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// Copyright (c) 2010 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 "pdf/chunk_stream.h"
#include <stddef.h>
#include <string.h>
#define __STDC_LIMIT_MACROS
#ifdef _WIN32
#include <limits.h>
#else
#include <stdint.h>
#endif
#include <algorithm>
namespace chrome_pdf {
ChunkStream::ChunkStream() : stream_size_(0) {
}
ChunkStream::~ChunkStream() {
}
void ChunkStream::Clear() {
chunks_.clear();
data_.clear();
stream_size_ = 0;
}
void ChunkStream::Preallocate(size_t stream_size) {
data_.reserve(stream_size);
stream_size_ = stream_size;
}
size_t ChunkStream::GetSize() const {
return data_.size();
}
bool ChunkStream::WriteData(size_t offset, void* buffer, size_t size) {
if (SIZE_MAX - size < offset)
return false;
if (data_.size() < offset + size)
data_.resize(offset + size);
memcpy(&data_[offset], buffer, size);
if (chunks_.empty()) {
chunks_[offset] = size;
return true;
}
std::map<size_t, size_t>::iterator start = chunks_.upper_bound(offset);
if (start != chunks_.begin())
--start; // start now points to the key equal or lower than offset.
if (start->first + start->second < offset)
++start; // start element is entirely before current chunk, skip it.
std::map<size_t, size_t>::iterator end = chunks_.upper_bound(offset + size);
if (start == end) { // No chunks to merge.
chunks_[offset] = size;
return true;
}
--end;
size_t new_offset = std::min<size_t>(start->first, offset);
size_t new_size =
std::max<size_t>(end->first + end->second, offset + size) - new_offset;
chunks_.erase(start, ++end);
chunks_[new_offset] = new_size;
return true;
}
bool ChunkStream::ReadData(size_t offset, size_t size, void* buffer) const {
if (!IsRangeAvailable(offset, size))
return false;
memcpy(buffer, &data_[offset], size);
return true;
}
bool ChunkStream::GetMissedRanges(
size_t offset, size_t size,
std::vector<std::pair<size_t, size_t> >* ranges) const {
if (IsRangeAvailable(offset, size))
return false;
ranges->clear();
if (chunks_.empty()) {
ranges->push_back(std::pair<size_t, size_t>(offset, size));
return true;
}
std::map<size_t, size_t>::const_iterator start = chunks_.upper_bound(offset);
if (start != chunks_.begin())
--start; // start now points to the key equal or lower than offset.
if (start->first + start->second < offset)
++start; // start element is entirely before current chunk, skip it.
std::map<size_t, size_t>::const_iterator end =
chunks_.upper_bound(offset + size);
if (start == end) { // No data in the current range available.
ranges->push_back(std::pair<size_t, size_t>(offset, size));
return true;
}
size_t cur_offset = offset;
std::map<size_t, size_t>::const_iterator it;
for (it = start; it != end; ++it) {
if (cur_offset < it->first) {
size_t new_size = it->first - cur_offset;
ranges->push_back(std::pair<size_t, size_t>(cur_offset, new_size));
cur_offset = it->first + it->second;
} else if (cur_offset < it->first + it->second) {
cur_offset = it->first + it->second;
}
}
// Add last chunk.
if (cur_offset < offset + size)
ranges->push_back(std::pair<size_t, size_t>(cur_offset,
offset + size - cur_offset));
return true;
}
bool ChunkStream::IsRangeAvailable(size_t offset, size_t size) const {
if (chunks_.empty())
return false;
if (SIZE_MAX - size < offset)
return false;
std::map<size_t, size_t>::const_iterator it = chunks_.upper_bound(offset);
if (it == chunks_.begin())
return false; // No chunks includes offset byte.
--it; // Now it starts equal or before offset.
return (it->first + it->second) >= (offset + size);
}
size_t ChunkStream::GetFirstMissingByte() const {
if (chunks_.empty())
return 0;
std::map<size_t, size_t>::const_iterator begin = chunks_.begin();
return begin->first > 0 ? 0 : begin->second;
}
size_t ChunkStream::GetFirstMissingByteInInterval(size_t offset) const {
if (chunks_.empty())
return 0;
std::map<size_t, size_t>::const_iterator it = chunks_.upper_bound(offset);
if (it == chunks_.begin())
return 0;
--it;
return it->first + it->second;
}
size_t ChunkStream::GetLastMissingByteInInterval(size_t offset) const {
if (chunks_.empty())
return stream_size_ - 1;
std::map<size_t, size_t>::const_iterator it = chunks_.upper_bound(offset);
if (it == chunks_.end())
return stream_size_ - 1;
return it->first - 1;
}
} // namespace chrome_pdf
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