X-Git-Url: https://git.danieliu.xyz/?a=blobdiff_plain;f=include%2Fbitops.h;h=df240670ff1073aa9fbc7e7aa0e6b6ae0a268562;hb=d4843ea375360f37e965709e73c0fbd68e302dca;hp=e18f3b0710aea6df465992aaa6aaae748de46594;hpb=4a1ae435f312e8d76558ef1e64f141ebffd15f9d;p=smdp.git

diff --git a/include/bitops.h b/include/bitops.h
index e18f3b0..df24067 100644
--- a/include/bitops.h
+++ b/include/bitops.h
@@ -1,6 +1,40 @@
 #if !defined( BITOPS_H )
 #define BITOPS_H
 
+/*
+ * Macros to do bit operations on integer variables.
+ * Copyright (C) 2014 Michael Goehler
+ *
+ * This file is part of mdp.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ *
+ * 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)))