swi.s

ARM嵌入式系统开发--软件设计与优化随书源代码。开发环境asm+c

; ****************************************************************************
; * Simple Little Operating System - SLOS
; ****************************************************************************

; ****************************************************************************
; *
; * Module     : swi.s
; * Project	: SLOS
; * Version	: 0.09
; * Originator	: Andrew N. Sloss
; * History    :
; * 
; * 16th July 2003 Andrew N. Sloss
; * - added header information
; *
; ****************************************************************************

	EXPORT		coreSWIHandler

; ****************************************************************************
; * IMPORT
; ****************************************************************************

	IMPORT	events_swi_cm920iap_handler


	AREA SWISLOS, CODE, READONLY

; ****************************************************************************
; * kernel swi handler event
; ****************************************************************************

coreSWIHandler
     
     STMFD   sp!,{r0-r12,lr}        ; Store registers
     LDR     r10,[lr,#-4]           ; Calculate address of SWI instruction
     BIC	   r10,r10,#0xff000000    ; Mask off top 8 bits
     MOV     r1,sp                  ; second parameter to C routine...
                                    ; is pointer to register values.
     MRS     r2,SPSR                ; move the spsr into gp register
	STMFD   sp!,{r2}		      ; store spsr onto the stack. 
                                    ; This is only really
					           ; needed in case of nested SWI's
     BL      swi_jumptable          ; call C routine to handle SWI
	LDMFD   sp!,{r2}		      ; restore spsr from stack into r2
	MSR     SPSR_cf,r2             ; and restore it into spsr.
	LDMFD   sp!,{r0-r12,pc}^       ; restore registers and return.

; ------------------------------------------------------------
; SWI Jump Table
; r0 - swi Number
; r1 - point to the r0-r12
; ------------------------------------------------------------

swi_jumptable

     MOV     r0,r10                ; move SWI number into r0
     B       events_swi_cm920iap_handler  ; calling c routine to handle swi call
	END