＃i nclude <stdio.h>
＃i nclude <string.h>
code unsigned char mul_str[]={4,2,9,4,9,6,7,2,9,6,0};//2^32 
/*------------------------------------------------------------------------------
    Name   :   int2str_64b
    Deion     :   convert 64bit integer to string 
    Parameters   :   
        Input       :   unsigned long High: Higher 32bits of the integer
      unsigned long Low : Lower 32bits of the integer
        Output      :   unsigned char *result : the pointer to the result, max_length = 21 bytes                        
    Return          :   length of the string
------------------------------------------------------------------------------*/
unsigned char int2str_64b(unsigned long High, unsigned long Low, unsigned char *result)
{
unsigned char tmp_str[11];
unsigned char i, j, k, inc, tmp;
//high * 2^32
memset(result, 0, 21);
sprintf(tmp_str, "%010lu", High); 
for(i = 0; i < 10; i++)
  tmp_str -= '0';
      
for(i = 10; i > 0; i--){
  for(j = 10; j > 0; j--){
   k = i + j - 1;
   inc = 0;
   tmp = tmp_str[i - 1] * mul_str[j - 1] + result[k];
   inc = tmp / 10;
   result[k] = tmp % 10;   
   while(inc != 0){
     k--;
    tmp = result[k] + inc;
    result[k] = tmp % 10;
    inc = tmp / 10;
     } 
  } 
}
  
// result + low
sprintf(tmp_str, "%010lu", Low);
for(i = 0; i < 10; i++)
  tmp_str -= '0';  

inc = 0;
for(i = 10; i > 0; i--){
  tmp = result[i + 9] + tmp_str[i - 1] + inc; 
  inc = tmp / 10;
  result[i + 9] = tmp % 10;   
}
k = 10;
while(inc != 0){
   k--;
  tmp  = result[k] + inc;
  inc = tmp / 10;
  result[k] = tmp % 10;
   } 
  
//remove addtional 0s
for(i = 0;i < 19; i++)
  if(result != 0)
   break;
for(j = i; j < 20; j++){
  result[j - i] = result[j] + '0';
}
result[20 - i] = 0;
return (20 - i);
}
//---------------------------------------------------------------------------------------------