keypad

#include <stdio.h>
/*
 * 	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 */
	"_exit: B .\n"				/* never return */
	) ;
}
typedef struct {
	uint32_t moder;
	uint16_t otyper; // +0x4
	uint16_t otReserved; //
	uint32_t ospeedr; // +0x8
	uint32_t pupdr; // +0xc (12)
	uint8_t idrLow; // +0x10
	uint8_t idrHigh; // +0x11
	uint16_t idrReserved;
	uint8_t odrLow; // +0x14
	uint8_t odrHigh; // +0x15
	uint16_t odrReserved;
} GPIO;
typedef volatile GPIO* gpioptr;
#define GPIO_D (*(gpioptr)0x40020c00)

void app_init(void){
	GPIO_D.moder = 0x55005555;
	GPIO_D.otyper = GPIO_D.otyper & 0x00FF;
	GPIO_D.pupdr = GPIO_D.pupdr & 0x0000FFFF | 0x00AA0000;
}
void kbdActivate (unsigned int row){
	switch (row){
		case 1: GPIO_D.odrHigh = 0x10; break;
		case 2: GPIO_D.odrHigh = 0x20; break;
		case 3: GPIO_D.odrHigh = 0x40; break;
		case 4: GPIO_D.odrHigh = 0x80; break;
		default: GPIO_D.odrHigh = 0x00; break;
	}
}

int kbdGetCol (void){
	unsigned char c;
	c = GPIO_D.idrHigh;
	if (c & 0x8) return 4;
	if (c & 0x4) return 3;
	if (c & 0x2) return 2;
	if (c & 0x1) return 1;
	return 0;
}

unsigned char keyb(void){
	unsigned char key[]={1,2,3,0xA,4,5,6,0xB,7,8,9,0xC,0xE,0,0xF,0xD};
	int row, col;
	for (row=1; row <=4; row++){
		kbdActivate(row);
		if ((col = kbdGetCol () )){
			kbdActivate(0);
			return key [4*(row-1)+(col-1)];
		}
	}
	kbdActivate (0);
	return 0xFF;
}



void out7seg(unsigned char c){
	switch (c){
		case 0 : GPIO_D.odrLow = 0x3F; break;
		case 1 : GPIO_D.odrLow = 0x06; break;
		case 2 : GPIO_D.odrLow = 0x5B; break;
		case 3 : GPIO_D.odrLow = 0x4F; break;
		case 4 : GPIO_D.odrLow = 0x66; break;
		case 5 : GPIO_D.odrLow = 0x6D; break;
		case 6 : GPIO_D.odrLow = 0x7D; break;
		case 7 : GPIO_D.odrLow = 0x07; break;
		case 8 : GPIO_D.odrLow = 0x7F; break;
		case 9 : GPIO_D.odrLow = 0x6F; break;
		case 10: GPIO_D.odrLow = 0x77; break;
		case 11: GPIO_D.odrLow = 0x7C; break;
		case 12: GPIO_D.odrLow = 0x39; break;
		case 13: GPIO_D.odrLow = 0x5E; break;
		case 14: GPIO_D.odrLow = 0x79; break;
		case 15: GPIO_D.odrLow = 0x71; break;
		default: GPIO_D.odrLow = 0x00; break;
	}
}

void main(void){
	app_init();
	while(1){
		out7seg(keyb());
	}
}