Fast 32bit signed itoa without division and with fixed width (base 10) filled up with spaces.

itoaFixedWidth.c

char *itoaFixedWidth(int32_t zahl) {
   static uint32_t subtractors[] = {1000000000, 100000000, 10000000, 1000000,
                                    100000, 10000, 1000, 100, 10, 1};
   static char string[12];
   char n, *str = string, sign = zahl < 0 ? '-' : ' ';	
   uint32_t *sub = subtractors;
   uint32_t u = zahl < 0 ? (uint32_t) -zahl : (uint32_t) zahl;    
   uint8_t  i = 10;	
   *str++ = ' ';
   while (i > 1 && u < *sub) {
       i--;
       sub++;
       *str++ = ' ';
   }
   *(str-1) = sign;
   while (i--) {
       n = '0';
       while (u >= *sub) {
           u -= *sub;
           n++;
       }
       *str++ = n;
       sub++;
   }
   *str = 0;
   return string;
}