Subversion Repositories mmcfpgaconfig

//

// MMC Card CRC7 calculator and checker

// www.openchip.org

//

//

#include <iostream>

#include <stdio.h>

using namespace std;

char crc7[8];

char cmd[49];

void do_crc7(char c) {

  char c3;

  char c0;

  // last stage and input bit

  c0 = (crc7[6] == c) ? '0' : '1';

  //

  c3 = (crc7[2] == c0) ? '0' : '1';

  // shift register  

  crc7[6] = crc7[5];

  crc7[5] = crc7[4];

  crc7[4] = crc7[3];

  crc7[3] = c3;

  crc7[2] = crc7[1];

  crc7[1] = crc7[0];

  crc7[0] = c0;

}

/*

CMD17 Argument=0x00000100 CRC7=0x43 OK, checked!

CMD17 Argument=0x00004000 CRC7=0x8F OK, checked!

*/

void calc_crc(int command, unsigned int arg) {

  int i;

  unsigned int mask;

  // fill CMD

  mask = 1;

  for (i=0;i<6;i++) {

    if (mask & command) {

      cmd[7-i] = '1';

    } else {

      cmd[7-i]='0';

    }

    mask <<= 1;

  }

  // fill ARG

  mask = 1;

  for (i=0;i<32;i++) {

    if (mask & arg) {

      cmd[39-i] = '1';

    } else {

      cmd[39-i]='0';

    }

    mask <<= 1;

  }

  // clear CRC

  for (i=0;i<7;i++) crc7[i] = '0';

  // calc CRC

  for (i=0;i<40;i++) do_crc7(cmd[i]);

  // copy CRC

  cmd[40] = crc7[6];

  cmd[41] = crc7[5];

  cmd[42] = crc7[4];

  cmd[43] = crc7[3];

  cmd[44] = crc7[2];

  cmd[45] = crc7[1];

  cmd[46] = crc7[0];

}

int main (int argc, char *argv[])

{

    char quit;

    int i;

    // clear CRC

    crc7[7] = 0;

    for (i=0;i<7;i++) crc7[i] = '0';

    // clear CMD, ARG

    cmd[48] = 0;

    for (i=0;i<48;i++) cmd[i] = '0';

    cmd[1] = '1';   // Start bit

    cmd[47] = '1';  // Stop Bit

    // check CRC calculation

    calc_crc(0,0);        printf("\n\rTest CMD0 ,0x0     %s", cmd);

    calc_crc(17,0x100);   printf("\n\rTest CMD17,0x0100  %s", cmd);

    calc_crc(17,0x4000);  printf("\n\rTest CMD17,0x04000 %s", cmd);

    printf("\n\rCalc CRCs");

    calc_crc(0,0);           printf("\n\rTest CMD0 ,0x0        %s", cmd);

    calc_crc(1,0x80FF8000);  printf("\n\rTest CMD1 ,0x80FF8000 %s", cmd);

    calc_crc(2,0);           printf("\n\rTest CMD2 ,0x0        %s", cmd);

    calc_crc(3,0x10000);     printf("\n\rTest CMD3 ,0x10000    %s", cmd);

    calc_crc(7,0x10000);     printf("\n\rTest CMD7 ,0x10000    %s", cmd);

    calc_crc(11,0x0000);     printf("\n\rTest CMD11,0x00000    %s", cmd);

    calc_crc(55,0x0000);     printf("\n\rTest CMD55,0x00000    %s", cmd);

    calc_crc(41,0x80FF8000); printf("\n\rTest ACMD41,0x80FF8000 %s", cmd);

    cin >>quit;

    return 0;

}