Use more accurate fz_mul255.

1 files changed, 6 insertions, 1 deletions

diff --git a/fitz/fitz_base.h b/fitz/fitz_base.h
index 9ef1cf46..293b0cc5 100644
--- a/fitz/fitz_base.h
+++ b/fitz/fitz_base.h
@@ -182,7 +182,12 @@ void *fz_hashgetval(fz_hashtable *table, int idx);
  */
 
 /* multiply 8-bit fixpoint (0..1) so that 0*0==0 and 255*255==255 */
-#define fz_mul255(a,b) (((a) * ((b) + ((b) >> 7))) >> 8)
+static inline int fz_mul255(int a, int b)
+{
+	int x = a * b + 0x80;
+	x += x >> 8;
+	return x >> 8;
+}
 
 typedef struct fz_matrix_s fz_matrix;
 typedef struct fz_point_s fz_point;