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1 // Copyright 2013 the V8 project authors. All rights reserved. | 1 // Copyright 2013 the V8 project 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 "src/utils/random-number-generator.h" | 5 #include "src/utils/random-number-generator.h" |
6 | 6 |
7 #include <stdio.h> | 7 #include <stdio.h> |
8 #include <stdlib.h> | 8 #include <stdlib.h> |
9 | 9 |
10 #include "src/flags.h" | 10 #include <new> |
| 11 |
| 12 #include "src/base/macros.h" |
11 #include "src/platform/mutex.h" | 13 #include "src/platform/mutex.h" |
12 #include "src/platform/time.h" | 14 #include "src/platform/time.h" |
13 #include "src/utils.h" | |
14 | 15 |
15 namespace v8 { | 16 namespace v8 { |
16 namespace internal { | 17 namespace internal { |
17 | 18 |
18 static LazyMutex entropy_mutex = LAZY_MUTEX_INITIALIZER; | 19 static LazyMutex entropy_mutex = LAZY_MUTEX_INITIALIZER; |
19 static RandomNumberGenerator::EntropySource entropy_source = NULL; | 20 static RandomNumberGenerator::EntropySource entropy_source = NULL; |
20 | 21 |
21 | 22 |
22 // static | 23 // static |
23 void RandomNumberGenerator::SetEntropySource(EntropySource source) { | 24 void RandomNumberGenerator::SetEntropySource(EntropySource source) { |
24 LockGuard<Mutex> lock_guard(entropy_mutex.Pointer()); | 25 LockGuard<Mutex> lock_guard(entropy_mutex.Pointer()); |
25 entropy_source = source; | 26 entropy_source = source; |
26 } | 27 } |
27 | 28 |
28 | 29 |
29 RandomNumberGenerator::RandomNumberGenerator() { | 30 RandomNumberGenerator::RandomNumberGenerator() { |
30 // Check --random-seed flag first. | |
31 if (FLAG_random_seed != 0) { | |
32 SetSeed(FLAG_random_seed); | |
33 return; | |
34 } | |
35 | |
36 // Check if embedder supplied an entropy source. | 31 // Check if embedder supplied an entropy source. |
37 { LockGuard<Mutex> lock_guard(entropy_mutex.Pointer()); | 32 { LockGuard<Mutex> lock_guard(entropy_mutex.Pointer()); |
38 if (entropy_source != NULL) { | 33 if (entropy_source != NULL) { |
39 int64_t seed; | 34 int64_t seed; |
40 if (entropy_source(reinterpret_cast<unsigned char*>(&seed), | 35 if (entropy_source(reinterpret_cast<unsigned char*>(&seed), |
41 sizeof(seed))) { | 36 sizeof(seed))) { |
42 SetSeed(seed); | 37 SetSeed(seed); |
43 return; | 38 return; |
44 } | 39 } |
45 } | 40 } |
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80 seed ^= TimeTicks::Now().ToInternalValue() << 8; | 75 seed ^= TimeTicks::Now().ToInternalValue() << 8; |
81 SetSeed(seed); | 76 SetSeed(seed); |
82 #endif // V8_OS_CYGWIN || V8_OS_WIN | 77 #endif // V8_OS_CYGWIN || V8_OS_WIN |
83 } | 78 } |
84 | 79 |
85 | 80 |
86 int RandomNumberGenerator::NextInt(int max) { | 81 int RandomNumberGenerator::NextInt(int max) { |
87 ASSERT_LE(0, max); | 82 ASSERT_LE(0, max); |
88 | 83 |
89 // Fast path if max is a power of 2. | 84 // Fast path if max is a power of 2. |
90 if (IsPowerOf2(max)) { | 85 if (IS_POWER_OF_TWO(max)) { |
91 return static_cast<int>((max * static_cast<int64_t>(Next(31))) >> 31); | 86 return static_cast<int>((max * static_cast<int64_t>(Next(31))) >> 31); |
92 } | 87 } |
93 | 88 |
94 while (true) { | 89 while (true) { |
95 int rnd = Next(31); | 90 int rnd = Next(31); |
96 int val = rnd % max; | 91 int val = rnd % max; |
97 if (rnd - val + (max - 1) >= 0) { | 92 if (rnd - val + (max - 1) >= 0) { |
98 return val; | 93 return val; |
99 } | 94 } |
100 } | 95 } |
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127 seed_ = seed; | 122 seed_ = seed; |
128 return static_cast<int>(seed >> (48 - bits)); | 123 return static_cast<int>(seed >> (48 - bits)); |
129 } | 124 } |
130 | 125 |
131 | 126 |
132 void RandomNumberGenerator::SetSeed(int64_t seed) { | 127 void RandomNumberGenerator::SetSeed(int64_t seed) { |
133 seed_ = (seed ^ kMultiplier) & kMask; | 128 seed_ = (seed ^ kMultiplier) & kMask; |
134 } | 129 } |
135 | 130 |
136 } } // namespace v8::internal | 131 } } // namespace v8::internal |
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