Mojo C++ bindings

mojo/public/bindings/lib/buffer.cc

+// Copyright 2013 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 "mojo/public/bindings/lib/buffer.h"
+
+#include <assert.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <algorithm>
+
+#include "mojo/public/bindings/lib/bindings_serialization.h"
+
+namespace mojo {
+
+//-----------------------------------------------------------------------------
+
+ScratchBuffer::ScratchBuffer()
+    : overflow_(NULL) {
+  fixed_.next = NULL;
+  fixed_.cursor = fixed_data_;
+  fixed_.end = fixed_data_ + kMinSegmentSize;
+}
+
+ScratchBuffer::~ScratchBuffer() {
+  while (overflow_) {
+    Segment* doomed = overflow_;
+    overflow_ = overflow_->next;
+    free(doomed);
+  }
+}
+
+void* ScratchBuffer::Allocate(size_t delta) {
+  delta = internal::Align(delta);
+
+  void* result =
+      AllocateInSegment((overflow_ != NULL) ? overflow_ : &fixed_, delta);
+  if (result)
+    return result;
+
+  AddOverflowSegment(delta);
+  return Allocate(delta);
+}
+
+void* ScratchBuffer::AllocateInSegment(Segment* segment, size_t delta) {
+  void* result;
+  if (static_cast<size_t>(segment->end - segment->cursor) >= delta) {
+    result = segment->cursor;
+    memset(result, 0, delta);
+    segment->cursor += delta;
+  } else {
+    result = NULL;
+  }
+  return result;
+}
+
+void ScratchBuffer::AddOverflowSegment(size_t delta) {
+  if (delta < kMinSegmentSize)
+    delta = kMinSegmentSize;
+  Segment* segment = static_cast<Segment*>(malloc(sizeof(Segment) + delta));

[dmichael (off chromium), 2013/10/14 22:41:19]

On 32-bit, pointers may be 4 bytes, so |Segment| is 24 bytes wide. I think in
that case |segment| is not aligned to 8 bytes. Did I miss something?

+  segment->next = overflow_;
+  segment->cursor = reinterpret_cast<char*>(segment + 1);
+  segment->end = segment->cursor + delta;
+  overflow_ = segment;
+}
+
+//-----------------------------------------------------------------------------
+
+FixedBuffer::FixedBuffer(size_t size)
+    : ptr_(NULL),
+      cursor_(0),
+      size_(internal::Align(size)) {
+  ptr_ = static_cast<char*>(calloc(size_, 1));
+}
+
+FixedBuffer::~FixedBuffer() {
+  free(ptr_);
+}
+
+void* FixedBuffer::Allocate(size_t delta) {
+  delta = internal::Align(delta);
+
+  // TODO(darin): Using <assert.h> is probably not going to cut it.
+  assert(delta > 0);
+  assert(cursor_ + delta <= size_);
+  if (cursor_ + delta > size_)
+    return NULL;
+
+  char* result = ptr_ + cursor_;
+  cursor_ += delta;
+
+  return result;
+}
+
+void* FixedBuffer::Leak() {
+  char* ptr = ptr_;
+  ptr_ = NULL;
+  cursor_ = 0;
+  size_ = 0;
+  return ptr;
+}
+
+}  // namespace mojo