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4349 | Serge | 1 | /* |
2 | * MLP codec common code |
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3 | * Copyright (c) 2007-2008 Ian Caulfield |
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4 | * |
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5 | * This file is part of FFmpeg. |
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6 | * |
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7 | * FFmpeg is free software; you can redistribute it and/or |
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8 | * modify it under the terms of the GNU Lesser General Public |
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9 | * License as published by the Free Software Foundation; either |
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10 | * version 2.1 of the License, or (at your option) any later version. |
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11 | * |
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12 | * FFmpeg is distributed in the hope that it will be useful, |
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13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
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14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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15 | * Lesser General Public License for more details. |
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16 | * |
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17 | * You should have received a copy of the GNU Lesser General Public |
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18 | * License along with FFmpeg; if not, write to the Free Software |
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19 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
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20 | */ |
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21 | |||
22 | #include |
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23 | |||
24 | #include "libavutil/crc.h" |
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25 | #include "libavutil/intreadwrite.h" |
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26 | #include "mlp.h" |
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27 | |||
28 | const uint8_t ff_mlp_huffman_tables[3][18][2] = { |
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29 | { /* Huffman table 0, -7 - +10 */ |
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30 | {0x01, 9}, {0x01, 8}, {0x01, 7}, {0x01, 6}, {0x01, 5}, {0x01, 4}, {0x01, 3}, |
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31 | {0x04, 3}, {0x05, 3}, {0x06, 3}, {0x07, 3}, |
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32 | {0x03, 3}, {0x05, 4}, {0x09, 5}, {0x11, 6}, {0x21, 7}, {0x41, 8}, {0x81, 9}, |
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33 | }, { /* Huffman table 1, -7 - +8 */ |
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34 | {0x01, 9}, {0x01, 8}, {0x01, 7}, {0x01, 6}, {0x01, 5}, {0x01, 4}, {0x01, 3}, |
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35 | {0x02, 2}, {0x03, 2}, |
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36 | {0x03, 3}, {0x05, 4}, {0x09, 5}, {0x11, 6}, {0x21, 7}, {0x41, 8}, {0x81, 9}, |
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37 | }, { /* Huffman table 2, -7 - +7 */ |
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38 | {0x01, 9}, {0x01, 8}, {0x01, 7}, {0x01, 6}, {0x01, 5}, {0x01, 4}, {0x01, 3}, |
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39 | {0x01, 1}, |
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40 | {0x03, 3}, {0x05, 4}, {0x09, 5}, {0x11, 6}, {0x21, 7}, {0x41, 8}, {0x81, 9}, |
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41 | } |
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42 | }; |
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43 | |||
44 | static int crc_init = 0; |
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45 | #if CONFIG_SMALL |
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46 | #define CRC_TABLE_SIZE 257 |
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47 | #else |
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48 | #define CRC_TABLE_SIZE 1024 |
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49 | #endif |
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50 | static AVCRC crc_63[CRC_TABLE_SIZE]; |
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51 | static AVCRC crc_1D[CRC_TABLE_SIZE]; |
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52 | static AVCRC crc_2D[CRC_TABLE_SIZE]; |
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53 | |||
54 | av_cold void ff_mlp_init_crc(void) |
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55 | { |
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56 | if (!crc_init) { |
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57 | av_crc_init(crc_63, 0, 8, 0x63, sizeof(crc_63)); |
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58 | av_crc_init(crc_1D, 0, 8, 0x1D, sizeof(crc_1D)); |
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59 | av_crc_init(crc_2D, 0, 16, 0x002D, sizeof(crc_2D)); |
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60 | crc_init = 1; |
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61 | } |
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62 | } |
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63 | |||
64 | uint16_t ff_mlp_checksum16(const uint8_t *buf, unsigned int buf_size) |
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65 | { |
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66 | uint16_t crc; |
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67 | |||
68 | crc = av_crc(crc_2D, 0, buf, buf_size - 2); |
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69 | crc ^= AV_RL16(buf + buf_size - 2); |
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70 | return crc; |
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71 | } |
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72 | |||
73 | uint8_t ff_mlp_checksum8(const uint8_t *buf, unsigned int buf_size) |
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74 | { |
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75 | uint8_t checksum = av_crc(crc_63, 0x3c, buf, buf_size - 1); // crc_63[0xa2] == 0x3c |
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76 | checksum ^= buf[buf_size-1]; |
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77 | return checksum; |
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78 | } |
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79 | |||
80 | uint8_t ff_mlp_restart_checksum(const uint8_t *buf, unsigned int bit_size) |
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81 | { |
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82 | int i; |
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83 | int num_bytes = (bit_size + 2) / 8; |
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84 | |||
85 | int crc = crc_1D[buf[0] & 0x3f]; |
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86 | crc = av_crc(crc_1D, crc, buf + 1, num_bytes - 2); |
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87 | crc ^= buf[num_bytes - 1]; |
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88 | |||
89 | for (i = 0; i < ((bit_size + 2) & 7); i++) { |
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90 | crc <<= 1; |
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91 | if (crc & 0x100) |
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92 | crc ^= 0x11D; |
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93 | crc ^= (buf[num_bytes] >> (7 - i)) & 1; |
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94 | } |
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95 | |||
96 | return crc; |
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97 | } |
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98 | |||
99 | uint8_t ff_mlp_calculate_parity(const uint8_t *buf, unsigned int buf_size) |
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100 | { |
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101 | uint32_t scratch = 0; |
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102 | const uint8_t *buf_end = buf + buf_size; |
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103 | |||
104 | for (; ((intptr_t) buf & 3) && buf < buf_end; buf++) |
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105 | scratch ^= *buf; |
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106 | for (; buf < buf_end - 3; buf += 4) |
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107 | scratch ^= *((const uint32_t*)buf); |
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108 | |||
109 | scratch = xor_32_to_8(scratch); |
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110 | |||
111 | for (; buf < buf_end; buf++) |
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112 | scratch ^= *buf; |
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113 | |||
114 | return scratch; |
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115 | }>>>=><=>> |