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author | Matt A. Tobin <mattatobin@localhost.localdomain> | 2018-02-02 04:16:08 -0500 |
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committer | Matt A. Tobin <mattatobin@localhost.localdomain> | 2018-02-02 04:16:08 -0500 |
commit | 5f8de423f190bbb79a62f804151bc24824fa32d8 (patch) | |
tree | 10027f336435511475e392454359edea8e25895d /ipc/chromium/src/base/rand_util.cc | |
parent | 49ee0794b5d912db1f95dce6eb52d781dc210db5 (diff) | |
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Add m-esr52 at 52.6.0
Diffstat (limited to 'ipc/chromium/src/base/rand_util.cc')
-rw-r--r-- | ipc/chromium/src/base/rand_util.cc | 42 |
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 |