#include <pic18fregs.h>
#include <delay.h>
#include <stdint.h>

// FUSES START
#pragma config XINST = OFF
#pragma config FOSC = HS
#pragma config WDT = OFF
#pragma config LVP = OFF
#pragma config MCLRE = OFF

#define NDIGITS 4
#define RATE 250
#define POLLINGRATE 100


uint8_t digit[NDIGITS] = { 0 };
uint8_t dsp_en = 0;

void isr(void) __interrupt (1);
void tmr_isr(void);
void numpad_isr(void);
uint8_t number_to_7seg(uint8_t);
void start_display(void);
void display(uint16_t);
void shift_left(void);
void setup(void);
int main(void);


void isr(void) __interrupt (1) {
    if (INTCONbits.TMR0IF){
        tmr_isr();
        TMR0 = RATE;
    }
    INTCONbits.TMR0IF = 0;
    if (INTCONbits.RBIF){
        numpad_isr();
    }
    INTCONbits.RBIF = 0;
}

void tmr_isr(void){
    LATA = LATE = 0;
    LATD = number_to_7seg(digit[dsp_en]);
    switch (dsp_en) {
        case 0:
            LATA = 0;
            LATE = 0x4;
            break;
        case 1:
            LATE = 0x2;
            break;
        case 2:
            LATE = 0x1;
            break;
        case 3:
            LATE = 0;
            LATA = 0x10;
            break;
    }
    dsp_en++;
    if (dsp_en > 3) dsp_en = 0;
}
void numpad_isr(void) {
    uint8_t n = 0;
    uint8_t number = 0;
    if ((PORTB & 0xf0) == 0xf0) return;
    if (!PORTBbits.RB0) {
        if (!PORTBbits.RB4) number = 1;
        if (!PORTBbits.RB5) number = 2;
        if (!PORTBbits.RB6) number = 3;
        if (!PORTBbits.RB7) number = 0xA;
    }
    else if (!PORTBbits.RB1) {
        if (!PORTBbits.RB4) number = 4;
        if (!PORTBbits.RB5) number = 5;
        if (!PORTBbits.RB6) number = 6;
        if (!PORTBbits.RB7) number = 0xB;
    }
    else if (!PORTBbits.RB2) {
        if (!PORTBbits.RB4) number = 7;
        if (!PORTBbits.RB5) number = 8;
        if (!PORTBbits.RB6) number = 9;
        if (!PORTBbits.RB7) number = 0xC;
    }
    else if (!PORTBbits.RB3) {
        //if (!PORTBbits.RB4) number = 1;
        if (!PORTBbits.RB5) number = 0;
        if (!PORTBbits.RB6) number = 0xF;
        if (!PORTBbits.RB7) number = 0xD;
    }
    shift_left();
    digit[0] = number;
}

uint8_t number_to_7seg(uint8_t number) {
    switch (number) {
        case 0:
            return 0x3F;
        case 1:
            return 0x06;
        case 2:
            return 0x5B;
        case 3:
            return 0x4F;
        case 4:
            return 0x66;
        case 5:
            return 0x6D;
        case 6:
            return 0x7D;
        case 7:
            return 0x07;
        case 8:
            return 0x7F;
        case 9:
            return 0x6F;
        case 0xa:
            return 0x77;
        case 0xb:
            return 0x7c;
        case 0xC:
            return 0x39;
        case 0xd:
            return 0x5e;
        case 0xe:
            return 0x79;
        case 0xf:
            return 0x71;
        default:
            return 0;
    }
}
void display(uint16_t num){
    uint8_t i = 0;
    if (num > 9999) return;
    while(num) {
        digit[i] = num%10;
        num = num/10;
        i++;
    }
}
void shift_left(void){
    digit[3] = digit[2];
    digit[2] = digit[1];
    digit[1] = digit[0];
}
void start_display(void) {
    /* timer interrupt setup */
    INTCONbits.TMR0IE = 1;
    INTCON2bits.TMR0IP = 1;

    T0CONbits.T08BIT = 1;
    T0CONbits.T0CS = 0; // Source internal oscilator
    T0CONbits.PSA = 0;
    T0CONbits.T0PS = 0x7;
    T0CONbits.TMR0ON = 1;
}
void setup(void){
    /* Port setup */
    LATD = 0;
    TRISD = 0;
    
    TRISB = 0xf0;
    LATB = 0x00;
    ADCON1 = 0xf;
    INTCON2bits.RBPU = 0;

    TRISE = 0;
    LATE = 0;

    TRISA = 0;
    LATA = 0;

    /* Interrupt setup */
    INTCONbits.GIE = 1;
    INTCONbits.PEIE = 1;
    INTCONbits.RBIE = 1;
    INTCON2bits.RBIP = 1;
    RCONbits.IPEN = 1;

}
int main(void) {
    uint16_t cuenta = 0;
    setup();
    start_display();
    for (;;) {
        PORTB = 0xe; 
        delay1ktcy(POLLINGRATE);
        PORTB = 0xD; 
        delay1ktcy(POLLINGRATE);
        PORTB = 0xB; 
        delay1ktcy(POLLINGRATE);
        PORTB = 0x7; 
        delay1ktcy(POLLINGRATE);
    }
    return 0;
}