typedef struct{  //char name[ 16 ];                // Name of the CAN controller hardware  //uint32_t ref_clk;               // CAN system clock frequency in Hz  //uint32_t sjw_max;               // Synchronisation jump width  uint32_t brp_min;                 // Bit-rate prescaler  uint32_t brp_max;  uint32_t brp_inc;  uint32_t tseg1_min;               // Time segement 1 = prop_seg + phase_seg1  uint32_t tseg1_max;  uint32_t tseg2_min;               // Time segement 2 = phase_seg2  uint32_t tseg2_max;} CAN_BitTimingConst_TypeDef;typedef struct{  uint32_t ref_clk;                 // CAN system clock frequency in Hz  uint32_t bitrate;                 // Bit-rate in bits/second  uint32_t sample_point;            // Sample point in one-tenth of a percent  uint32_t brp;                     // Bit-rate prescaler  uint32_t tq;                      // Time quanta ( TQ )  in nanoseconds  uint32_t tseg1;                   // Time segement 1 = prop_seg + phase_seg1  uint32_t tseg2;                   // Time segement 2 = phase_seg2  uint32_t sjw;                     // Synchronisation jump width in TQs//uint32_t prop_seg;                // Propagation segment in TQs//uint32_t phase_seg1;              // Phase buffer segment 1 in TQs//uint32_t phase_seg2;              // Phase buffer segment 2 in TQs} CAN_BitTiming_TypeDef;int32_t CAN_CalcBitTiming( CAN_BitTimingConst_TypeDef *btc,  CAN_BitTiming_TypeDef *bt );

#define CAN_CALC_MAX_ERROR 50   // in one-tenth of a percentint32_t CAN_UpdateSamplePoint( CAN_BitTimingConst_TypeDef *btc,  int32_t sampl_pt, int32_t tseg, int32_t *tseg1, int32_t *tseg2 ){  *tseg2 = tseg + 1 - ( sampl_pt * ( tseg + 1 ) ) / 1000;  if ( *tseg2 < btc->tseg2_min )    *tseg2 = btc->tseg2_min;  if ( *tseg2 > btc->tseg2_max )    *tseg2 = btc->tseg2_max;  *tseg1 = tseg - *tseg2;  if ( *tseg1 > btc->tseg1_max )  {    *tseg1 = btc->tseg1_max;    *tseg2 = tseg - *tseg1;  }  return 1000 * ( tseg + 1 - *tseg2 ) / ( tseg + 1 );}// CIA Sample Point : 75.0% : Speed > 800000// CIA Sample Point : 80.0% : Speed > 500000// CIA Sample Point : 87.5% : Speed <= 500000uint32_t CAN_CIA_SamplePoint( uint32_t bitrate ){  uint32_t sampl_pt;  if ( bitrate > 800000 )    sampl_pt = 750;  else if ( bitrate > 500000 )    sampl_pt = 800;  else    sampl_pt = 875;  return sampl_pt;}int32_t CAN_CalcBitTiming( CAN_BitTimingConst_TypeDef *btc,  CAN_BitTiming_TypeDef *bt ){  uint64_t v64;  int32_t rate = 0;  int32_t best_error = 1000000000, error = 0;  int32_t best_tseg = 0, best_brp = 0, brp = 0;  int32_t tsegall, tseg = 0, tseg1 = 0, tseg2 = 0;  int32_t spt_error = 1000, spt = 0, sampl_pt;  // Use gived sample points  if ( bt->sample_point )    sampl_pt = bt->sample_point;  else    // Use CIA recommended sample points    sampl_pt = CAN_CIA_SamplePoint( bt->bitrate );  // tseg even = round down, odd = round up  for ( tseg = ( btc->tseg1_max + btc->tseg2_max ) * 2 + 1;      tseg >= ( btc->tseg1_min + btc->tseg2_min ) * 2; tseg-- )  {    tsegall = 1 + tseg / 2;    // Compute all possible tseg choices (tseg=tseg1+tseg2)    brp = bt->ref_clk / ( tsegall * bt->bitrate ) + tseg % 2;    // chose brp step which is possible in system    brp = ( brp / btc->brp_inc ) * btc->brp_inc;    if ( ( brp < btc->brp_min ) || ( brp > btc->brp_max ) )      continue;    rate = bt->ref_clk / ( brp * tsegall );    error = bt->bitrate - rate;    // tseg brp biterror    if ( error < 0 )      error = -error;    if ( error > best_error )      continue;    best_error = error;    if ( error == 0 )    {      spt = CAN_UpdateSamplePoint( btc, sampl_pt, tseg / 2, &tseg1, &tseg2 );      error = sampl_pt - spt;      if ( error < 0 )        error = -error;      if ( error > spt_error )        continue;      spt_error = error;    }    best_tseg = tseg / 2;    best_brp = brp;    if ( error == 0 )      break;  }  if ( best_error )  {    /* Error in one-tenth of a percent */    error = ( best_error * 1000 ) / bt->bitrate;    if ( error > CAN_CALC_MAX_ERROR )    {      // error ( "bitrate error %ld.%ld%% too high\n", error / 10, error % 10 );      return DRIVER_ERROR_PARAMETER;    }    else    {      // warn( "bitrate error %ld.%ld%%\n", error / 10,  error % 10 );    }  }  v64 = ( (uint64_t) best_brp * 1000000000UL ) / bt->ref_clk;  bt->tq = (uint32_t) v64;  bt->brp = best_brp;  bt->tseg2 = tseg2;  bt->tseg1 = tseg1;  bt->sjw = 1;  // bt->prop_seg = tseg1 / 2;  // bt->phase_seg1 = tseg1 - bt->prop_seg;  // bt->phase_seg2 = tseg2;  // real bit-rate  bt->bitrate = bt->ref_clk / ( bt->brp * ( tseg1 + tseg2 + 1 ) );  // real sample point  bt->sample_point = CAN_UpdateSamplePoint( btc, sampl_pt, best_tseg, &tseg1,    &tseg2 );  return DRIVER_OK;}