proc_zlib.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_SP_ZLIB class. Implements a compression processor for the ZLIB
**  compression library. See PQDIF documentation for details.
**  --------------------------------------------------------------------------
**
**  File name:          $Workfile: proc_zlib.cpp $
**  Last modified:      $Modtime: 3/24/98 10:43a $
**  Last modified by:   $Author: Rob $
**
**  VCS archive path:   $Archive: /Hank/DMM/FirmWare/Level3/ObDatMgr/proc_zlib.cpp $
**  VCS revision:       $Revision: 5 $ 
*/
#include "PQDIF_classes.h"
    
//  Public-domain ZLIB code
#include "zlib.h"



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

CPQDIF_SP_ZLIB::CPQDIF_SP_ZLIB()
    {
    //  Allocate input buffer
    AllocateBuffer( 16384 );

    //  Allocate output buffer
    m_sizeOutput = 16384;
    m_bufferOutput = new BYTE[ m_sizeOutput ];
    }


CPQDIF_SP_ZLIB::~CPQDIF_SP_ZLIB()
    {
    delete [] m_bufferOutput;
    }


bool CPQDIF_SP_ZLIB::StreamEncode( void )
    {
    bool    status = TRUE;
    bool    haveData = FALSE;
    long    sizeActual = 0;

    z_stream    c_stream; /* compression stream */
    int         err;

    //  Init ZLIB for best compression ratio
    memset( &c_stream, 0, sizeof( c_stream ) );
    c_stream.zalloc = (alloc_func)0;
    c_stream.zfree = (free_func)0;
    c_stream.opaque = (voidpf)0;
    err = deflateInit( &c_stream, Z_BEST_COMPRESSION );

    //  Init output buffer
    c_stream.next_out  = m_bufferOutput;
    c_stream.avail_out = m_sizeOutput;
    c_stream.total_out = 0;

    do
        {
        //  Fill up the input buffer?
        if( c_stream.avail_in == 0 )
            {
            haveData = m_pstrm->ProcessRead( m_buffer, m_maxBuffer, sizeActual );
            //  End of data?
            if( !haveData )
                break;
            c_stream.next_in  = m_buffer;
            c_stream.avail_in = sizeActual;
            }        

        //  Compress!
        err = deflate( &c_stream, Z_NO_FLUSH );

        //  Flush output buffer?
        if( c_stream.total_out > 0 )
            {
            //  Suck up what's in there
            m_checksum = adler32( m_checksum, (const Bytef *) m_bufferOutput, c_stream.total_out );
            status = m_pstrm->ProcessWrite( m_bufferOutput, c_stream.total_out );

            //  Re-init the output buffer
            c_stream.next_out  = m_bufferOutput;
            c_stream.avail_out = m_sizeOutput;
            c_stream.total_out = 0;
            }
        }
    while( err == Z_OK );

    //  Finish flushing it out
    do
        {
        //  Compress!
        err = deflate( &c_stream, Z_FINISH );

        //  Flush output buffer?
        if( c_stream.total_out > 0 )
            {
            //  Suck up what's in there
            m_checksum = adler32( m_checksum, (const Bytef *) m_bufferOutput, c_stream.total_out );
            status = m_pstrm->ProcessWrite( m_bufferOutput, c_stream.total_out );

            //  Re-init the output buffer
            c_stream.next_out  = m_bufferOutput;
            c_stream.avail_out = m_sizeOutput;
            c_stream.total_out = 0;
            }
        }
    while( err != Z_STREAM_END );

    err = deflateEnd(&c_stream);

    return status;
    }


bool CPQDIF_SP_ZLIB::StreamDecode( void )
    {
    bool        status = FALSE;
    bool        haveData;
    long        sizeActual = 0;

    z_stream    c_stream; /* decompression stream */
    int         err;

    //  Init
    memset( &c_stream, 0, sizeof( c_stream ) );
    c_stream.zalloc = (alloc_func)0;
    c_stream.zfree = (free_func)0;
    c_stream.opaque = (voidpf)0;
    err = inflateInit(&c_stream);

    //  Init output buffer
    c_stream.next_out  = m_bufferOutput;
    c_stream.avail_out = m_sizeOutput;
    c_stream.total_out = 0;

    do
        {
        //  Fill up the input buffer?
        if( c_stream.avail_in == 0 )
            {
            haveData = m_pstrm->ProcessRead( m_buffer, m_maxBuffer, sizeActual );
            if( !haveData )
                {
                //  End of data
                break;
                }
            c_stream.next_in  = m_buffer;
            c_stream.avail_in = sizeActual;
            }        

        //  Compress!
        err = inflate( &c_stream, Z_NO_FLUSH );

        //  Flush output buffer?
        if( c_stream.total_out > 0 )
            {
            //  Suck up what's in there
            status = m_pstrm->ProcessWrite( m_bufferOutput, c_stream.total_out );

            //  Re-init the output buffer
            c_stream.next_out  = m_bufferOutput;
            c_stream.avail_out = m_sizeOutput;
            c_stream.total_out = 0;
            }

        if (err == Z_STREAM_END) 
            break;
        }
    while( err == Z_OK );

    err = inflateEnd(&c_stream);

    return status;
    }