snippets/C/bitwise.c

   1 /*
   2  * An example of bitwise operations in C
   3  *
   4  * Luiz Fernando N. Capitulino <lcapitulino@mandriva.com.br>
   5  */
   6 #include <stdio.h>
   7
   8 static void show(unsigned char var)
   9 {
  10         printf("-> %#x\n", var);
  11 }
  12
  13 static void set_bit(unsigned char *var, unsigned char bits)
  14 {
  15         *var |= bits;
  16 }
  17
  18 static void unset_bit(unsigned char *var, unsigned char bits)
  19 {
  20         *var &= ~bits;
  21 }
  22
  23 static void left_shift(unsigned char *var, int positions)
  24 {
  25         *var <<= positions;
  26 }
  27
  28 static void right_shift(unsigned char *var, int positions)
  29 {
  30         *var >>= positions;
  31 }
  32
  33 int main(void)
  34 {
  35         unsigned char var = 0;
  36
  37         show(var);
  38
  39         set_bit(&var, 0x1);
  40         show(var);
  41
  42         set_bit(&var, 0x8);
  43         show(var);
  44
  45         set_bit(&var, 0x80);
  46         show(var);
  47
  48         unset_bit(&var, 0x8);
  49         show(var);
  50
  51         left_shift(&var, 2);
  52         show(var);
  53
  54         right_shift(&var, 2);
  55         show(var);
  56
  57         return 0;
  58 }