idm_assert
idm_assert(idm, count);
idm_assert(idm, count);
idm_assert(idm, count <= idm->used);
idm_assert(idm, start < idm->total);
idm_assert(idm, start + count - 1 < idm->total);
idm_assert(idm, test_bit(start + n, idm->bitmap));
idm_assert(idm, count);
idm_assert(idm, retain);
idm_assert(idm, !idm->bitmap);
idm_assert(idm, !idm->total);
idm_assert(idm, !idm->used);