Factor out, simplify and document clipping.

[bertos.git] / gfx / gfx_p.h

diff --git a/gfx/gfx_p.h b/gfx/gfx_p.h
index 5b483ab1db659bd868689da578c39755eb96a3e6..a599a8aa9ca8b903a58df4f2b3cd8f09f02abf70 100755 (executable)
--- a/gfx/gfx_p.h
+++ b/gfx/gfx_p.h
@@ -15,6 +15,9 @@
 
 /*#*
  *#* $Log$
+ *#* Revision 1.6  2006/05/27 17:17:34  bernie
+ *#* Optimize away divisions in RAST_ADDR/MASK macros.
+ *#*
  *#* Revision 1.5  2006/05/25 23:35:40  bernie
  *#* Cleanup.
  *#*
@@ -35,16 +38,23 @@
 #ifndef GFX_GFX_P_H
 #define GFX_GFX_P_H
 
+#include <gfx/gfx.h>
 
 #if CONFIG_BITMAP_FMT == BITMAP_FMT_PLANAR_H_MSB
 
-       #define RAST_ADDR(raster, x, y, stride)  ((raster) + (y) * (stride) + (x) / 8)
-       #define RAST_MASK(raster, x, y)          (1 << (7 - (x) % 8))
+       /* We use ucoord_t to let the compiler optimize away the division/modulo. */
+       #define RAST_ADDR(raster, x, y, stride) \
+                       ((raster) + (ucoord_t)(y) * (ucoord_t)(stride) + (ucoord_t)(x) / 8)
+       #define RAST_MASK(raster, x, y) \
+                       (1 << (7 - (ucoord_t)(x) % 8))
 
 #elif CONFIG_BITMAP_FMT == BITMAP_FMT_PLANAR_V_LSB
 
-       #define RAST_ADDR(raster, x, y, stride)  ((raster) + ((y) / 8) * (stride) + (x))
-       #define RAST_MASK(raster, x, y)          (1 << ((y) % 8))
+       /* We use ucoord_t to let the compiler optimize away the division/modulo. */
+       #define RAST_ADDR(raster, x, y, stride) \
+                       ((raster) + ((ucoord_t)(y) / 8) * (ucoord_t)(stride) + (ucoord_t)(x))
+       #define RAST_MASK(raster, x, y) \
+                       (1 << ((ucoord_t)(y) % 8))
 
 #else
        #error Unknown value of CONFIG_BITMAP_FMT