mlp.c

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/*
 * 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 <stdint.h>
 
#include "libavutil/channel_layout.h"
#include "libavutil/crc.h"
#include "libavutil/intreadwrite.h"
#include "libavutil/thread.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},
    }
};
 
const ChannelInformation ff_mlp_ch_info[21] = {
    { 0x01, 0x01, 0x00, 0x1f }, { 0x03, 0x02, 0x00, 0x1b },
    { 0x07, 0x02, 0x01, 0x1f }, { 0x0F, 0x02, 0x02, 0x19 },
    { 0x07, 0x02, 0x01, 0x03 }, { 0x0F, 0x02, 0x02, 0x1f },
    { 0x1F, 0x02, 0x03, 0x01 }, { 0x07, 0x02, 0x01, 0x1a },
    { 0x0F, 0x02, 0x02, 0x1f }, { 0x1F, 0x02, 0x03, 0x18 },
    { 0x0F, 0x02, 0x02, 0x02 }, { 0x1F, 0x02, 0x03, 0x1f },
    { 0x3F, 0x02, 0x04, 0x00 }, { 0x0F, 0x03, 0x01, 0x1f },
    { 0x1F, 0x03, 0x02, 0x18 }, { 0x0F, 0x03, 0x01, 0x02 },
    { 0x1F, 0x03, 0x02, 0x1f }, { 0x3F, 0x03, 0x03, 0x00 },
    { 0x1F, 0x04, 0x01, 0x01 }, { 0x1F, 0x04, 0x01, 0x18 },
    { 0x3F, 0x04, 0x02, 0x00 },
};
 
const AVChannelLayout ff_mlp_ch_layouts[12] = {
    AV_CHANNEL_LAYOUT_MONO, AV_CHANNEL_LAYOUT_STEREO, AV_CHANNEL_LAYOUT_2_1,
    AV_CHANNEL_LAYOUT_QUAD, AV_CHANNEL_LAYOUT_2POINT1, AV_CHANNEL_LAYOUT_SURROUND,
    AV_CHANNEL_LAYOUT_4POINT0, AV_CHANNEL_LAYOUT_5POINT0_BACK, AV_CHANNEL_LAYOUT_3POINT1,
    AV_CHANNEL_LAYOUT_4POINT1, AV_CHANNEL_LAYOUT_5POINT1_BACK, { 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_2D[CRC_TABLE_SIZE];
 
static av_cold void mlp_init_crc(void)
{
    av_crc_init(crc_63, 0,  8,   0x63, sizeof(crc_63));
    av_crc_init(crc_2D, 0, 16, 0x002D, sizeof(crc_2D));
}
 
av_cold void ff_mlp_init_crc(void)
{
    static AVOnce init_static_once = AV_ONCE_INIT;
    ff_thread_once(&init_static_once, mlp_init_crc);
}
 
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)
{
    const AVCRC *crc_1D = av_crc_get_table(AV_CRC_8_EBU);
    int i;
    int num_bytes = (bit_size + 2) / 8;
 
    // The two most significant bits of buf[0] are not supposed
    // to be contained in the checksum; using buf[0] & 0xC0 as start value
    // achieves this.
    int crc = av_crc(crc_1D, buf[0] & 0xC0, buf, num_bytes - 1);
 
    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;
}