The Tor Browser: ipc/chromium/src/base/rand_util.cc@b8a032363ba2 (annotated)

ipc/chromium/src/base/rand_util.cc@b8a032363ba2 (annotated)

Thu, 22 Jan 2015 13:21:57 +0100

Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6

 // 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