/*
 *  dfm09 (dfm06)
 *  sync header: correlation/matched filter
 *  files: dfm09dm.c demod.h demod.c
 *  compile:
 *      gcc -c demod.c
 *      gcc dfm09dm.c demod.o -lm -o dfm09dm
 *
 *  author: zilog80
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>

#ifdef CYGWIN
  #include <fcntl.h>  // cygwin: _setmode()
  #include <io.h>
#endif


typedef unsigned char ui8_t;
typedef unsigned int ui32_t;

//#include "demod.c"
#include "demod.h"


typedef struct {
    int frnr;
    int sonde_typ;
    ui32_t SN6;
    ui32_t SN9;
    int week; int gpssec;
    int jahr; int monat; int tag;
    int std; int min; float sek;
    double lat; double lon; double alt;
    double dir; double horiV; double vertV;
    float meas24[5];
    float status[2];
} gpx_t;

gpx_t gpx;

char dat_str[9][13+1];


int option_verbose = 0,  // ausfuehrliche Anzeige
    option_raw = 0,      // rohe Frames
    option_inv = 0,      // invertiert Signal
    option_ecc = 0,
    option_ptu = 0,
    option_ths = 0,
    wavloaded = 0;

int start = 0;


//#define HEADLEN 32
// DFM09: Manchester2: 01->1,10->0
char rawheader[] = "10011010100110010101101001010101"; //->"0100010111001111"; // 0x45CF (big endian)

#define BITFRAME_LEN     280
char frame_bits[BITFRAME_LEN+4] = "0100010111001111";

/* ------------------------------------------------------------------------------------ */

#define BAUD_RATE   2500

/* ------------------------------------------------------------------------------------ */


#define B 8 // codeword: 8 bit
#define S 4 // davon 4 bit data

#define HEAD 0        //  16 bit
#define CONF (16+0)   //  56 bit
#define DAT1 (16+56)  // 104 bit
#define DAT2 (16+160) // 104 bit
               // frame: 280 bit

ui8_t H[4][8] =  // Parity-Check
             {{ 0, 1, 1, 1, 1, 0, 0, 0},
              { 1, 0, 1, 1, 0, 1, 0, 0},
              { 1, 1, 0, 1, 0, 0, 1, 0},
              { 1, 1, 1, 0, 0, 0, 0, 1}};
ui8_t He[8] = { 0x7, 0xB, 0xD, 0xE, 0x8, 0x4, 0x2, 0x1}; // Spalten von H:
                                                         // 1-bit-error-Syndrome
ui8_t hamming_conf[ 7*B];  //  7*8=56
ui8_t hamming_dat1[13*B];  // 13*8=104
ui8_t hamming_dat2[13*B];

ui8_t block_conf[ 7*S];  //  7*4=28
ui8_t block_dat1[13*S];  // 13*4=52
ui8_t block_dat2[13*S];

ui32_t bits2val(ui8_t *bits, int len) { // big endian
    int j;
    ui32_t val;
    if ((len < 0) || (len > 32)) return -1; // = 0xFFFF
    val = 0;
    for (j = 0; j < len; j++) {
        val |= (bits[j] << (len-1-j));
    }
    return val;
}

void deinterleave(char *str, int L, ui8_t *block) {
    int i, j;
    for (j = 0; j < B; j++) {  // L = 7, 13
        for (i = 0; i < L; i++) {
            if (str[L*j+i] >= 0x30 && str[L*j+i] <= 0x31) {
                block[B*i+j] = str[L*j+i] - 0x30; // ASCII -> bit
            }
        }
    }
}

int check(ui8_t code[8]) {
    int i, j;               // Bei Demodulierung durch Nulldurchgaenge, wenn durch Fehler ausser Takt,
    ui32_t synval = 0;      // verschieben sich die bits. Fuer Hamming-Decode waere es besser,
    ui8_t syndrom[4];       // sync zu Beginn mit Header und dann Takt beibehalten fuer decision.
    int ret=0;

    for (i = 0; i < 4; i++) { // S = 4
        syndrom[i] = 0;
        for (j = 0; j < 8; j++) { // B = 8
            syndrom[i] ^= H[i][j] & code[j];
        }
    }
    synval = bits2val(syndrom, 4);
    if (synval) {
        ret = -1;
        for (j = 0; j < 8; j++) {   // 1-bit-error
            if (synval == He[j]) {  // reicht auf databits zu pruefen, d.h.
                ret = j+1;          // (systematischer Code) He[0..3]
                break;
            }
        }
    }
    else ret = 0;
    if (ret > 0) code[ret-1] ^= 0x1;

    return ret;
}

int hamming(ui8_t *ham, int L, ui8_t *sym) {
    int i, j;
    int ret = 0;               // L = 7, 13
    for (i = 0; i < L; i++) {  // L * 2 nibble (data+parity)
        if (option_ecc) ret |= check(ham+B*i);
        for (j = 0; j < S; j++) {  // systematic: bits 0..S-1 data
            sym[S*i+j] = ham[B*i+j];
        }
    }
    return ret;
}

char nib2chr(ui8_t nib) {
    char c = '_';
    if (nib < 0x10) {
        if (nib < 0xA)  c = 0x30 + nib;
        else            c = 0x41 + nib-0xA;
    }
    return c;
}

int dat_out(ui8_t *dat_bits) {
    int i, ret = 0;
    static int fr_id;
    // int jahr = 0, monat = 0, tag = 0, std = 0, min = 0;
    int frnr = 0;
    int msek = 0;
    int lat = 0, lon = 0, alt = 0;
    int nib;
    int dvv;  // signed/unsigned 16bit

    fr_id = bits2val(dat_bits+48, 4);


    if (fr_id >= 0  && fr_id <= 8) {
        for (i = 0; i < 13; i++) {
            nib = bits2val(dat_bits+4*i, 4);
            dat_str[fr_id][i] = nib2chr(nib);
        }
        dat_str[fr_id][13] = '\0';
    }

    if (fr_id == 0) {
        start = 1;
        frnr = bits2val(dat_bits+24, 8);
        gpx.frnr = frnr;
    }

    if (fr_id == 1) {
        // 00..31: ? GPS-Sats in Sicht?
        msek = bits2val(dat_bits+32, 16);
        gpx.sek = msek/1000.0;
    }

    if (fr_id == 2) {
        lat = bits2val(dat_bits, 32);
        gpx.lat = lat/1e7;
        dvv = (short)bits2val(dat_bits+32, 16);  // (short)? zusammen mit dir sollte unsigned sein
        gpx.horiV = dvv/1e2;
    }

    if (fr_id == 3) {
        lon = bits2val(dat_bits, 32);
        gpx.lon = lon/1e7;
        dvv = bits2val(dat_bits+32, 16) & 0xFFFF;  // unsigned
        gpx.dir = dvv/1e2;
    }

    if (fr_id == 4) {
        alt = bits2val(dat_bits, 32);
        gpx.alt = alt/1e2;
        dvv = (short)bits2val(dat_bits+32, 16);  // signed
        gpx.vertV = dvv/1e2;
    }

    if (fr_id == 5) {
    }

    if (fr_id == 6) {
    }

    if (fr_id == 7) {
    }

    if (fr_id == 8) {
        gpx.jahr  = bits2val(dat_bits,   12);
        gpx.monat = bits2val(dat_bits+12, 4);
        gpx.tag   = bits2val(dat_bits+16, 5);
        gpx.std   = bits2val(dat_bits+21, 5);
        gpx.min   = bits2val(dat_bits+26, 6);
    }

    ret = fr_id;
    return ret;
}

// DFM-06 (NXP8)
float fl20(int d) {  // float20
    int val, p;
    float f;
    p = (d>>16) & 0xF;
    val = d & 0xFFFF;
    f = val/(float)(1<<p);
    return  f;
}
/*
float flo20(int d) {
    int m, e;
    float f1, f;
    m = d & 0xFFFF;
    e = (d >> 16) & 0xF;
    f =  m / pow(2,e);
    return  f;
}
*/

// DFM-09 (STM32)
float fl24(int d) {  // float24
    int val, p;
    float f;
    p = (d>>20) & 0xF;
    val = d & 0xFFFFF;
    f = val/(float)(1<<p);
    return  f;
}

// temperature approximation
float get_Temp(float *meas) { // meas[0..4]
// NTC-Thermistor EPCOS B57540G0502
// R/T No 8402, R25=Ro=5k
// B0/100=3450
// 1/T = 1/To + 1/B log(r) , r=R/Ro
// GRAW calibration data -80C..+40C on EEPROM ?
// meas0 = g*(R + Rs)
// meas3 = g*Rs , Rs: dfm6:10k, dfm9:20k
// meas4 = g*Rf , Rf=220k
    float B0 = 3260.0;       // B/Kelvin, fit -55C..+40C
    float T0 = 25 + 273.15;  // t0=25C
    float R0 = 5.0e3;        // R0=R25=5k
    float Rf = 220e3;        // Rf = 220k
    float g = meas[4]/Rf;
    float R = (meas[0]-meas[3]) / g; // meas[0,3,4] > 0 ?
    float T = 0;                     // T/Kelvin
    if (meas[0]*meas[3]*meas[4] == 0) R = 0;
    if (R > 0)  T = 1/(1/T0 + 1/B0 * log(R/R0));
    return  T - 273.15; // Celsius
//  DFM-06: meas20 * 16 = meas24
//      -> (meas24[0]-meas24[3])/meas24[4]=(meas20[0]-meas20[3])/meas20[4]
}
float get_Temp2(float *meas) { // meas[0..4]
// NTC-Thermistor EPCOS B57540G0502
// R/T No 8402, R25=Ro=5k
// B0/100=3450
// 1/T = 1/To + 1/B log(r) , r=R/Ro
// GRAW calibration data -80C..+40C on EEPROM ?
// meas0 = g*(R+Rs)+ofs
// meas3 = g*Rs+ofs , Rs: dfm6:10k, dfm9:20k
// meas4 = g*Rf+ofs , Rf=220k
    float f  = meas[0],
          f1 = meas[3],
          f2 = meas[4];
    float B0 = 3260.0;      // B/Kelvin, fit -55C..+40C
    float T0 = 25 + 273.15; // t0=25C
    float R0 = 5.0e3;       // R0=R25=5k
    float Rf2 = 220e3;      // Rf2 = Rf = 220k
    float g_o = f2/Rf2;     // approx gain
    float Rs_o = f1/g_o;    // = Rf2 * f1/f2;
    float Rf1 = Rs_o;       // Rf1 = Rs: dfm6:10k, dfm9:20k
    float g = g_o;          // gain
    float Rb = 0.0;         // offset
    float R = 0;            // thermistor
    float T = 0;            // T/Kelvin

    if       ( 8e3 < Rs_o && Rs_o < 12e3) Rf1 = 10e3;  // dfm6
    else if  (18e3 < Rs_o && Rs_o < 22e3) Rf1 = 20e3;  // dfm9
    g = (f2 - f1) / (Rf2 - Rf1);
    Rb = (f1*Rf2-f2*Rf1)/(f2-f1); // ofs/g

    R = (f-f1)/g;                    // meas[0,3,4] > 0 ?
    if (R > 0)  T = 1/(1/T0 + 1/B0 * log(R/R0));

    if (option_ptu && option_verbose == 2) {
        printf("  (Rso: %.1f , Rb: %.1f)", Rs_o/1e3, Rb/1e3);
    }

    return  T - 273.15;
//  DFM-06: meas20 * 16 = meas24
}
float get_Temp4(float *meas) { // meas[0..4]
// NTC-Thermistor EPCOS B57540G0502
// [  T/C  ,   R/R25   , alpha ] :
// [ -55.0 ,  51.991   ,   6.4 ]
// [ -50.0 ,  37.989   ,   6.2 ]
// [ -45.0 ,  28.07    ,   5.9 ]
// [ -40.0 ,  20.96    ,   5.7 ]
// [ -35.0 ,  15.809   ,   5.5 ]
// [ -30.0 ,  12.037   ,   5.4 ]
// [ -25.0 ,   9.2484  ,   5.2 ]
// [ -20.0 ,   7.1668  ,   5.0 ]
// [ -15.0 ,   5.5993  ,   4.9 ]
// [ -10.0 ,   4.4087  ,   4.7 ]
// [  -5.0 ,   3.4971  ,   4.6 ]
// [   0.0 ,   2.7936  ,   4.4 ]
// [   5.0 ,   2.2468  ,   4.3 ]
// [  10.0 ,   1.8187  ,   4.2 ]
// [  15.0 ,   1.4813  ,   4.0 ]
// [  20.0 ,   1.2136  ,   3.9 ]
// [  25.0 ,   1.0000  ,   3.8 ]
// [  30.0 ,   0.82845 ,   3.7 ]
// [  35.0 ,   0.68991 ,   3.6 ]
// [  40.0 ,   0.57742 ,   3.5 ]
// -> Steinhart–Hart coefficients (polyfit):
    float p0 = 1.09698417e-03,
          p1 = 2.39564629e-04,
          p2 = 2.48821437e-06,
          p3 = 5.84354921e-08;
// T/K = 1/( p0 + p1*ln(R) + p2*ln(R)^2 + p3*ln(R)^3 )
    float Rf = 220e3;    // Rf = 220k
    float g = meas[4]/Rf;
    float R = (meas[0]-meas[3]) / g; // meas[0,3,4] > 0 ?
    float T = 0; // T/Kelvin
    if (R > 0)  T = 1/( p0 + p1*log(R) + p2*log(R)*log(R) + p3*log(R)*log(R)*log(R) );
    return  T - 273.15; // Celsius
//  DFM-06: meas20 * 16 = meas24
//      -> (meas24[0]-meas24[3])/meas24[4]=(meas20[0]-meas20[3])/meas20[4]
}


#define SNbit 0x0100
int conf_out(ui8_t *conf_bits) {
    int conf_id;
    int ret = 0;
    int val, hl;
    static int chAbit, chA[2];
    ui32_t SN6, SN9;

    conf_id = bits2val(conf_bits, 4);

    //if (conf_id > 6) gpx.SN6 = 0;  //// gpx.sonde_typ & 0xF = 9; // SNbit?

    if ((gpx.sonde_typ & 0xFF) < 9  &&  conf_id == 6) {
        SN6 = bits2val(conf_bits+4, 4*6);  // DFM-06: Kanal 6
        if ( SN6 == gpx.SN6 ) {            // nur Nibble-Werte 0..9
            gpx.sonde_typ = SNbit | 6;
            ret = 6;
        }
        else {
            gpx.sonde_typ = 0;
        }
        gpx.SN6 = SN6;
    }
    if (conf_id == 0xA) {  // 0xACxxxxy
        val = bits2val(conf_bits+8, 4*5);
        hl =  (val & 1) == 0;
        chA[hl] = (val >> 4) & 0xFFFF;
        chAbit |= 1 << hl;
        if (chAbit == 3) {  // DFM-09: Kanal A
            SN9 = (chA[1] << 16) | chA[0];
            if ( SN9 == gpx.SN9 ) {
                gpx.sonde_typ = SNbit | 9;
                ret = 9;
            }
            else {
                gpx.sonde_typ = 0;
            }
            gpx.SN9 = SN9;
            chAbit = 0;
        }
    }

    if (conf_id >= 0 && conf_id <= 4) {
        val = bits2val(conf_bits+4, 4*6);
        gpx.meas24[conf_id] = fl24(val);
        // DFM-09 (STM32): 24bit 0exxxxx
        // DFM-06 (NXP8):  20bit 0exxxx0
        //   fl20(bits2val(conf_bits+4, 4*5))
        //       = fl20(exxxx)
        //       = fl24(exxxx0)/2^4
        //   meas20 * 16 = meas24
    }

    // STM32-status: Bat, MCU-Temp
    if ((gpx.sonde_typ & 0xFF) == 9) { // DFM-09 (STM32)
        if (conf_id == 0x5) { // voltage
            val = bits2val(conf_bits+8, 4*4);
            gpx.status[0] = val/1000.0;
        }
        if (conf_id == 0x6) { // T-intern (STM32)
            val = bits2val(conf_bits+8, 4*4);
            gpx.status[1] = val/100.0;
        }
    }

    return ret;
}

void print_gpx() {
  int i, j;

  if (start) {

      if (option_raw == 2) {
           for (i = 0; i < 9; i++) {
               printf(" %s", dat_str[i]);
           }
           for (i = 0; i < 9; i++) {
               for (j = 0; j < 13; j++) dat_str[i][j] = ' ';
           }
      }
      else {
          //if (option_auto && option_verbose) printf("[%c] ", option_inv?'-':'+');
          printf("[%3d] ", gpx.frnr);
          printf("%4d-%02d-%02d ", gpx.jahr, gpx.monat, gpx.tag);
          printf("%02d:%02d:%04.1f ", gpx.std, gpx.min, gpx.sek);
          printf("  ");
          printf("lat: %.6f  ", gpx.lat);
          printf("lon: %.6f  ", gpx.lon);
          printf("alt: %.1f  ", gpx.alt);
          printf(" vH: %5.2f ", gpx.horiV);
          printf(" D: %5.1f ", gpx.dir);
          printf(" vV: %5.2f ", gpx.vertV);
          if (option_ptu) {
              float t = get_Temp(gpx.meas24);
              if (t > -270.0) printf("  T=%.1fC ", t);
              if (option_verbose == 2) {
                  float t2 = get_Temp2(gpx.meas24);
                  float t4 = get_Temp4(gpx.meas24);
                  if (t2 > -270.0) printf("  T2=%.1fC ", t2);
                  if (t4 > -270.0) printf(" T4=%.1fC  ", t4);
                  printf(" f0: %.2f ", gpx.meas24[0]);
                  printf(" f3: %.2f ", gpx.meas24[3]);
                  printf(" f4: %.2f ", gpx.meas24[4]);
              }
          }
          if (option_verbose == 2  &&  (gpx.sonde_typ & 0xFF) == 9) {
              printf("  U: %.2fV ", gpx.status[0]);
              printf("  Ti: %.1fK ", gpx.status[1]);
          }
          if (option_verbose  &&  (gpx.sonde_typ & SNbit))
          {
              if ((gpx.sonde_typ & 0xFF) == 6) {
                  printf(" (ID%1d:%06X) ", gpx.sonde_typ & 0xF, gpx.SN6);
              }
              if ((gpx.sonde_typ & 0xFF) == 9) {
                  printf(" (ID%1d:%06u) ", gpx.sonde_typ & 0xF, gpx.SN9);
              }
              gpx.sonde_typ ^= SNbit;
          }
      }
      printf("\n");

  }
}

int print_frame() {
    int i;
    int nib = 0;
    int frid = -1;
    int ret0, ret1, ret2;
    int ret = 0;


    deinterleave(frame_bits+CONF,  7, hamming_conf);
    deinterleave(frame_bits+DAT1, 13, hamming_dat1);
    deinterleave(frame_bits+DAT2, 13, hamming_dat2);

    ret0 = hamming(hamming_conf,  7, block_conf);
    ret1 = hamming(hamming_dat1, 13, block_dat1);
    ret2 = hamming(hamming_dat2, 13, block_dat2);
    ret = ret0 | ret1 | ret2;

    if (option_raw == 1) {

        for (i = 0; i < 7; i++) {
            nib = bits2val(block_conf+S*i, S);
            printf("%01X", nib & 0xFF);
        }
        if (option_ecc) {
            if      (ret0 == 0) printf(" [OK] ");
            else if (ret0  > 0) printf(" [KO] ");
            else                printf(" [NO] ");
        }
        printf("  ");
        for (i = 0; i < 13; i++) {
            nib = bits2val(block_dat1+S*i, S);
            printf("%01X", nib & 0xFF);
        }
        if (option_ecc) {
            if      (ret1 == 0) printf(" [OK] ");
            else if (ret1  > 0) printf(" [KO] ");
            else                printf(" [NO] ");
        }
        printf("  ");
        for (i = 0; i < 13; i++) {
            nib = bits2val(block_dat2+S*i, S);
            printf("%01X", nib & 0xFF);
        }
        if (option_ecc) {
            if      (ret2 == 0) printf(" [OK] ");
            else if (ret2  > 0) printf(" [KO] ");
            else                printf(" [NO] ");
        }
        printf("\n");

    }
    else if (option_ecc) {

        if (ret0 == 0 || ret0 > 0) {
            conf_out(block_conf);
        }
        if (ret1 == 0 || ret1 > 0) {
            frid = dat_out(block_dat1);
            if (frid == 8) print_gpx();
        }
        if (ret2 == 0 || ret2 > 0) {
            frid = dat_out(block_dat2);
            if (frid == 8) print_gpx();
        }

    }
    else {

        conf_out(block_conf);
        frid = dat_out(block_dat1);
        if (frid == 8) print_gpx();
        frid = dat_out(block_dat2);
        if (frid == 8) print_gpx();

    }

    return ret;
}

/* -------------------------------------------------------------------------- */


int main(int argc, char **argv) {

    FILE *fp = NULL;
    char *fpname = NULL;
    float spb = 0.0;
    int header_found = 0;
    int ret = 0;

    int bit;
    int bitpos = 0;
    int bitQ;
    int pos;
    int herrs, herr1;
    int headerlen = 0;
    int frm = 0, nfrms = 8; // nfrms=1,2,4,8

    float mv;
    unsigned int mv_pos, mv0_pos;

    float thres = 0.6;

    int bitofs = 0, dif = 0;
    int symlen = 2;


#ifdef CYGWIN
    _setmode(fileno(stdin), _O_BINARY);  // _setmode(_fileno(stdin), _O_BINARY);
#endif
    setbuf(stdout, NULL);

    fpname = argv[0];
    ++argv;
    while ((*argv) && (!wavloaded)) {
        if      ( (strcmp(*argv, "-h") == 0) || (strcmp(*argv, "--help") == 0) ) {
            fprintf(stderr, "%s [options] audio.wav\n", fpname);
            fprintf(stderr, "  options:\n");
            fprintf(stderr, "       -v, -vv\n");
            fprintf(stderr, "       -r, --raw\n");
            fprintf(stderr, "       -i, --invert\n");
            fprintf(stderr, "       --ecc        (Hamming ECC)\n");
            fprintf(stderr, "       --ths <x>    (peak threshold; default=%.1f)\n", thres);
            return 0;
        }
        else if ( (strcmp(*argv, "-v") == 0) || (strcmp(*argv, "--verbose") == 0) ) {
            option_verbose = 1;
        }
        else if ( (strcmp(*argv, "-vv") == 0) ) { option_verbose = 2; }
        else if ( (strcmp(*argv, "-r") == 0) || (strcmp(*argv, "--raw") == 0) ) {
            option_raw = 1;
        }
        else if ( (strcmp(*argv, "-R") == 0) || (strcmp(*argv, "--RAW") == 0) ) {
            option_raw = 2;
        }
        else if ( (strcmp(*argv, "-i") == 0) || (strcmp(*argv, "--invert") == 0) ) {
            option_inv = 0x1;
        }
        else if ( (strcmp(*argv, "--ecc") == 0) ) { option_ecc = 1; }
        else if ( (strcmp(*argv, "--ptu") == 0) ) { option_ptu = 1; }
        else if ( (strcmp(*argv, "--ths") == 0) ) {
            ++argv;
            if (*argv) {
                thres = atof(*argv);
            }
            else return -1;
        }
        else {
            fp = fopen(*argv, "rb");
            if (fp == NULL) {
                fprintf(stderr, "%s konnte nicht geoeffnet werden\n", *argv);
                return -1;
            }
            wavloaded = 1;
        }
        ++argv;
    }
    if (!wavloaded) fp = stdin;


    spb = read_wav_header(fp, (float)BAUD_RATE);
    if ( spb < 0 ) {
        fclose(fp);
        fprintf(stderr, "error: wav header\n");
        return -1;
    }
    if ( spb < 8 ) {
        fprintf(stderr, "note: sample rate low\n");
    }


    symlen = 2;
    headerlen = strlen(rawheader);
    bitofs = 2; // +1 .. +2
    if (init_buffers(rawheader, headerlen, 0) < 0) { // shape=0 (alt. shape=1)
        fprintf(stderr, "error: init buffers\n");
        return -1;
    };


    mv = -1; mv_pos = 0;

    while ( f32buf_sample(fp, option_inv, 1) != EOF ) {

        mv0_pos = mv_pos;
        dif = getmaxCorr(&mv, &mv_pos, headerlen+headerlen/2);

        if (mv > thres) {
            if (mv_pos > mv0_pos) {

                header_found = 0;
                herrs = headcmp(symlen, rawheader, headerlen, mv_pos); // symlen=2
                herr1 = 0;
                if (herrs <= 3 && herrs > 0) {
                    herr1 = headcmp(symlen, rawheader, headerlen, mv_pos+1);
                    if (herr1 < herrs) {
                        herrs = herr1;
                        herr1 = 1;
                    }
                }
                if (herrs <= 1) header_found = 1; // herrs <= 1 bitfehler in header

                if (header_found) {

                    bitpos = 0;
                    pos = headerlen;
                    pos /= 2;

                    frm = 0;
                    while ( frm < nfrms ) { // nfrms=1,2,4,8
                        while ( pos < BITFRAME_LEN ) {
                            header_found = !(frm==nfrms-1 && pos>=BITFRAME_LEN-10);
                            bitQ = read_sbit(fp, symlen, &bit, option_inv, bitofs, bitpos==0, !header_found); // symlen=2, return: zeroX/bit
                            if (bitQ == EOF) { frm = nfrms; break; }
                            frame_bits[pos] = 0x30 + bit;
                            pos++;
                            bitpos += 1;
                        }
                        frame_bits[pos] = '\0';
                        ret = print_frame();
                        if (pos < BITFRAME_LEN) break;
                        pos = 0;
                        frm += 1;
                        //if (ret < 0) frms += 1;
                    }

                    header_found = 0;
                    pos = headerlen;
                }
            }
        }

    }


    free_buffers();

    fclose(fp);

    return 0;
}