1 files changed, 53 insertions, 0 deletions
diff --git a/js/src/jslibmath.h b/js/src/jslibmath.h
new file mode 100644
index 0000000000..5c6416ef36
--- /dev/null
+++ b/js/src/jslibmath.h
@@ -0,0 +1,53 @@
+/* -*- 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 jslibmath_h
+#define jslibmath_h
+
+#include "mozilla/FloatingPoint.h"
+
+#include <math.h>
+
+#include "js/Value.h"
+#include "vm/JSContext.h"
+
+namespace js {
+
+inline double NumberDiv(double a, double b) {
+  AutoUnsafeCallWithABI unsafe;
+  if (b == 0) {
+    if (a == 0 || std::isnan(a)) {
+      return JS::GenericNaN();
+    }
+    if (mozilla::IsNegative(a) != mozilla::IsNegative(b)) {
+      return mozilla::NegativeInfinity<double>();
+    }
+    return mozilla::PositiveInfinity<double>();
+  }
+
+  return a / b;
+}
+
+inline double NumberMod(double a, double b) {
+  AutoUnsafeCallWithABI unsafe;
+  if (b == 0) {
+    return JS::GenericNaN();
+  }
+  double r = fmod(a, b);
+#if defined(XP_WIN)
+  // Some versions of Windows (Win 10 v1803, v1809) miscompute the sign of zero
+  // results from fmod. The sign should match the sign of the LHS. This bug
+  // only affects 64-bit builds. See bug 1527007.
+  if (mozilla::IsPositiveZero(r) && mozilla::IsNegative(a)) {
+    return -0.0;
+  }
+#endif
+  return r;
+}
+
+}  // namespace js
+
+#endif /* jslibmath_h */