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-rw-r--r--common/util.c37
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diff --git a/common/util.c b/common/util.c
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+/*
+Copyright 2011 Jun Wako <wakojun@gmail.com>
+
+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 2 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/>.
+*/
+
+#include "util.h"
+
+// bit population
+int bitpop(uint8_t bits)
+{
+ int c;
+ for (c = 0; bits; c++)
+ bits &= bits -1;
+ return c;
+}
+
+// most significant on-bit
+int biton(uint8_t bits)
+{
+ int n = 0;
+ if (bits >> 4) { bits >>= 4; n += 4;}
+ if (bits >> 2) { bits >>= 2; n += 2;}
+ if (bits >> 1) { bits >>= 1; n += 1;}
+ return n;
+}