memstream.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/>.
 *
 */

#ifndef COMMON_MEMSTREAM_H
#define COMMON_MEMSTREAM_H

#include "common/stream.h"
#include "common/types.h"
#include "common/util.h"

namespace Common {

class MemoryReadStream : virtual public SeekableReadStream {
private:
    struct CastFreeDeleter {
        inline void operator()(const byte *object) {
            free(const_cast<byte *>(object));
        }
    };

    // Note when using SharedPtr, then deleting is handled
    // by SharedPtr and not by CastFreeDeleter
    Common::DisposablePtr<const byte, CastFreeDeleter> _ptrOrig;
    const byte *_ptr;
    uint32 _size;
    uint32 _pos;
    bool _eos;

public:
    MemoryReadStream(MemoryReadStream &&other) : _ptrOrig(Common::move(other._ptrOrig)), _ptr(other._ptr), _size(other._size), _pos(other._pos), _eos(other._eos) {
        // other must remaining in a valid state. Let's make it into zero-sized stream.
        other._ptr = nullptr;
        other._size = 0;
        other._pos = 0;
        other._eos = false;
    }

    MemoryReadStream(const byte *dataPtr, uint32 dataSize, DisposeAfterUse::Flag disposeMemory = DisposeAfterUse::NO) :
        _ptrOrig(dataPtr, disposeMemory),
        _ptr(dataPtr),
        _size(dataSize),
        _pos(0),
        _eos(false) {}

    MemoryReadStream(SharedPtr<byte> dataPtr, uint32 dataSize) :
        _ptrOrig(dataPtr),
        _ptr(dataPtr.get()),
        _size(dataSize),
        _pos(0),
        _eos(false) {}

    uint32 read(void *dataPtr, uint32 dataSize);

    bool eos() const { return _eos; }
    void clearErr() { _eos = false; }

    int64 pos() const { return _pos; }
    int64 size() const { return _size; }

    bool seek(int64 offs, int whence = SEEK_SET);
};


class MemoryReadStreamEndian : public MemoryReadStream, public SeekableReadStreamEndian {
public:
    MemoryReadStreamEndian(const byte *buf, uint32 len, bool bigEndian, DisposeAfterUse::Flag disposeMemory = DisposeAfterUse::NO)
        : MemoryReadStream(buf, len, disposeMemory), SeekableReadStreamEndian(bigEndian), ReadStreamEndian(bigEndian) {}

    int64 pos() const override { return MemoryReadStream::pos(); }
    int64 size() const override { return MemoryReadStream::size(); }

    bool seek(int64 offs, int whence = SEEK_SET) override { return MemoryReadStream::seek(offs, whence); }

    bool skip(uint32 offset) override { return MemoryReadStream::seek(offset, SEEK_CUR); }
};

class MemoryWriteStream : public SeekableWriteStream {
private:
    const uint32 _bufSize;
protected:
    byte *_ptr;
    uint32 _pos;
    bool _err;
public:
    MemoryWriteStream(byte *buf, uint32 len) : _ptr(buf), _bufSize(len), _pos(0), _err(false) {}

    uint32 write(const void *dataPtr, uint32 dataSize) override {
        // Write at most as many bytes as are still available...
        if (dataSize > _bufSize - _pos) {
            dataSize = _bufSize - _pos;
            // We couldn't write all the data => set error indicator
            _err = true;
        }
        memcpy(_ptr, dataPtr, dataSize);
        _ptr += dataSize;
        _pos += dataSize;
        return dataSize;
    }

    int64 pos() const override { return _pos; }
    int64 size() const override { return _bufSize; }

    bool err() const override { return _err; }
    void clearErr() override { _err = false; }

    bool seek(int64 offset, int whence = SEEK_SET) override { return false; }
};

class SeekableMemoryWriteStream : public MemoryWriteStream {
private:
    byte *_ptrOrig;
public:
    SeekableMemoryWriteStream(byte *buf, uint32 len) : MemoryWriteStream(buf, len), _ptrOrig(buf) {}

    bool seek(int64 offset, int whence = SEEK_SET) override {
        switch (whence) {
        case SEEK_END:
            // SEEK_END works just like SEEK_SET, only 'reversed',
            // i.e. from the end.
            offset = size() + offset;
            // Fall through
        case SEEK_SET:
            // Fall through
        default:
            _ptr = _ptrOrig + offset;
            _pos = offset;
            break;
        case SEEK_CUR:
            _ptr += offset;
            _pos += offset;
            break;
        }
        // Post-Condition
        if ((int32)_pos > size()) {
            _pos = size();
            _ptr = _ptrOrig + _pos;
        }

        return true;
    }
};


class MemoryWriteStreamDynamic : public SeekableWriteStream {
protected:
    uint32 _capacity;
    uint32 _size;
    byte *_ptr;
    byte *_data;
    uint32 _pos;
    DisposeAfterUse::Flag _disposeMemory;

    void ensureCapacity(uint32 capacity) {
        if (capacity <= _capacity)
            return;

        byte *old_data = _data;

        _capacity = capacity;
        _data = (byte *)malloc(_capacity);
        _ptr = _data + _pos;

        if (old_data) {
            // Copy old data
            memcpy(_data, old_data, _size);
            free(old_data);
        }
    }

    static size_t roundUpCapacity(size_t capacity) {
        size_t capa = 8;
        while (capa < capacity)
            capa <<= 1;
        return capa;
    }
public:
    explicit MemoryWriteStreamDynamic(DisposeAfterUse::Flag disposeMemory) : _capacity(0), _size(0), _ptr(nullptr), _data(nullptr), _pos(0), _disposeMemory(disposeMemory) {}

    ~MemoryWriteStreamDynamic() {
        if (_disposeMemory)
            free(_data);
    }

    uint32 write(const void *dataPtr, uint32 dataSize) override {
        if ((_pos + dataSize) >= _capacity)
            ensureCapacity(roundUpCapacity(_pos + dataSize));

        memcpy(_ptr, dataPtr, dataSize);
        _ptr += dataSize;
        _pos += dataSize;
        if (_pos > _size)
            _size = _pos;
        return dataSize;
    }

    int64 pos() const override { return _pos; }
    int64 size() const override { return _size; }

    byte *getData() { return _data; }

    bool seek(int64 offs, int whence = SEEK_SET) override {
        // Pre-Condition
        assert(_pos <= _size);
        switch (whence) {
        case SEEK_END:
            // SEEK_END works just like SEEK_SET, only 'reversed', i.e. from the end.
            offs = _size + offs;
            // Fall through
        case SEEK_SET:
            // Fall through
        default:
            _ptr = _data + offs;
            _pos = offs;
            break;

        case SEEK_CUR:
            _ptr += offs;
            _pos += offs;
            break;
        }

        assert(_pos <= _size);
        return true;
    }
};

class MemoryReadWriteStream : public SeekableReadStream, public SeekableWriteStream {
private:
    uint32 _capacity;
    uint32 _size;
    byte *_data;
    uint32 _writePos, _readPos, _pos, _length;
    DisposeAfterUse::Flag _disposeMemory;
    bool _eos;

    void ensureCapacity(uint32 new_len) {
        if (new_len <= _capacity)
            return;

        byte *old_data = _data;
        uint32 oldCapacity = _capacity;

        _capacity = MAX(new_len + 32, _capacity * 2);
        _data = (byte *)malloc(_capacity);

        if (old_data) {
            // Copy old data
            if (_readPos < _writePos) {
                memcpy(_data, old_data + _readPos, _writePos - _readPos);
                _writePos = _length;
                _readPos = 0;
            } else {
                memcpy(_data, old_data + _readPos, oldCapacity - _readPos);
                memcpy(_data + oldCapacity - _readPos, old_data, _writePos);
                _writePos = _length;
                _readPos = 0;
            }
            free(old_data);
        }
    }
public:
    explicit MemoryReadWriteStream(DisposeAfterUse::Flag disposeMemory) : _capacity(0), _size(0), _data(nullptr), _writePos(0), _readPos(0), _pos(0), _length(0), _disposeMemory(disposeMemory), _eos(false) {}

    ~MemoryReadWriteStream() {
        if (_disposeMemory)
            free(_data);
    }

    uint32 write(const void *dataPtr, uint32 dataSize) override {
        if (dataSize == 0) {
            return 0;
        }
        ensureCapacity(_length + dataSize);
        if (_writePos + dataSize < _capacity) {
            memcpy(_data + _writePos, dataPtr, dataSize);
        } else {
            memcpy(_data + _writePos, dataPtr, _capacity - _writePos);
            const byte *shiftedPtr = (const byte *)dataPtr + _capacity - _writePos;
            memcpy(_data, shiftedPtr, dataSize - (_capacity - _writePos));
        }
        _writePos = (_writePos + dataSize) % _capacity;
        _pos += dataSize;
        _length += dataSize;
        if (_pos > _size)
            _size = _pos;
        return dataSize;
    }

    uint32 read(void *dataPtr, uint32 dataSize) override {
        if (_length < dataSize) {
            dataSize = _length;
            _eos = true;
        }
        if (dataSize == 0 || _capacity == 0) return 0;
        if (_readPos + dataSize < _capacity) {
            memcpy(dataPtr, _data + _readPos, dataSize);
        } else {
            memcpy(dataPtr, _data + _readPos, _capacity - _readPos);
            byte *shiftedPtr = (byte *)dataPtr + _capacity - _readPos;
            memcpy(shiftedPtr, _data, dataSize - (_capacity - _readPos));
        }
        _readPos = (_readPos + dataSize) % _capacity;
        _length -= dataSize;
        return dataSize;
    }

    bool seek(int64 offset, int whence) override {
        switch (whence) {
        case SEEK_END:
            // SEEK_END works just like SEEK_SET, only 'reversed',
            // i.e. from the end.
            offset = size() + offset;
            // Fall through
        case SEEK_SET:
            // Fall through
        default:
            _writePos = offset;
            _readPos = offset;
            break;
        case SEEK_CUR:
            // Not supported
            return false;
        }

        // Post-Condition
        _eos = (int64)_readPos >= size();
        return true;
    }

    int64 pos() const override { return _pos - _length; }
    int64 size() const override { return _size; }
    bool eos() const override { return _eos; }
    void clearErr() override { _eos = false; }

    byte *getData() { return _data; }
};

class MemorySeekableReadWriteStream : public SeekableReadStream, public SeekableWriteStream {
private:
    const uint32 _bufSize;
    byte *_ptrOrig;
    byte *_ptr;
    uint32 _pos;
    bool _err;
    bool _eos;
    DisposeAfterUse::Flag _disposeMemory;

public:
    MemorySeekableReadWriteStream(byte *buf, uint32 len, DisposeAfterUse::Flag disposeMemory = DisposeAfterUse::NO) :
            _ptrOrig(buf), _ptr(buf), _bufSize(len), _pos(0), _err(false), _eos(false), _disposeMemory(disposeMemory) {}

    ~MemorySeekableReadWriteStream() {
        if (_disposeMemory) {
            free(_ptrOrig);
        }
    }

    uint32 write(const void *dataPtr, uint32 dataSize) override {
        // Write at most as many bytes as are still available...
        if (dataSize > _bufSize - _pos) {
            dataSize = _bufSize - _pos;
            // We couldn't write all the data => set error indicator
            _err = true;
        }
        memcpy(_ptr, dataPtr, dataSize);
        _ptr += dataSize;
        _pos += dataSize;
        return dataSize;
    }

    int64 pos() const override { return _pos; }
    int64 size() const override { return _bufSize; }

    bool eos() const override { return _eos; }

    bool err() const override { return _err; }
    void clearErr() override { _err = false; }

    inline void rewind(int32 bytes) {
        seek(pos() - bytes);
    }

    byte peekByte() {
        if (_bufSize - _pos <= 0) {
            _eos = true;
            return 0;
        }
        return *_ptr;
    }

    uint32 read(void *dataPtr, uint32 dataSize) override {
        // Read at most as many bytes as are still available...
        if (dataSize > _bufSize - _pos) {
            dataSize = _bufSize - _pos;
            _eos = true;
        }
        memcpy(dataPtr, _ptr, dataSize);

        _ptr += dataSize;
        _pos += dataSize;

        return dataSize;
    }

    bool seek(int64 offset, int whence = SEEK_SET) override {
        switch (whence) {
        case SEEK_END:
            // SEEK_END works just like SEEK_SET, only 'reversed',
            // i.e. from the end.
            offset = size() + offset;
            // Fall through
        case SEEK_SET:
            // Fall through
        default:
            _ptr = _ptrOrig + offset;
            _pos = offset;
            break;
        case SEEK_CUR:
            _ptr += offset;
            _pos += offset;
            break;
        }
        // Post-Condition
        if ((int32)_pos > size()) {
            _pos = size();
            _ptr = _ptrOrig + _pos;
        }

        _eos = false;
        return true;
    }
};

} // End of namespace Common

#endif