#include <LPC17xx.h>

#define RS_CTRL 0x08000000
#define EN_CTRL 0x10000000
#define DT_CTRL 0x07800000

unsigned long result, y;
unsigned long int temp1 = 0, temp2 = 0, i, j;
unsigned char flag1 = 0, flag2 = 0;
unsigned char msg[] = ("ADC: ");

void lcd_write(void);
void port_write(void);
void delay_lcd(unsigned long);
void display_adc(unsigned long);

unsigned long int init_command[] = {
  0x30, 0x30, 0x30, 0x20, 0x28, 0x0C, 0x01, 0x80
};

int main() {
  LPC_GPIO0->FIODIR = DT_CTRL | RS_CTRL | EN_CTRL;
  LPC_PINCON->PINSEL3 = 3 << 28;
  LPC_SC->PCONP = 1 << 12;

  LPC_ADC->ADCR = 1 << 4 | 1 << 16 | 1 << 21;
  LPC_ADC->ADINTEN = (1 << 4);

  NVIC_EnableIRQ(ADC_IRQn);

  flag1 = 0;

  for (i = 0; i < 8; i++) {
    temp1 = init_command[i];
    lcd_write();
  }

  flag1 = 1;
  i = 0;

  while (msg[i] != '\0') {
    temp1 = msg[i];
    i++;
    lcd_write();
  }

  display_adc(result);

  while (1);
}

void display_adc(unsigned long adc_val) {
  unsigned char digits[4];
  int k;

  digits[0] = (adc_val / 1000) % 10 + 0x30;
  digits[1] = (adc_val / 100) % 10 + 0x30;
  digits[2] = (adc_val / 10) % 10 + 0x30;
  digits[3] = adc_val % 10 + 0x30;

  for (k = 0; k < 4; k++) {
    temp1 = digits[k];
    lcd_write();
  }
}

void lcd_write(void) {
  flag2 = (flag1 == 1) ? 0 : (((temp1 == 0x30) || (temp1 == 0x20)) ? 1 : 0);

  temp2 = temp1 & 0xf0;
  temp2 = temp2 << 19;

  port_write();

  if (!flag2) {
    temp2 = temp1 & 0x0f;
    temp2 = temp2 << 23;
    port_write();
  }
}

void port_write(void) {
  LPC_GPIO0->FIOPIN = temp2;

  if (flag1 == 0) {
    LPC_GPIO0->FIOCLR = RS_CTRL;
  } else {
    LPC_GPIO0->FIOSET = RS_CTRL;
  }

  LPC_GPIO0->FIOSET = EN_CTRL;
  delay_lcd(100);
  LPC_GPIO0->FIOCLR = EN_CTRL;

  delay_lcd(500000);
}

void delay_lcd(unsigned long r1) {
  unsigned long r;

  for (r = 0; r < r1; r++);
  return;
}

void ADC_IRQHandler(void) {
  result = (LPC_ADC->ADGDR & (0xFFF << 4)) >> 4;
  y = (LPC_ADC->ADDR4 & (0xFFF << 4)) >> 4;
}