1 files changed, 70 insertions, 0 deletions
diff --git a/deps/v8/src/math-random.cc b/deps/v8/src/math-random.cc
new file mode 100644
index 0000000000..932d4b9d2a
--- /dev/null
+++ b/deps/v8/src/math-random.cc
@@ -0,0 +1,70 @@
+// Copyright 2018 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/math-random.h"
+
+#include "src/assert-scope.h"
+#include "src/base/utils/random-number-generator.h"
+#include "src/contexts-inl.h"
+#include "src/isolate.h"
+#include "src/objects/fixed-array.h"
+
+namespace v8 {
+namespace internal {
+
+void MathRandom::InitializeContext(Isolate* isolate,
+                                   Handle<Context> native_context) {
+  Handle<FixedDoubleArray> cache = Handle<FixedDoubleArray>::cast(
+      isolate->factory()->NewFixedDoubleArray(kCacheSize, TENURED));
+  for (int i = 0; i < kCacheSize; i++) cache->set(i, 0);
+  native_context->set_math_random_cache(*cache);
+  Handle<PodArray<State>> pod = PodArray<State>::New(isolate, 1, TENURED);
+  native_context->set_math_random_state(*pod);
+  ResetContext(*native_context);
+}
+
+void MathRandom::ResetContext(Context* native_context) {
+  native_context->set_math_random_index(Smi::kZero);
+  State state = {0, 0};
+  PodArray<State>::cast(native_context->math_random_state())->set(0, state);
+}
+
+Smi* MathRandom::RefillCache(Isolate* isolate, Context* native_context) {
+  DisallowHeapAllocation no_gc;
+  PodArray<State>* pod =
+      PodArray<State>::cast(native_context->math_random_state());
+  State state = pod->get(0);
+  // Initialize state if not yet initialized. If a fixed random seed was
+  // requested, use it to reset our state the first time a script asks for
+  // random numbers in this context. This ensures the script sees a consistent
+  // sequence.
+  if (state.s0 == 0 && state.s1 == 0) {
+    uint64_t seed;
+    if (FLAG_random_seed != 0) {
+      seed = FLAG_random_seed;
+    } else {
+      isolate->random_number_generator()->NextBytes(&seed, sizeof(seed));
+    }
+    state.s0 = base::RandomNumberGenerator::MurmurHash3(seed);
+    state.s1 = base::RandomNumberGenerator::MurmurHash3(~seed);
+    CHECK(state.s0 != 0 || state.s1 != 0);
+  }
+
+  FixedDoubleArray* cache =
+      FixedDoubleArray::cast(native_context->math_random_cache());
+  // Create random numbers.
+  for (int i = 0; i < kCacheSize; i++) {
+    // Generate random numbers using xorshift128+.
+    base::RandomNumberGenerator::XorShift128(&state.s0, &state.s1);
+    cache->set(i, base::RandomNumberGenerator::ToDouble(state.s0));
+  }
+  pod->set(0, state);
+
+  Smi* new_index = Smi::FromInt(kCacheSize);
+  native_context->set_math_random_index(new_index);
+  return new_index;
+}
+
+}  // namespace internal
+}  // namespace v8