1/* 2 * MLP codec common code 3 * Copyright (c) 2007-2008 Ian Caulfield 4 * 5 * This file is part of Libav. 6 * 7 * Libav 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 * Libav 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 Libav; 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 28const 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 44static int crc_init = 0; 45#if CONFIG_SMALL 46#define CRC_TABLE_SIZE 257 47#else 48#define CRC_TABLE_SIZE 1024 49#endif 50static AVCRC crc_63[CRC_TABLE_SIZE]; 51static AVCRC crc_1D[CRC_TABLE_SIZE]; 52static AVCRC crc_2D[CRC_TABLE_SIZE]; 53 54av_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 64uint16_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 73uint8_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 80uint8_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 99uint8_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} 116