unsigned long
find_index (key, data)
        unsigned long         key
        SV    *               data
    INIT:
       STRLEN          datalen;
       char * s;
       if ((!SvROK(data))
          || (SvTYPE(SvRV(data)) != SVt_PV))
       {
          XSRETURN_UNDEF;
       }
       s = SvPV(SvRV(data), datalen);
    CODE:
      RETVAL = find_index (key, s, datalen);
    OUTPUT:
      RETVAL

I'm still not sure if SvPV copies its internal data somewhere or just returns a pointer to it.

Comments please

dino