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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 3 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, see <http://www.gnu.org/licenses/>.
*
*/
#include "common/concatstream.h"
namespace Common {
ConcatReadStream::ConcatReadStream(ParentStreamArray parentStreams) : _parentStreams(parentStreams), _totalSize(0), _linearPos(0), _volume(0), _volumePos(0), _err(false), _eos(false) {
_sizes.resize(parentStreams.size());
_startOffsets.resize(parentStreams.size());
for (uint i = 0; i < parentStreams.size(); i++) {
_sizes[i] = parentStreams[i]->size();
_totalSize += _sizes[i];
}
_startOffsets[0] = 0;
for (uint i = 1; i < parentStreams.size(); i++)
_startOffsets[i] = _startOffsets[i - 1] + _sizes[i - 1];
}
bool ConcatReadStream::seek(int64 offset, int whence) {
int64 target = 0;
switch (whence) {
case SEEK_SET:
target = offset;
break;
case SEEK_CUR:
target = _linearPos + offset;
break;
case SEEK_END:
target = _totalSize + offset;
break;
default:
return false;
}
if (target < 0 || target > _totalSize) {
return false;
}
_linearPos = target;
_eos = false;
_err = false;
// Special case: seek'ing to the EOF.
if (target == _totalSize) {
if (_parentStreams.empty()) {
_volume = 0;
_volumePos = 0;
return true;
}
_volume = _parentStreams.size() - 1;
_volumePos = _sizes[_parentStreams.size() - 1];
return true;
}
// Find volume
for (unsigned vol = 0; vol < _parentStreams.size(); vol++) {
if (_startOffsets[vol] <= _linearPos &&
_linearPos < _startOffsets[vol] + _sizes[vol]) {
_volume = vol;
_volumePos = _linearPos - _startOffsets[vol];
return true;
}
}
// Should never be reached.
_err = true;
return false;
}
bool ConcatReadStream::seekToVolume(int volume, int64 offset) {
if (volume < 0 || (uint) volume >= _parentStreams.size()
|| offset < 0 || offset >= _sizes[volume]) {
_err = true;
return false;
}
_err = false;
_eos = false;
_volume = volume;
_volumePos = offset;
_linearPos = _startOffsets[volume] + offset;
return true;
}
uint32 ConcatReadStream::read(void *dataPtr, uint32 dataSize) {
uint32 rem = dataSize;
uint32 alreadyRead = 0;
byte *curPtr = (byte*) dataPtr;
while (rem > 0) {
int64 avail = _startOffsets[_volume] + _sizes[_volume];
while (avail == 0) {
if (_volume + 1 >= _startOffsets.size()) {
_eos = true;
return alreadyRead;
}
_volume++;
_volumePos = 0;
avail = _startOffsets[_volume] + _sizes[_volume];
}
uint32 toRead = MIN((int64) rem, avail);
_parentStreams[_volume]->seek(_volumePos); // Also clears error and EOS.
uint32 actuallyRead = _parentStreams[_volume]->read(curPtr, toRead);
alreadyRead += actuallyRead;
rem -= actuallyRead;
curPtr += actuallyRead;
_volumePos += actuallyRead;
_linearPos += actuallyRead;
if (_volumePos == _sizes[_volume] && _volume + 1 < _startOffsets.size()) {
_volume++;
_volumePos = 0;
}
if (_parentStreams[_volume]->err()) {
_err = true;
return alreadyRead;
}
}
return alreadyRead;
}
} // End of namespace Common
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