    GC_API int GC_CALL GC_get_stack_base(
                                struct GC_stack_base *b GC_ATTR_UNUSED)
    {
#     if defined(GET_MAIN_STACKBASE_SPECIAL) && !defined(THREADS) \
         && !defined(IA64)
        b->mem_base = GC_get_main_stack_base();
        return GC_SUCCESS;
#     else
        return GC_UNIMPLEMENTED;
#     endif
    }
    GC_API int GC_CALL GC_get_stack_base(
                                struct GC_stack_base *b GC_ATTR_UNUSED)
    {
#     if defined(GET_MAIN_STACKBASE_SPECIAL) && !defined(THREADS) \
         && !defined(IA64)
        b->mem_base = GC_get_main_stack_base();
        return GC_SUCCESS;
#     else
        return GC_UNIMPLEMENTED;
#     endif
    }