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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 } |
| (...skipping 34 matching lines...) Expand 10 before | Expand all | Expand 10 after Loading... |
| 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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