send_comstr( CMD_0, 0, 6);
  ocr = 0;
  do {
    send_comstr(CMD_55, 0, 6);
    send_comstr(ACMD_41, ocr, 6);
    ocr = (comstr->arg3)|(comstr->arg2<<8)|(comstr->arg1<<16)|(comstr->arg0<<24);
  }  while (!(comstr->arg0 & 0x80));

  send_comstr( CMD_0, 0, 6);
  ocr = 0;
  do {
    send_comstr( CMD_8, 0, 6);  // !!! нет ответа
    send_comstr(CMD_55, 0, 6);
    send_comstr(ACMD_41, ocr, 6);
    ocr = (comstr->arg3)|(comstr->arg2<<8)|(comstr->arg1<<16)|(comstr->arg0<<24);
  }  while (!(comstr->arg0 & 0x80));

unsigned char calc_crc7(unsigned char *ptr, signed char count ){
  char crc=0;
  unsigned char i,data;
  while (count--) {
    data=*ptr++;
    for (i=0;i<8;i++) {
      crc <<= 1;
      if ((data & 0x80)^(crc & 0x80)) crc ^=0x09;
      data <<= 1;
    }
  }
  return((crc<<1)|1);
}

#define CRC7_POLYNOMIAL 0x89            /* x^7 + x^3 + 1 */
static unsigned char crc7_syndrome_table[256];

void gen_crc7_syndrome_table (void) {
  int i, j, syndrome;
  for (i = 0;  i < 256;  ++i) {
      syndrome = ((i & 0x80) != 0)? i ^ CRC7_POLYNOMIAL : i;
      for (j = 0;  j < 7;  ++j)
        if (((syndrome <<= 1) & 0x80) != 0)  syndrome ^= CRC7_POLYNOMIAL;
      crc7_syndrome_table[i] = (unsigned char) syndrome;
  }
}

char crc7 (const unsigned char *ptr) {
  unsigned char i, crc7_accum = 0;
  for (i = 0;  i < 5;  ++i)  // 6 - адаптировано для SD
    crc7_accum = crc7_syndrome_table[(crc7_accum << 1) ^ *ptr++];
  return ((crc7_accum<<1)|1);  // адаптировано для SD (+ стоп бит)
}