/* * Copyright © 2012 Keith Packard * * 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 #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_ */