1 files changed, 42 insertions, 0 deletions
diff --git a/ipc/chromium/src/base/rand_util.cc b/ipc/chromium/src/base/rand_util.cc
new file mode 100644
index 000000000..912978616
--- /dev/null
+++ b/ipc/chromium/src/base/rand_util.cc
@@ -0,0 +1,42 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+// Copyright (c) 2008 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/rand_util.h"
+
+#include <math.h>
+
+#include <limits>
+
+#include "base/basictypes.h"
+#include "base/logging.h"
+
+namespace base {
+
+int RandInt(int min, int max) {
+  DCHECK(min <= max);
+
+  uint64_t range = static_cast<int64_t>(max) - min + 1;
+  uint64_t number = base::RandUint64();
+  int result = min + static_cast<int>(number % range);
+  DCHECK(result >= min && result <= max);
+  return result;
+}
+
+double RandDouble() {
+  // We try to get maximum precision by masking out as many bits as will fit
+  // in the target type's mantissa, and raising it to an appropriate power to
+  // produce output in the range [0, 1).  For IEEE 754 doubles, the mantissa
+  // is expected to accommodate 53 bits.
+
+  COMPILE_ASSERT(std::numeric_limits<double>::radix == 2, otherwise_use_scalbn);
+  static const int kBits = std::numeric_limits<double>::digits;
+  uint64_t random_bits = base::RandUint64() & ((GG_UINT64_C(1) << kBits) - 1);
+  double result = ldexp(static_cast<double>(random_bits), -1 * kBits);
+  DCHECK(result >= 0.0 && result < 1.0);
+  return result;
+}
+
+}  // namespace base