bufferwritertemplate.h

Linux下比较早的基于命令行的DVD播放器

//
// Copyright (c) 2003 by Istv醤 V醨adi
//
// This file is part of dxr3Player, a DVD player written specifically 
// for the DXR3 (aka Hollywood+) decoder card.

// 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

#ifndef DXR3PLAYER_BUFFERWRITERTEMPLATE_H
#define DXR3PLAYER_BUFFERWRITERTEMPLATE_H
//------------------------------------------------------------------------------

#include <cstdlib>
#include <cassert>

//------------------------------------------------------------------------------

/**
 * Buffer writer template. 
 */
template <class BufferT>
class BufferWriterTemplate : public BufferT
{
private:
    /**
     * The current offset.
     */
    size_t offset;

public:
    /**
     * Construct the writer.
     */
    BufferWriterTemplate();

    /**
     * Get the offset.
     */
    size_t getOffset() const;

    /**
     * Set the offset.
     */
    void setOffset(size_t o);

    /**
     * Write a byte into the buffer.
     */
    void write(unsigned char c);

    /**
     * Write a number of bytes into the buffer.
     */
    void write(const void* src, size_t length);

    /**
     * Write a 16-bit value.
     */
    void write16(unsigned x);

    /**
     * Import 'getData' from the buffer class.
     */
    BufferT::getData;

    /**
     * Import 'ensureCapacity' from the buffer class.
     */
    BufferT::ensureCapacity;
};

//------------------------------------------------------------------------------

/**
 * Writer for buffers that can also write individual bits or sequences
 * of bits.
 */
template <class BufferT>
class BufferBitWriterTemplate : public BufferWriterTemplate<BufferT>
{
private:
    /**
     * The current byte being written for bit-level writing.
     */
    unsigned char currentByte;

    /**
     * The number of bits remaining of the current byte.
     */
    unsigned char bitsLeft;

public:
    /**
     * Construct a bit writer.
     */
    BufferBitWriterTemplate();

    /**
     * Write a byte into the buffer.
     */
    void write(unsigned char c);

    /**
     * Write a number of bytes into the buffer.
     */
    void write(const void* src, size_t length);

    /**
     * Write a 16-bit value.
     */
    void write16(unsigned x);

    /**
     * Write the given number of bits.
     */
    void writeBits(unsigned x, size_t bitsToWrite);

    /**
     * Finalize the current byte.
     */
    void finishCurrentByte();
};

//------------------------------------------------------------------------------

/**
 * Buffer reference. It contains a pointer to a buffer of a certain
 * type, and provides an interface for the buffer writers.
 */
template <class BufferT>
class WritableBufferReferenceTemplate
{
private:
    /**
     * The pointer to the buffer.
     */
    BufferT* buffer;

public:
    /**
     * Construct a buffer reference with no pointer.
     */
    WritableBufferReferenceTemplate();

    /**
     * Construct a buffer reference pointing to the given buffer.
     */
    explicit WritableBufferReferenceTemplate(BufferT& buffer);

    /**
     * Set the buffer.
     */
    void setBuffer(BufferT& buf);

    /**
     * Get the buffer.
     */
    BufferT& getBuffer() const;

    /**
     * Get the data of the buffer.
     */
    unsigned char* getData() const;

    /**
     * Ensure that the buffer has the given number of bytes.
     */
    void ensureCapacity(size_t capacity) const;
};

//------------------------------------------------------------------------------
// Template definitions
//------------------------------------------------------------------------------

template <class BufferT>
inline BufferWriterTemplate<BufferT>::BufferWriterTemplate() : offset(0)
{
}

//------------------------------------------------------------------------------

template <class BufferT>
inline size_t BufferWriterTemplate<BufferT>::getOffset() const
{
    return offset;
}

//------------------------------------------------------------------------------

template <class BufferT>
inline void BufferWriterTemplate<BufferT>::setOffset(size_t o)
{
    offset = o;
}

//------------------------------------------------------------------------------

template <class BufferT>
inline void BufferWriterTemplate<BufferT>::write(unsigned char c)
{
    ensureCapacity(offset + 1);

    getData()[offset++] = c;
}

//------------------------------------------------------------------------------

template <class BufferT>
inline void BufferWriterTemplate<BufferT>::write(const void* src, size_t length)
{
    ensureCapacity(offset + length);
    
    memcpy(getData()+offset, src, length);
    offset += length;
}

//------------------------------------------------------------------------------

template <class BufferT>
inline void BufferWriterTemplate<BufferT>::write16(unsigned x)
{
    write( (x>>8)&0xff );
    write( (x>>0)&0xff );
}

//------------------------------------------------------------------------------
//------------------------------------------------------------------------------

template <class BufferT>
inline BufferBitWriterTemplate<BufferT>::BufferBitWriterTemplate() :
    currentByte(0),
    bitsLeft(8)
{
}

//------------------------------------------------------------------------------

template <class BufferT>
inline void BufferBitWriterTemplate<BufferT>::write(unsigned char c)
{
    assert(bitsLeft==8);
    BufferWriterTemplate<BufferT>::write(c);
}

//------------------------------------------------------------------------------

template <class BufferT>
inline void BufferBitWriterTemplate<BufferT>::write(const void* src, size_t length)
{
    assert(bitsLeft==8);
    BufferWriterTemplate<BufferT>::write(src, length);
}

//------------------------------------------------------------------------------

template <class BufferT>
inline void BufferBitWriterTemplate<BufferT>::write16(unsigned x)
{
    assert(bitsLeft==8);
    BufferWriterTemplate<BufferT>::write16(x);
}

//------------------------------------------------------------------------------

template <class BufferT>
void BufferBitWriterTemplate<BufferT>::writeBits(unsigned x, size_t bitsToWrite)
{
    while(bitsToWrite>0) {
        x &= (1<<bitsToWrite)-1;
        if (bitsToWrite >= bitsLeft) {
            currentByte |= x >> (bitsToWrite - bitsLeft);
            bitsToWrite -= bitsLeft;

            BufferWriterTemplate<BufferT>::write(currentByte);

            currentByte = 0; bitsLeft = 8;
        } else {
            currentByte |= x << (bitsLeft - bitsToWrite);

            bitsLeft -= bitsToWrite;
            bitsToWrite = 0;
        }
    }
}

//------------------------------------------------------------------------------

template <class BufferT>
inline void BufferBitWriterTemplate<BufferT>::finishCurrentByte()
{
    if (bitsLeft<8) {
        BufferWriterTemplate<BufferT>::write(currentByte);
        currentByte = 0;
        bitsLeft = 8;
    }
}

//------------------------------------------------------------------------------
//------------------------------------------------------------------------------

template <class BufferT>
inline WritableBufferReferenceTemplate<BufferT>::
WritableBufferReferenceTemplate() :
    buffer(0)
{
}

//------------------------------------------------------------------------------

template <class BufferT>
inline WritableBufferReferenceTemplate<BufferT>::
WritableBufferReferenceTemplate(BufferT& buffer) :
    buffer(&buffer)
{
}

//------------------------------------------------------------------------------

template <class BufferT>
inline void WritableBufferReferenceTemplate<BufferT>::setBuffer(BufferT& buf)
{
    buffer = &buf;
}

//------------------------------------------------------------------------------

template <class BufferT>
inline BufferT& WritableBufferReferenceTemplate<BufferT>::getBuffer() const
{
    assert(buffer!=0);
    return *buffer;
}

//------------------------------------------------------------------------------

template <class BufferT>
inline unsigned char* WritableBufferReferenceTemplate<BufferT>::getData() const
{
    assert(buffer!=0);
    return buffer->getData();
}

//------------------------------------------------------------------------------

template <class BufferT>
inline void WritableBufferReferenceTemplate<BufferT>::
ensureCapacity(size_t capacity) const
{
    assert(buffer!=0);
    buffer->ensureCapacity(capacity);
}

//------------------------------------------------------------------------------
#endif // DXR3PLAYER_BUFFERWRITERTEMPLATE_H

// Local variables:
// mode: c++
// End: