PDF version - ARM Information Center
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프로세서 예외 처리9. 사용자 모드 LR과 스택 조정 값을 복원합니다.10. 필요한 경우 스택을 다시 조정합니다.11. IRQ 모드로 전환합니다.12. 다른 레지스터와 IRQ 모드 SPSR을 복원합니다.13. IRQ에서 복귀합니다.예제 6-2 및 6-14페이지의 예제 6-3에서는 시스템 모드에서 이 작업을 수행하는방법을 보여 줍니다.예제 6-2 <strong>ARM</strong>v4/v5TE용 재진입 인터럽트 처리기PRESERVE8AREA INTERRUPT, CODE, READONLYIMPORT C_irq_handlerIMPORT identify_and_clear_sourceIRQ_HandlerSUB lr, lr, #4 ; construct the return addressPUSH {lr} ; and push the adjusted lr_IRQMRS lr, SPSR ; copy spsr_IRQ to lrPUSH {R0-R4,R12,lr} ; save AAPCS regs and spsr_IRQBL identify_and_clear_sourceMSR CPSR_c, #0x9F ; switch to SYS mode, IRQ is; still disabled. USR mode; registers are now current.AND R1, sp, #4 ; test alignment of the stackSUB sp, sp, R1 ; remove any misalignment (0 or 4)PUSH {R1,lr} ; store the adjustment and lr_USRMSR CPSR_c, #0x1F ; enable IRQBL C_irq_handlerMSR CPSR_c, #0x9F ; disable IRQ, remain in SYS modePOP {R1,lr} ; restore stack adjustment and lr_USRADD sp, sp, R1 ; add the stack adjustment (0 or 4)MSR CPSR_c, #0x92 ; switch to IRQ mode and keep IRQ; disabled. FIQ is still enabled.POP {R0-R4,R12,lr} ; restore registers andMSR SPSR_cxsf, lr ; spsr_IRQLDM sp!, {pc}^ ; return from IRQ.END<strong>ARM</strong> DUI 0203IK Copyright © 2002-2008 <strong>ARM</strong> Limited. All rights reserved. 6-13Unrestricted AccessNon-Confidential
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