typedef char bool;

typedef enum
{
    STATE_I = 0,
    STATE_A,
    STATE_B,
    STATE_C,
    STATE_D
}
testfsm_state_t;

typedef struct
{
    testfsm_state_t m_state;
    bool m_a;
    bool m_b;
} testfsm_t;

void process(testfsm_t *p_fsm, const bool input)
{
    testfsm_state_t nextState = p_fsm->m_state;

    p_fsm->m_a = false;
    p_fsm->m_b = false;

    switch(p_fsm->m_state)
    {
        case STATE_I:
            if (!input)
                nextState = STATE_A;
            else
                nextState = STATE_B;
            break;
        case STATE_A:
            p_fsm->m_a = true;
            if (!input)
                nextState = STATE_D;
            else
                nextState = STATE_C;
            break;
        case STATE_B:
            p_fsm->m_a = true;
            p_fsm->m_b = true;
            nextState = STATE_C;
            break;
        case STATE_C:
            p_fsm->m_b = true;
            nextState = STATE_A;
            break;
        case STATE_D:
            nextState = STATE_B;
            break;
    }

    p_fsm->m_state = nextState;
}

bool randbool(int throws)
{
    bool stillTrue = true;
    for (int i = 0; i < throws; ++i)
    {
        stillTrue &= rand() & 1;
    }
    return stillTrue;
}

int main()
{
    testfsm_t fsm = { .m_state = STATE_I, .m_a = false, .m_b = false };
    bool input = false;

    srand(0);
    for (int j = 0; j < 100; ++j)
    {
        input = randbool(1);
        process(&fsm, input);
    }

    return 0;
}