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C-/C++-Quelltext

#include <stdio.h>
#include <stdlib.h>
 
// Globals

const int g_iMessage[]={1,1,0,1,0,1,1,0,1,1};   // the message to be transferred

const int g_iPolynom[]={1,0,0,1,1};             // the generator polynom

const int g_iMessageSize = sizeof(g_iMessage)/sizeof(int);
const int g_iPolynomSize = sizeof(g_iPolynom)/sizeof(int);
const int g_iRealMessageSize = g_iMessageSize+g_iPolynomSize-1;



/*
`* FUNCTION: int* Division( void )
 *
 * PURPOSE: - divides the global g_iMessage with the global g_iPolynom
 *            and calculates the remainder
 *          - adds the remainder to the global g_iMessage
 *          - returns the real SenderMessage (g_iMessage + remainder)
 *
 * RETURN Values: returns the real SenderMessage */
int* Division( void )
{
    // Variables

    int iMessage[g_iRealMessageSize];
    int iRemainder[g_iPolynomSize];
    int iStart = 0;
    int i = 0;
    int j = 0;
    int k = g_iPolynomSize;
    int iRemainderPosition = g_iPolynomSize;
    int* iSenderMessage = NULL;
    int iSenderMessageSize = 0;

    // copy the message in the real message to be transferred

    // initialize the remainder of the division

    for( i=0; i<g_iRealMessageSize; i++ )
            iMessage[i] = g_iMessage[i];
    for( i=0; i<g_iPolynomSize; i++ )
        iRemainder[i] = 0;

    // add degree of polynom times zeroes to the end of the message

    for( i=0; i<g_iPolynomSize-1; i++ )
        iMessage[g_iMessageSize+i] = 0;

    // find the first 1 of the message to be transferred, to begin division

    for( i=0; i<g_iMessageSize; i++ )
        if( iMessage[i] == 1 )
        {
            iStart = i;
            break;
        }

    // start the divison

    for( i=iStart; i<g_iRealMessageSize; i++ )
    {
        if( k>=g_iRealMessageSize-1 )
            break;
        if( i == iStart )
        {
            // there is no remainder at the beginning

            // calculate it

            for( j=0; j<g_iPolynomSize; j++)
                iRemainder[j] = iMessage[i+j] ^ g_iPolynom[j];
            iRemainder[j] = iMessage[i+j];
        }
        else
        {
            // get the new remainder to be divided

            // find the first 1 of the remainder

            for( j=0; j<g_iPolynomSize; j++)
                if( iRemainder[j] == 1 )
                {
                    iRemainderPosition = j;
                    break;
                }
            // shift the numbers of the right hand side of the founded 1

            // to the left

            for( j=0; j<g_iPolynomSize-iRemainderPosition; j++)
                iRemainder[j] = iRemainder[iRemainderPosition+j];
            // add to the tail of the remainder the remaining numbers of the message

            for( j=g_iPolynomSize-iRemainderPosition; j<g_iPolynomSize; j++)
            {
                iRemainder[j] = iMessage[k];
                k++;
            }
            // divide the new remainder with the polynom

            for( j=0; j<g_iPolynomSize; j++)
                iRemainder[j] = iRemainder[j] ^ g_iPolynom[j];
            iRemainderPosition = g_iPolynomSize;
        }
    }

    // create the remainder by deleting heading zeroes

    for( j=0; j<g_iPolynomSize; j++)
        if( iRemainder[j] == 1 )
        {
            iRemainderPosition = j;
            break;
        }
    for( j=0; j<g_iPolynomSize-iRemainderPosition; j++)
        iRemainder[j] = iRemainder[iRemainderPosition+j];
    iRemainder[g_iPolynomSize-iRemainderPosition] = iMessage[g_iRealMessageSize-1];

    // create the real sender message to be transferred

    // by adding the remainder to the message

    iSenderMessageSize = g_iMessageSize + g_iPolynomSize-iRemainderPosition+1;
    iSenderMessage = (int*)malloc( sizeof(int) * iSenderMessageSize );
    j = 0;
    for( i=0; i < iSenderMessageSize; i++ )
    {
        if( i < g_iMessageSize )
            iSenderMessage[i] = iMessage[i];
        else
        {
            iSenderMessage[i] = iRemainder[j];
            j++;
        }
    }

    // return the real message to be transferred

    return iSenderMessage;
}


int main(void)
{   
    // Variables

    int* iSenderMessage = Division(); 
    int i = 0;

    
    printf( "Die Sender Nachricht lautet:\n" );
    //for( i=0; i<sizeof(iSenderMessage)/sizeof(int); i++ )

    //  printf("%d", iSenderMessage[i] );


    //free( iSenderMessage );


    return 0;
}