arm 跑马灯，蜂鸣器

/* c.c */
#define GPJ2CON  *((volatile unsigned int *)0xE0200280)
#define GPJ2DAT  *((volatile unsigned int *)0xE0200284)
#define LED_ON  0
#define LED_OFF 1
#define GPD0CON  *((volatile unsigned int *)0xE02000A0)
#define GPD0DAT  *((volatile unsigned int *)0xE02000A4)
#define BEEP_ON  1
#define BEEP_OFF 0


typedef unsigned char u8_t;

void delay(int n)
{
	unsigned int i, j;
	for(i=0; i<n; i++)
		for(j=0; j< 1000000; j++)
			j = j + 0;
}

void led_init(void)
{	
	GPJ2CON &= 0XFFFF0000;   // 好习惯
	GPJ2CON |= 0x00001111;   // 4个等处在 output 模式
}


void led(u8_t t1, u8_t t2, u8_t t3, u8_t t4)
{
	u8_t stat = 0;
	stat += t1;
	stat <<= 1;
	stat += t2;
	stat <<= 1;
	stat += t3;
	stat <<= 1;
	stat +=t4;
	GPJ2DAT = stat;
}

void beep_init(void)
{
	GPD0CON &= 0xffff0000;
	GPD0CON |= 0X00001111;
}

void beep(u8_t stat)
{
	GPD0DAT = stat;
}


void key1_init(void)
{
	;
}
int ky1_is_down(void)
{
	return 0;
}


int c_entry(void)
{

	led_init();
	
	while(1){
			led(LED_ON, LED_OFF, LED_OFF, LED_OFF);
			delay(100);
			led(LED_OFF, LED_ON, LED_OFF, LED_OFF);
			delay(100);
			led(LED_OFF, LED_OFF, LED_ON, LED_OFF);
			delay(100);
			led(LED_OFF, LED_OFF, LED_OFF, LED_ON);
			beep(BEEP_ON);
			delay(100)
			beep(BEEP_OFF);
	}
	
	return 0;
}

; 汇编 a.s 调用 c.c  
; ARM linker Equivalent Commandline 链接参数 -info totals -ro-base 0x21000000 -first a.o
	area start,code,readonly
	code32
	entry
	import c_entry

aaaaa
	ldr r13,=0x38000000
	b c_entry
	 
	end