void

constant(sv)

    PREINIT:

#ifdef dXSTARG

	dXSTARG; /* Faster if we have it.  */

#else

	dTARGET;

#endif

	STRLEN		len;

        int		type;

	IV		iv;

	/* NV		nv;	Uncomment this if you need to return NVs */

	const char	*pv;

    INPUT:

	SV *		sv;

        const char *	s = SvPV(sv, len);

    PPCODE:

        /* Change this to constant(aTHX_ s, len, &iv, &nv);

           if you need to return both NVs and IVs */

	type = constant(aTHX_ s, len, &iv, &pv;;

      /* Return 1 or 2 items. First is error message, or undef if no error.

           Second, if present, is found value */

        switch (type) {

        case PERL_constant_NOTFOUND:

          sv =

	    sv_2mortal(newSVpvf("%s is not a valid Zlib macro", s));

          PUSHs(sv);

          break;

        case PERL_constant_NOTDEF:

          sv = sv_2mortal(newSVpvf(

	    "Your vendor has not defined Zlib macro %s, used",

				   s));

          PUSHs(sv);

          break;

        case PERL_constant_ISIV:

          EXTEND(SP, 1);

          PUSHs(&PL_sv_undef);

          PUSHi(iv);

          break;

	/* Uncomment this if you need to return NOs

        case PERL_constant_ISNO:

          EXTEND(SP, 1);

          PUSHs(&PL_sv_undef);

          PUSHs(&PL_sv_no);

          break; */

	/* Uncomment this if you need to return NVs

        case PERL_constant_ISNV:

          EXTEND(SP, 1);

          PUSHs(&PL_sv_undef);

          PUSHn(nv);

          break; */

        case PERL_constant_ISPV:

          EXTEND(SP, 1);

          PUSHs(&PL_sv_undef);

          PUSHp(pv, strlen(pv));

          break;

	/* Uncomment this if you need to return PVNs

        case PERL_constant_ISPVN:

          EXTEND(SP, 1);

          PUSHs(&PL_sv_undef);

          PUSHp(pv, iv);

          break; */

	/* Uncomment this if you need to return SVs

        case PERL_constant_ISSV:

          EXTEND(SP, 1);

          PUSHs(&PL_sv_undef);

          PUSHs(sv);

          break; */

	/* Uncomment this if you need to return UNDEFs

        case PERL_constant_ISUNDEF:

          break; */

	/* Uncomment this if you need to return UVs

        case PERL_constant_ISUV:

          EXTEND(SP, 1);

          PUSHs(&PL_sv_undef);

          PUSHu((UV)iv);

          break; */

	/* Uncomment this if you need to return YESs

        case PERL_constant_ISYES:

          EXTEND(SP, 1);

          PUSHs(&PL_sv_undef);

          PUSHs(&PL_sv_yes);

          break; */

        default:

          sv = sv_2mortal(newSVpvf(

	    "Unexpected return type %d while processing Zlib macro %s, used",

               type, s));

          PUSHs(sv);

        }