readstream.cpp

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/* xoreos - A reimplementation of BioWare's Aurora engine
 *
 * xoreos is the legal property of its developers, whose names
 * can be found in the AUTHORS file distributed with this source
 * distribution.
 *
 * xoreos 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.
 *
 * xoreos 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 xoreos. If not, see <http://www.gnu.org/licenses/>.
 */

/* Based on ScummVM (<http://scummvm.org>) code, which is released
 * under the terms of version 2 or later of the GNU General Public
 * License.
 *
 * The original copyright note in ScummVM reads as follows:
 *
 * 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.
 */

#include <cassert>

#include "src/common/readstream.h"
#include "src/common/memreadstream.h"
#include "src/common/error.h"
#include "src/common/scopedptr.h"

namespace Common {

const uint32 ReadStream::kEOF;

ReadStream::ReadStream() {
}

ReadStream::~ReadStream() {
}

MemoryReadStream *ReadStream::readStream(size_t dataSize) {
    ScopedArray<byte> buf(new byte[dataSize]);

    if (read(buf.get(), dataSize) != dataSize)
        throw Exception(kReadError);

    return new MemoryReadStream(buf.release(), dataSize, true);
}


SeekableReadStream::SeekableReadStream() {
}

SeekableReadStream::~SeekableReadStream() {
}

size_t SeekableReadStream::evalSeek(ptrdiff_t offset, Origin whence, size_t pos, size_t begin, size_t size) {
    switch (whence) {
        case kOriginEnd:
            offset = size + offset;
            XOREOS_FALLTHROUGH;
        case kOriginBegin:
            return begin + offset;
        case kOriginCurrent:
            return pos + offset;

        default:
            break;
    }

    throw Exception("Invalid whence (%d)", (int) whence);
}


SubReadStream::SubReadStream(ReadStream *parentStream, size_t end, bool disposeParentStream) :
    _parentStream(parentStream, disposeParentStream), _pos(0), _end(end), _eos(false) {

    assert(parentStream);
}

SubReadStream::~SubReadStream() {
}

bool SubReadStream::eos() const {
    return _eos | _parentStream->eos();
}

size_t SubReadStream::read(void *dataPtr, size_t dataSize) {
    if (dataSize > (size_t)(_end - _pos)) {
        dataSize = _end - _pos;
        _eos = true;
    }

    dataSize = _parentStream->read(dataPtr, dataSize);
    _pos += dataSize;

    return dataSize;
}


SeekableSubReadStream::SeekableSubReadStream(SeekableReadStream *parentStream, size_t begin,
                                             size_t end, bool disposeParentStream) :
    SubReadStream(parentStream, end, disposeParentStream), _parentStream(parentStream), _begin(begin) {

    assert(_begin <= _end);

    _pos = begin;
    _parentStream->seek(_pos);
}

SeekableSubReadStream::~SeekableSubReadStream() {
}

size_t SeekableSubReadStream::pos() const {
    return _pos - _begin;
}

size_t SeekableSubReadStream::size() const {
    return _end - _begin;
}

size_t SeekableSubReadStream::seek(ptrdiff_t offset, Origin whence) {
    assert(_pos >= _begin);
    assert(_pos <= _end);

    const size_t oldPos = _pos;
    const size_t newPos = evalSeek(offset, whence, _pos, _begin, size());
    if ((newPos < _begin) || (newPos > _end))
        throw Exception(kSeekError);

    _pos = newPos;

    _parentStream->seek(_pos);
    _eos = false; // reset eos on successful seek

    return oldPos;
}


SeekableSubReadStreamEndian::SeekableSubReadStreamEndian(SeekableReadStream *parentStream,
        size_t begin, size_t end, bool bigEndian, bool disposeParentStream) :
        SeekableSubReadStream(parentStream, begin, end, disposeParentStream), _bigEndian(bigEndian) {

}

SeekableSubReadStreamEndian::~SeekableSubReadStreamEndian() {
}

} // End of namespace Common