kopia lustrzana https://github.com/rs1729/RS
rs41mod: home-brewed RS soft decoding w/ erasures v0.2
Zilog80
rodzic
9b622463a9
commit
873189c573
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@ -73,6 +73,18 @@ static rscfg_t cfg_rs41 = { 41, (320-56)/2, 56, 8, 8, 320}; // const: msgpos, pa
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ui8_t //xframe[FRAME_LEN] = { 0x10, 0xB6, 0xCA, 0x11, 0x22, 0x96, 0x12, 0xF8}, = xorbyte( frame)
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frame[FRAME_LEN] = { 0x86, 0x35, 0xf4, 0x40, 0x93, 0xdf, 0x1a, 0x60}; // = xorbyte(xframe)
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*/
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typedef struct {
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float frm_bytescore[FRAME_LEN+8];
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float ts;
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float last_frnb_ts;
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float last_calfrm_ts;
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ui16_t last_frnb;
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ui8_t last_calfrm;
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int sort_idx1[FRAME_LEN]; // ui8_t[] sort_cw1_idx
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int sort_idx2[FRAME_LEN]; // ui8_t[] sort_cw2_idx
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} ecdat_t;
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typedef struct {
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int out;
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int frnr;
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@ -109,6 +121,7 @@ typedef struct {
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char xdata[XDATA_LEN+16]; // xdata: aux_str1#aux_str2 ...
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option_t option;
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RS_t RS;
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ecdat_t ecdat;
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} gpx_t;
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@ -139,19 +152,6 @@ static ui8_t mask[MASK_LEN] = { 0x96, 0x83, 0x3E, 0x51, 0xB1, 0x49, 0x08, 0x98,
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frame[pos] = xframe[pos] ^ mask[pos % MASK_LEN];
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*/
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typedef struct {
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float frm_softbits[FRAME_LEN*BITS+64];
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float ts;
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float last_frnb_ts;
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float last_calfrm_ts;
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ui16_t last_frnb;
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ui8_t last_calfrm;
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} ecdat_t;
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static ecdat_t ecdat;
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static int sort_idx1[FRAME_LEN]; // ui8_t[] codeword
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static int sort_idx2[FRAME_LEN];
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/* ------------------------------------------------------------------------------------ */
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#define BAUD_RATE 4800
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@ -378,8 +378,8 @@ static int get_FrameNb(gpx_t *gpx, int crc, int ofs) {
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// crc check
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if (crc == 0) {
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ecdat.last_frnb = frnr;
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ecdat.last_frnb_ts = ecdat.ts;
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gpx->ecdat.last_frnb = frnr;
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gpx->ecdat.last_frnb_ts = gpx->ecdat.ts;
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}
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return 0;
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@ -432,7 +432,7 @@ static int get_SondeID(gpx_t *gpx, int crc, int ofs) {
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memcpy(gpx->id, sondeid_bytes, 8);
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gpx->id[8] = '\0';
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ecdat.last_frnb = 0;
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gpx->ecdat.last_frnb = 0;
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}
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}
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@ -462,8 +462,8 @@ static int get_FrameConf(gpx_t *gpx, int ofs) {
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gpx->calfrchk[calfr] = 1;
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}
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ecdat.last_calfrm = calfr;
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ecdat.last_calfrm_ts = ecdat.ts;
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gpx->ecdat.last_calfrm = calfr;
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gpx->ecdat.last_calfrm_ts = gpx->ecdat.ts;
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}
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return err;
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@ -1112,10 +1112,10 @@ static int rs41_ecc(gpx_t *gpx, int frmlen) {
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if (gpx->option.ecc > 3) // set (probably) known bytes (if same rs41)
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{
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float frnb_ts = ecdat.ts - ecdat.last_frnb_ts + 0.5f;
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int frnb = ecdat.last_frnb + (unsigned)frnb_ts;
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float calfr_ts = ecdat.ts - ecdat.last_calfrm_ts + 0.5f;
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int calfr = (ecdat.last_calfrm + (unsigned)calfr_ts) % 51;
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float frnb_ts = gpx->ecdat.ts - gpx->ecdat.last_frnb_ts + 0.5f;
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int frnb = gpx->ecdat.last_frnb + (unsigned)frnb_ts;
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float calfr_ts = gpx->ecdat.ts - gpx->ecdat.last_calfrm_ts + 0.5f;
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int calfr = (gpx->ecdat.last_calfrm + (unsigned)calfr_ts) % 51;
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if (errors1 < 0) {
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// chkCRC
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@ -1145,7 +1145,7 @@ static int rs41_ecc(gpx_t *gpx, int frmlen) {
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//pos_FrameNb: 0x03B=59
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if (crc && ((frnb>>8)&0xFF) != gpx->frame[pos_FrameNb+1]) {
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// last valid check, last_frnb>0 ...
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if (ecdat.last_frnb > 0) gpx->frame[pos_FrameNb+1] = (frnb>>8)&0xFF;
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if (gpx->ecdat.last_frnb > 0) gpx->frame[pos_FrameNb+1] = (frnb>>8)&0xFF;
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}
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}
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@ -1174,7 +1174,7 @@ static int rs41_ecc(gpx_t *gpx, int frmlen) {
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//pos_FrameNb: 0x03B=59
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if (crc && (frnb&0xFF) != gpx->frame[pos_FrameNb]) {
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// last valid check, last_frnb>0 ...
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if (ecdat.last_frnb > 0) gpx->frame[pos_FrameNb] = frnb&0xFF;
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if (gpx->ecdat.last_frnb > 0) gpx->frame[pos_FrameNb] = frnb&0xFF;
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}
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}
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@ -1187,6 +1187,7 @@ static int rs41_ecc(gpx_t *gpx, int frmlen) {
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// 3rd pass:
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// 2 RS codewords interleaved: 2x12 errors can be corrected;
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// CRC is good for list decoding, high rate is not;
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// burst errors could affect neighboring bytes, however
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// if AWGN and 24 bit-errors per frame, probability for 2 bit-errors in 1 byte is low;
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// erasures: 11 + 2/2 = 12 (11 errors and 2 erasures per codeword can be corrected)
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@ -1195,14 +1196,14 @@ static int rs41_ecc(gpx_t *gpx, int frmlen) {
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if (errors1 < 0)
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{
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for (i = 1; i < Era_max; i++) {
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pos_frm = sort_idx1[i];
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pos_frm = gpx->ecdat.sort_idx1[i];
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if (inFixed(gpx, pos_frm)) continue;
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if (pos_frm < cfg_rs41.msgpos) pos_cw = pos_frm - cfg_rs41.parpos;
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else pos_cw = rs_R + (pos_frm - cfg_rs41.msgpos)/2;
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if (pos_cw < 0 || pos_cw > 254) continue;
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era_pos[0] = pos_cw;
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for (j = 0; j < i; j++) {
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pos_frm = sort_idx1[j];
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pos_frm = gpx->ecdat.sort_idx1[j];
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if (inFixed(gpx, pos_frm)) continue;
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if (pos_frm < cfg_rs41.msgpos) pos_cw = pos_frm - cfg_rs41.parpos;
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else pos_cw = rs_R + (pos_frm - cfg_rs41.msgpos)/2;
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@ -1217,14 +1218,14 @@ static int rs41_ecc(gpx_t *gpx, int frmlen) {
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if (errors2 < 0)
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{
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for (i = 1; i < Era_max; i++) {
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pos_frm = sort_idx2[i];
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pos_frm = gpx->ecdat.sort_idx2[i];
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if (inFixed(gpx, pos_frm)) continue;
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if (pos_frm < cfg_rs41.msgpos) pos_cw = pos_frm - cfg_rs41.parpos - rs_R;
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else pos_cw = rs_R + (pos_frm - cfg_rs41.msgpos)/2;
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if (pos_cw < 0 || pos_cw > 254) continue;
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era_pos[0] = pos_cw;
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for (j = 0; j < i; j++) {
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pos_frm = sort_idx2[j];
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pos_frm = gpx->ecdat.sort_idx2[j];
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if (inFixed(gpx, pos_frm)) continue;
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if (pos_frm < cfg_rs41.msgpos) pos_cw = pos_frm - cfg_rs41.parpos - rs_R;
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else pos_cw = rs_R + (pos_frm - cfg_rs41.msgpos)/2;
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@ -1630,8 +1631,7 @@ static void print_frame(gpx_t *gpx, int len) {
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int j1 = 0;
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int j2 = 0;
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int sort_score_idx[FRAME_LEN];
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float byte_min_score[FRAME_LEN];
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float max_score = 0.0;
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float max_minscore = 0.0;
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gpx->crc = 0;
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@ -1647,41 +1647,34 @@ static void print_frame(gpx_t *gpx, int len) {
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else len = FRAME_LEN; // ft < 0: FRAME_LEN (aux)
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for (i = FRAMESTART; i < BITS*len; i++) {
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if (fabs(ecdat.frm_softbits[i]) > max_score) max_score = fabs(ecdat.frm_softbits[i]);
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for (i = FRAMESTART; i < len; i++) {
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if (fabs(gpx->ecdat.frm_bytescore[i]) > max_minscore) max_minscore = fabs(gpx->ecdat.frm_bytescore[i]);
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}
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max_score = floor(max_score+1.5);
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for (i = 0; i < FRAME_LEN; i++) byte_min_score[i] = max_score;
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max_minscore = floor(max_minscore+1.5);
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if (gpx->option.ecc > 2) {
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for (i = FRAMESTART; i < len; i++) {
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float min_score_byte = ecdat.frm_softbits[BITS*i];
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for (j = 1; j < 8; j++) {
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float serr = ecdat.frm_softbits[BITS*i+j];
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if (fabs(serr) < fabs(min_score_byte)) min_score_byte = ecdat.frm_softbits[BITS*i+j];
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}
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byte_min_score[i] = min_score_byte;
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}
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for (i = 0; i < FRAMESTART; i++) gpx->ecdat.frm_bytescore[i] = max_minscore*2.0; //*sign
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for (i = len; i < FRAME_LEN; i++) gpx->ecdat.frm_bytescore[i] = max_minscore;
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}
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for (i = 0; i < FRAME_LEN; i++) sort_score_idx[i] = i;
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if (gpx->option.ecc > 2) {
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for (i = 0; i < FRAME_LEN; i++) {
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for (j = 0; j < FRAME_LEN-1; j++) {
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if (fabs(byte_min_score[sort_score_idx[j+1]]) < fabs(byte_min_score[sort_score_idx[j]])) {
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if (fabs(gpx->ecdat.frm_bytescore[sort_score_idx[j+1]]) < fabs(gpx->ecdat.frm_bytescore[sort_score_idx[j]])) {
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int tmp = sort_score_idx[j+1];
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sort_score_idx[j+1] = sort_score_idx[j];
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sort_score_idx[j] = tmp;
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}
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}
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}
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for (i = 0; i < FRAME_LEN; i++) sort_idx1[i] = i;
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for (i = 0; i < FRAME_LEN; i++) sort_idx2[i] = i;
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for (i = 0; i < FRAME_LEN; i++) gpx->ecdat.sort_idx1[i] = i;
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for (i = 0; i < FRAME_LEN; i++) gpx->ecdat.sort_idx2[i] = i;
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j1 = 0;
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j2 = 0;
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for (i = 0; i < FRAME_LEN; i++) {
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if (sort_score_idx[i] >= cfg_rs41.parpos && sort_score_idx[i] < cfg_rs41.parpos+ rs_R) sort_idx1[j1++] = sort_score_idx[i];
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else if (sort_score_idx[i] >= cfg_rs41.parpos+rs_R && sort_score_idx[i] < cfg_rs41.parpos+2*rs_R) sort_idx2[j2++] = sort_score_idx[i];
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else if (sort_score_idx[i] >= cfg_rs41.msgpos && sort_score_idx[i] % 2 == 0) sort_idx1[j1++] = sort_score_idx[i];
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else if (sort_score_idx[i] >= cfg_rs41.msgpos && sort_score_idx[i] % 2 == 1) sort_idx2[j2++] = sort_score_idx[i];
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if (sort_score_idx[i] >= cfg_rs41.parpos && sort_score_idx[i] < cfg_rs41.parpos+ rs_R) gpx->ecdat.sort_idx1[j1++] = sort_score_idx[i];
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else if (sort_score_idx[i] >= cfg_rs41.parpos+rs_R && sort_score_idx[i] < cfg_rs41.parpos+2*rs_R) gpx->ecdat.sort_idx2[j2++] = sort_score_idx[i];
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else if (sort_score_idx[i] >= cfg_rs41.msgpos && sort_score_idx[i] % 2 == 0) gpx->ecdat.sort_idx1[j1++] = sort_score_idx[i];
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else if (sort_score_idx[i] >= cfg_rs41.msgpos && sort_score_idx[i] % 2 == 1) gpx->ecdat.sort_idx2[j2++] = sort_score_idx[i];
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}
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}
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@ -1761,6 +1754,7 @@ int main(int argc, char *argv[]) {
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gpx_t gpx = {0};
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hdb_t hdb = {0};
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float softbits[BITS];
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#ifdef CYGWIN
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@ -2016,12 +2010,20 @@ int main(int argc, char *argv[]) {
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{
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if (option_bin) {
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bitQ = fgetc(fp);
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if (bitQ != EOF) bit = bitQ & 0x1;
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if (bitQ != EOF) {
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bit = bitQ & 0x1;
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hsbit.hb = bit;
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hsbit.sb = 2*bit-1;
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}
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}
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else if (option_softin) {
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float s = 0.0;
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bitQ = f32soft_read(fp, &s);
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if (bitQ != EOF) bit = (s>=0.0); // no soft decoding
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if (bitQ != EOF) {
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bit = (s>=0.0);
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hsbit.hb = bit;
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hsbit.sb = s;
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}
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}
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else {
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float bl = -1;
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@ -2034,16 +2036,23 @@ int main(int argc, char *argv[]) {
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if (bitpos < FRAME_LEN*BITS && hsbit.sb*hsbit1.sb < 0) {
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difbyte |= 1<<b8pos;
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}
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ecdat.frm_softbits[HEADLEN + bitpos] = hsbit.sb;
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}
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if ( bitQ == EOF ) break; // liest 2x EOF
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softbits[b8pos] = hsbit.sb;
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if (gpx.option.inv) bit ^= 1;
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bitpos += 1;
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bitbuf[b8pos] = bit;
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b8pos++;
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if (b8pos == BITS) {
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int j;
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float min_score_byte = softbits[0];
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for (j = 1; j < BITS; j++) {
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if (fabs(softbits[j]) < fabs(min_score_byte)) min_score_byte = softbits[j];
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}
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gpx.ecdat.frm_bytescore[byte_count] = min_score_byte;
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b8pos = 0;
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byte = bits2byte(bitbuf);
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gpx.frame[byte_count] = byte ^ mask[byte_count % MASK_LEN];
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@ -2052,7 +2061,7 @@ int main(int argc, char *argv[]) {
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byte_count++;
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}
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}
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ecdat.ts = dsp.mv_pos/(float)dsp.sr;
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gpx.ecdat.ts = dsp.mv_pos/(float)dsp.sr;
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print_frame(&gpx, byte_count);
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byte_count = FRAMESTART;
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