X-Git-Url: https://git.danieliu.xyz/?a=blobdiff_plain;f=include%2Fbitops.h;h=d0225ffe77e54b8cf2ab174be52ebb665bd39b76;hb=b416f18295f7edcb5474396a6b26a59fd5ddb1f5;hp=e18f3b0710aea6df465992aaa6aaae748de46594;hpb=0f870f29388a36d32ec9ffaabe9ffe03edc038c0;p=smdp.git

diff --git a/include/bitops.h b/include/bitops.h
index e18f3b0..d0225ff 100644
--- a/include/bitops.h
+++ b/include/bitops.h
@@ -1,6 +1,23 @@
 #if !defined( BITOPS_H )
 #define BITOPS_H
 
+/*
+ * Macros to do bit operations on integer variables.
+ *
+ * macro: SET_BIT to set bit at pos of var to 1
+ * macro: CLEAR_BIT to set bit at pos of var to 0
+ * macro: TOGGLE_BIT to toggle bit at pos of var from 1 to 0 and vice versa
+ * macro: CHECK_BIT returns > 0 if bit at pos of var is set to 1
+ *
+ * Example:
+ *      int i = 0;
+ *      i = SET_BIT(i, 2);
+ *      if(CHECK_BIT(i, 2))
+ *          printf("bit 2 is set\n");
+ *      printf("value of i is %d\n", i);
+ *
+ */
+
 #define SET_BIT(var, pos)    ((var) |= (1<<(pos)))
 #define CLEAR_BIT(var, pos)  ((var) &= (~(1<<(pos))))
 #define TOGGLE_BIT(var, pos) ((var) ^= (1<<(pos)))