stream.h

/* 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/>.
 *
 */

//=============================================================================
//
// Base stream class.
//
// Provides default implementation for a few helper methods.
//
// Only streams with uncommon behavior should be derived directly from Stream.
// Most I/O devices should inherit DataStream instead.
//
//=============================================================================

#ifndef AGS_SHARED_UTIL_STREAM_H
#define AGS_SHARED_UTIL_STREAM_H

#include "ags/shared/util/iags_stream.h"
#include "ags/shared/util/string.h"
#include "ags/lib/allegro/file.h"
#include "common/stream.h"
#include "common/types.h"

namespace AGS3 {
namespace AGS {
namespace Shared {

// TODO: merge with FileWorkMode (historical mistake)
enum StreamWorkMode {
    kStream_Read,
    kStream_Write
};

class Stream : public IAGSStream {
public:
    Stream() = default;
    Stream(const String &path)
        : _path(path) {}
    virtual ~Stream() {}

    // Returns an optional path of a stream's source, such as a filepath;
    // primarily for diagnostic purposes
    const String &GetPath() const { return _path; }
    // Tells if there were errors during previous io operation(s);
    // the call to GetError() *resets* the error record.
    virtual bool GetError() const { return false; }
    // Flush stream buffer to the underlying device
    virtual bool Flush() = 0;

    //-----------------------------------------------------
    // Helper methods
    //-----------------------------------------------------
    int8_t ReadInt8() override {
        return ReadByte();
    }

    size_t WriteInt8(int8_t val) override {
        int32_t ival = WriteByte(val);
        return ival >= 0 ? ival : 0;
    }

    bool ReadBool() override {
        return ReadInt8() != 0;
    }

    size_t WriteBool(bool val) override {
        return WriteInt8(val ? 1 : 0);
    }

    // Practically identical to Read() and Write(), these two helpers' only
    // meaning is to underline the purpose of data being (de)serialized
    size_t ReadArrayOfInt8(int8_t *buffer, size_t count) override {
        return Read(buffer, count);
    }
    size_t WriteArrayOfInt8(const int8_t *buffer, size_t count) override {
        return Write(buffer, count);
    }

    // Fill the requested number of bytes with particular value
    size_t WriteByteCount(uint8_t b, size_t count);

protected:
    String _path; // optional name of the stream's source (e.g. filepath)
};

class ScummVMReadStream : public Common::SeekableReadStream {
private:
    IAGSStream *_stream;
    DisposeAfterUse::Flag _disposeAfterUse;
public:
    ScummVMReadStream(IAGSStream *src, DisposeAfterUse::Flag disposeAfterUse =
                          DisposeAfterUse::YES) : _stream(src), _disposeAfterUse(disposeAfterUse) {
    }
    ~ScummVMReadStream() override {
        if (_disposeAfterUse == DisposeAfterUse::YES)
            delete _stream;
    }

    bool eos() const override {
        return _stream->EOS();
    }

    uint32 read(void *dataPtr, uint32 dataSize) override {
        return _stream->Read(dataPtr, dataSize);
    }

    int64 pos() const override {
        return _stream->GetPosition();
    }

    int64 size() const override {
        return _stream->GetLength();
    }

    bool seek(int64 offset, int whence = SEEK_SET) override {
        StreamSeek origin = kSeekBegin;
        if (whence == SEEK_CUR)
            origin = kSeekCurrent;
        if (whence == SEEK_END)
            origin = kSeekEnd;

        return _stream->Seek(offset, origin);
    }
};


class ScummVMPackReadStream : public Common::SeekableReadStream {
private:
    PACKFILE *_file;
    DisposeAfterUse::Flag _disposeAfterUse;
public:
    ScummVMPackReadStream(PACKFILE *src, DisposeAfterUse::Flag disposeAfterUse =
        DisposeAfterUse::YES) : _file(src), _disposeAfterUse(disposeAfterUse) {
    }
    ~ScummVMPackReadStream() override {
        if (_disposeAfterUse == DisposeAfterUse::YES)
            delete _file;
    }

    bool eos() const override {
        return _file->pack_feof();
    }

    uint32 read(void *dataPtr, uint32 dataSize) override {
        return _file->pack_fread(dataPtr, dataSize);
    }

    int64 pos() const override {
        error("Unsupported");
    }

    int64 size() const override {
        error("Unsupported");
    }

    bool seek(int64 offset, int whence = SEEK_SET) override {
        error("Unsupported");
    }
};

class StreamScummVMFile : public Stream {
private:
    Common::SeekableReadStream *_stream;
    DisposeAfterUse::Flag _disposeAfterUse;
public:
    StreamScummVMFile(Common::SeekableReadStream *stream,
                      DisposeAfterUse::Flag disposeAfterUse = DisposeAfterUse::NO) :
        _stream(stream), _disposeAfterUse(disposeAfterUse) {
    }
    ~StreamScummVMFile() override {
        Close();
    }

    void Close() override {
        if (_disposeAfterUse == DisposeAfterUse::YES)
            delete _stream;
        _stream = nullptr;
    }

    bool IsValid() const override {
        return _stream != nullptr;
    }
    bool EOS() const override {
        return _stream->eos();
    }
    soff_t GetLength() const override {
        return _stream->size();
    }
    soff_t GetPosition() const override {
        return _stream->pos();
    }
    bool CanRead() const override {
        return true;
    }
    bool CanWrite() const override {
        return false;
    }
    bool CanSeek() const override {
        return true;
    }

    size_t Read(void *buffer, size_t size) override {
        return _stream->read(buffer, size);
    }
    int32_t ReadByte() override {
        return _stream->readByte();
    }
    size_t Write(const void *buffer, size_t size) override {
        return 0;
    }
    int32_t WriteByte(uint8_t b) override {
        return 0;
    }

    int8_t ReadInt8() override {
        return (int8)_stream->readByte();
    }
    int16_t ReadInt16() override {
        return _stream->readSint16LE();
    }
    int32_t ReadInt32() override {
        return _stream->readSint32LE();
    }
    int64_t ReadInt64() override {
        return _stream->readSint64LE();
    }
    bool ReadBool() override {
        return _stream->readByte() != 0;
    }
    size_t ReadArray(void *buffer, size_t elem_size, size_t count) override {
        return _stream->read(buffer, elem_size * count) / elem_size;
    }
    size_t ReadArrayOfInt8(int8_t *buffer, size_t count) override {
        return _stream->read(buffer, count);
    }
    size_t ReadArrayOfInt16(int16_t *buffer, size_t count) override {
        for (size_t i = 0; i < count; ++i)
            *buffer++ = _stream->readSint16LE();
        return count;
    }
    size_t ReadArrayOfInt32(int32_t *buffer, size_t count) override {
        for (size_t i = 0; i < count; ++i)
            *buffer++ = _stream->readSint32LE();
        return count;
    }
    size_t ReadArrayOfInt64(int64_t *buffer, size_t count) override {
        for (size_t i = 0; i < count; ++i)
            *buffer++ = _stream->readSint64LE();
        return count;
    }

    size_t WriteInt8(int8_t val) override {
        return 0;
    }
    size_t WriteInt16(int16_t val) override {
        return 0;
    }
    size_t WriteInt32(int32_t val) override {
        return 0;
    }
    size_t WriteInt64(int64_t val) override {
        return 0;
    }
    size_t WriteBool(bool val) override {
        return 0;
    }
    size_t WriteArray(const void *buffer, size_t elem_size, size_t count) override {
        return 0;
    }
    size_t WriteArrayOfInt8(const int8_t *buffer, size_t count) override {
        return 0;
    }
    size_t WriteArrayOfInt16(const int16_t *buffer, size_t count) override {
        return 0;
    }
    size_t WriteArrayOfInt32(const int32_t *buffer, size_t count) override {
        return 0;
    }
    size_t WriteArrayOfInt64(const int64_t *buffer, size_t count) override {
        return 0;
    }

    soff_t Seek(soff_t offset, StreamSeek origin = kSeekCurrent) override {
        return _stream->seek(offset, origin);
    }

    bool GetError() const override {
        return _stream->err();
    }
    bool Flush() override {
        return true;
    }
};

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

#endif