//
// autotest helper function
//
void validate_crc(crc_scheme _check,
unsigned int _n)
{
unsigned int i;
// generate pseudo-random data
unsigned char data[_n];
msequence ms = msequence_create_default(9);
for (i=0; i<_n; i++)
data[i] = msequence_generate_symbol(ms,8);
msequence_destroy(ms);
// generate key
unsigned int key = crc_generate_key(_check, data, _n);
// contend data/key are valid
CONTEND_EXPRESSION(crc_validate_message(_check, data, _n, key));
//
unsigned char data_corrupt[_n];
unsigned int j;
for (i=0; i<_n; i++) {
for (j=0; j<8; j++) {
// copy original data sequence
memmove(data_corrupt, data, _n*sizeof(unsigned char));
// flip bit j at byte i
data[i] ^= (1 << j);
// contend data/key are invalid
CONTEND_EXPRESSION(crc_validate_message(_check, data, _n, key)==0);
}
}
}
// Execute the packetizer to decode an input message, return validity
// check of resulting data
//
// _p : packetizer object
// _pkt : input message (coded soft bits)
// _msg : decoded output message
int packetizer_decode_soft(packetizer _p,
unsigned char * _pkt,
unsigned char * _msg)
{
// copy coded message to internal buffer[0]
memmove(_p->buffer_0, _pkt, 8*_p->packet_len);
//
// decode outer level using soft decoding
//
// run the de-interleaver: buffer[0] > buffer[1]
interleaver_decode_soft(_p->plan[1].q,
_p->buffer_0,
_p->buffer_1);
// run the decoder: buffer[1] > buffer[0]
fec_decode_soft(_p->plan[1].f,
_p->plan[1].dec_msg_len,
_p->buffer_1,
_p->buffer_0);
//
// decode inner level using hard decoding
//
// run the de-interleaver: buffer[0] > buffer[1]
interleaver_decode(_p->plan[0].q,
_p->buffer_0,
_p->buffer_1);
// run the decoder: buffer[1] > buffer[0]
fec_decode(_p->plan[0].f,
_p->plan[0].dec_msg_len,
_p->buffer_1,
_p->buffer_0);
// strip crc, validate message
unsigned int key = 0;
unsigned int i;
for (i=0; i<_p->crc_length; i++) {
key <<= 8;
key |= _p->buffer_0[_p->msg_len+i];
}
// copy result to output
memmove(_msg, _p->buffer_0, _p->msg_len);
// return crc validity
return crc_validate_message(_p->check,
_p->buffer_0,
_p->msg_len,
key);
}
// Execute the packetizer to decode an input message, return validity
// check of resulting data
//
// _p : packetizer object
// _pkt : input message (coded bytes)
// _msg : decoded output message
int packetizer_decode(packetizer _p,
unsigned char * _pkt,
unsigned char * _msg)
{
// copy coded message to internal buffer[0]
memmove(_p->buffer_0, _pkt, _p->packet_len);
// execute fec/interleaver plans
unsigned int i;
for (i=_p->plan_len; i>0; i--) {
// run the de-interleaver: buffer[0] > buffer[1]
interleaver_decode(_p->plan[i-1].q,
_p->buffer_0,
_p->buffer_1);
// run the decoder: buffer[1] > buffer[0]
fec_decode(_p->plan[i-1].f,
_p->plan[i-1].dec_msg_len,
_p->buffer_1,
_p->buffer_0);
}
// strip crc, validate message
unsigned int key = 0;
for (i=0; i<_p->crc_length; i++) {
key <<= 8;
key |= _p->buffer_0[_p->msg_len+i];
}
// copy result to output
memmove(_msg, _p->buffer_0, _p->msg_len);
// return crc validity
return crc_validate_message(_p->check,
_p->buffer_0,
_p->msg_len,
key);
}