LED灯亮灭控制

.text 
.global _start
_start: 
@1
	ldr r0,=0x50000a28
	ldr r1,[r0]
	orr r1,r1,#(0x3<<4)
	str r1,[r0]
@2
	ldr r0,=0x50006000
	ldr r1,[r0]
	bic r1,r1,#(0x3<<20)
	orr r1,r1,#(0x1<<20)
	bic r1,r1,#(0x3<<16)
	orr r1,r1,#(0x1<<16)
	str r1,[r0]

	ldr r0,=0x50007000
	ldr r1,[r0]
	bic r1,r1,#(0x3<<20)
	orr r1,r1,#(0x1<<20)
	str r1,[r0]
@3
	ldr r0,=0x50006004
	ldr r1,[r0]
	bic r1,r1,#(0x1<<10)
	bic r1,r1,#(0x1<<8)
	str r1,[r0]

	ldr r0,=0x50007004
	ldr r1,[r0]
	bic r1,r1,#(0x1<<10)
	str r1,[r0]
@4
	ldr r0,=0x50006008
	ldr r1,[r0]
	bic r1,r1,#(0x3<<20)
	bic r1,r1,#(0x3<<16)
	str r1,[r0]

	ldr r0,=0x50007008
	ldr r1,[r0]
	bic r1,r1,#(0x3<<20)
	str r1,[r0]
@5
	ldr r0,=0x5000600c
	ldr r1,[r0]
	bic r1,r1,#(0x3<<20)
	bic r1,r1,#(0x3<<16)
	str r1,[r0]

	ldr r0,=0x5000700c
	ldr r1,[r0]
	bic r1,r1,#(0x3<<20)
	str r1,[r0]

loop:
	bl led1_on
	bl delay

	bl led1_off
	bl delay

    bl led2_on
    bl delay

    bl led2_off
    bl delay

    bl led3_on
    bl delay

    bl led3_off
    bl delay

	b loop

led1_on:
	ldr r0,=0x50006014
	ldr r1,[r0]
	bic r1,r1,#(0x1<<10)
	str r1,[r0]
	mov pc,lr

led1_off:
	ldr r0,=0x50006014
	ldr r1,[r0]
	bic r1,r1,#(0x1<<10)
	str r1,[r0]


led2_on:
    ldr r0,=0x50007014
    ldr r2,[r0]
    bic r2,r2,#(0x1<<8)
    str r2,[r0]
    mov pc,lr                                                                                       

led2_off:
    ldr r0,=0x50007014
    ldr r2,[r0]
    bic r2,r2,#(0x1<<8)
    str r2,[r0]

led3_on:
    ldr r0,=0x50006014
    ldr r3,[r0]
    bic r3,r3,#(0x1<<8)
    str r3,[r0]
    mov pc,lr                                                                                       

led3_off:
    ldr r0,=0x50006014
    ldr r3,[r0]
    bic r3,r3,#(0x1<<8)
    str r3,[r0]


delay:
	ldr r4,=0x10000000

mm:
	cmp r4,#0
	subne r4,r4,#1
	bne mm
	mov pc,lr

.end