Thanks for reply.
But this approach does not solve my problem. On further investigation I have found out a clue that why this is behaving like this with Perl v5.8.3, but can not find the solution.
I have already metioned I have xs file, a.xs where the xs code is present. I have also a .map file say c.map file in c.map file I have written following code (the code has been taken from Advanced Perl Programming book)

TYPEMAP
const char * T_PV
test_class       * ANY OBJECT

OUTPUT

ANY OBJECT
  sv_setref_pv($arg, CLASS, (void *) $var);

INPUT
  ANY OBJECT
   $var = ($type) SvIV((SV*)SvRV($arg));
[download]

Now when Perl v5.6.1 generates .c file from .xs file following code was generated

XS(XS_Test_TestMethod)
{
    dXSARGS;
    if (items != 2)
        Perl_croak(aTHX_ "Usage: Test::TestMethod(CLASS, param1)");
    {
        char*   CLASS = (char *)SvPV(ST(0),PL_na);
        pstruct *  param1;
[download]

On the other hand Perl v5.8.3 generated following code

XS(XS_Test_TestMethod)
{
    dXSARGS;
    if (items != 2)
        Perl_croak(aTHX_ "Usage: Test::TestMethod(CLASS, param1)");
    {
        char*    CLASS = (char *)SvPV_nolen(ST(0));
        pstruct *  param1 = (pstruct *) SvIV((SV*)SvRV(ST(1)));
[download]

Can anybody please tell me why code generation is different for Perl v5.6.1 and Perl v5.8.3? I also doubt that code generated by Perl v5.8.3 may cause problem in my script when no valid reference address passed to the TestMethod. Can anybody kindly give me any pointers to overcome this problem?
Thanks in advance.
Regards
-Pijush