add SkFixedFloorToFixed



git-svn-id: http://skia.googlecode.com/svn/trunk@1524 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/include/core/SkFixed.h b/include/core/SkFixed.h
index c58c6de..8b56c50 100644
--- a/include/core/SkFixed.h
+++ b/include/core/SkFixed.h
@@ -111,6 +111,9 @@
 #define SkFixedAbs(x)       SkAbs32(x)
 #define SkFixedAve(a, b)    (((a) + (b)) >> 1)
 
+// The same as SkIntToFixed(SkFixedFloor(x))
+#define SkFixedFloorToFixed(x)  ((x) & ~0xFFFF)
+
 SkFixed SkFixedMul_portable(SkFixed, SkFixed);
 SkFract SkFractMul_portable(SkFract, SkFract);
 inline SkFixed SkFixedSquare_portable(SkFixed value)