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// Copyright 2014 the V8 project 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 "src/runtime/runtime-utils.h"
#include "src/arguments.h"
#include "src/assembler.h"
#include "src/base/utils/random-number-generator.h"
#include "src/bootstrapper.h"
#include "src/codegen.h"
#include "src/counters.h"
#include "src/double.h"
#include "src/objects-inl.h"
namespace v8 {
namespace internal {
RUNTIME_FUNCTION(Runtime_GenerateRandomNumbers) {
HandleScope scope(isolate);
DCHECK_EQ(0, args.length());
Handle<Context> native_context = isolate->native_context();
DCHECK_EQ(0, native_context->math_random_index()->value());
static const int kCacheSize = 64;
static const int kState0Offset = kCacheSize - 1;
static const int kState1Offset = kState0Offset - 1;
// The index is decremented before used to access the cache.
static const int kInitialIndex = kState1Offset;
Handle<FixedDoubleArray> cache;
uint64_t state0 = 0;
uint64_t state1 = 0;
if (native_context->math_random_cache()->IsFixedDoubleArray()) {
cache = Handle<FixedDoubleArray>(
FixedDoubleArray::cast(native_context->math_random_cache()), isolate);
state0 = double_to_uint64(cache->get_scalar(kState0Offset));
state1 = double_to_uint64(cache->get_scalar(kState1Offset));
} else {
cache = Handle<FixedDoubleArray>::cast(
isolate->factory()->NewFixedDoubleArray(kCacheSize, TENURED));
native_context->set_math_random_cache(*cache);
// Initialize state if not yet initialized.
while (state0 == 0 || state1 == 0) {
isolate->random_number_generator()->NextBytes(&state0, sizeof(state0));
isolate->random_number_generator()->NextBytes(&state1, sizeof(state1));
}
}
DisallowHeapAllocation no_gc;
FixedDoubleArray* raw_cache = *cache;
// Create random numbers.
for (int i = 0; i < kInitialIndex; i++) {
// Generate random numbers using xorshift128+.
base::RandomNumberGenerator::XorShift128(&state0, &state1);
raw_cache->set(i, base::RandomNumberGenerator::ToDouble(state0, state1));
}
// Persist current state.
raw_cache->set(kState0Offset, uint64_to_double(state0));
raw_cache->set(kState1Offset, uint64_to_double(state1));
return Smi::FromInt(kInitialIndex);
}
} // namespace internal
} // namespace v8
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