#include <stdio.h>
#include <string.h>

#define DELAY_TIME 200
#define delay_time 10

#define ZERO 0x01
#define ONE 0x02
#define TWO 0x04
#define THREE 0x08
#define FOUR 0x10
#define FIVE 0x20
#define SIX 0x40
#define SEVEN 0x80
#define EIGHT 0x01
#define NINE 0x02
#define error 0xae
#define DISNUM0 0x30
#define DISNUM1 0x31
#define DISNUM2 0x32
#define DISNUM3 0x33
#define DISNUM4 0x34
#define DISNUM5 0x35
#define DISNUM6 0x36
#define DISNUM7 0x37
#define DISNUM8 0x38
#define DISNUM9 0x39
#define DISNUMA 0x2b
#define DISNUMB 0x2d
#define DISNUMC 0X01
#define DISNUMD 0x25
#define DISNUMM 0x2a
#define DISNUMH 0x01

#define DELAY 1000000


volatile char keypad_array[4][8] = {
    {DISNUM1, DISNUM2, error, DISNUM3, error, error, error, DISNUMA},
    {DISNUM4, DISNUM5, error, DISNUM6, error, error, error, DISNUMB},
    {DISNUM7, DISNUM8, error, DISNUM9, error, error, error, DISNUMC},
    {DISNUMM, DISNUM0, error, DISNUMH, error, error, error, DISNUMD}};


volatile int keypad_num[4][8] = {
    {'1', '2', '0', '3', '0', '0', '0', '+'},
    {'4', '5', '0', '6', '0', '0', '0', '-'},
    {'7', '8', '0', '9', '0', '0', '0', ':'},
    {'*', '0', '0', '=', '0', '0', '0', '/'}
};

void lcd_cmd(unsigned char ch);
void lcd_data(unsigned char ch);
void lcd_string_print(unsigned char *ch);
void lcd_string_leftrotate(unsigned char *str);
void lcd_string_rightrotate(unsigned char *str);
void travel_display(unsigned char till);
void keypad_input_calculation();
void calculation(unsigned char *str);

void setup() {
    volatile unsigned char *dirl, *dirk, *dirf, *outf, *outl, *outk, *dirc, *inc;
    dirf = (volatile unsigned char *)0x30; *dirf = 0xFF;
    dirk = (volatile unsigned char *)0x107; *dirk = 0xFF;
    dirl = (volatile unsigned char *)0x10A; *dirl = 0xFF;
    dirc = (volatile unsigned char *)0x27; *dirc = 0x00;

    outf = (volatile unsigned char *)0x31;
    outk = (volatile unsigned char *)0x108;
    outl = (volatile unsigned char *)0x10b;
    inc = (volatile unsigned char *)0x26;
}

void loop()
 {
    lcd_cmd(0x0c);
    lcd_cmd(0x80);
    keypad_input_calculation();
}

void intToString(int number, char *str)
 {
    sprintf(str, "%d", number);//direct function to 
}

void lcd_string_leftrotate(unsigned char *str)
 {
    int len = strlen((char *)str);
    if (len == 0) return;
    char temp = str[0];
    for (int i = 0; i < len - 1; i++) {
        str[i] = str[i + 1];
    }
    str[len - 1] = temp;
}

void lcd_string_rightrotate(unsigned char *str) 
{
    int len = strlen((char *)str);
    if (len == 0) return;
    char temp = str[len - 1];
    for (int i = len - 2; i >= 0; i--) {
        str[i + 1] = str[i];
    }
    str[0] = temp;
}

void lcd_cmd(unsigned char ch)
 {
    volatile unsigned char *outf = (volatile unsigned char *)0x31;
    volatile unsigned char *outk = (volatile unsigned char *)0x108;
    *outk = ch;
    *outf = 0x02;
    delay(delay_time);
    *outf = 0x00;
}

void lcd_data(unsigned char ch)
 {
    volatile unsigned char *outf = (volatile unsigned char *)0x31;
    volatile unsigned char *outk = (volatile unsigned char *)0x108;
    *outk = ch;
    *outf = 0x03;
    delay(delay_time);
    *outf = 0x01;
}

void lcd_string_print(unsigned char *str)
 {
    for (unsigned int i = 0; str[i] != '\0'; i++) {
        lcd_data(str[i]);
    }
}

void lcd_string_print_till(unsigned char *str, unsigned int j)
 {
    for (unsigned int i = 0; i < j; i++) {
        lcd_data(str[i]);
    }
}

void travel_display(unsigned char till) 
{
    for (int i = 0; i < till; i++) {
        lcd_data(' ');
    }
}

void keypad_input_calculation()
 {
    volatile unsigned char *outk, *inc, *outl;
    inc = (unsigned char *)0x26;
    outl = (unsigned char *)0x10b;
    outk = (volatile unsigned char *)0x108;

    int j = 0;
    volatile char buffer[100];

    while (1) {
        for (volatile long i = 0; i < 4; i++) {
            *outl = 1 << i;
            volatile unsigned char y = *inc;
            if (y != 0) {
                if (i == 2 && y == 8) {
                    lcd_cmd(0x01);
                    memset(buffer, 0, sizeof(buffer));
                    j=0;
                }
             else if (i == 3 && y == 4) {
                    lcd_cmd(0xc0);
                  
                    calculation(buffer);
                } 
            else {
                    *outk = keypad_array[i][y - 1];
                    if (keypad_num[i][y - 1] != ':' && keypad_num[i][y - 1] != '=') {
                        buffer[j] = keypad_num[i][y - 1];
                        j++;
                    }
                    lcd_data(*outk);
                    delay(DELAY_TIME);
                }
            }
        }
    }
}

void calculation(unsigned char *str) 
{
    unsigned char t_strf[100], t_str1[100], t_str2[100];
    unsigned char temp_opr;
    long num1, num2, ans;
    long i = 0, j = 0;

    while (str[i] != '+' && str[i] != '*' && str[i] != '-' && str[i] != '/' && str[i] != '\0') {
        t_str1[i] = str[i];
        i++;
    }
    t_str1[i] = '\0';

    temp_opr = str[i];
    i++;
    while (str[i] != '\0') {
        t_str2[j] = str[i];
        i++;
        j++;
    }
    t_str2[j] = '\0';

    num1 = atoi((char *)t_str1);
    num2 = atoi((char *)t_str2);

    switch (temp_opr) {
        case '+':
            ans = num1 + num2;
            break;
        case '-':
            ans = num1 - num2;
            break;
        case '*':
            ans = num1 * num2;
            break;
        case '/':
            ans = num1 / num2;
            break;
        default:
            ans = 0;
            break;
    }

    intToString(ans, (char *)t_strf);
    lcd_cmd(0xc0);
    // travel_display(4);
    lcd_string_print(t_strf);
}