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https://github.com/FFmpeg/FFmpeg.git
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109 lines
3.2 KiB
C
109 lines
3.2 KiB
C
/*
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* MLP codec common code
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* Copyright (c) 2007-2008 Ian Caulfield
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include <stdint.h>
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#include "libavutil/crc.h"
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#include "libavutil/intreadwrite.h"
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#include "mlp.h"
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const uint8_t ff_mlp_huffman_tables[3][18][2] = {
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{ /* Huffman table 0, -7 - +10 */
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{0x01, 9}, {0x01, 8}, {0x01, 7}, {0x01, 6}, {0x01, 5}, {0x01, 4}, {0x01, 3},
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{0x04, 3}, {0x05, 3}, {0x06, 3}, {0x07, 3},
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{0x03, 3}, {0x05, 4}, {0x09, 5}, {0x11, 6}, {0x21, 7}, {0x41, 8}, {0x81, 9},
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}, { /* Huffman table 1, -7 - +8 */
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{0x01, 9}, {0x01, 8}, {0x01, 7}, {0x01, 6}, {0x01, 5}, {0x01, 4}, {0x01, 3},
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{0x02, 2}, {0x03, 2},
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{0x03, 3}, {0x05, 4}, {0x09, 5}, {0x11, 6}, {0x21, 7}, {0x41, 8}, {0x81, 9},
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}, { /* Huffman table 2, -7 - +7 */
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{0x01, 9}, {0x01, 8}, {0x01, 7}, {0x01, 6}, {0x01, 5}, {0x01, 4}, {0x01, 3},
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{0x01, 1},
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{0x03, 3}, {0x05, 4}, {0x09, 5}, {0x11, 6}, {0x21, 7}, {0x41, 8}, {0x81, 9},
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}
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};
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static int crc_init = 0;
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static AVCRC crc_63[1024];
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static AVCRC crc_1D[1024];
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static AVCRC crc_2D[1024];
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av_cold void ff_mlp_init_crc(void)
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{
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if (!crc_init) {
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av_crc_init(crc_63, 0, 8, 0x63, sizeof(crc_63));
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av_crc_init(crc_1D, 0, 8, 0x1D, sizeof(crc_1D));
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av_crc_init(crc_2D, 0, 16, 0x002D, sizeof(crc_2D));
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crc_init = 1;
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}
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}
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uint16_t ff_mlp_checksum16(const uint8_t *buf, unsigned int buf_size)
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{
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uint16_t crc;
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crc = av_crc(crc_2D, 0, buf, buf_size - 2);
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crc ^= AV_RL16(buf + buf_size - 2);
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return crc;
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}
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uint8_t ff_mlp_checksum8(const uint8_t *buf, unsigned int buf_size)
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{
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uint8_t checksum = av_crc(crc_63, 0x3c, buf, buf_size - 1); // crc_63[0xa2] == 0x3c
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checksum ^= buf[buf_size-1];
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return checksum;
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}
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uint8_t ff_mlp_restart_checksum(const uint8_t *buf, unsigned int bit_size)
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{
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int i;
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int num_bytes = (bit_size + 2) / 8;
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int crc = crc_1D[buf[0] & 0x3f];
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crc = av_crc(crc_1D, crc, buf + 1, num_bytes - 2);
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crc ^= buf[num_bytes - 1];
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for (i = 0; i < ((bit_size + 2) & 7); i++) {
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crc <<= 1;
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if (crc & 0x100)
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crc ^= 0x11D;
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crc ^= (buf[num_bytes] >> (7 - i)) & 1;
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}
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return crc;
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}
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uint8_t ff_mlp_calculate_parity(const uint8_t *buf, unsigned int buf_size)
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{
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uint32_t scratch = 0;
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const uint8_t *buf_end = buf + buf_size;
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for (; buf < buf_end - 3; buf += 4)
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scratch ^= *((const uint32_t*)buf);
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scratch = xor_32_to_8(scratch);
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for (; buf < buf_end; buf++)
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scratch ^= *buf;
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return scratch;
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}
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