRT(x) lrint((x) * 8192) | ||
36 | #else | ||
37 | #define CBRT(x) av_float2int((float)(x)) | ||
38 | #endif | ||
39 | |||
40 | union CBRT AAC_RENAME(ff_cbrt_tab_internal); | ||
41 | |||
42 | 187 | av_cold void AAC_RENAME(ff_cbrt_tableinit)(void) | |
43 | { | ||
44 | static_assert(2 * sizeof(AAC_RENAME(ff_cbrt_tab_internal).cbrt_tab[0]) | ||
45 | >= sizeof(AAC_RENAME(ff_cbrt_tab_internal).tmp[0]), | ||
46 | "unexpected sizeofs"); | ||
47 | // We reuse ff_cbrt_tab_internal.tmp as a LUT (of doubles) for the roots | ||
48 | // of the odd integers: tmp[idx] contains (2 * idx + 1)^{4/3}. | ||
49 | 187 | ff_cbrt_dbl_tableinit(AAC_RENAME(ff_cbrt_tab_internal).tmp); | |
50 | |||
51 | 187 | double cbrt_2 = 2 * cbrt(2); | |
52 |
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766139 | for (int idx = TMP_LUT_SIZE - 1; idx >= 0; --idx) { |
53 | 765952 | double cbrt_val = AAC_RENAME(ff_cbrt_tab_internal).tmp[idx]; | |
54 | // Due to i * sizeof(ff_cbrt_tab_internal.cbrt_tab[0]) >= | ||
55 | // 2 * idx * sizeof(ff_cbrt_tab_internal.cbrt_tab[0]) >= idx * sizeof(double) | ||
56 | // we don't clobber the double-LUT entries with index < idx | ||
57 | // in the loop below. This is why we process idx in descending order. | ||
58 |
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2297669 | for (int i = 2 * idx + 1; i < LUT_SIZE; i *= 2) { |
59 | 1531717 | AAC_RENAME(ff_cbrt_tab_internal).cbrt_tab[i] = CBRT(cbrt_val); | |
60 | 1531717 | cbrt_val *= cbrt_2; | |
61 | } | ||
62 | } | ||
63 | 187 | AAC_RENAME(ff_cbrt_tab_internal).cbrt_tab[0] = CBRT(0); | |
64 | 187 | } | |
65 | |||
66 | #endif /* AVCODEC_CBRT_TABLEGEN_H */ | ||
67 |