/* a simple example that just rotates the leds. */

#include "plasma.h"

#define MemoryRead(A) (*(volatile unsigned long*)(A))
#define MemoryWrite(A,V) *(volatile unsigned long*)(A)=(V)
#define MemoryWriteXor(A,V) *(volatile unsigned long*)(A)^=(V)


const int LCD_D_SHIFT = 11;
const int LCD_RS = 0x0400;
const int LCD_RW = 0x0200;	/* always low: we never read the LCD */
const int LCD_E  = 0x0100;


void delay1us(void) {
  int i;

  for (i = 3; i; --i) { }
}


void delay40us(void) {
  int i;

  for (i = 120; i; --i) { }
}


void delay1ms(void) {
  int i;

  for (i = 3125; i; --i) { }
}


void delay1s(void) {
  int i;

  for (i = 3125000; i; --i) { }
}

/* an unprecise delay function */
void delay(int value) {
  int i;

  for (; value ;--value) {
    for (i = 0xfff; i; --i) ;
  }
}


void pulse_e(void) {
  MemoryWriteXor(GPIO0_OUT, LCD_E);
  delay1us();
  MemoryWriteXor(GPIO0_OUT, LCD_E);
  delay1us();
}


void write_char_lcd(char ch) {
  int lcd_output;

  /* write upper nibble: */
  lcd_output = (ch & 0xf0) << (LCD_D_SHIFT - 4);
  lcd_output |= LCD_RS;
  MemoryWrite(GPIO0_OUT, lcd_output);
  pulse_e();

  /* write lower nibble: */
  lcd_output = (ch & 0x0f) << LCD_D_SHIFT;
  lcd_output |= LCD_RS;
  MemoryWrite(GPIO0_OUT, lcd_output);
  pulse_e();
  delay40us();

  MemoryWriteXor(GPIO0_OUT, LCD_RS);
}


void write_command4_lcd(char ch) {
  int lcd_output;

  /* write lower nibble: */
  lcd_output = (ch & 0x0f) << LCD_D_SHIFT;
  MemoryWrite(GPIO0_OUT, lcd_output);
  pulse_e();
}


void write_command8_lcd(char ch) {
  int lcd_output;

  /* write upper nibble: */
  lcd_output = (ch & 0xf0) << LCD_D_SHIFT;
  MemoryWrite(GPIO0_OUT, lcd_output);
  pulse_e();

  /* write lower nibble: */
  lcd_output = (ch & 0x0f) << LCD_D_SHIFT;
  MemoryWrite(GPIO0_OUT, lcd_output);
  pulse_e();

  delay40us();
}


void initialize_lcd(void) {
  int i;

  for (i=0; i<15; i++) {
    delay1us();
  };

  write_command4_lcd(3);

  for (i=0; i<5; i++) {
    delay1ms();
  }

  write_command4_lcd(3);

  for (i=0; i<100; i++) {
    delay1us();
  };

  write_command4_lcd(3);

  for (i=0; i<40; i++) {
    delay1us();
  };

  write_command4_lcd(2);

  for (i=0; i<40; i++) {
    delay1us();
  };

  write_command8_lcd(0x28);
  write_command8_lcd(0x06);
  write_command8_lcd(0x0c);
  write_command8_lcd(0x01);

  delay1ms();
  delay1ms();
}
 

int main(void)
{
  const int LEFT_LED_ON = 0x80;
  int led_value = LEFT_LED_ON;
  int i;

  initialize_lcd();
  write_char_lcd(0x6c);
  write_char_lcd(0x65);
  write_char_lcd(0x6f);

  for (;;) {
    MemoryWrite(GPIO0_OUT, led_value);

    led_value >>= 1;
    if (led_value == 0) {
      led_value = LEFT_LED_ON;
    }
    
    for (i = 3125000; i; --i) { }
    // delay1s();
  }

  return 0;
}