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dirac_arith.c
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1 /*
2  * Copyright (C) 2007 Marco Gerards <marco@gnu.org>
3  * Copyright (C) 2009 David Conrad
4  *
5  * This file is part of FFmpeg.
6  *
7  * FFmpeg is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public
9  * License as published by the Free Software Foundation; either
10  * version 2.1 of the License, or (at your option) any later version.
11  *
12  * FFmpeg is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with FFmpeg; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
22 /**
23  * @file
24  * Arithmetic decoder for Dirac
25  * @author Marco Gerards <marco@gnu.org>
26  */
27 
28 #include "dirac_arith.h"
29 
30 
31 const uint16_t ff_dirac_prob[256] = {
32  0, 2, 5, 8, 11, 15, 20, 24,
33  29, 35, 41, 47, 53, 60, 67, 74,
34  82, 89, 97, 106, 114, 123, 132, 141,
35  150, 160, 170, 180, 190, 201, 211, 222,
36  233, 244, 256, 267, 279, 291, 303, 315,
37  327, 340, 353, 366, 379, 392, 405, 419,
38  433, 447, 461, 475, 489, 504, 518, 533,
39  548, 563, 578, 593, 609, 624, 640, 656,
40  672, 688, 705, 721, 738, 754, 771, 788,
41  805, 822, 840, 857, 875, 892, 910, 928,
42  946, 964, 983, 1001, 1020, 1038, 1057, 1076,
43  1095, 1114, 1133, 1153, 1172, 1192, 1211, 1231,
44  1251, 1271, 1291, 1311, 1332, 1352, 1373, 1393,
45  1414, 1435, 1456, 1477, 1498, 1520, 1541, 1562,
46  1584, 1606, 1628, 1649, 1671, 1694, 1716, 1738,
47  1760, 1783, 1806, 1828, 1851, 1874, 1897, 1920,
48  1935, 1942, 1949, 1955, 1961, 1968, 1974, 1980,
49  1985, 1991, 1996, 2001, 2006, 2011, 2016, 2021,
50  2025, 2029, 2033, 2037, 2040, 2044, 2047, 2050,
51  2053, 2056, 2058, 2061, 2063, 2065, 2066, 2068,
52  2069, 2070, 2071, 2072, 2072, 2072, 2072, 2072,
53  2072, 2071, 2070, 2069, 2068, 2066, 2065, 2063,
54  2060, 2058, 2055, 2052, 2049, 2045, 2042, 2038,
55  2033, 2029, 2024, 2019, 2013, 2008, 2002, 1996,
56  1989, 1982, 1975, 1968, 1960, 1952, 1943, 1934,
57  1925, 1916, 1906, 1896, 1885, 1874, 1863, 1851,
58  1839, 1827, 1814, 1800, 1786, 1772, 1757, 1742,
59  1727, 1710, 1694, 1676, 1659, 1640, 1622, 1602,
60  1582, 1561, 1540, 1518, 1495, 1471, 1447, 1422,
61  1396, 1369, 1341, 1312, 1282, 1251, 1219, 1186,
62  1151, 1114, 1077, 1037, 995, 952, 906, 857,
63  805, 750, 690, 625, 553, 471, 376, 255
64 };
65 
69  [CTX_ZP_F2] = CTX_ZP_F3,
70  [CTX_ZP_F3] = CTX_ZP_F4,
71  [CTX_ZP_F4] = CTX_ZP_F5,
72  [CTX_ZP_F5] = CTX_ZP_F6,
73  [CTX_ZP_F6] = CTX_ZP_F6,
76  [CTX_NP_F2] = CTX_NP_F3,
77  [CTX_NP_F3] = CTX_NP_F4,
78  [CTX_NP_F4] = CTX_NP_F5,
79  [CTX_NP_F5] = CTX_NP_F6,
80  [CTX_NP_F6] = CTX_NP_F6,
82 };
83 
84 int16_t ff_dirac_prob_branchless[256][2];
85 
87 {
88  int i;
89 
90  for (i = 0; i < 256; i++) {
93  }
94 }
95 
97 {
98  int i;
99  align_get_bits(gb);
100 
101  length = FFMIN(length, get_bits_left(gb)/8);
102 
103  c->bytestream = gb->buffer + get_bits_count(gb)/8;
104  c->bytestream_end = c->bytestream + length;
105  skip_bits_long(gb, length*8);
106 
107  c->low = 0;
108  for (i = 0; i < 4; i++) {
109  c->low <<= 8;
110  if (c->bytestream < c->bytestream_end)
111  c->low |= *c->bytestream++;
112  else
113  c->low |= 0xff;
114  }
115 
116  c->counter = -16;
117  c->range = 0xffff;
118 
119  for (i = 0; i < DIRAC_CTX_COUNT; i++)
120  c->contexts[i] = 0x8000;
121 }
int16_t ff_dirac_prob_branchless[256][2]
Definition: dirac_arith.c:84
static void skip_bits_long(GetBitContext *s, int n)
Definition: get_bits.h:204
const uint8_t ff_dirac_next_ctx[DIRAC_CTX_COUNT]
Definition: dirac_arith.c:66
void ff_dirac_init_arith_decoder(DiracArith *c, GetBitContext *gb, int length)
Definition: dirac_arith.c:96
uint16_t contexts[DIRAC_CTX_COUNT]
Definition: dirac_arith.h:83
const uint8_t * buffer
Definition: get_bits.h:56
int16_t counter
Definition: dirac_arith.h:78
uint8_t
#define av_cold
Definition: attributes.h:82
static int get_bits_count(const GetBitContext *s)
Definition: get_bits.h:199
uint16_t range
Definition: dirac_arith.h:77
static int get_bits_left(GetBitContext *gb)
Definition: get_bits.h:588
GLsizei GLsizei * length
Definition: opengl_enc.c:115
#define FFMIN(a, b)
Definition: common.h:96
const uint8_t * bytestream
Definition: dirac_arith.h:80
const uint16_t ff_dirac_prob[256]
Definition: dirac_arith.c:31
const uint8_t * bytestream_end
Definition: dirac_arith.h:81
Arithmetic decoder for Dirac.
unsigned low
Definition: dirac_arith.h:76
static double c[64]
static const uint8_t * align_get_bits(GetBitContext *s)
Definition: get_bits.h:464
av_cold void ff_dirac_init_arith_tables(void)
Definition: dirac_arith.c:86