c
if (dec->tilewidth <= 0 || dec->tileheight <= 0) {
    // Handle invalid tile size
} else {
    dec->numhtiles = JPC_CEILDIV(dec->xend - dec->tilexoff, dec->tilewidth);
    dec->numvtiles = JPC_CEILDIV(dec->yend - dec->tileyoff, dec->tileheight);
    if (dec->numhtiles > 0 && dec->numvtiles > INT_MAX / dec->numhtiles) {
        // Handle overflow scenario
    } else {
        dec->numtiles = dec->numhtiles * dec->numvtiles;
    }
}
