裸机程序1[led]

【led1.S】

#define GPECON 0x56000040
#define GPEDAT 0x56000044

	.text
	.align 2
	.global _start
_start:
	
	ldr r1, =GPECON
	ldr r0, [r1]
	bic r0, r0, #(0xf << 24)	
	orr r0, r0, #(0x5 << 24)
	str r0, [r1]

	ldr r1, =GPEDAT
	ldr r0, [r1]
	bic r0, r0, #( 0x3 << 12 )
	str r0, [r1]

die_loop:
	b die_loop

【led.S】

#define GPECON 0x56000040
#define GPEDAT 0x56000044

	.text
	.align 2
	.global _start
_start:
	
	ldr r1, =GPECON
	ldr r0, [r1]
	bic r0, r0, #(0xf << 24)	
	orr r0, r0, #(0x5 << 24)
	str r0, [r1]

eloop:

	ldr r1, =GPEDAT
	ldr r0, [r1]
	bic r0, r0, #( 0x3 << 12 )
	str r0, [r1]

	mov r0, #0x10000
	bl delay

	ldr r1, =GPEDAT
	ldr r0, [r1]
	orr r0, r0, #( 0x3 << 12 )
	str r0, [r1]

	mov r0, #0x10000
	bl delay

	b eloop

delay:
	sub r0, r0, #1
	cmp r0, #0
	bne delay
	mov pc, lr


【Makefile】

all:
	arm-linux-gcc led.S -c -o led.o
	arm-linux-ld led.o -o led
	arm-linux-objcopy -O binary led led.bin
	cp led.bin /exe/