source: libebml/src/MemIOCallback.cpp @ 1443

/****************************************************************************
** libebml : parse EBML files, see http://embl.sourceforge.net/
**
** <file/class description>
**
** Copyright (C) 2003 Jory Stone.  All rights reserved.
**
** This library is free software; you can redistribute it and/or
** modify it under the terms of the GNU Lesser General Public
** License as published by the Free Software Foundation; either
** version 2.1 of the License, or (at your option) any later version.
** 
** This library 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
** Lesser General Public License for more details.
** 
** You should have received a copy of the GNU Lesser General Public
** License along with this library; if not, write to the Free Software
** Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
**
** See http://www.matroska.org/license/lgpl/ for LGPL licensing information.
**
** Contact license@matroska.org if any conditions of this licensing are
** not clear to you.
**
**********************************************************************/

/*!
        \file
        \version \$Id: MemIOCallback.cpp 693 2004-07-31 08:56:28Z robux4 $
        \author Jory Stone <jcsston @ toughguy.net>
*/

#include "ebml/MemIOCallback.h"
#include "ebml/Debug.h"
#include "ebml/EbmlConfig.h"

START_LIBEBML_NAMESPACE

MemIOCallback::MemIOCallback(uint64 DefaultSize)
{
        //The default size of the buffer is 128 bytes
        dataBuffer = (binary *)malloc(DefaultSize);
        if (dataBuffer == NULL) {
                mOk = false;
                std::stringstream Msg;
                Msg << "Failed to alloc memory block of size ";
// not working with VC6         Msg << DefaultSize;
                mLastErrorStr = Msg.str();                              
                return;
        }
        
        dataBufferMemorySize = DefaultSize;
        dataBufferPos = 0;
        dataBufferTotalSize = 0;
        mOk = true;
}

MemIOCallback::~MemIOCallback()
{
        if (dataBuffer != NULL)
                free(dataBuffer);
}

uint32 MemIOCallback::read(void *Buffer, size_t Size)
{
        if (Buffer == NULL || Size < 1)
                return 0;
        //If the size is larger than than the amount left in the buffer
        if (Size + dataBufferPos > dataBufferTotalSize)
        {
                //We will only return the remaining data
                memcpy(Buffer, dataBuffer + dataBufferPos, dataBufferTotalSize - dataBufferPos);
        uint64 oldDataPos = dataBufferPos;
                dataBufferPos = dataBufferTotalSize;
                return dataBufferTotalSize - oldDataPos;
        }
                
        //Well... We made it here, so do a quick and simple copy
        memcpy(Buffer, dataBuffer+dataBufferPos, Size);
        dataBufferPos += Size;

        return Size;
}

void MemIOCallback::setFilePointer(int64 Offset, seek_mode Mode)
{
        if (Mode == seek_beginning)
                dataBufferPos = Offset;
        else if (Mode == seek_current)
                dataBufferPos = dataBufferPos + Offset;
        else if (Mode == seek_end)
                dataBufferPos = dataBufferTotalSize + Offset;
}

size_t MemIOCallback::write(const void *Buffer, size_t Size)
{
        if (dataBufferMemorySize < dataBufferPos + Size)
        {
                //We need more memory!
                dataBuffer = (binary *)realloc((void *)dataBuffer, dataBufferPos + Size);               
        }
        memcpy(dataBuffer+dataBufferPos, Buffer, Size);
        dataBufferPos += Size;
        if (dataBufferPos > dataBufferTotalSize)
                dataBufferTotalSize = dataBufferPos;

        return Size;
}

uint32 MemIOCallback::write(IOCallback & IOToRead, size_t Size)
{
        if (dataBufferMemorySize < dataBufferPos + Size)
        {
                //We need more memory!
                dataBuffer = (binary *)realloc((void *)dataBuffer, dataBufferPos + Size);               
        }
        IOToRead.readFully(&dataBuffer[dataBufferPos], Size);
        dataBufferTotalSize = Size;
        return Size;
}

END_LIBEBML_NAMESPACE