// reconfigure internal buffers, objects, etc.
void ofdmflexframegen_reconfigure(ofdmflexframegen _q)
{
// re-create payload packetizer
_q->p_payload = packetizer_recreate(_q->p_payload,
_q->payload_dec_len,
_q->props.check,
_q->props.fec0,
_q->props.fec1);
// re-allocate memory for encoded message
_q->payload_enc_len = packetizer_get_enc_msg_len(_q->p_payload);
_q->payload_enc = (unsigned char*) realloc(_q->payload_enc,
_q->payload_enc_len*sizeof(unsigned char));
#if DEBUG_OFDMFLEXFRAMEGEN
printf(">>>> payload : %u (%u encoded)\n", _q->props.payload_len, _q->payload_enc_len);
#endif
// re-create modem
// TODO : only do this if necessary
_q->mod_payload = modem_recreate(_q->mod_payload, _q->props.mod_scheme);
// re-allocate memory for payload modem symbols
unsigned int bps = modulation_types[_q->props.mod_scheme].bps;
div_t d = div(8*_q->payload_enc_len, bps);
_q->payload_mod_len = d.quot + (d.rem ? 1 : 0);
_q->payload_mod = (unsigned char*)realloc(_q->payload_mod,
_q->payload_mod_len*sizeof(unsigned char));
// re-compute number of payload OFDM symbols
d = div(_q->payload_mod_len, _q->M_data);
_q->num_symbols_payload = d.quot + (d.rem ? 1 : 0);
}
// decode header
void ofdmflexframesync_decode_header(ofdmflexframesync _q)
{
#if OFDMFLEXFRAME_H_SOFT
# if 0
unsigned int i;
// copy soft bits
for (i=0; i<8*OFDMFLEXFRAME_H_ENC; i++)
_q->header_enc[i] = _q->header_mod[i];
# else
// TODO: ensure lengths are the same
memmove(_q->header_enc, _q->header_mod, 8*OFDMFLEXFRAME_H_ENC);
# endif
// unscramble header using soft bits
unscramble_data_soft(_q->header_enc, OFDMFLEXFRAME_H_ENC);
// run packet decoder
_q->header_valid = packetizer_decode_soft(_q->p_header, _q->header_enc, _q->header);
#else
// pack 1-bit header symbols into 8-bit bytes
unsigned int num_written;
liquid_repack_bytes(_q->header_mod, OFDMFLEXFRAME_H_BPS, OFDMFLEXFRAME_H_SYM,
_q->header_enc, 8, OFDMFLEXFRAME_H_ENC,
&num_written);
assert(num_written==OFDMFLEXFRAME_H_ENC);
// unscramble header
unscramble_data(_q->header_enc, OFDMFLEXFRAME_H_ENC);
// run packet decoder
_q->header_valid = packetizer_decode(_q->p_header, _q->header_enc, _q->header);
#endif
#if 0
// print header
printf("header rx (enc) : ");
for (i=0; i<OFDMFLEXFRAME_H_ENC; i++)
printf("%.2X ", _q->header_enc[i]);
printf("\n");
// print header
printf("header rx (dec) : ");
for (i=0; i<OFDMFLEXFRAME_H_DEC; i++)
printf("%.2X ", _q->header[i]);
printf("\n");
#endif
#if DEBUG_OFDMFLEXFRAMESYNC
printf("****** header extracted [%s]\n", _q->header_valid ? "valid" : "INVALID!");
#endif
if (!_q->header_valid)
return;
unsigned int n = OFDMFLEXFRAME_H_USER;
// first byte is for expansion/version validation
if (_q->header[n+0] != OFDMFLEXFRAME_PROTOCOL) {
fprintf(stderr,"warning: ofdmflexframesync_decode_header(), invalid framing version\n");
_q->header_valid = 0;
}
// strip off payload length
unsigned int payload_len = (_q->header[n+1] << 8) | (_q->header[n+2]);
// strip off modulation scheme/depth
unsigned int mod_scheme = _q->header[n+3];
if (mod_scheme == 0 || mod_scheme >= LIQUID_MODEM_NUM_SCHEMES) {
fprintf(stderr,"warning: ofdmflexframesync_decode_header(), invalid modulation scheme\n");
_q->header_valid = 0;
return;
}
// strip off CRC, forward error-correction schemes
// CRC : most-significant 3 bits of [n+4]
// fec0 : least-significant 5 bits of [n+4]
// fec1 : least-significant 5 bits of [n+5]
unsigned int check = (_q->header[n+4] >> 5 ) & 0x07;
unsigned int fec0 = (_q->header[n+4] ) & 0x1f;
unsigned int fec1 = (_q->header[n+5] ) & 0x1f;
// validate properties
if (check >= LIQUID_CRC_NUM_SCHEMES) {
fprintf(stderr,"warning: ofdmflexframesync_decode_header(), decoded CRC exceeds available\n");
check = LIQUID_CRC_UNKNOWN;
_q->header_valid = 0;
}
if (fec0 >= LIQUID_FEC_NUM_SCHEMES) {
fprintf(stderr,"warning: ofdmflexframesync_decode_header(), decoded FEC (inner) exceeds available\n");
fec0 = LIQUID_FEC_UNKNOWN;
_q->header_valid = 0;
}
if (fec1 >= LIQUID_FEC_NUM_SCHEMES) {
fprintf(stderr,"warning: ofdmflexframesync_decode_header(), decoded FEC (outer) exceeds available\n");
fec1 = LIQUID_FEC_UNKNOWN;
_q->header_valid = 0;
}
// print results
#if DEBUG_OFDMFLEXFRAMESYNC
printf(" properties:\n");
printf(" * mod scheme : %s\n", modulation_types[mod_scheme].fullname);
printf(" * fec (inner) : %s\n", fec_scheme_str[fec0][1]);
printf(" * fec (outer) : %s\n", fec_scheme_str[fec1][1]);
printf(" * CRC scheme : %s\n", crc_scheme_str[check][1]);
printf(" * payload length : %u bytes\n", payload_len);
#endif
// configure payload receiver
if (_q->header_valid) {
// configure modem
if (mod_scheme != _q->ms_payload) {
// set new properties
_q->ms_payload = mod_scheme;
_q->bps_payload = modulation_types[mod_scheme].bps;
// recreate modem (destroy/create)
_q->mod_payload = modem_recreate(_q->mod_payload, _q->ms_payload);
}
// set new packetizer properties
_q->payload_len = payload_len;
_q->check = check;
_q->fec0 = fec0;
_q->fec1 = fec1;
// recreate packetizer object
_q->p_payload = packetizer_recreate(_q->p_payload,
_q->payload_len,
_q->check,
_q->fec0,
_q->fec1);
// re-compute payload encoded message length
_q->payload_enc_len = packetizer_get_enc_msg_len(_q->p_payload);
#if DEBUG_OFDMFLEXFRAMESYNC
printf(" * payload encoded : %u bytes\n", _q->payload_enc_len);
#endif
// re-allocate buffers accordingly
_q->payload_enc = (unsigned char*) realloc(_q->payload_enc, _q->payload_enc_len*sizeof(unsigned char));
_q->payload_dec = (unsigned char*) realloc(_q->payload_dec, _q->payload_len*sizeof(unsigned char));
// re-compute number of modulated payload symbols
div_t d = div(8*_q->payload_enc_len, _q->bps_payload);
_q->payload_mod_len = d.quot + (d.rem ? 1 : 0);
#if DEBUG_OFDMFLEXFRAMESYNC
printf(" * payload mod syms: %u symbols\n", _q->payload_mod_len);
#endif
}
}
// decode header
void flexframesync_decode_header(flexframesync _q)
{
#if DEMOD_HEADER_SOFT
// soft decoding operates on 'header_mod' array directly;
// no need to pack bits
#else
// pack 256 1-bit header symbols into 32 8-bit bytes
unsigned int num_written;
liquid_pack_bytes(_q->header_mod, FLEXFRAME_H_SYM,
_q->header_enc, FLEXFRAME_H_ENC,
&num_written);
assert(num_written==FLEXFRAME_H_ENC);
#endif
#if DEBUG_FLEXFRAMESYNC_PRINT
unsigned int i;
// print header (encoded)
printf("header rx (enc) : ");
for (i=0; i<FLEXFRAME_H_ENC; i++)
printf("%.2X ", _q->header_enc[i]);
printf("\n");
#endif
// unscramble header and run packet decoder
#if DEMOD_HEADER_SOFT
// soft demodulation operates on header_mod directly
unscramble_data_soft(_q->header_mod, FLEXFRAME_H_ENC);
_q->header_valid =
packetizer_decode_soft(_q->p_header, _q->header_mod, _q->header);
#else
unscramble_data(_q->header_enc, FLEXFRAME_H_ENC);
_q->header_valid =
packetizer_decode(_q->p_header, _q->header_enc, _q->header);
#endif
// return if header is invalid
if (!_q->header_valid)
return;
// first several bytes of header are user-defined
unsigned int n = FLEXFRAME_H_USER;
// first byte is for expansion/version validation
if (_q->header[n+0] != FLEXFRAME_VERSION) {
fprintf(stderr,"warning: flexframesync_decode_header(), invalid framing version\n");
_q->header_valid = 0;
return;
}
// strip off payload length
unsigned int payload_dec_len = (_q->header[n+1] << 8) | (_q->header[n+2]);
_q->payload_dec_len = payload_dec_len;
// strip off modulation scheme/depth
unsigned int mod_scheme = _q->header[n+3];
// strip off CRC, forward error-correction schemes
// CRC : most-significant 3 bits of [n+4]
// fec0 : least-significant 5 bits of [n+4]
// fec1 : least-significant 5 bits of [n+5]
unsigned int check = (_q->header[n+4] >> 5 ) & 0x07;
unsigned int fec0 = (_q->header[n+4] ) & 0x1f;
unsigned int fec1 = (_q->header[n+5] ) & 0x1f;
// validate properties
if (mod_scheme == 0 || mod_scheme >= LIQUID_MODEM_NUM_SCHEMES) {
fprintf(stderr,"warning: flexframesync_decode_header(), invalid modulation scheme\n");
_q->header_valid = 0;
return;
}
if (check >= LIQUID_CRC_NUM_SCHEMES) {
fprintf(stderr,"warning: flexframesync_decode_header(), decoded CRC exceeds available\n");
_q->header_valid = 0;
return;
}
if (fec0 >= LIQUID_FEC_NUM_SCHEMES) {
fprintf(stderr,"warning: flexframesync_decode_header(), decoded FEC (inner) exceeds available\n");
_q->header_valid = 0;
return;
}
if (fec1 >= LIQUID_FEC_NUM_SCHEMES) {
fprintf(stderr,"warning: flexframesync_decode_header(), decoded FEC (outer) exceeds available\n");
_q->header_valid = 0;
return;
}
// configure payload receiver
if (_q->header_valid) {
// recreate modem
_q->ms_payload = mod_scheme;
_q->bps_payload = modulation_types[mod_scheme].bps;
_q->demod_payload = modem_recreate(_q->demod_payload, _q->ms_payload);
// set new packetizer properties
_q->check = check;
_q->fec0 = fec0;
_q->fec1 = fec1;
// recreate packetizer object
_q->p_payload = packetizer_recreate(_q->p_payload,
_q->payload_dec_len,
_q->check,
_q->fec0,
_q->fec1);
// re-compute payload encoded message length
_q->payload_enc_len = packetizer_get_enc_msg_len(_q->p_payload);
// re-compute number of modulated payload symbols
div_t d = div(8*_q->payload_enc_len, _q->bps_payload);
_q->payload_mod_len = d.quot + (d.rem ? 1 : 0);
// re-allocate buffers accordingly
// (give encoded a few extra bytes to compensate for repacking)
_q->payload_mod = (unsigned char*) realloc(_q->payload_mod, (_q->payload_mod_len )*sizeof(unsigned char));
_q->payload_enc = (unsigned char*) realloc(_q->payload_enc, (_q->payload_enc_len+8)*sizeof(unsigned char));
_q->payload_dec = (unsigned char*) realloc(_q->payload_dec, (_q->payload_dec_len )*sizeof(unsigned char));
if (_q->payload_mod == NULL || _q->payload_enc == NULL || _q->payload_dec == NULL) {
fprintf(stderr,"error: flexframesync_decode_header(), could not re-allocate payload arrays\n");
_q->header_valid = 0;
return;
}
}
#if DEBUG_FLEXFRAMESYNC_PRINT
// print results
printf("flexframesync_decode_header():\n");
printf(" header crc : %s\n", _q->header_valid ? "pass" : "FAIL");
printf(" check : %s\n", crc_scheme_str[check][1]);
printf(" fec (inner) : %s\n", fec_scheme_str[fec0][1]);
printf(" fec (outer) : %s\n", fec_scheme_str[fec1][1]);
printf(" mod scheme : %s\n", modulation_types[mod_scheme].name);
printf(" payload dec len : %u\n", _q->payload_dec_len);
printf(" payload enc len : %u\n", _q->payload_enc_len);
printf(" payload mod len : %u\n", _q->payload_mod_len);
printf(" user data :");
for (i=0; i<FLEXFRAME_H_USER; i++)
printf(" %.2x", _q->header[i]);
printf("\n");
#endif
}
// decode header
void flexframesync_decode_header(flexframesync _q)
{
// recover data symbols from pilots
qpilotsync_execute(_q->header_pilotsync, _q->header_sym, _q->header_mod);
// decode payload
_q->header_valid = qpacketmodem_decode(_q->header_decoder,
_q->header_mod,
_q->header_dec);
if (!_q->header_valid)
return;
// set fine carrier frequency and phase
float dphi_hat = qpilotsync_get_dphi(_q->header_pilotsync);
float phi_hat = qpilotsync_get_phi (_q->header_pilotsync);
//printf("residual offset: dphi=%12.8f, phi=%12.8f\n", dphi_hat, phi_hat);
nco_crcf_set_frequency(_q->pll, dphi_hat);
nco_crcf_set_phase (_q->pll, phi_hat + dphi_hat * _q->header_sym_len);
// first several bytes of header are user-defined
unsigned int n = FLEXFRAME_H_USER;
// first byte is for expansion/version validation
unsigned int protocol = _q->header_dec[n+0];
if (protocol != FLEXFRAME_PROTOCOL) {
fprintf(stderr,"warning: flexframesync_decode_header(), invalid framing protocol %u (expected %u)\n", protocol, FLEXFRAME_PROTOCOL);
_q->header_valid = 0;
return;
}
// strip off payload length
unsigned int payload_dec_len = (_q->header_dec[n+1] << 8) | (_q->header_dec[n+2]);
_q->payload_dec_len = payload_dec_len;
// strip off modulation scheme/depth
unsigned int mod_scheme = _q->header_dec[n+3];
// strip off CRC, forward error-correction schemes
// CRC : most-significant 3 bits of [n+4]
// fec0 : least-significant 5 bits of [n+4]
// fec1 : least-significant 5 bits of [n+5]
unsigned int check = (_q->header_dec[n+4] >> 5 ) & 0x07;
unsigned int fec0 = (_q->header_dec[n+4] ) & 0x1f;
unsigned int fec1 = (_q->header_dec[n+5] ) & 0x1f;
// validate properties
if (mod_scheme == 0 || mod_scheme >= LIQUID_MODEM_NUM_SCHEMES) {
fprintf(stderr,"warning: flexframesync_decode_header(), invalid modulation scheme\n");
_q->header_valid = 0;
return;
} else if (check == LIQUID_CRC_UNKNOWN || check >= LIQUID_CRC_NUM_SCHEMES) {
fprintf(stderr,"warning: flexframesync_decode_header(), decoded CRC exceeds available\n");
_q->header_valid = 0;
return;
} else if (fec0 == LIQUID_FEC_UNKNOWN || fec0 >= LIQUID_FEC_NUM_SCHEMES) {
fprintf(stderr,"warning: flexframesync_decode_header(), decoded FEC (inner) exceeds available\n");
_q->header_valid = 0;
return;
} else if (fec1 == LIQUID_FEC_UNKNOWN || fec1 >= LIQUID_FEC_NUM_SCHEMES) {
fprintf(stderr,"warning: flexframesync_decode_header(), decoded FEC (outer) exceeds available\n");
_q->header_valid = 0;
return;
}
// re-create payload demodulator for phase-locked loop
_q->payload_demod = modem_recreate(_q->payload_demod, mod_scheme);
// reconfigure payload demodulator/decoder
qpacketmodem_configure(_q->payload_decoder,
payload_dec_len, check, fec0, fec1, mod_scheme);
// set length appropriately
_q->payload_sym_len = qpacketmodem_get_frame_len(_q->payload_decoder);
// re-allocate buffers accordingly
_q->payload_sym = (float complex*) realloc(_q->payload_sym, (_q->payload_sym_len)*sizeof(float complex));
_q->payload_dec = (unsigned char*) realloc(_q->payload_dec, (_q->payload_dec_len)*sizeof(unsigned char));
if (_q->payload_sym == NULL || _q->payload_dec == NULL) {
fprintf(stderr,"error: flexframesync_decode_header(), could not re-allocate payload arrays\n");
_q->header_valid = 0;
return;
}
#if DEBUG_FLEXFRAMESYNC_PRINT
// print results
printf("flexframesync_decode_header():\n");
printf(" header crc : %s\n", _q->header_valid ? "pass" : "FAIL");
printf(" check : %s\n", crc_scheme_str[check][1]);
printf(" fec (inner) : %s\n", fec_scheme_str[fec0][1]);
printf(" fec (outer) : %s\n", fec_scheme_str[fec1][1]);
printf(" mod scheme : %s\n", modulation_types[mod_scheme].name);
printf(" payload sym len : %u\n", _q->payload_sym_len);
printf(" payload dec len : %u\n", _q->payload_dec_len);
printf(" user data :");
unsigned int i;
for (i=0; i<FLEXFRAME_H_USER; i++)
printf(" %.2x", _q->header_dec[i]);
printf("\n");
#endif
}
