Initial commit

engines/ags/shared/util/memory_stream.cpp

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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/std/algorithm.h"
+#include "ags/shared/util/memory_stream.h"
+
+namespace AGS3 {
+namespace AGS {
+namespace Shared {
+
+MemoryStream::MemoryStream(const uint8_t *cbuf, size_t buf_sz, DataEndianess stream_endianess)
+	: DataStream(stream_endianess)
+	, _cbuf(cbuf)
+	, _buf_sz(buf_sz)
+	, _len(buf_sz)
+	, _mode(kStream_Read)
+	, _pos(0)
+	, _buf(nullptr) {
+}
+
+MemoryStream::MemoryStream(uint8_t *buf, size_t buf_sz, StreamWorkMode mode, DataEndianess stream_endianess)
+	: DataStream(stream_endianess)
+	, _cbuf(nullptr)
+	, _buf_sz(buf_sz)
+	, _len(0)
+	, _mode(mode)
+	, _pos(0)
+	, _buf(nullptr) {
+	if (mode == kStream_Read) {
+		_cbuf = buf;
+		_len = buf_sz;
+	} else {
+		_buf = buf;
+	}
+}
+
+void MemoryStream::Close() {
+	_cbuf = nullptr;
+	_buf = nullptr;
+	_buf_sz = 0;
+	_len = 0;
+	_pos = 0;
+}
+
+bool MemoryStream::Flush() {
+	return true;
+}
+
+bool MemoryStream::IsValid() const {
+	return _cbuf != nullptr || _buf != nullptr;
+}
+
+bool MemoryStream::EOS() const {
+	return _pos >= _len;
+}
+
+soff_t MemoryStream::GetLength() const {
+	return _len;
+}
+
+soff_t MemoryStream::GetPosition() const {
+	return _pos;
+}
+
+bool MemoryStream::CanRead() const {
+	return (_cbuf != nullptr) && (_mode == kStream_Read);
+}
+
+bool MemoryStream::CanWrite() const {
+	return (_buf != nullptr) && (_mode == kStream_Write);
+}
+
+bool MemoryStream::CanSeek() const {
+	return true;
+}
+
+size_t MemoryStream::Read(void *buffer, size_t size) {
+	if (EOS()) {
+		return 0;
+	}
+	assert(_len > _pos);
+	size_t remain = _len - _pos;
+	size_t read_sz = MIN(remain, size);
+	memcpy(buffer, _cbuf + _pos, read_sz);
+	_pos += read_sz;
+	return read_sz;
+}
+
+int32_t MemoryStream::ReadByte() {
+	if (EOS()) {
+		return -1;
+	}
+	return _cbuf[_pos++];
+}
+
+soff_t MemoryStream::Seek(soff_t offset, StreamSeek origin) {
+	if (!CanSeek()) {
+		return false;
+	}
+	soff_t want_pos = -1;
+	switch (origin) {
+	case kSeekBegin:    want_pos = 0 + offset; break;
+	case kSeekCurrent:  want_pos = _pos + offset; break;
+	case kSeekEnd:      want_pos = _len + offset; break;
+	default:
+		return -1;
+	}
+	// clamp to a valid range
+	_pos = static_cast<size_t>(MAX<soff_t>(0, want_pos));
+	_pos = std::min(_len, _pos); // clamp to EOS
+	return static_cast<soff_t>(_pos);
+}
+
+size_t MemoryStream::Write(const void *buffer, size_t size) {
+	if (!_buf || (_pos >= _buf_sz)) {
+		return 0;
+	}
+	size = MIN(size, _buf_sz - _pos);
+	memcpy(_buf + _pos, buffer, size);
+	_pos += size;
+	// will increase len if writing after eos, otherwise = overwrite at pos
+	_len = MAX(_len, _pos);
+	return size;
+}
+
+int32_t MemoryStream::WriteByte(uint8_t val) {
+	if (!_buf || (_pos >= _buf_sz)) {
+		return -1;
+	}
+	*(_buf + _pos) = val;
+	_pos++;
+	// will increase len if writing after eos, otherwise = overwrite at pos
+	_len = MAX(_len, _pos);
+	return val;
+}
+
+
+VectorStream::VectorStream(const std::vector<uint8_t> &cbuf, DataEndianess stream_endianess)
+	: MemoryStream(&cbuf.front(), cbuf.size(), stream_endianess)
+	, _vec(nullptr) {
+}
+
+VectorStream::VectorStream(std::vector<uint8_t> &buf, StreamWorkMode mode, DataEndianess stream_endianess)
+	: MemoryStream(((mode == kStream_Read) && (buf.size() > 0)) ? &buf.front() : nullptr, buf.size(), mode, stream_endianess)
+	, _vec(&buf) {
+}
+
+void VectorStream::Close() {
+	_vec = nullptr;
+	MemoryStream::Close();
+}
+
+bool VectorStream::CanRead() const {
+	return _mode == kStream_Read;
+}
+
+bool VectorStream::CanWrite() const {
+	return _mode == kStream_Write;
+}
+
+size_t VectorStream::Write(const void *buffer, size_t size) {
+	if (_pos + size > _len) {
+		_vec->resize(_pos + size);
+		_len = _pos + size;
+	}
+	memcpy(_vec->data() + _pos, buffer, size);
+	_pos += size;
+	return size;
+}
+
+int32_t VectorStream::WriteByte(uint8_t val) {
+	if (_pos == _len) {
+		_vec->push_back(val);
+		_len++;
+	} else {
+		(*_vec)[_pos] = val;
+	}
+	_pos++;
+	return val;
+}
+
+} // namespace Shared
+} // namespace AGS
+} // namespace AGS3