1 files changed, 46 insertions, 0 deletions
diff --git a/gfx/2d/NumericTools.h b/gfx/2d/NumericTools.h
new file mode 100644
index 0000000000..d60cf1cc8d
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+++ b/gfx/2d/NumericTools.h
@@ -0,0 +1,46 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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_
+
+#include <cstdint>
+
+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;
+}
+
+inline int32_t RoundToMultiple(int32_t x, int32_t aMultiplier) {
+  return RoundDownToMultiple(x + aMultiplier / 2, aMultiplier);
+}
+
+}  // namespace mozilla
+
+#endif /* MOZILLA_GFX_NUMERICTOOLS_H_ */