1 files changed, 109 insertions, 0 deletions
diff --git a/xpcom/ds/nsMathUtils.h b/xpcom/ds/nsMathUtils.h
new file mode 100644
index 0000000000..527e0c3eb2
--- /dev/null
+++ b/xpcom/ds/nsMathUtils.h
@@ -0,0 +1,109 @@
+/* -*- 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 nsMathUtils_h__
+#define nsMathUtils_h__
+
+#include "nscore.h"
+#include <cmath>
+#include <float.h>
+
+#if defined(XP_SOLARIS)
+#  include <ieeefp.h>
+#endif
+
+/*
+ * round
+ */
+inline double NS_round(double aNum) {
+  return aNum >= 0.0 ? floor(aNum + 0.5) : ceil(aNum - 0.5);
+}
+inline float NS_roundf(float aNum) {
+  return aNum >= 0.0f ? floorf(aNum + 0.5f) : ceilf(aNum - 0.5f);
+}
+inline int32_t NS_lround(double aNum) {
+  return aNum >= 0.0 ? int32_t(aNum + 0.5) : int32_t(aNum - 0.5);
+}
+
+/* NS_roundup30 rounds towards infinity for positive and       */
+/* negative numbers.                                           */
+
+#if defined(XP_WIN) && defined(_M_IX86) && !defined(__GNUC__) && \
+    !defined(__clang__)
+inline int32_t NS_lroundup30(float x) {
+  /* Code derived from Laurent de Soras' paper at             */
+  /* http://ldesoras.free.fr/doc/articles/rounding_en.pdf     */
+
+  /* Rounding up on Windows is expensive using the float to   */
+  /* int conversion and the floor function. A faster          */
+  /* approach is to use f87 rounding while assuming the       */
+  /* default rounding mode of rounding to the nearest         */
+  /* integer. This rounding mode, however, actually rounds    */
+  /* to the nearest integer so we add the floating point      */
+  /* number to itself and add our rounding factor before      */
+  /* doing the conversion to an integer. We then do a right   */
+  /* shift of one bit on the integer to divide by two.        */
+
+  /* This routine doesn't handle numbers larger in magnitude  */
+  /* than 2^30 but this is fine for NSToCoordRound because    */
+  /* Coords are limited to 2^30 in magnitude.                 */
+
+  static const double round_to_nearest = 0.5f;
+  int i;
+
+  __asm {
+    fld     x                   ; load fp argument
+    fadd    st, st(0)           ; double it
+    fadd    round_to_nearest    ; add the rounding factor
+    fistp   dword ptr i         ; convert the result to int
+  }
+  return i >> 1; /* divide by 2 */
+}
+#endif /* XP_WIN && _M_IX86 && !__GNUC__ */
+
+inline int32_t NS_lroundf(float aNum) {
+  return aNum >= 0.0f ? int32_t(aNum + 0.5f) : int32_t(aNum - 0.5f);
+}
+
+/*
+ * hypot.  We don't need a super accurate version of this, if a platform
+ * turns up with none of the possibilities below it would be okay to fall
+ * back to sqrt(x*x + y*y).
+ */
+inline double NS_hypot(double aNum1, double aNum2) {
+#ifdef __GNUC__
+  return __builtin_hypot(aNum1, aNum2);
+#elif defined _WIN32
+  return _hypot(aNum1, aNum2);
+#else
+  return hypot(aNum1, aNum2);
+#endif
+}
+
+/**
+ * Check whether a floating point number is finite (not +/-infinity and not a
+ * NaN value).
+ */
+inline bool NS_finite(double aNum) {
+#ifdef WIN32
+  // NOTE: '!!' casts an int to bool without spamming MSVC warning C4800.
+  return !!_finite(aNum);
+#else
+  return std::isfinite(aNum);
+#endif
+}
+
+/**
+ * Returns the result of the modulo of x by y using a floored division.
+ * fmod(x, y) is using a truncated division.
+ * The main difference is that the result of this method will have the sign of
+ * y while the result of fmod(x, y) will have the sign of x.
+ */
+inline double NS_floorModulo(double aNum1, double aNum2) {
+  return (aNum1 - aNum2 * floor(aNum1 / aNum2));
+}
+
+#endif