text: /* Toggle the 16 bit unsigned integer pointed by *p from little endian to
   * big endian */
  void memrev16(void *p) {
      unsigned char *x = p, t;
  
      t = x[0];
      x[0] = x[1];
      x[1] = t;
  }
  
  /* Toggle the 32 bit unsigned integer pointed by *p from little endian to
   * big endian */
  void memrev32(void *p) {
      unsigned char *x = p, t;
  
      t = x[0];
      x[0] = x[3];
      x[3] = t;
      t = x[1];
      x[1] = x[2];
      x[2] = t;
  }
  
  /* Toggle the 64 bit unsigned integer pointed by *p from little endian to
   * big endian */
  void memrev64(void *p) {
      unsigned char *x = p, t;
  
      t = x[0];
      x[0] = x[7];
      x[7] = t;
      t = x[1];
      x[1] = x[6];
      x[6] = t;
      t = x[2];
      x[2] = x[5];
      x[5] = t;
      t = x[3];
      x[3] = x[4];
      x[4] = t;
  }