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/*
* Copyright © 2012 Keith Packard <keithp@keithp.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; version 2 of the License.
*
* This program 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
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
*/
#ifndef _AO_FEC_H_
#define _AO_FEC_H_
#include <stdint.h>
#define AO_FEC_CRC_INIT 0xffff
#define AO_FEC_TRELLIS_TERMINATOR 0x0b
#define AO_FEC_PREPARE_EXTRA 4
extern const uint8_t ao_fec_whiten_table[];
#if AO_FEC_DEBUG
void
ao_fec_dump_bytes(const uint8_t *bytes, uint16_t len, const char *name);
#endif
static inline uint16_t
ao_fec_crc_byte(uint8_t byte, uint16_t crc)
{
uint8_t bit;
for (bit = 0; bit < 8; bit++) {
if (((crc & 0x8000) >> 8) ^ (byte & 0x80))
crc = (crc << 1) ^ 0x8005;
else
crc = (crc << 1);
byte <<= 1;
}
return crc;
}
uint16_t
ao_fec_crc(const uint8_t *bytes, uint8_t len);
/*
* 'len' is the length of the original data; 'bytes'
* must be four bytes longer than that, and the first
* two after 'len' must be the received crc
*/
uint8_t
ao_fec_check_crc(const uint8_t *bytes, uint8_t len);
/*
* Compute CRC, whiten, convolve and interleave data. 'out' must be (len + 4) * 2 bytes long
*/
uint8_t
ao_fec_encode(const uint8_t *in, uint8_t len, uint8_t *out);
/*
* Decode data. 'in' is one byte per bit, soft decision
* 'out' must be len/8 bytes long
*/
#define AO_FEC_DECODE_BLOCK (32) /* callback must return multiples of this many bits */
#define AO_FEC_DECODE_CRC_OK 0x80 /* stored in out[out_len-1] */
uint8_t
ao_fec_decode(const uint8_t *in, uint16_t in_len, uint8_t *out, uint8_t out_len, uint16_t (*callback)(void));
/*
* Interleave data packed in bytes. 'out' must be 'len' bytes long.
*/
uint16_t
ao_fec_interleave_bytes(uint8_t *in, uint16_t len, uint8_t *out);
#endif /* _AO_FEC_H_ */
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