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107 lines
3.2 KiB
107 lines
3.2 KiB
/* |
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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 "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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void av_cold ff_mlp_init_crc() |
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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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