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Issue 10767: RandUInt -> RandUint to match the style of other Uint functions. (Closed) Base URL: svn://chrome-svn/chrome/trunk/src/
Patch Set: Created 12 years, 1 month ago
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1 // Copyright (c) 2008 The Chromium Authors. All rights reserved. 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 2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file. 3 // found in the LICENSE file.
4 4
5 #include "base/rand_util.h" 5 #include "base/rand_util.h"
6 6
7 #include <math.h> 7 #include <math.h>
8 8
9 #include <limits> 9 #include <limits>
10 10
11 #include "base/basictypes.h" 11 #include "base/basictypes.h"
12 #include "base/logging.h" 12 #include "base/logging.h"
13 13
14 namespace base { 14 namespace base {
15 15
16 int RandInt(int min, int max) { 16 int RandInt(int min, int max) {
17 DCHECK(min <= max); 17 DCHECK(min <= max);
18 18
19 uint64 range = static_cast<int64>(max) - min + 1; 19 uint64 range = static_cast<int64>(max) - min + 1;
20 uint64 number = base::RandUInt64(); 20 uint64 number = base::RandUint64();
21 int result = min + static_cast<int>(number % range); 21 int result = min + static_cast<int>(number % range);
22 DCHECK(result >= min && result <= max); 22 DCHECK(result >= min && result <= max);
23 return result; 23 return result;
24 } 24 }
25 25
26 double RandDouble() { 26 double RandDouble() {
27 // We try to get maximum precision by masking out as many bits as will fit 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 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 29 // produce output in the range [0, 1). For IEEE 754 doubles, the mantissa
30 // is expected to accommodate 53 bits. 30 // is expected to accommodate 53 bits.
31 31
32 COMPILE_ASSERT(std::numeric_limits<double>::radix == 2, otherwise_use_scalbn); 32 COMPILE_ASSERT(std::numeric_limits<double>::radix == 2, otherwise_use_scalbn);
33 static const int kBits = std::numeric_limits<double>::digits; 33 static const int kBits = std::numeric_limits<double>::digits;
34 uint64 random_bits = base::RandUInt64() & ((GG_UINT64_C(1) << kBits) - 1); 34 uint64 random_bits = base::RandUint64() & ((GG_UINT64_C(1) << kBits) - 1);
35 double result = ldexp(static_cast<double>(random_bits), -1 * kBits); 35 double result = ldexp(static_cast<double>(random_bits), -1 * kBits);
36 DCHECK(result >= 0.0 && result < 1.0); 36 DCHECK(result >= 0.0 && result < 1.0);
37 return result; 37 return result;
38 } 38 }
39 39
40 } // namespace base 40 } // namespace base
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