LCOV - code coverage report
Current view: directory - ipc/chromium/src/base - rand_util.cc (source / functions) Found Hit Coverage
Test: app.info Lines: 12 0 0.0 %
Date: 2012-06-02 Functions: 2 0 0.0 %

       1                 : // Copyright (c) 2008 The Chromium Authors. All rights reserved.
       2                 : // Use of this source code is governed by a BSD-style license that can be
       3                 : // found in the LICENSE file.
       4                 : 
       5                 : #include "base/rand_util.h"
       6                 : 
       7                 : #include <math.h>
       8                 : 
       9                 : #include <limits>
      10                 : 
      11                 : #include "base/basictypes.h"
      12                 : #include "base/logging.h"
      13                 : 
      14                 : namespace base {
      15                 : 
      16               0 : int RandInt(int min, int max) {
      17               0 :   DCHECK(min <= max);
      18                 : 
      19               0 :   uint64 range = static_cast<int64>(max) - min + 1;
      20               0 :   uint64 number = base::RandUint64();
      21               0 :   int result = min + static_cast<int>(number % range);
      22               0 :   DCHECK(result >= min && result <= max);
      23               0 :   return result;
      24                 : }
      25                 : 
      26               0 : double RandDouble() {
      27                 :   // We try to get maximum precision by masking out as many bits as will fit
      28                 :   // in the target type's mantissa, and raising it to an appropriate power to
      29                 :   // produce output in the range [0, 1).  For IEEE 754 doubles, the mantissa
      30                 :   // is expected to accommodate 53 bits.
      31                 : 
      32                 :   COMPILE_ASSERT(std::numeric_limits<double>::radix == 2, otherwise_use_scalbn);
      33                 :   static const int kBits = std::numeric_limits<double>::digits;
      34               0 :   uint64 random_bits = base::RandUint64() & ((GG_UINT64_C(1) << kBits) - 1);
      35               0 :   double result = ldexp(static_cast<double>(random_bits), -1 * kBits);
      36               0 :   DCHECK(result >= 0.0 && result < 1.0);
      37               0 :   return result;
      38                 : }
      39                 : 
      40                 : }  // namespace base

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