replace popcount with ctz

1 files changed, 8 insertions, 12 deletions

diff --git a/src/main.c b/src/main.c
index e67792f..f093b91 100644
--- a/src/main.c
+++ b/src/main.c
@@ -34,23 +34,19 @@ void usage(){
 	exit(1);
 }
 
-static int popcount(unsigned long mask){
+unsigned int getshift(unsigned int mask){
 #if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
-    return __builtin_popcount(mask);
+	return __builtin_ctz(mask);
 #else
-    int y;
-
-    y = (mask >> 1) & 033333333333;
-    y = mask - y - ((y >> 1) & 033333333333);
-    return (((y + (y >> 3)) & 030707070707) % 077);
+	int i = 0;
+	while((mask & 1) == 0){
+		i++;
+		mask >>= 1;
+	}
+	return i;
 #endif
 }
 
-
-unsigned int getshift(unsigned int mask){
-	return popcount((mask - 1) & ~mask) & 31;
-}
-
 void setaspect(int w, int h){
 	XSizeHints *hints = XAllocSizeHints();
 	hints->flags = PAspect;