push_old.s

ARM push assembly example

.code 32

.equ	MODE_USR,		0x10
.equ	MODE_IRQ,		0x12
.equ	MODE_SVC,		0x13
.equ	I_BIT,			0x80
.equ	F_BIT,			0x40

.equ	IRQ_STACK,		0x0101ffff

.equ	PORTA_MUX,		0x09000000
.equ	PORTA_DIR,		0x09001604
.equ	PORTA_DATA,		0x09001600
.equ	PORT7_MUX,		0x09000020
.equ	PORT7_DIR,		0x09001644
.equ	PORT7_DATA,		0x09001640
.equ	GLOBAL_MASK,		0x09001200
.equ	TRIGGER_MODE,		0x09001204
.equ	TRIGGER_POLARITY,	0x09001208
.equ	INTERRUPT_DIRECTION,	0x0900120c
.equ	FIQ_STATUS,		0x09001210
.equ	IRQ_STATUS,		0x09001214
.equ	FIQ_MASK,		0x09001218
.equ	IRQ_MASK,		0x0900121c
.equ	INTERRUPT_STATUS_CLEAR,	0x09001220
.equ	DELAY_CNT,		0xffff

.global _start

_start:

.text	0
		b	reset_handler
		b	undefined_handler
		b	swi_handler
		b	prefetch_handler
		b	abort_handler
		nop
		b	irq_handler
		b	fiq_handler
		

.text	1
reset_handler:		mov	r0, #MODE_IRQ | I_BIT | F_BIT
			msr	cpsr, r0
			ldr	sp, =IRQ_STACK
			mov	r0, #MODE_USR
			msr	cpsr, r0
			b	start

undefined_handler:	movs	pc, lr

swi_handler:		movs	pc, lr

prefetch_handler:	subs	pc, lr, #4

abort_handler:		subs	pc, lr, #8

irq_handler:		
			stmfd	sp!, {r0-r12,lr}
			
			mrs	r12, cpsr
			orr	r12, r12, #0x90
			msr	cpsr, r12
		
			ldr	r7, =GLOBAL_MASK
			ldr	r1, =0x01ffff3e
			str	r1, [r7]				

			ldr	r7, =INTERRUPT_STATUS_CLEAR
			ldr	r1, =0x000000c1
			str	r1, [r7]				

			ldr	r7, =PORTA_DATA
			mov	r1, sp
			str	r1, [r7]

			ldmfd	sp!, {r0-r12,lr}

			subs	pc, lr, #4

fiq_handler:		subs	pc, lr, #4


start:		ldr	r0, =PORTA_MUX			@setup port a		
		ldr	r1, =0x3fff
		str	r1, [r0]
		
		ldr	r0, =PORTA_DIR
		mov	r1, #0
		str	r1, [r0]
		
		ldr	r0, =PORT7_DIR			@setup port 7
		ldr	r1, =0x000000ff
		str	r1, [r0]
		
		ldr	r0, =PORT7_MUX			
		ldr	r1, =0x000000a0
		str	r1, [r0]

		ldr	r0, =TRIGGER_MODE		@setup interrupt
		ldr	r1, =0x00000000
		str	r1, [r0]
		
		ldr	r0, =TRIGGER_POLARITY
		ldr	r1, =0x00000000
		str	r1, [r0]
		
		ldr	r0, =INTERRUPT_DIRECTION
		ldr	r1, =0x00000000
		str	r1, [r0]
		
		ldr	r0, =FIQ_MASK
		ldr	r1, =0x01ffffff
		str	r1, [r0]
		
		ldr	r0, =IRQ_MASK
		ldr	r1, =0x01ffff3e
		str	r1, [r0]
		
		ldr	r0, =GLOBAL_MASK
		ldr	r1, =0x01ffff3e
		str	r1, [r0]
		
		ldr	r0, =INTERRUPT_STATUS_CLEAR
		ldr	r1, =0x000000c1
		str	r1, [r0]		

/*		
		swi	0x0				@debug swi
*/
		
		ldr	r5, =PORTA_DATA
		mov	r2, #0
main_loop:	str	r2, [r5, #0]
		ldr	r0, =DELAY_CNT
		bl	delay
		add	r2, r2, #1
		b	main_loop

delay:		subs	r0, r0, #1
		bhs	delay
		mov	pc, lr

.pool