Update from chromium 62675d9fb31fb8cedc40f68e78e8445a74f362e7

tools/relocation_packer/src/leb128.cc

+// Copyright 2014 The Chromium 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 "leb128.h"
+
+#include <stdint.h>
+#include <vector>
+
+#include "elf_traits.h"
+
+namespace relocation_packer {
+
+// Empty constructor and destructor to silence chromium-style.
+Leb128Encoder::Leb128Encoder() { }
+Leb128Encoder::~Leb128Encoder() { }
+
+// Add a single value to the encoding.  Values are encoded with variable
+// length.  The least significant 7 bits of each byte hold 7 bits of data,
+// and the most significant bit is set on each byte except the last.
+void Leb128Encoder::Enqueue(ELF::Xword value) {
+  do {
+    const uint8_t byte = value & 127;
+    value >>= 7;
+    encoding_.push_back((value ? 128 : 0) | byte);
+  } while (value);
+}
+
+// Add a vector of values to the encoding.
+void Leb128Encoder::EnqueueAll(const std::vector<ELF::Xword>& values) {
+  for (size_t i = 0; i < values.size(); ++i)
+    Enqueue(values[i]);
+}
+
+// Create a new decoder for the given encoded stream.
+Leb128Decoder::Leb128Decoder(const std::vector<uint8_t>& encoding) {
+  encoding_ = encoding;
+  cursor_ = 0;
+}
+
+// Empty destructor to silence chromium-style.
+Leb128Decoder::~Leb128Decoder() { }
+
+// Decode and retrieve a single value from the encoding.  Read forwards until
+// a byte without its most significant bit is found, then read the 7 bit
+// fields of the bytes spanned to re-form the value.
+ELF::Xword Leb128Decoder::Dequeue() {
+  ELF::Xword value = 0;
+
+  size_t shift = 0;
+  uint8_t byte;
+
+  // Loop until we reach a byte with its high order bit clear.
+  do {
+    byte = encoding_[cursor_++];
+    value |= static_cast<ELF::Xword>(byte & 127) << shift;
+    shift += 7;
+  } while (byte & 128);
+
+  return value;
+}
+
+// Decode and retrieve all remaining values from the encoding.
+void Leb128Decoder::DequeueAll(std::vector<ELF::Xword>* values) {
+  while (cursor_ < encoding_.size())
+    values->push_back(Dequeue());
+}
+
+}  // namespace relocation_packer