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