/*
 * 	startup.c
 *
 */
#define	GPIO_E				0x40021000
#define	GPIO_E_MODER		((volatile unsigned int *)		(GPIO_E))
#define	GPIO_E_IDR_LOW		((volatile unsigned char *)	(GPIO_E+0x10))
#define	GPIO_E_IDR_HIGH		((volatile unsigned char *)	(GPIO_E+0x11))
#define	GPIO_E_ODR_LOW		((volatile unsigned char *)	(GPIO_E+0x14))
#define	GPIO_E_ODR_HIGH		((volatile unsigned char *)	(GPIO_E+0x15))

#define	SysTick			0xE000E010
#define	STK_CTRL		((volatile unsigned int *)	(SysTick))
#define	STK_LOAD		((volatile unsigned int *)	(SysTick+0x4))
#define	STK_VAL			((volatile unsigned int *)	(SysTick+0x8))

#define B_E 			0x40  	// Enable-signal
#define B_SELECT 		4 		// Select ASCII-display
#define B_RW 			2 		// 0=Write, 1=Read
#define B_RS 			1 		// 0=Control, 1=Data

void startup(void) __attribute__((naked)) __attribute__((section (".start_section")) );

void startup ( void )
{
__asm volatile(
	" LDR R0,=0x2001C000\n"		/* set stack */
	" MOV SP,R0\n"
	" BL main\n"				/* call main */
	".L1: B .L1\n"				/* never return */
	) ;
}

void app_init(void) {
	*GPIO_E_MODER = 0x55555555;
}

void delay_250ns(void){
	*STK_CTRL = 0;
	*STK_LOAD = ((168/4) -1);
	*STK_VAL = 0;
	*STK_CTRL = 5;
	while ((*STK_CTRL & 0x10000) == 0);
	*STK_CTRL = 0;
}

void delay_mikro(unsigned int us) {
	#ifdef				SIMULATOR
		us = us / 1000;
		us++;
	#endif
		while (us > 0){
			delay_250ns();
			delay_250ns();
			delay_250ns();
			delay_250ns();
			us--;
		}
}

void delay_milli(unsigned int ms) {
	#ifdef				SIMULATOR
		ms = ms / 1000;
		ms++;
	#endif
		while (ms > 0){
			delay_mikro(1000);
			ms--;
		}
}

void ascii_ctrl_bit_set(unsigned char x) {
	unsigned char c = *GPIO_E_ODR_LOW;
	c |= ( B_SELECT | x );
	*GPIO_E_ODR_LOW = c;
}

void ascii_ctrl_bit_clear(unsigned char x) {
	unsigned char c = *GPIO_E_ODR_LOW;
	c &= (B_SELECT | ~x);
	*GPIO_E_ODR_LOW = c;
}

void ascii_write_controller(unsigned char byte) {
	ascii_ctrl_bit_set(B_E);
	*GPIO_E_ODR_HIGH = byte;
	ascii_ctrl_bit_clear(B_E);
	delay_250ns();

}

unsigned char ascii_read_controller(void) {
	unsigned char c;
	ascii_ctrl_bit_set(B_E);
	delay_250ns();
	delay_250ns();
	c = *GPIO_E_IDR_HIGH;
	ascii_ctrl_bit_clear(B_E);
	return c;
}

void ascii_write_cmd(unsigned char command){
	ascii_ctrl_bit_clear(B_RS);
	ascii_ctrl_bit_clear(B_RW);
	ascii_write_controller(command);
}

void ascii_write_data(unsigned char data){
	ascii_ctrl_bit_set(B_RS);
	ascii_ctrl_bit_clear(B_RW);
	ascii_write_controller(data);
}

unsigned char ascii_read_status (void){
	unsigned char c;
	*GPIO_E_MODER = 0x00005555;
	ascii_ctrl_bit_clear(B_RS);
	ascii_ctrl_bit_set(B_RW);
	c = ascii_read_controller();
	*GPIO_E_MODER = 0x55555555;
	return c;
}

unsigned char ascii_read_data (void){
	unsigned char c;
	*GPIO_E_MODER = 0x00005555;
	ascii_ctrl_bit_set(B_RS);
	ascii_ctrl_bit_set(B_RW);
	c = ascii_read_controller();
	*GPIO_E_MODER = 0x55555555;
	return c;
}

void ascii_Function_Set(unsigned char command){
	while ((ascii_read_status() & 0x80) == 0x80){
		delay_mikro(8);
		ascii_write_cmd(command);
		delay_mikro(40);
	}
}

void ascii_Display_Control(unsigned char command){
	while ((ascii_read_status() & 0x80) == 0x80){
		delay_mikro(8);
		ascii_write_cmd(command);
		delay_mikro(40);
	}
}
void ascii_Entry_Mode_Set(unsigned char command){
	while ((ascii_read_status() & 0x80) == 0x80){
		delay_mikro(8);
		ascii_write_cmd(command);
		delay_mikro(40);
	}
}

void ascii_init(void){
	ascii_Function_Set(0x38);
	ascii_Display_Control(0xE);
	ascii_Function_Set(0x6);
}

void ascii_gotoxy(int x, int y){
	unsigned int adress;
	adress = x-1;
	if (y == 2) {
		adress += 0x40;
	}
	ascii_write_cmd(0x80 | adress);
}

void ascii_write_char (unsigned char c){
	while((ascii_read_status() & 0x80) == 0x80);
	delay_mikro(8);
	ascii_write_data(c);
	delay_mikro(50);
}

int main(int argc, char **argv)
{
	char *s;
	char test1[] = "Alfanumeriskt ";
	char test2[] = "Display - test";

	app_init();
	ascii_init();
	ascii_gotoxy(1,1);
	s = test1;
	while(*s) {
		ascii_write_char(*s++);
	}
	ascii_gotoxy(1,2);
	s = test2;
	while(*s) {
		ascii_write_char(*s++);
	}
	return 0;
}