Add a host tool to pack R_ARM_RELATIVE relocations in libchrome.<ver>.so.

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.
+
+// TODO(simonb): Extend for 64-bit target libraries.
+
+#include "leb128.h"
+
+#include <stdint.h>
+#include <vector>
+
+namespace relocation_packer {
+
+// 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(uint32_t value) {
+  while (value > 127) {
+    encoding_.push_back((1 << 7) | (value & 127));
+    value >>= 7;
+  }
+  encoding_.push_back(value);
+}
+
+// Add a vector of values to the encoding.
+void Leb128Encoder::EnqueueAll(const std::vector<uint32_t>& values) {
+  for (size_t i = 0; i < values.size(); ++i)
+    Enqueue(values[i]);
+}
+
+// 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.
+uint32_t Leb128Decoder::Dequeue() {
+  size_t extent = cursor_;
+  while (encoding_[extent] >> 7)
+    extent++;
+
+  uint32_t value = 0;
+  for (size_t i = extent; i > cursor_; --i) {
+    value = (value << 7) | (encoding_[i] & 127);
+  }
+  value = (value << 7) | (encoding_[cursor_] & 127);
+
+  cursor_ = extent + 1;
+  return value;
+}
+
+// Decode and retrieve all remaining values from the encoding.
+void Leb128Decoder::DequeueAll(std::vector<uint32_t>* values) {
+  while (cursor_ < encoding_.size())
+    values->push_back(Dequeue());
+}
+
+}  // namespace relocation_packer