count_objects

static VALUE
count_objects(int argc, VALUE *argv, VALUE os)
{
    rb_objspace_t *objspace = &rb_objspace;
    size_t counts[T_MASK+1];
    size_t freed = 0;
    size_t total = 0;
    size_t i;
    VALUE hash;

    if (rb_scan_args(argc, argv, "01", &hash) == 1) {
        if (!RB_TYPE_P(hash, T_HASH))
            rb_raise(rb_eTypeError, "non-hash given");
    }

    for (i = 0; i <= T_MASK; i++) {
        counts[i] = 0;
    }

    for (i = 0; i < heap_allocated_pages; i++) {
        struct heap_page *page = heap_pages_sorted[i];
        RVALUE *p, *pend;

        p = page->start; pend = p + page->total_slots;
        for (;p < pend; p++) {
            if (p->as.basic.flags) {
                counts[BUILTIN_TYPE(p)]++;
            }
            else {
                freed++;
            }
        }
        total += page->total_slots;
    }

    if (hash == Qnil) {
        hash = rb_hash_new();
    }
    else if (!RHASH_EMPTY_P(hash)) {
        st_foreach(RHASH_TBL_RAW(hash), set_zero, hash);
    }
    rb_hash_aset(hash, ID2SYM(rb_intern("TOTAL")), SIZET2NUM(total));
    rb_hash_aset(hash, ID2SYM(rb_intern("FREE")), SIZET2NUM(freed));

    for (i = 0; i <= T_MASK; i++) {
        VALUE type;
        switch (i) {
#define COUNT_TYPE(t) case (t): type = ID2SYM(rb_intern(#t)); break;
            COUNT_TYPE(T_NONE);
            COUNT_TYPE(T_OBJECT);
            COUNT_TYPE(T_CLASS);
            COUNT_TYPE(T_MODULE);
            COUNT_TYPE(T_FLOAT);
            COUNT_TYPE(T_STRING);
            COUNT_TYPE(T_REGEXP);
            COUNT_TYPE(T_ARRAY);
            COUNT_TYPE(T_HASH);
            COUNT_TYPE(T_STRUCT);
            COUNT_TYPE(T_BIGNUM);
            COUNT_TYPE(T_FILE);
            COUNT_TYPE(T_DATA);
            COUNT_TYPE(T_MATCH);
            COUNT_TYPE(T_COMPLEX);
            COUNT_TYPE(T_RATIONAL);
            COUNT_TYPE(T_NIL);
            COUNT_TYPE(T_TRUE);
            COUNT_TYPE(T_FALSE);
            COUNT_TYPE(T_SYMBOL);
            COUNT_TYPE(T_FIXNUM);
            COUNT_TYPE(T_IMEMO);
            COUNT_TYPE(T_UNDEF);
            COUNT_TYPE(T_ICLASS);
            COUNT_TYPE(T_ZOMBIE);
#undef COUNT_TYPE
          default:              type = INT2NUM(i); break;
        }
        if (counts[i])
            rb_hash_aset(hash, type, SIZET2NUM(counts[i]));
    }

    return hash;
}