#include <reg515.sfr>
#include <lcd.h>

int a;
int b;
int state;
char buff[24];

void print(const char *str){
    //out_instr(1);
    while(*str){
        out_char(*str++);
    }
}
void sleep(){
    int t;
    int i;
    t = 20000;
    for(i=0;i<t;i++);
}

char * itoa(int s){
    int x;
    char *buffPos;
    buff[23] = '\0';
    buffPos = buff + 22;
    while(s != 0){
        x = s % 10;
        s /= 10;
        *buffPos-- = x + '0';
    }
    return buffPos + 1;
}

void main(){
    int x;
    int c;
    char *str;
    a = 0;
    b = 0;
    state = 0;
    sleep();
    lcd_init();
    sleep();
    out_instr(1);
    sleep();
    //print("Hello");
    while(1){

        unsigned char z = get_kb();
        if( z != '\0' ){
            if( z >= '0' && z <= '9'){
                x = z - '0';
                if(state){//liczba b
                     b = b * 10 + x;
                }else{//liczba a
                     a = a * 10 + x;
                }
                out_char(z);
            }else{
                switch(state){
                    case 0: {
                        state = 1;
                        out_char('+');
                        break;
                    }
                    case 1: {
                        state = 2;
                        out_char('=');
                        c = a + b;
                        //out_char(c);
                        str = itoa(c);
                        out_instr(1);
                        print(str);
                        break;
                    }
                    case 2: {
                        state = 0;
                        a = 0;
                        b = 0;
                        out_instr(1);
                        break;
                    }
                }
                /*
                if(state){
                     state = 0;
                     int c = a + b;
                     char *str = itoa(c);
                     print(str);
                }else{
                     state = 1;
                     out_char('+');
                }
                */
            }
        }
        sleep();
    }
}