RSHIFT(x,0) fix

git-svn-id: file:///var/local/repositories/ffmpeg/trunk@3041 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b

libavcodec/common.h

@@ -227,7 +227,7 @@ inline void dprintf(const char* fmt,...) {}
 #    define av_abort()      do { av_log(NULL, AV_LOG_ERROR, "Abort at %s:%d\n", __FILE__, __LINE__); abort(); } while (0)
 
 //rounded divison & shift
-#define RSHIFT(a,b) ((a) > 0 ? ((a) + (1<<((b)-1)))>>(b) : ((a) + (1<<((b)-1))-1)>>(b))
+#define RSHIFT(a,b) ((a) > 0 ? ((a) + ((1<<(b))>>1))>>(b) : ((a) + ((1<<(b))>>1)-1)>>(b))
 /* assume b>0 */
 #define ROUNDED_DIV(a,b) (((a)>0 ? (a) + ((b)>>1) : (a) - ((b)>>1))/(b))
 #define ABS(a) ((a) >= 0 ? (a) : (-(a)))