diff -r 000000000000 -r 6474c204b198 ipc/chromium/src/base/rand_util.cc --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/ipc/chromium/src/base/rand_util.cc Wed Dec 31 06:09:35 2014 +0100 @@ -0,0 +1,40 @@ +// 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 + +#include + +#include "base/basictypes.h" +#include "base/logging.h" + +namespace base { + +int RandInt(int min, int max) { + DCHECK(min <= max); + + uint64_t range = static_cast(max) - min + 1; + uint64_t number = base::RandUint64(); + int result = min + static_cast(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::radix == 2, otherwise_use_scalbn); + static const int kBits = std::numeric_limits::digits; + uint64_t random_bits = base::RandUint64() & ((GG_UINT64_C(1) << kBits) - 1); + double result = ldexp(static_cast(random_bits), -1 * kBits); + DCHECK(result >= 0.0 && result < 1.0); + return result; +} + +} // namespace base