87f7c771395c35bc1f4bda3020841012a4e168a1
[libav.git] / libavcodec / mlp.c
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 }