/* * MLP codec common code * Copyright (c) 2007-2008 Ian Caulfield * * This file is part of Libav. * * Libav is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * * Libav is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with Libav; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ #include <stdint.h> #include "libavutil/crc.h" #include "libavutil/intreadwrite.h" #include "mlp.h" const uint8_t ff_mlp_huffman_tables[3][18][2] = { { /* Huffman table 0, -7 - +10 */ {0x01, 9}, {0x01, 8}, {0x01, 7}, {0x01, 6}, {0x01, 5}, {0x01, 4}, {0x01, 3}, {0x04, 3}, {0x05, 3}, {0x06, 3}, {0x07, 3}, {0x03, 3}, {0x05, 4}, {0x09, 5}, {0x11, 6}, {0x21, 7}, {0x41, 8}, {0x81, 9}, }, { /* Huffman table 1, -7 - +8 */ {0x01, 9}, {0x01, 8}, {0x01, 7}, {0x01, 6}, {0x01, 5}, {0x01, 4}, {0x01, 3}, {0x02, 2}, {0x03, 2}, {0x03, 3}, {0x05, 4}, {0x09, 5}, {0x11, 6}, {0x21, 7}, {0x41, 8}, {0x81, 9}, }, { /* Huffman table 2, -7 - +7 */ {0x01, 9}, {0x01, 8}, {0x01, 7}, {0x01, 6}, {0x01, 5}, {0x01, 4}, {0x01, 3}, {0x01, 1}, {0x03, 3}, {0x05, 4}, {0x09, 5}, {0x11, 6}, {0x21, 7}, {0x41, 8}, {0x81, 9}, } }; static int crc_init = 0; #if CONFIG_SMALL #define CRC_TABLE_SIZE 257 #else #define CRC_TABLE_SIZE 1024 #endif static AVCRC crc_63[CRC_TABLE_SIZE]; static AVCRC crc_1D[CRC_TABLE_SIZE]; static AVCRC crc_2D[CRC_TABLE_SIZE]; av_cold void ff_mlp_init_crc(void) { if (!crc_init) { av_crc_init(crc_63, 0, 8, 0x63, sizeof(crc_63)); av_crc_init(crc_1D, 0, 8, 0x1D, sizeof(crc_1D)); av_crc_init(crc_2D, 0, 16, 0x002D, sizeof(crc_2D)); crc_init = 1; } } uint16_t ff_mlp_checksum16(const uint8_t *buf, unsigned int buf_size) { uint16_t crc; crc = av_crc(crc_2D, 0, buf, buf_size - 2); crc ^= AV_RL16(buf + buf_size - 2); return crc; } uint8_t ff_mlp_checksum8(const uint8_t *buf, unsigned int buf_size) { uint8_t checksum = av_crc(crc_63, 0x3c, buf, buf_size - 1); // crc_63[0xa2] == 0x3c checksum ^= buf[buf_size-1]; return checksum; } uint8_t ff_mlp_restart_checksum(const uint8_t *buf, unsigned int bit_size) { int i; int num_bytes = (bit_size + 2) / 8; int crc = crc_1D[buf[0] & 0x3f]; crc = av_crc(crc_1D, crc, buf + 1, num_bytes - 2); crc ^= buf[num_bytes - 1]; for (i = 0; i < ((bit_size + 2) & 7); i++) { crc <<= 1; if (crc & 0x100) crc ^= 0x11D; crc ^= (buf[num_bytes] >> (7 - i)) & 1; } return crc; } uint8_t ff_mlp_calculate_parity(const uint8_t *buf, unsigned int buf_size) { uint32_t scratch = 0; const uint8_t *buf_end = buf + buf_size; for (; ((intptr_t) buf & 3) && buf < buf_end; buf++) scratch ^= *buf; for (; buf < buf_end - 3; buf += 4) scratch ^= *((const uint32_t*)buf); scratch = xor_32_to_8(scratch); for (; buf < buf_end; buf++) scratch ^= *buf; return scratch; }