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  1. #include <stdio.h>
  2. #include <string.h>
  3. #include <ctype.h>
  4.  
  5. void hex_dump(void *data, int size)
  6. {
  7.   /* dumps size bytes of *data to stdout. Looks like:
  8.    * [0000] 75 6E 6B 6E 6F 77 6E 20
  9.    *                  30 FF 00 00 00 00 39 00 unknown 0.....9.
  10.    * (in a single line of course)
  11.    */
  12.  
  13.   unsigned char *p = data;
  14.   unsigned char c;
  15.   int n;
  16.   char bytestr[20] = {0};
  17.   char addrstr[10] = {0};
  18.   char hexstr[ 16*3 + 5 + 20] = {0};
  19.   char charstr[16*1 + 5] = {0};
  20.   for (n=1;n<=size;n++)
  21.   {
  22.     if (n%8 == 1)
  23.     {
  24.       /* store address for this line */
  25.       snprintf(addrstr, sizeof(addrstr), "%.4x",
  26.           ((unsigned int)p-(unsigned int)data) );
  27.     }
  28.  
  29.     c = *p;
  30.     if (isalnum(c) == 0)
  31.       c = '.';
  32.  
  33.     /* store hex str (for left side) */
  34.     snprintf(bytestr, sizeof(bytestr), "0x%02x    ", *p);
  35.     strncat(hexstr, bytestr, sizeof(hexstr)-strlen(hexstr)-1);
  36.  
  37.     /* store char str (for right side) */
  38.     snprintf(bytestr, sizeof(bytestr), "%c", c);
  39.     strncat(charstr, bytestr, sizeof(charstr)-strlen(charstr)-1);
  40.  
  41.     if (n%8 == 0)
  42.     {
  43.       /* line completed */
  44.       fprintf(stderr, "[%4.4s]          %-65.65s  %s\n", addrstr, hexstr, charstr);
  45.       hexstr[0] = 0;
  46.       charstr[0] = 0;
  47.     }
  48.     else if (n%8 == 0)
  49.     {
  50.       /* half line: add whitespaces */
  51.       strncat(hexstr, "  ", sizeof(hexstr)-strlen(hexstr)-1);
  52.       strncat(charstr, " ", sizeof(charstr)-strlen(charstr)-1);
  53.     }
  54.     p++; /* next byte */
  55.   }
  56.  
  57.   if (strlen(hexstr) > 0)
  58.   {
  59.     /* print rest of buffer if not empty */
  60.     fprintf(stderr, "[%4.4s]          %-65.65s  %s\n", addrstr, hexstr, charstr);
  61.   }
  62. }
  63.  
  64.