2 * MLP codec common code
3 * Copyright (c) 2007-2008 Ian Caulfield
5 * This file is part of FFmpeg.
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.
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.
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
24 #include "libavutil/crc.h"
27 const uint8_t ff_mlp_huffman_tables
[3][18][2] = {
28 { /* Huffman table 0, -7 - +10 */
29 {0x01, 9}, {0x01, 8}, {0x01, 7}, {0x01, 6}, {0x01, 5}, {0x01, 4}, {0x01, 3},
30 {0x04, 3}, {0x05, 3}, {0x06, 3}, {0x07, 3},
31 {0x03, 3}, {0x05, 4}, {0x09, 5}, {0x11, 6}, {0x21, 7}, {0x41, 8}, {0x81, 9},
32 }, { /* Huffman table 1, -7 - +8 */
33 {0x01, 9}, {0x01, 8}, {0x01, 7}, {0x01, 6}, {0x01, 5}, {0x01, 4}, {0x01, 3},
35 {0x03, 3}, {0x05, 4}, {0x09, 5}, {0x11, 6}, {0x21, 7}, {0x41, 8}, {0x81, 9},
36 }, { /* Huffman table 2, -7 - +7 */
37 {0x01, 9}, {0x01, 8}, {0x01, 7}, {0x01, 6}, {0x01, 5}, {0x01, 4}, {0x01, 3},
39 {0x03, 3}, {0x05, 4}, {0x09, 5}, {0x11, 6}, {0x21, 7}, {0x41, 8}, {0x81, 9},
43 static int crc_init
= 0;
44 static AVCRC crc_63
[1024];
45 static AVCRC crc_1D
[1024];
48 static int crc_init_2D
= 0;
49 static AVCRC crc_2D
[1024];
51 int av_cold
ff_mlp_init_crc2D(AVCodecParserContext
*s
)
54 av_crc_init(crc_2D
, 0, 16, 0x002D, sizeof(crc_2D
));
61 void av_cold
ff_mlp_init_crc()
64 av_crc_init(crc_63
, 0, 8, 0x63, sizeof(crc_63
));
65 av_crc_init(crc_1D
, 0, 8, 0x1D, sizeof(crc_1D
));
70 uint16_t ff_mlp_checksum16(const uint8_t *buf
, unsigned int buf_size
)
74 crc
= av_crc(crc_2D
, 0, buf
, buf_size
- 2);
75 crc
^= AV_RL16(buf
+ buf_size
- 2);
79 uint8_t ff_mlp_checksum8(const uint8_t *buf
, unsigned int buf_size
)
81 uint8_t checksum
= av_crc(crc_63
, 0x3c, buf
, buf_size
- 1); // crc_63[0xa2] == 0x3c
82 checksum
^= buf
[buf_size
-1];
86 uint8_t ff_mlp_restart_checksum(const uint8_t *buf
, unsigned int bit_size
)
89 int num_bytes
= (bit_size
+ 2) / 8;
91 int crc
= crc_1D
[buf
[0] & 0x3f];
92 crc
= av_crc(crc_1D
, crc
, buf
+ 1, num_bytes
- 2);
93 crc
^= buf
[num_bytes
- 1];
95 for (i
= 0; i
< ((bit_size
+ 2) & 7); i
++) {
99 crc
^= (buf
[num_bytes
] >> (7 - i
)) & 1;
105 uint8_t ff_mlp_calculate_parity(const uint8_t *buf
, unsigned int buf_size
)
107 uint32_t scratch
= 0;
108 const uint8_t *buf_end
= buf
+ buf_size
;
110 for (; buf
< buf_end
- 3; buf
+= 4)
111 scratch
^= *((const uint32_t*)buf
);
113 scratch
= xor_32_to_8(scratch
);
115 for (; buf
< buf_end
; buf
++)