AGS: Added MemoryStream

Found upstream e3208df5afeed6cef118dc71a0af45cfce72f4d7

engines/ags/module.mk

@@ -81,6 +81,7 @@ MODULE_OBJS = \
 	shared/util/ini_util.o \
 	shared/util/lzw.o \
 	shared/util/misc.o \
+	shared/util/memory_stream.o \
 	shared/util/multi_file_lib.o \
 	shared/util/path.o \
 	shared/util/proxy_stream.o \

engines/ags/shared/util/memory_stream.cpp

@@ -0,0 +1,155 @@
+/* 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.
+ *
+ */
+
+#include "ags/lib/std/algorithm.h"
+#include "ags/shared/util/memory_stream.h"
+
+namespace AGS3 {
+namespace AGS {
+namespace Shared {
+
+MemoryStream::MemoryStream(const std::vector<char> &cbuf, DataEndianess stream_endianess)
+	: DataStream(stream_endianess)
+	, _cbuf(&cbuf.front())
+	, _len(cbuf.size())
+	, _buf(nullptr)
+	, _mode(kStream_Read)
+	, _pos(0) {
+}
+
+MemoryStream::MemoryStream(const String &cbuf, DataEndianess stream_endianess)
+	: DataStream(stream_endianess)
+	, _cbuf(cbuf.GetCStr())
+	, _len(cbuf.GetLength())
+	, _buf(nullptr)
+	, _mode(kStream_Read)
+	, _pos(0) {
+}
+
+MemoryStream::MemoryStream(std::vector<char> &buf, StreamWorkMode mode, DataEndianess stream_endianess)
+	: DataStream(stream_endianess)
+	, _len(buf.size())
+	, _buf(&buf)
+	, _mode(mode)
+	, _pos(buf.size()) {
+	_cbuf = (mode == kStream_Read) ? &buf.front() : nullptr;
+}
+
+MemoryStream::~MemoryStream() {
+}
+
+void MemoryStream::Close() {
+	_cbuf = nullptr;
+	_buf = nullptr;
+	_pos = -1;
+}
+
+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 CanRead(); // TODO: support seeking in writable stream?
+}
+
+size_t MemoryStream::Read(void *buffer, size_t size) {
+	if (EOS()) {
+		return 0;
+	}
+	soff_t remain = _len - _pos;
+	assert(remain > 0);
+	size_t read_sz = std::min((size_t)remain, size);
+	memcpy(buffer, _cbuf + _pos, read_sz);
+	_pos += read_sz;
+	return read_sz;
+}
+
+int32_t MemoryStream::ReadByte() {
+	if (EOS()) {
+		return -1;
+	}
+	return _cbuf[(size_t)(_pos++)];
+}
+
+size_t MemoryStream::Write(const void *buffer, size_t size) {
+	if (!_buf) {
+		return 0;
+	}
+	_buf->resize(_buf->size() + size);
+	memcpy(_buf->data() + _pos, buffer, size);
+	_pos += size;
+	_len += size;
+	return size;
+}
+
+int32_t MemoryStream::WriteByte(uint8_t val) {
+	if (!_buf) {
+		return -1;
+	}
+	_buf->push_back(val);
+	_pos++; _len++;
+	return val;
+}
+
+bool MemoryStream::Seek(soff_t offset, StreamSeek origin) {
+	if (!CanSeek()) {
+		return false;
+	}
+	switch (origin) {
+	case kSeekBegin:    _pos = 0 + offset; break;
+	case kSeekCurrent:  _pos = _pos + offset; break;
+	case kSeekEnd:      _pos = _len + offset; break;
+	default:
+		return false;
+	}
+	_pos = std::max<soff_t>(0, _pos);
+	_pos = std::min<soff_t>(_len, _pos); // clamp to EOS
+	return true;
+}
+
+} // namespace Shared
+} // namespace AGS
+} // namespace AGS3

engines/ags/shared/util/memory_stream.h

@@ -0,0 +1,93 @@
+/* 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.
+ *
+ */
+
+//=============================================================================
+//
+// MemoryStream does reading and writing over the buffer of chars stored in
+// memory. Currently has rather trivial implementation. Does not own a buffer
+// itself, but works with the provided std::vector reference, which means that
+// the buffer *must* persist until stream is closed.
+// TODO: perhaps accept const char* for reading mode, for compatibility with
+// the older code, and maybe to let also read String objects?
+// TODO: separate StringStream for reading & writing String object?
+//
+//=============================================================================
+
+#ifndef AGS_SHARED_UTIL_MEMORY_STREAM_H
+#define AGS_SHARED_UTIL_MEMORY_STREAM_H
+
+#include "ags/lib/std/vector.h"
+#include "ags/shared/util/data_stream.h"
+#include "ags/shared/util/string.h"
+
+namespace AGS3 {
+namespace AGS {
+namespace Shared {
+
+class MemoryStream : public DataStream {
+public:
+	// Construct memory stream in the read-only mode over a const std::vector;
+	// vector must persist in memory until the stream is closed.
+	MemoryStream(const std::vector<char> &cbuf, DataEndianess stream_endianess = kLittleEndian);
+	// Construct memory stream in the read-only mode over a const String;
+	// String object must persist in memory until the stream is closed.
+	MemoryStream(const String &cbuf, DataEndianess stream_endianess = kLittleEndian);
+	// Construct memory stream in the chosen mode over a given std::vector;
+	// vector must persist in memory until the stream is closed.
+	MemoryStream(std::vector<char> &buf, StreamWorkMode mode, DataEndianess stream_endianess = kLittleEndian);
+	~MemoryStream() override;
+
+	void    Close() override;
+	bool    Flush() override;
+
+	// Is stream valid (underlying data initialized properly)
+	bool    IsValid() const override;
+	// Is end of stream
+	bool    EOS() const override;
+	// Total length of stream (if known)
+	soff_t  GetLength() const override;
+	// Current position (if known)
+	soff_t  GetPosition() const override;
+	bool    CanRead() const override;
+	bool    CanWrite() const override;
+	bool    CanSeek() const override;
+
+	size_t  Read(void *buffer, size_t size) override;
+	int32_t ReadByte() override;
+	size_t  Write(const void *buffer, size_t size) override;
+	int32_t WriteByte(uint8_t b) override;
+
+	bool    Seek(soff_t offset, StreamSeek origin) override;
+
+private:
+	const char *_cbuf;
+	size_t _len;
+	std::vector<char> *_buf;
+	const StreamWorkMode _mode;
+	soff_t _pos;
+};
+
+} // namespace Shared
+} // namespace AGS
+} // namespace AGS3
+
+#endif

engines/ags/shared/util/stream.h

@@ -43,6 +43,12 @@ namespace AGS3 {
 namespace AGS {
 namespace Shared {
 
+// TODO: merge with FileWorkMode (historical mistake)
+enum StreamWorkMode {
+	kStream_Read,
+	kStream_Write
+};
+
 class Stream : public IAGSStream {
 public:
 	virtual ~Stream() {}