examples.cpp

研读AxCrypt对加解密的处理方法

/*! \file
    \brief Implementation of various patterns and examples to start with

    @(#) $Id: Examples.cpp,v 1.2 2004/01/01 20:05:54 svante Exp $

    AxPipe - Binary Stream Framework

    Copyright (C) 2003 Svante Seleborg/Axon Data, All rights reserved.

    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

    The author may be reached at mailto:[e-mail] and http://axpipe.sourceforge.net

    Why is this framework released as GPL and not LGPL? See http://www.gnu.org/philosophy/why-not-lgpl.html

----
\verbatim
    Examples.cpp                    Implementation of various patterns and examples to start with

    E-mail                          YYYY-MM-DD              Reason
    [e-mail]              2003-12-01              Initial
\endverbatim
*/
#include "stdafx.h"
#include "Examples.h"

#include "AxAssert.h"
#define AXLIB_ASSERT_FILE "Examples.cpp"

/// \brief A dummy filter that does nothing, but provides the basic loop
///
/// Do the real stuff here. Use Open(), Read(), Pump() and Close().
/// This is a copying sample. It does nothing, but demonstrates possible techniques.
/// Always initialize everything at start - you may be called any number of times.
void CFilterNop::InFilter() {
    AxPipe::CSeg *pInSeg;
    size_t cbIn;
    Open();
    // End of this stream is signalled by NULL
    while (pInSeg = Read(), (pInSeg && (cbIn = pInSeg->Len()))) {
        // We're not guaranteed to get an output segment of the required
        // size, so we must loop here.
        while (cbIn) {
            AxPipe::CSeg *pOutSeg = GetSeg(cbIn);

            if (!pOutSeg) {
                return;         // Error of some kind
            }
            // This might be a good place to do something...
            memcpy(pOutSeg->PtrWr(), pInSeg->PtrRd(), pOutSeg->Len());

            cbIn -= pOutSeg->Len();
            Pump(pOutSeg);
        }
        // We're done with the inbuffer, let it go.
        pInSeg->Release();
    }
    Close();
    // This might be a good place to flush, if there's anything to flush. There's
    // no explicit Flush() method for pull-style filters. When returning, you should
    // be ready for a new call to InFilter().
}

/// \brief The overridden In()
///
/// This is what must be overriden to actually do anything. The following
/// is a sample that picks data from one, and then the other, until end
/// of all streams is reached.
/// \return A segment from each input stream in round-robin fashion until all are empty.
AxPipe::CSeg *
CJoinInterleave::In() {
    static int nThisIx = 0;
    int nStartIx = nThisIx;
    do {
        if (!StreamEmpty(nThisIx)) {
            AxPipe::CSeg *pSeg = StreamSeg(nThisIx);
            if (pSeg && pSeg->Len()) {
                // This is where you would do something with the data before passing it on
                // by returning a segment. At this point you know which stream the data
                // came from.
                return pSeg;
            }
        }
        // Next stream
        nThisIx = StreamIx(nThisIx + 1);
    } while (nThisIx != nStartIx);

    // Only signal end of stream when all streams are empty.
    return new AxPipe::CSeg;
}