On Wed, Mar 18, 2009, Carter Browne wrote:
> You need to look at your data to see how the bytes are swapped:
> 3 common patterns:
>
> 1) Even odd bytes are swapped
> 2) The data was treated as 32 bit, one system is little ended and the
> other big ended.
> 3) The entire buffer is reversed.
>
> Assume pcBuffer is the char * pointer to your data, uiLen is the
> unsigned length of the data.
>
> For 1)
>
> char acTemp = new char[ uiLen ];
>
> _swab(pcBuffer,acTemp,uiLen);
> memcpy(pcBuffer,acTemp,uiLen);
> delete acTemp;
>
> Note: uiLen is assumed to be even
>
> For 2)
>
> char cTemp;
> int i,j;
>
> for (i=0;i<uiLen;i+=4)
> {
> for (j=0;j<2;j++)
> {
> cTemp = pcBuffer[ i+j];
> pcBuffer[ i+j ] = pcBuffer[ i+3-j ];
> pcBuffer[ i+3-j] = cTemp;
> }
>
> Note: This code assumes that uiLen is a multiple of 4;
>
>
> For 3)
>
> char cTemp;
>
> for (i=0;i<uiLen/2;i++)
> {
> cTemp = pcBuffer[ i];
> pcBuffer[ i ] = pcBuffer[ i+uiLen-i-1 ];
> pcBuffer[ i+uiLen-i-1] = cTemp;
> }
>
Just to note that its #3 that is required by the OP.
Steve.
--
Dr Stephen N. Henson. Email, S/MIME and PGP keys: see homepage
OpenSSL project core developer and freelance consultant.
Homepage: http://www.drh-consultancy.demon.co.uk
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