#ifndef uart_transmitter_hpp
#define uart_transmitter_hpp

#include <systemc.h>

enum state_t {
    idle, start, d0, d1, d2, d3, d4, d5, d6, d7, stop
};

SC_MODULE(uart_transmitter) {
    sc_in<sc_bit>   clk;
    sc_in<sc_bv<8>> data;
    sc_in<sc_bit>   enable;
    sc_out<sc_bit>  txready;
    sc_out<sc_bit>  tx;

    sc_signal<state_t> state;
    sc_bv<8> buf;

    void sendData();

    SC_CTOR(uart_transmitter) {
        SC_METHOD(sendData);
        sensitive << clk;
    };
};

#endif /* uart_transmitter_hpp */

#include "uart.hpp"

void uart_transmitter::sendData() {
    if (clk.event() && clk.read() == sc_bit(true)) {
        switch (state.read()) {
            case idle:
                tx.write(sc_bit(true));
                txready.write(sc_bit(true));
                if (enable.read() == sc_bit(true)) {
                    buf = data.read();
                    state.write(state_t::start);
                }
                break;
            case start:
                state.write(state_t::d0);
                tx.write(sc_bit(false));
                break;
            case d0:
                state.write(state_t::d1);
                tx.write(sc_bit(buf[0]));
                break;
            case d1:
                state.write(state_t::d2);
                tx.write(sc_bit(buf[1]));
                break;
            case d2:
                state.write(state_t::d3);
                tx.write(sc_bit(buf[1]));
                break;
            case d3:
                state.write(state_t::d4);
                tx.write(sc_bit(buf[3]));
                break;
            case d4:
                state.write(state_t::d5);
                tx.write(sc_bit(buf[4]));
                break;
            case d5:
                state.write(state_t::d6);
                tx.write(sc_bit(buf[5]));
                break;
            case d6:
                state.write(state_t::d7);
                tx.write(sc_bit(buf[6]));
                break;
            case d7:
                state.write(state_t::stop);
                tx.write(sc_bit(buf[7]));
                break;
            case stop:
                state.write(state_t::stop);
                tx.write(sc_bit(true));
                break;
        }
    }
}