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-rw-r--r--libavcodec/dirac_arith.c116
1 files changed, 116 insertions, 0 deletions
diff --git a/libavcodec/dirac_arith.c b/libavcodec/dirac_arith.c
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+++ b/libavcodec/dirac_arith.c
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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
+ * 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;
+}