str_chnk.cpp

PQDIF软件包(SDK,Software Development Kit),它能转换、生成并且显示PQDIF文件.对于开发电力系统的数据输出非常有用。

/*
**  CPQDIF_S_Chunk class. A stream I/O implementing which supports "chunks."
**  This will allow a PQDIF file to be embedded in a database binary field,
**  for example.
**  --------------------------------------------------------------------------
**
**  File name:          $Workfile: str_chnk.cpp $
**  Last modified:      $Modtime: 8/22/97 11:12a $
**  Last modified by:   $Author: Rob $
**
**  VCS archive path:   $Archive: /ElectrotekLibs/PQDIF/BasicPQDIF/str_chnk.cpp $
**  VCS revision:       $Revision: 3 $ 
*/
#include "PQDIF_classes.h"


//  Construction
//  ============

CPQDIF_S_Chunk::CPQDIF_S_Chunk()
    {
    m_chunkRead = NULL;
    m_sizeChunkRead = 0;
    m_chunkWrite.SetSize( 0, 64 );
    m_posChunk = 0;
    }

CPQDIF_S_Chunk::~CPQDIF_S_Chunk()
    {
    //  Nothing to delete
    }


bool CPQDIF_S_Chunk::SetInput( BYTE * chunk, long size )
    {
    bool    status = FALSE;
    
    if( chunk && size > 0 )
        {
        m_chunkRead = chunk;
        m_sizeChunkRead = size;
        status = TRUE;
        }
    else
        {
        m_chunkRead = NULL;
        m_sizeChunkRead = 0;
        }

    return status;
    }


bool CPQDIF_S_Chunk::GetOutputSize( long& size )
    {
    bool    status = FALSE;

    size = m_chunkWrite.GetSize();
    status = TRUE;

    return status;
    }


bool CPQDIF_S_Chunk::GetOutput( BYTE * chunk, long maxSize )
    {
    bool    status = FALSE;
    long    sizeActual;
    
    if( chunk && maxSize > 0 )
        {
        sizeActual = min( maxSize, m_chunkWrite.GetSize() );
        memcpy( chunk, (BYTE *) m_chunkWrite.GetData(), sizeActual );
        status = TRUE;
        }

    return status;
    }


bool CPQDIF_S_Chunk::SeekPos( long pos )
    {
    bool    status = FALSE;
    
    m_posChunk = pos;
    status = TRUE;

    return status;
    }

bool CPQDIF_S_Chunk::SeekEnd( void )
    {
    bool    status = FALSE;
    
    //  Are we in read mode?
    if( m_chunkRead )
        {
        m_posChunk = m_sizeChunkRead;
        status = TRUE;
        }
    else
        {
        //  Nope, write mode.
        m_posChunk = m_chunkWrite.GetSize();
        status = TRUE;
        }

    return status;
    }

bool CPQDIF_S_Chunk::GetPos( long& pos )
    {
    bool    status = FALSE;
    
    pos = m_posChunk;
    status = TRUE;

    return status;
    }

BYTE * CPQDIF_S_Chunk::ReadBlock( long size, long& actualSize )
    {
    BYTE *  buffRet = NULL;
    long    sizeAvailable;
    long    sizeRead;
    bool    status = FALSE;
    
    //  Init
    sizeRead = 0;

    //  Clear buffers
    m_buffRead.SetSize( 0, 64 );
    m_posRead = 0;
    m_buffWrite.SetSize( 0, 64 );

    //  Do we have a valid chunk to read?
    if( m_chunkRead && m_sizeChunkRead > 0 && m_posChunk > 0 )
        {
        //  Attempt to read the block
        sizeAvailable = m_sizeChunkRead - m_posChunk;
        if( sizeAvailable > size )
            {
            sizeRead = size;
            }
        else
            {
            sizeRead = sizeAvailable;
            }

        //  Did we get anything?
        //  (If not, we are at the end of the chunk and will return NULL.)
        if( sizeRead > 0 )
            {
            //  Increment past the part we just read.
            m_posChunk += sizeRead;

            //  Size the buffer first & then copy the block
            m_buffRead.SetSize( sizeRead );
            memcpy( m_buffRead.GetData(), m_chunkRead, sizeRead );

            //  We got the block -- now decode it.
            status = ExecuteProcessorDecode();
            if( status )
                {
                //  Pass back the decoded buffer
                buffRet = m_buffWrite.GetData();
                actualSize = (long) m_buffWrite.GetSize();
                }
            }
        }

    return buffRet;
    }


bool CPQDIF_S_Chunk::WriteBlock( long &sizeActual )
    {
    bool    status = FALSE;
    BYTE *  pdataChunk;
    
    //  Init
    m_buffWrite.SetSize( 0, 64 );
    sizeActual = 0;

    //  Encode the block
    status = ExecuteProcessorEncode();
    if( status )
        {
        //  The write buffer should contain the output
        sizeActual = m_buffWrite.GetSize();
        if( sizeActual > 0 )
            {
            //  Force the position to the end of the chunk...
            //  and resize the write chunk.
            m_posChunk = m_chunkWrite.GetSize();
            m_chunkWrite.SetSize( m_posChunk + sizeActual );

            //  Find where this block goes
            pdataChunk = (BYTE *) m_buffWrite.GetData();
            pdataChunk += m_posChunk;

            //  Copy over the block
            memcpy( pdataChunk, (BYTE *) m_buffWrite.GetData(), sizeActual );
            m_posChunk += sizeActual;
            status = TRUE;
            }
        }

    return status;
    }