Support external startup data in V8.

src/snapshot-source-sink.cc

+// 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 "snapshot-source-sink.h"
+
+#include "serialize.h"  // for SerializerDeserializer::nop() in AtEOF()
+
+namespace v8 {
+namespace internal {
+
+
+SnapshotByteSource::SnapshotByteSource(const byte* array, int length)
+    : data_(array), length_(length), position_(0) {
+}
+
+
+SnapshotByteSource::~SnapshotByteSource() { }
+
+
+int32_t SnapshotByteSource::GetUnalignedInt() {
+  ASSERT(position_ < length_);  // Require at least one byte left.
+#if defined(V8_HOST_CAN_READ_UNALIGNED) &&  __BYTE_ORDER == __LITTLE_ENDIAN
+  int32_t answer = *reinterpret_cast<const int32_t*>(data_ + position_);
+#else
+  int32_t answer = data_[position_];
+  answer |= data_[position_ + 1] << 8;
+  answer |= data_[position_ + 2] << 16;
+  answer |= data_[position_ + 3] << 24;
+#endif
+  return answer;
+}
+
+
+void SnapshotByteSource::CopyRaw(byte* to, int number_of_bytes) {
+  OS::MemCopy(to, data_ + position_, number_of_bytes);
+  position_ += number_of_bytes;
+}
+
+
+void SnapshotByteSink::PutInt(uintptr_t integer, const char* description) {
+  ASSERT(integer < 1 << 22);
+  integer <<= 2;
+  int bytes = 1;
+  if (integer > 0xff) bytes = 2;
+  if (integer > 0xffff) bytes = 3;
+  integer |= bytes;
+  Put(static_cast<int>(integer & 0xff), "IntPart1");
+  if (bytes > 1) Put(static_cast<int>((integer >> 8) & 0xff), "IntPart2");
+  if (bytes > 2) Put(static_cast<int>((integer >> 16) & 0xff), "IntPart3");
+}
+
+void SnapshotByteSink::PutRaw(byte* data, int number_of_bytes,
+                              const char* description) {
+  for (int i = 0; i < number_of_bytes; ++i) {
+    Put(data[i], description);
+  }
+}
+
+void SnapshotByteSink::PutBlob(byte* data, int number_of_bytes,
+                               const char* description) {
+  PutInt(number_of_bytes, description);
+  PutRaw(data, number_of_bytes, description);
+}
+
+
+bool SnapshotByteSource::AtEOF() {
+  if (0u + length_ - position_ > 2 * sizeof(uint32_t)) return false;
+  for (int x = position_; x < length_; x++) {
+    if (data_[x] != SerializerDeserializer::nop()) return false;
+  }
+  return true;
+}
+
+
+bool SnapshotByteSource::GetBlob(const byte** data, int* number_of_bytes) {
+  int size = GetInt();
+  *number_of_bytes = size;
+
+  if (position_ + size < length_) {
+    *data = &data_[position_];
+    Advance(size);
+    return true;
+  } else {
+    Advance(length_ - position_);  // proceed until end.
+    return false;
+  }
+}
+
+}  // namespace v8::internal
+}  // namespace v8