content/browser/speech/chunked_byte_buffer.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "content/browser/speech/chunked_byte_buffer.h"
   6
   7 #include <algorithm>
   8
   9 #include "base/basictypes.h"
  10 #include "base/lazy_instance.h"
  11 #include "base/logging.h"
  12
  13 namespace {
  14
  15 static const size_t kHeaderLength = sizeof(uint32);
  16
  17 static_assert(sizeof(size_t) >= kHeaderLength,
  18               "chunked byte buffer not supported on this architecture");
  19
  20 uint32 ReadBigEndian32(const uint8* buffer) {
  21   return (static_cast<uint32>(buffer[3])) |
  22          (static_cast<uint32>(buffer[2]) <<  8) |
  23          (static_cast<uint32>(buffer[1]) << 16) |
  24          (static_cast<uint32>(buffer[0]) << 24);
  25 }
  26
  27 }  // namespace
  28
  29 namespace content {
  30
  31 ChunkedByteBuffer::ChunkedByteBuffer()
  32     : partial_chunk_(new Chunk()),
  33       total_bytes_stored_(0) {
  34 }
  35
  36 ChunkedByteBuffer::~ChunkedByteBuffer() {
  37   Clear();
  38 }
  39
  40 void ChunkedByteBuffer::Append(const uint8* start, size_t length) {
  41   size_t remaining_bytes = length;
  42   const uint8* next_data = start;
  43
  44   while (remaining_bytes > 0) {
  45     DCHECK(partial_chunk_ != NULL);
  46     size_t insert_length = 0;
  47     bool header_completed = false;
  48     bool content_completed = false;
  49     std::vector<uint8>* insert_target;
  50
  51     if (partial_chunk_->header.size() < kHeaderLength) {
  52       const size_t bytes_to_complete_header =
  53           kHeaderLength - partial_chunk_->header.size();
  54       insert_length = std::min(bytes_to_complete_header, remaining_bytes);
  55       insert_target = &partial_chunk_->header;
  56       header_completed = (remaining_bytes >= bytes_to_complete_header);
  57     } else {
  58       DCHECK_LT(partial_chunk_->content->size(),
  59                 partial_chunk_->ExpectedContentLength());
  60       const size_t bytes_to_complete_chunk =
  61           partial_chunk_->ExpectedContentLength() -
  62           partial_chunk_->content->size();
  63       insert_length = std::min(bytes_to_complete_chunk, remaining_bytes);
  64       insert_target = partial_chunk_->content.get();
  65       content_completed = (remaining_bytes >= bytes_to_complete_chunk);
  66     }
  67
  68     DCHECK_GT(insert_length, 0U);
  69     DCHECK_LE(insert_length, remaining_bytes);
  70     DCHECK_LE(next_data + insert_length, start + length);
  71     insert_target->insert(insert_target->end(),
  72                           next_data,
  73                           next_data + insert_length);
  74     next_data += insert_length;
  75     remaining_bytes -= insert_length;
  76
  77     if (header_completed) {
  78       DCHECK_EQ(partial_chunk_->header.size(), kHeaderLength);
  79       if (partial_chunk_->ExpectedContentLength() == 0) {
  80         // Handle zero-byte chunks.
  81         chunks_.push_back(partial_chunk_.release());
  82         partial_chunk_.reset(new Chunk());
  83       } else {
  84         partial_chunk_->content->reserve(
  85             partial_chunk_->ExpectedContentLength());
  86       }
  87     } else if (content_completed) {
  88       DCHECK_EQ(partial_chunk_->content->size(),
  89                 partial_chunk_->ExpectedContentLength());
  90       chunks_.push_back(partial_chunk_.release());
  91       partial_chunk_.reset(new Chunk());
  92     }
  93   }
  94   DCHECK_EQ(next_data, start + length);
  95   total_bytes_stored_ += length;
  96 }
  97
  98 void ChunkedByteBuffer::Append(const std::string& string) {
  99   Append(reinterpret_cast<const uint8*>(string.data()), string.size());
 100 }
 101
 102 bool ChunkedByteBuffer::HasChunks() const {
 103   return !chunks_.empty();
 104 }
 105
 106 scoped_ptr< std::vector<uint8> > ChunkedByteBuffer::PopChunk() {
 107   if (chunks_.empty())
 108     return scoped_ptr< std::vector<uint8> >();
 109   scoped_ptr<Chunk> chunk(*chunks_.begin());
 110   chunks_.weak_erase(chunks_.begin());
 111   DCHECK_EQ(chunk->header.size(), kHeaderLength);
 112   DCHECK_EQ(chunk->content->size(), chunk->ExpectedContentLength());
 113   total_bytes_stored_ -= chunk->content->size();
 114   total_bytes_stored_ -= kHeaderLength;
 115   return chunk->content.Pass();
 116 }
 117
 118 void ChunkedByteBuffer::Clear() {
 119   chunks_.clear();
 120   partial_chunk_.reset(new Chunk());
 121   total_bytes_stored_ = 0;
 122 }
 123
 124 ChunkedByteBuffer::Chunk::Chunk()
 125     : content(new std::vector<uint8>()) {
 126 }
 127
 128 ChunkedByteBuffer::Chunk::~Chunk() {
 129 }
 130
 131 size_t ChunkedByteBuffer::Chunk::ExpectedContentLength() const {
 132   DCHECK_EQ(header.size(), kHeaderLength);
 133   return static_cast<size_t>(ReadBigEndian32(&header[0]));
 134 }
 135
 136 }  // namespace content