455    unsigned int     tsp;               /* nsp from the last run; this is the  member
530       png_destroy_write_struct(&dp->write_pp, dp->tsp > 0 ? NULL : &dp->ip);  in display_clean_write()
794    if (sp >= dp->tsp)  in record_opt()
835    assert(sp == dp->tsp && sp < SL);  in push_opt()
851    dp->tsp = sp+1U;  in push_opt()
895       dp->nsp = dp->tsp;  in push_opt()
919    assert(sp+1U == dp->tsp && !dp->stack[sp].end);  in next_opt()
1130       dp->nsp = dp->tsp;  in next_opt()
1186    if (sp >= dp->tsp)  in advance_opt()
1211       if (sp+1U >= dp->tsp)  in advance_opt()
2016    dp->tsp = dp->nsp;  in write_png()
2226       assert(dp->curr[0] == ' ' && dp->tsp > 0);  in cp_one_file()