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/*
* Copyright (C) 2007 Marco Gerards <marco@gnu.org>
* Copyright (C) 2009 David Conrad
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file libavcodec/dirac_arith.c
* Arithmetic decoder for Dirac
* @author Marco Gerards <marco@gnu.org>
*/
#include "dirac_arith.h"
const uint16_t ff_dirac_prob[256] = {
0, 2, 5, 8, 11, 15, 20, 24,
29, 35, 41, 47, 53, 60, 67, 74,
82, 89, 97, 106, 114, 123, 132, 141,
150, 160, 170, 180, 190, 201, 211, 222,
233, 244, 256, 267, 279, 291, 303, 315,
327, 340, 353, 366, 379, 392, 405, 419,
433, 447, 461, 475, 489, 504, 518, 533,
548, 563, 578, 593, 609, 624, 640, 656,
672, 688, 705, 721, 738, 754, 771, 788,
805, 822, 840, 857, 875, 892, 910, 928,
946, 964, 983, 1001, 1020, 1038, 1057, 1076,
1095, 1114, 1133, 1153, 1172, 1192, 1211, 1231,
1251, 1271, 1291, 1311, 1332, 1352, 1373, 1393,
1414, 1435, 1456, 1477, 1498, 1520, 1541, 1562,
1584, 1606, 1628, 1649, 1671, 1694, 1716, 1738,
1760, 1783, 1806, 1828, 1851, 1874, 1897, 1920,
1935, 1942, 1949, 1955, 1961, 1968, 1974, 1980,
1985, 1991, 1996, 2001, 2006, 2011, 2016, 2021,
2025, 2029, 2033, 2037, 2040, 2044, 2047, 2050,
2053, 2056, 2058, 2061, 2063, 2065, 2066, 2068,
2069, 2070, 2071, 2072, 2072, 2072, 2072, 2072,
2072, 2071, 2070, 2069, 2068, 2066, 2065, 2063,
2060, 2058, 2055, 2052, 2049, 2045, 2042, 2038,
2033, 2029, 2024, 2019, 2013, 2008, 2002, 1996,
1989, 1982, 1975, 1968, 1960, 1952, 1943, 1934,
1925, 1916, 1906, 1896, 1885, 1874, 1863, 1851,
1839, 1827, 1814, 1800, 1786, 1772, 1757, 1742,
1727, 1710, 1694, 1676, 1659, 1640, 1622, 1602,
1582, 1561, 1540, 1518, 1495, 1471, 1447, 1422,
1396, 1369, 1341, 1312, 1282, 1251, 1219, 1186,
1151, 1114, 1077, 1037, 995, 952, 906, 857,
805, 750, 690, 625, 553, 471, 376, 255
};
const uint8_t ff_dirac_next_ctx[DIRAC_CTX_COUNT] = {
[CTX_ZPZN_F1] = CTX_ZP_F2,
[CTX_ZPNN_F1] = CTX_ZP_F2,
[CTX_ZP_F2] = CTX_ZP_F3,
[CTX_ZP_F3] = CTX_ZP_F4,
[CTX_ZP_F4] = CTX_ZP_F5,
[CTX_ZP_F5] = CTX_ZP_F6,
[CTX_ZP_F6] = CTX_ZP_F6,
[CTX_NPZN_F1] = CTX_NP_F2,
[CTX_NPNN_F1] = CTX_NP_F2,
[CTX_NP_F2] = CTX_NP_F3,
[CTX_NP_F3] = CTX_NP_F4,
[CTX_NP_F4] = CTX_NP_F5,
[CTX_NP_F5] = CTX_NP_F6,
[CTX_NP_F6] = CTX_NP_F6,
[CTX_DELTA_Q_F] = CTX_DELTA_Q_F,
};
int16_t ff_dirac_prob_branchless[256][2];
void ff_dirac_init_arith_decoder(DiracArith *c, GetBitContext *gb, int length)
{
int i;
align_get_bits(gb);
length = FFMIN(length, get_bits_left(gb)/8);
c->bytestream = gb->buffer + get_bits_count(gb)/8;
c->bytestream_end = c->bytestream + length;
skip_bits_long(gb, length*8);
c->low = 0;
for (i = 0; i < 4; i++) {
c->low <<= 8;
if (c->bytestream < c->bytestream_end)
c->low |= *c->bytestream++;
else
c->low |= 0xff;
}
c->counter = -16;
c->range = 0xffff;
for (i = 0; i < 256; i++) {
ff_dirac_prob_branchless[i][0] = ff_dirac_prob[255-i];
ff_dirac_prob_branchless[i][1] = -ff_dirac_prob[i];
}
for (i = 0; i < DIRAC_CTX_COUNT; i++)
c->contexts[i] = 0x8000;
}
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