/*
 * 	startup.c
 *
 */
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) {
	* ( (unsigned int *) 0x40020C00 ) = 0x55005555;
	* ( (unsigned char *) 0x40020C05 ) = 0x0;
	* ( (unsigned short *) 0x40020C0E ) = 0x00AA;

}

void activateRow( int row ){
	unsigned char bits = 0;
	switch (row){
		case 1: bits = 0x10;
			break;
		case 2: bits = 0x20;
			break;
		case 3: bits = 0x40;
			break;
		case 4: bits = 0x80;
			break;
	}
	*((unsigned char*) 0x40020C15) = bits;
}

//läser in inport
unsigned char readColumn( void){
	unsigned char bits = 0;
	unsigned char  column = 0;

	bits = *((unsigned char*) 0x40020C11);

	switch(bits){
		case 1:
			column = 1;
			break;
		case 2:
			column = 2;
			break;
		case 4:
			column = 3;
			break;
		case 8:
			column = 4;
			break;
	}

	return column;
}

unsigned char keyb(void){
	unsigned char keyMatrix[16] = {1,2,3,10,
								4,5,6,11,
								7,8,9,12,
								14,0,15,13};
	unsigned int index;
	unsigned char column;
	unsigned char keyValue = 0xFF;
	int row = 1;
	while(row <=4){
		activateRow(row);
		column = readColumn();


		if( column != 0){
			index = (row-1)*4  +  (column-1);
			keyValue = keyMatrix[index];
		}
		row++;
	}
	return keyValue;
}

void out7seg( unsigned char key){
	unsigned char hexMatrix[16] = {0x3F, 0x06, 0x5B, 0x4F,
								0x66, 0x6D, 0x7D, 0x07,
								0x7F, 0x67, 0x77, 0x7F,
								0x39, 0x3F, 0x79, 0x71 };

	unsigned char hex = 0x00;
	unsigned int index = 0;

	if (key != 0xFF) {
		index = (unsigned int) (key & 0x0F);
		hex = hexMatrix[index];
	}
	*((unsigned char*) 0x40020C14) = hex;

}



void main(void)
{
	unsigned char c;
	app_init();

	while(1){
		out7seg( keyb() );

	}
}