diff --git a/bitblt.c b/bitblt.c
index 0597d77..7862335 100644
--- a/bitblt.c
+++ b/bitblt.c
@@ -72,9 +72,7 @@ Bitmap *bitblt (Bitmap *src_bitmap,
 		Rect src_rect,
 		Bitmap *dest_bitmap,
 		Point dest_upper_left,
-		boolean flip_horizontal,
-		boolean flip_vertical,
-		boolean transpose,
+		int scan,
 		int tfn)
 {
   Point src_point, dest_point;
@@ -82,7 +80,7 @@ Bitmap *bitblt (Bitmap *src_bitmap,
 
   if (! dest_bitmap)
     {
-      if (transpose)
+      if (scan & TRANSPOSE)
 	dest_bitmap = create_bitmap (rect_height (src_rect),
 				     rect_width (src_rect));
       else
@@ -102,17 +100,32 @@ Bitmap *bitblt (Bitmap *src_bitmap,
 	{
 	  boolean a, b, c;
 
-	  if (transpose)
+	  if (scan & TRANSPOSE)
 	    {
-	      dest_point.x = dest_upper_left.x + (src_point.y - src_rect.upper_left.y);
-	      dest_point.y = dest_upper_left.y + (src_point.x - src_rect.upper_left.x);
+	      dest_point.x = src_point.y - src_rect.upper_left.y;
+	      dest_point.y = src_point.x - src_rect.upper_left.x;
+
+	      if (scan & FLIP_H)
+		dest_point.x = (rect_height (src_rect) - 1) - dest_point.x;
+
+	      if (scan & FLIP_V)
+		dest_point.y = (rect_width (src_rect) - 1) - dest_point.y;
 	    }
 	  else
 	    {
-	      dest_point.x = dest_upper_left.x + (src_point.x - src_rect.upper_left.x);
-	      dest_point.y = dest_upper_left.y + (src_point.y - src_rect.upper_left.y);
+	      dest_point.x = src_point.x - src_rect.upper_left.x;
+	      dest_point.y = src_point.y - src_rect.upper_left.y;
+
+	      if (scan & FLIP_H)
+		dest_point.x = (rect_width (src_rect) - 1) - dest_point.x;
+
+	      if (scan & FLIP_V)
+		dest_point.y = (rect_height (src_rect) - 1) - dest_point.y;
 	    }
 
+	  dest_point.x += dest_upper_left.x;
+	  dest_point.y += dest_upper_left.y;
+
 	  a = get_pixel (src_bitmap, src_point);
 	  b = get_pixel (dest_bitmap, dest_point);
 	  c = (tfn & (1 << (a * 2 + b))) != 0;
diff --git a/bitblt.h b/bitblt.h
index c19fece..dd87064 100644
--- a/bitblt.h
+++ b/bitblt.h
@@ -29,6 +29,16 @@ typedef struct Bitmap
 #define TF_XOR 0x6
 
 
+#define FLIP_H    0x1
+#define FLIP_V    0x2
+#define TRANSPOSE 0x4
+
+#define ROT_0     0x0
+#define ROT_90    (TRANSPOSE + FLIP_H)
+#define ROT_180   (FLIP_H + FLIP_V)
+#define ROT_270   (TRANSPOSE + FLIP_V)
+
+
 Bitmap *create_bitmap (u32 width, u32 height);
 void free_bitmap (Bitmap *bitmap);
 boolean get_pixel (Bitmap *bitmap, Point coord);
@@ -38,7 +48,5 @@ Bitmap *bitblt (Bitmap *src_bitmap,
 		Rect src_rect,
 		Bitmap *dest_bitmap,
 		Point dest_upper_left,
-		boolean flip_horizontal,
-		boolean flip_vertical,
-		boolean transpose,
+		int scan,
 		int tfn);
diff --git a/bitblt_test.c b/bitblt_test.c
index 3653d43..a2f4213 100644
--- a/bitblt_test.c
+++ b/bitblt_test.c
@@ -16,7 +16,7 @@ char test_data [HEIGHT][WIDTH] =
   ".....X....X...X.....",
   ".....X.....X..X.....",
   ".....XXXXXXXXXX.....",
-  ".....XXXXXXXXXX....."
+  ".....X.X.X.X.X......"
 };
 
 Bitmap *setup (void)
@@ -82,8 +82,7 @@ int main (int argc, char *argv[])
 
   b2 = bitblt (b, r,
 	       NULL, p,
-	       0, 0, 
-	       1,  /* transpose */
+	       ROT_90,
 	       TF_SRC);
   if (! b2)
     {