2 * Copyright © 2012 Keith Packard <keithp@keithp.com>
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
9 * This program is distributed in the hope that it will be useful, but
10 * WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * General Public License for more details.
14 * You should have received a copy of the GNU General Public License along
15 * with this program; if not, write to the Free Software Foundation, Inc.,
16 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
24 #define AO_FEC_CRC_INIT 0xffff
25 #define AO_FEC_TRELLIS_TERMINATOR 0x0b
26 #define AO_FEC_PREPARE_EXTRA 4
28 extern const uint8_t ao_fec_whiten_table[];
32 ao_fec_dump_bytes(const uint8_t *bytes, uint16_t len, const char *name);
35 static inline uint16_t
36 ao_fec_crc_byte(uint8_t byte, uint16_t crc)
40 for (bit = 0; bit < 8; bit++) {
41 if (((crc & 0x8000) >> 8) ^ (byte & 0x80))
42 crc = (crc << 1) ^ 0x8005;
51 ao_fec_crc(const uint8_t *bytes, uint8_t len);
54 * 'len' is the length of the original data; 'bytes'
55 * must be four bytes longer than that, and the first
56 * two after 'len' must be the received crc
59 ao_fec_check_crc(const uint8_t *bytes, uint8_t len);
62 * Compute CRC, whiten, convolve and interleave data. 'out' must be (len + 4) * 2 bytes long
65 ao_fec_encode(const uint8_t *in, uint8_t len, uint8_t *out);
68 * Decode data. 'in' is one byte per bit, soft decision
69 * 'out' must be len/8 bytes long
72 #define AO_FEC_DECODE_BLOCK (32) /* callback must return multiples of this many bits */
74 #define AO_FEC_DECODE_CRC_OK 0x80 /* stored in out[out_len-1] */
77 ao_fec_decode(const uint8_t *in, uint16_t in_len, uint8_t *out, uint8_t out_len, uint16_t (*callback)(void));
80 * Interleave data packed in bytes. 'out' must be 'len' bytes long.
83 ao_fec_interleave_bytes(uint8_t *in, uint16_t len, uint8_t *out);
85 #endif /* _AO_FEC_H_ */