go_deeper(trystate_T *stack, int depth, int score_add)
{
    stack[depth + 1] = stack[depth];
    stack[depth + 1].ts_state = STATE_START;
    stack[depth + 1].ts_score = stack[depth].ts_score + score_add;
    stack[depth + 1].ts_curi = 1;	// start just after length byte
    stack[depth + 1].ts_flags = 0;
}