/*******************************************************
This program was created by the
CodeWizardAVR V3.12 Advanced
Automatic Program Generator
© Copyright 1998-2014 Pavel Haiduc, HP InfoTech s.r.l.
http://www.hpinfotech.com

Project : Calculator
Version : 
Date    : 11/29/2017
Author  : Mohsen Dastjerdi Zade
Company : 
Comments: 6th Assignment

Simple, integer-only, one-operation calculator

Chip type               : ATmega8
Program type            : Application
AVR Core Clock frequency: 1.000000 MHz
Memory model            : Small
External RAM size       : 0
Data Stack size         : 256
*******************************************************/

#include <mega8.h>
#include <delay.h>
#include <stdint.h>
#include <stdlib.h>

// Alphanumeric LCD functions
#include <alcd.h>

// Declare your global variables here
char buffer[16];
int a = 0, b = 0;
uint8_t i = 0;
char operator;

// get a character from numpad
char numpad() {
  static const char keypad[4][4] = {
    '7', '8', '9', '/',
    '4', '5', '6', '*',
    '1', '2', '3', '-',
    'c', '0', '=', '+'
  }; 
  uint8_t x, y;
  for (y = 0; y < 5; y++) {
    PORTD = ~(1 << y);
    x = (~PIND & 0b11110000) >> 4; 
    if (x) {
      x = (x == 8)? 3 : x >> 1;
      return keypad[y][x];
    }
  }
  return 0;
}

int calc() {
  if (operator == '+') {
    return a + b;
  } else if (operator == '-') {
    return a - b;
  } else if (operator == '/') {
    return a / b;
  } else if (operator == '*') {
    return a * b;
  } else if (operator == '=') {
    return a;
  }
}


void reset() {
  for (i = 0; i <= 16; i++) {
     buffer[i] = 0;
  }
  lcd_clear();
  if (operator) {
  lcd_gotoxy(0, 1);
  lcd_putchar(operator);
  }
  lcd_gotoxy(0, 0);
}

void main(void)
{
// Declare your local variables here

// Input/Output Ports initialization
// Port B initialization
// Function: Bit7=In Bit6=In Bit5=In Bit4=In Bit3=In Bit2=In Bit1=In Bit0=In 
DDRB=(0<<DDB7) | (0<<DDB6) | (0<<DDB5) | (0<<DDB4) | (0<<DDB3) | (0<<DDB2) | (0<<DDB1) | (0<<DDB0);
// State: Bit7=T Bit6=T Bit5=T Bit4=T Bit3=T Bit2=T Bit1=T Bit0=T 
PORTB=(0<<PORTB7) | (0<<PORTB6) | (0<<PORTB5) | (0<<PORTB4) | (0<<PORTB3) | (0<<PORTB2) | (0<<PORTB1) | (0<<PORTB0);

// Port C initialization
// Function: Bit6=In Bit5=In Bit4=In Bit3=In Bit2=In Bit1=In Bit0=In 
DDRC=(0<<DDC6) | (0<<DDC5) | (0<<DDC4) | (0<<DDC3) | (0<<DDC2) | (0<<DDC1) | (0<<DDC0);
// State: Bit6=T Bit5=T Bit4=T Bit3=T Bit2=T Bit1=T Bit0=T 
PORTC=(0<<PORTC6) | (0<<PORTC5) | (0<<PORTC4) | (0<<PORTC3) | (0<<PORTC2) | (0<<PORTC1) | (0<<PORTC0);

// Port D initialization
// Function: Bit7=In Bit6=In Bit5=In Bit4=In Bit3=Out Bit2=Out Bit1=Out Bit0=Out 
DDRD=(0<<DDD7) | (0<<DDD6) | (0<<DDD5) | (0<<DDD4) | (1<<DDD3) | (1<<DDD2) | (1<<DDD1) | (1<<DDD0);
// State: Bit7=P Bit6=P Bit5=P Bit4=P Bit3=0 Bit2=0 Bit1=0 Bit0=0 
PORTD=(1<<PORTD7) | (1<<PORTD6) | (1<<PORTD5) | (1<<PORTD4) | (0<<PORTD3) | (0<<PORTD2) | (0<<PORTD1) | (0<<PORTD0);

// Timer/Counter 0 initialization
// Clock source: System Clock
// Clock value: Timer 0 Stopped
TCCR0=(0<<CS02) | (0<<CS01) | (0<<CS00);
TCNT0=0x00;

// Timer/Counter 1 initialization
// Clock source: System Clock
// Clock value: Timer1 Stopped
// Mode: Normal top=0xFFFF
// OC1A output: Disconnected
// OC1B output: Disconnected
// Noise Canceler: Off
// Input Capture on Falling Edge
// Timer1 Overflow Interrupt: Off
// Input Capture Interrupt: Off
// Compare A Match Interrupt: Off
// Compare B Match Interrupt: Off
TCCR1A=(0<<COM1A1) | (0<<COM1A0) | (0<<COM1B1) | (0<<COM1B0) | (0<<WGM11) | (0<<WGM10);
TCCR1B=(0<<ICNC1) | (0<<ICES1) | (0<<WGM13) | (0<<WGM12) | (0<<CS12) | (0<<CS11) | (0<<CS10);
TCNT1H=0x00;
TCNT1L=0x00;
ICR1H=0x00;
ICR1L=0x00;
OCR1AH=0x00;
OCR1AL=0x00;
OCR1BH=0x00;
OCR1BL=0x00;

// Timer/Counter 2 initialization
// Clock source: System Clock
// Clock value: Timer2 Stopped
// Mode: Normal top=0xFF
// OC2 output: Disconnected
ASSR=0<<AS2;
TCCR2=(0<<PWM2) | (0<<COM21) | (0<<COM20) | (0<<CTC2) | (0<<CS22) | (0<<CS21) | (0<<CS20);
TCNT2=0x00;
OCR2=0x00;

// Timer(s)/Counter(s) Interrupt(s) initialization
TIMSK=(0<<OCIE2) | (0<<TOIE2) | (0<<TICIE1) | (0<<OCIE1A) | (0<<OCIE1B) | (0<<TOIE1) | (0<<TOIE0);

// External Interrupt(s) initialization
// INT0: Off
// INT1: Off
MCUCR=(0<<ISC11) | (0<<ISC10) | (0<<ISC01) | (0<<ISC00);

// USART initialization
// USART disabled
UCSRB=(0<<RXCIE) | (0<<TXCIE) | (0<<UDRIE) | (0<<RXEN) | (0<<TXEN) | (0<<UCSZ2) | (0<<RXB8) | (0<<TXB8);

// Analog Comparator initialization
// Analog Comparator: Off
// The Analog Comparator's positive input is
// connected to the AIN0 pin
// The Analog Comparator's negative input is
// connected to the AIN1 pin
ACSR=(1<<ACD) | (0<<ACBG) | (0<<ACO) | (0<<ACI) | (0<<ACIE) | (0<<ACIC) | (0<<ACIS1) | (0<<ACIS0);
SFIOR=(0<<ACME);

// ADC initialization
// ADC disabled
ADCSRA=(0<<ADEN) | (0<<ADSC) | (0<<ADFR) | (0<<ADIF) | (0<<ADIE) | (0<<ADPS2) | (0<<ADPS1) | (0<<ADPS0);

// SPI initialization
// SPI disabled
SPCR=(0<<SPIE) | (0<<SPE) | (0<<DORD) | (0<<MSTR) | (0<<CPOL) | (0<<CPHA) | (0<<SPR1) | (0<<SPR0);

// TWI initialization
// TWI disabled
TWCR=(0<<TWEA) | (0<<TWSTA) | (0<<TWSTO) | (0<<TWEN) | (0<<TWIE);

// Alphanumeric LCD initialization
// Connections are specified in the
// Project|Configure|C Compiler|Libraries|Alphanumeric LCD menu:
// RS - PORTB Bit 6
// RD - PORTB Bit 5
// EN - PORTB Bit 4
// D4 - PORTB Bit 3
// D5 - PORTB Bit 2
// D6 - PORTB Bit 1
// D7 - PORTB Bit 0
// Characters/line: 16
lcd_init(16);
lcd_clear();

// Main loop
while (1) {
    // Get 4 inputs from numpad, save in buffer and echo on LCD 
    int i = 0;
    while (i < 16) {
      char x = 0;
      x = numpad();
      if (x == 'c') {
        b = 0;
        reset();
        i = 0;
      } else if (x == '+' || x == '-' || x == '/' || x == '*' || x == '=') {
        if (operator) {
          a = b;
          b = atoi(buffer);
          b = calc();
          operator = x;
          reset();
          itoa(b,buffer);
          lcd_puts(buffer);
          i = 0;
        } else {
          operator = x;
        }
     } else if (x) {
        if (i == 0) reset();
        buffer[i] = x;
        lcd_gotoxy(i,0); 
        lcd_putchar(x);
        i++;
      }
      delay_ms(200);
    }
  }
}