1 files changed, 43 insertions, 0 deletions
diff --git a/gfx/2d/NumericTools.h b/gfx/2d/NumericTools.h
new file mode 100644
index 000000000..03aa7a8e2
--- /dev/null
+++ b/gfx/2d/NumericTools.h
@@ -0,0 +1,43 @@
+/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef MOZILLA_GFX_NUMERICTOOLS_H_
+#define MOZILLA_GFX_NUMERICTOOLS_H_
+
+namespace mozilla {
+
+// XXX - Move these into mfbt/MathAlgorithms.h?
+
+// Returns the largest multiple of aMultiplied that's <= x.
+// Same as int32_t(floor(double(x) / aMultiplier)) * aMultiplier,
+// but faster.
+inline int32_t
+RoundDownToMultiple(int32_t x, int32_t aMultiplier)
+{
+  // We don't use float division + floor because that's hard for the compiler
+  // to optimize.
+  int mod = x % aMultiplier;
+  if (x > 0) {
+    return x - mod;
+  }
+  return mod ? x - aMultiplier - mod : x;
+}
+
+// Returns the smallest multiple of aMultiplied that's >= x.
+// Same as int32_t(ceil(double(x) / aMultiplier)) * aMultiplier,
+// but faster.
+inline int32_t
+RoundUpToMultiple(int32_t x, int32_t aMultiplier)
+{
+  int mod = x % aMultiplier;
+  if (x > 0) {
+    return mod ? x + aMultiplier - mod : x;
+  }
+  return x - mod;
+}
+
+} // namespace mozilla
+
+#endif /* MOZILLA_GFX_NUMERICTOOLS_H_ */