scummvm-cursorfix/engines/ags/shared/util/data_stream.cpp

/* 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/std/algorithm.h"
#include "ags/shared/util/data_stream.h"

namespace AGS3 {
namespace AGS {
namespace Shared {

DataStream::DataStream(DataEndianess stream_endianess)
	: _streamEndianess(stream_endianess) {
}

DataStream::~DataStream() {}

int16_t DataStream::ReadInt16() {
	int16_t val = 0;
	Read(&val, sizeof(int16_t));
	ConvertInt16(val);
	return val;
}

int32_t DataStream::ReadInt32() {
	int32_t val = 0;
	Read(&val, sizeof(int32_t));
	ConvertInt32(val);
	return val;
}

int64_t DataStream::ReadInt64() {
	int64_t val = 0;
	Read(&val, sizeof(int64_t));
	ConvertInt64(val);
	return val;
}

size_t DataStream::WriteInt16(int16_t val) {
	ConvertInt16(val);
	return Write(&val, sizeof(int16_t));
}

size_t DataStream::WriteInt32(int32_t val) {
	ConvertInt32(val);
	return Write(&val, sizeof(int32_t));
}

size_t DataStream::WriteInt64(int64_t val) {
	ConvertInt64(val);
	return Write(&val, sizeof(int64_t));
}

size_t DataStream::ReadAndConvertArrayOfInt16(int16_t *buffer, size_t count) {
	count = ReadArray(buffer, sizeof(int16_t), count);
	for (size_t i = 0; i < count; ++i, ++buffer) {
		*buffer = BBOp::SwapBytesInt16(*buffer);
	}
	return count;
}

size_t DataStream::ReadAndConvertArrayOfInt32(int32_t *buffer, size_t count) {
	count = ReadArray(buffer, sizeof(int32_t), count);
	for (size_t i = 0; i < count; ++i, ++buffer) {
		*buffer = BBOp::SwapBytesInt32(*buffer);
	}
	return count;
}

size_t DataStream::ReadAndConvertArrayOfInt64(int64_t *buffer, size_t count) {
	count = ReadArray(buffer, sizeof(int64_t), count);
	for (size_t i = 0; i < count; ++i, ++buffer) {
		*buffer = BBOp::SwapBytesInt64(*buffer);
	}
	return count;
}

size_t DataStream::WriteAndConvertArrayOfInt16(const int16_t *buffer, size_t count) {
	size_t elem;
	for (elem = 0; elem < count; ++elem, ++buffer) {
		int16_t val = *buffer;
		ConvertInt16(val);
		if (Write(&val, sizeof(int16_t)) < sizeof(int16_t)) {
			break;
		}
	}
	return elem;
}

size_t DataStream::WriteAndConvertArrayOfInt32(const int32_t *buffer, size_t count) {
	size_t elem;
	for (elem = 0; elem < count; ++elem, ++buffer) {
		int32_t val = *buffer;
		ConvertInt32(val);
		if (Write(&val, sizeof(int32_t)) < sizeof(int32_t)) {
			break;
		}
	}
	return elem;
}

size_t DataStream::WriteAndConvertArrayOfInt64(const int64_t *buffer, size_t count) {
	size_t elem;
	for (elem = 0; elem < count; ++elem, ++buffer) {
		int64_t val = *buffer;
		ConvertInt64(val);
		if (Write(&val, sizeof(int64_t)) < sizeof(int64_t)) {
			break;
		}
	}
	return elem;
}

DataStreamSection::DataStreamSection(Stream *base, soff_t start, soff_t end)
	: _base(base) {
	_start = std::max((soff_t)0, std::min(start, end));
	_end = std::min(std::max((soff_t)0, end), base->GetLength());
	soff_t pos = base->Seek(_start, kSeekBegin);
	if (pos >= 0)
		_position = pos;
	else
		_position = base->GetPosition();
}

size_t DataStreamSection::Read(void *buffer, size_t len) {
	if (_position >= _end)
		return 0;
	len = std::min(len, static_cast<size_t>(_end - _position));
	_position += _base->Read(buffer, len);
	return len;
}

int32_t DataStreamSection::ReadByte() {
	if (_position >= _end)
		return -1;
	int32_t b = _base->ReadByte();
	if (b >= 0)
		_position++;
	return b;
}

size_t DataStreamSection::Write(const void *buffer, size_t len) {
	len = _base->Write(buffer, len);
	_position += len;
	_end = std::max(_end, _position); // we might be overwriting after seeking back
	return len;
}

int32_t DataStreamSection::WriteByte(uint8_t b) {
	int32_t rb = _base->WriteByte(b);
	if (rb == b) {
		_position++;
		_end = std::max(_end, _position); // we might be overwriting after seeking back
	}
	return rb;
}

soff_t DataStreamSection::Seek(soff_t offset, StreamSeek origin) {
	soff_t want_pos = -1;
	switch (origin) {
	case StreamSeek::kSeekCurrent:
		want_pos = _position + offset;
		break;
	case StreamSeek::kSeekBegin:
		want_pos = _start + offset;
		break;
	case StreamSeek::kSeekEnd:
		want_pos = _end + offset;
		break;
	default:
		return -1;
	}
	want_pos = std::min(std::max(want_pos, _start), _end);
	soff_t new_pos = _base->Seek(want_pos, kSeekBegin);
	if (new_pos >= 0) // the position remains in case of seek error
		_position = want_pos;
	return _position - _start; // convert to a stream section pos
}

void DataStreamSection::Close() {
	// We do not close nor delete the base stream, but release it from use
	_base = nullptr;
}

} // namespace Shared
} // namespace AGS
} // namespace AGS3