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/* ScummVM - Graphic Adventure Engine
*
* ScummVM is the legal property of its developers, whose names
* are too numerous to list here. Please refer to the COPYRIGHT
* file distributed with this source distribution.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
*/
// Disable symbol overrides so that we can use system headers.
#define FORBIDDEN_SYMBOL_ALLOW_ALL
#include "search.h"
#include "md5.h"
#include <algorithm>
#include <cassert>
Hasher::Hash Hasher::createHash(const byte *data, uint32 size) {
md5_context ctx;
md5_starts(&ctx);
md5_update(&ctx, data, size);
Hash hash;
md5_finish(&ctx, hash.digest);
return hash;
}
SearchData SearchCreator::create(const char *filename) {
FILE *f = fopen(filename, "rb");
assert(f);
SearchData data;
data.size = fileSize(f);
byte *buffer = new byte[data.size];
fread(buffer, 1, data.size, f);
fclose(f);
data = create(buffer, data.size);
delete[] buffer;
return data;
}
SearchData SearchCreator::create(const byte *buffer, uint32 size) {
SearchData data;
data.size = size;
data.hash = Hasher::createHash(buffer, data.size);
data.byteSum = 0;
for (uint32 i = 0; i < data.size; ++i)
data.byteSum += buffer[i];
return data;
}
SumCreator::SumCreator(InputList list, const DataInput &input) : _curOffset(0), _input(input), _sums() {
// Sort in ascending order
list.sort(std::less<uint32>());
uint32 byteSum = 0;
uint32 oldSize = 0;
for (InputList::const_iterator i = list.begin(); i != list.end(); ++i) {
// Strip out entries, which exceed the buffer size
if (*i > _input.size())
continue;
// Strip out duplicates
if (_sums.find(*i) != _sums.end())
continue;
// Only add the bytes exceeding the old sum's size
// to the sum. This saves a few accesses.
for (uint32 j = oldSize; j < *i; ++j)
byteSum += _input[j];
_sums[*i] = byteSum;
// Save this sum's size
oldSize = *i;
}
}
bool SumCreator::nextByte() {
// Calculate the bytes available for summing. We need to add
// 1 here, since we will only update the offset AFTER everything
// is done.
const uint32 sizeLeft = _input.size() - (_curOffset + 1);
if (!sizeLeft) {
_sums.clear();
return false;
}
// Grab the old first byte.
const byte firstByte = _input[_curOffset];
typedef std::list<uint32> DeletionList;
DeletionList toRemove;
for (SumMap::iterator i = _sums.begin(); i != _sums.end(); ++i) {
// If this entry needs to sum up a larger buffer than the buffer
// size left, we will remove the entry and continue to the next
// one.
if (i->first > sizeLeft) {
// Add the current entry to the removal list.
toRemove.push_back(i->first);
continue;
}
// Update the byte sum. First we remove the old first byte
// from the sum, next we add the next available byte.
i->second -= firstByte;
i->second += _input[_curOffset + i->first];
}
// Remove all entries flagged for removal
for (DeletionList::const_iterator i = toRemove.begin(); i != toRemove.end(); ++i)
_sums.erase(*i);
// Update out offset.
++_curOffset;
// We return whether there are still some sums left available.
return !_sums.empty();
}
bool SumCreator::hasSum(uint32 size) const {
return _sums.find(size) != _sums.end();
}
uint32 SumCreator::getSum(uint32 size) const {
SumMap::const_iterator s = _sums.find(size);
if (s == _sums.end())
return 0;
return s->second;
}
Search::Search(const char *filename) : _data(), _search() {
FILE *src = fopen(filename, "rb");
assert(src);
uint32 size = fileSize(src);
byte *data = new byte[size];
fread(data, 1, size, src);
fclose(src);
_data.resize(size);
std::copy(data, data + size, _data.begin());
delete[] data;
}
Search::Search(const byte *data, uint32 size) : _data(), _search() {
_data.resize(size);
std::copy(data, data + size, _data.begin());
}
void Search::addData(SearchData data) {
// Do not add any duplicates
if (std::find(_search.begin(), _search.end(), data) != _search.end())
return;
_search.push_back(data);
}
bool Search::search(ResultList &res) {
SumCreator::InputList list;
for (SearchList::const_iterator i = _search.begin(); i != _search.end(); ++i)
list.push_back(i->size);
SumCreator sum(list, _data);
list.clear();
do {
const uint32 offset = sum.getOffset();
for (SearchList::iterator i = _search.begin(); i != _search.end(); ) {
if (!sum.hasSum(i->size)) {
i = _search.erase(i);
continue;
}
const uint32 byteSum = sum.getSum(i->size);
if (byteSum == i->byteSum) {
if (Hasher::createHash(&_data[offset], i->size) == i->hash) {
res.push_back(ResultData(*i, offset));
i = _search.erase(i);
continue;
}
}
++i;
}
} while (sum.nextByte());
return !res.empty();
}
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