Add SkDivMod with a special case for ARM.

src/core/SkBitmap.cpp

Index: src/core/SkBitmap.cpp
diff --git a/src/core/SkBitmap.cpp b/src/core/SkBitmap.cpp
index d3bbecd7066dfe4d826d5bd778e635c1e5215910..446926fde4b9827f82b689519aba3d4518093c50 100644
--- a/src/core/SkBitmap.cpp
+++ b/src/core/SkBitmap.cpp
@@ -911,9 +911,11 @@ bool get_upper_left_from_offset(SkBitmap::Config config, size_t offset, size_t r
         return true;
     }
     // Use integer division to find the correct y position.
-    *y = SkToS32(offset / rowBytes);
     // The remainder will be the x position, after we reverse get_sub_offset.
-    *x = SkToS32(offset % rowBytes);
+    size_t xSizeT, ySizeT;

[reed1, 2013/09/20 19:02:39]

do we really need to have two local vars to call this? :(
If we had SkDivMod32() hard coded to int32_t, could we avoid this?

[mtklein, 2013/09/20 19:29:35]

We could, but that'd force offset and rowBytes to cast down.

How do you feel about this version, which allows the inputs and outputs to be
different types?

+    SkDivMod(offset, rowBytes, &ySizeT, &xSizeT);
+    *y = SkToS32(ySizeT);
+    *x = SkToS32(xSizeT);
     switch (config) {
         case SkBitmap::kA8_Config:
             // Fall through.