src/endian.c

   1 /* Toggle the 16 bit unsigned integer pointed by *p from little endian to
   2  * big endian */
   3 void memrev16(void *p) {
   4     unsigned char *x = p, t;
   5
   6     t = x[0];
   7     x[0] = x[1];
   8     x[1] = t;
   9 }
  10
  11 /* Toggle the 32 bit unsigned integer pointed by *p from little endian to
  12  * big endian */
  13 void memrev32(void *p) {
  14     unsigned char *x = p, t;
  15
  16     t = x[0];
  17     x[0] = x[3];
  18     x[3] = t;
  19     t = x[1];
  20     x[1] = x[2];
  21     x[2] = t;
  22 }
  23
  24 /* Toggle the 64 bit unsigned integer pointed by *p from little endian to
  25  * big endian */
  26 void memrev64(void *p) {
  27     unsigned char *x = p, t;
  28
  29     t = x[0];
  30     x[0] = x[7];
  31     x[7] = t;
  32     t = x[1];
  33     x[1] = x[6];
  34     x[6] = t;
  35     t = x[2];
  36     x[2] = x[5];
  37     x[5] = t;
  38     t = x[3];
  39     x[3] = x[4];
  40     x[4] = t;
  41 }
  42
  43 #ifdef TESTMAIN
  44 #include <stdio.h>
  45
  46 int main(void) {
  47     char buf[32];
  48
  49     sprintf(buf,"ciaoroma");
  50     memrev16(buf);
  51     printf("%s\n", buf);
  52
  53     sprintf(buf,"ciaoroma");
  54     memrev32(buf);
  55     printf("%s\n", buf);
  56
  57     sprintf(buf,"ciaoroma");
  58     memrev64(buf);
  59     printf("%s\n", buf);
  60
  61     return 0;
  62 }
  63 #endif