From ce15710f554ef3520f968c8b4284a0f576611c95 Mon Sep 17 00:00:00 2001 From: Ramiro Polla Date: Wed, 13 Aug 2008 18:47:03 +0000 Subject: mlp: Split common code from parser and decoder to be used by encoder. Originally committed as revision 14733 to svn://svn.ffmpeg.org/ffmpeg/trunk --- libavcodec/mlp.c | 120 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 120 insertions(+) create mode 100644 libavcodec/mlp.c (limited to 'libavcodec/mlp.c') diff --git a/libavcodec/mlp.c b/libavcodec/mlp.c new file mode 100644 index 0000000000..f2a0276574 --- /dev/null +++ b/libavcodec/mlp.c @@ -0,0 +1,120 @@ +/* + * MLP codec common code + * Copyright (c) 2007-2008 Ian Caulfield + * + * This file is part of FFmpeg. + * + * FFmpeg 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. + * + * FFmpeg 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 FFmpeg; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA + */ + +#include + +#include "libavutil/crc.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; +static AVCRC crc_63[1024]; +static AVCRC crc_1D[1024]; + + +static int crc_init_2D = 0; +static AVCRC crc_2D[1024]; + +int av_cold ff_mlp_init_crc2D(AVCodecParserContext *s) +{ + if (!crc_init_2D) { + av_crc_init(crc_2D, 0, 16, 0x002D, sizeof(crc_2D)); + crc_init_2D = 1; + } + + return 0; +} + +void av_cold ff_mlp_init_crc() +{ + 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)); + 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 (; buf < buf_end - 3; buf += 4) + scratch ^= *((const uint32_t*)buf); + + scratch ^= scratch >> 16; + scratch ^= scratch >> 8; + + for (; buf < buf_end; buf++) + scratch ^= *buf; + + return scratch; +} -- cgit v1.2.3