stt.asm

nucleusPlus是一个优秀的多任务调度内核

	AREA IDLE_TASK, CODE, READONLY

LOCKOUT		EQU	   0xC0   ; Interrupt lockout value
LOCK_MSK        EQU     0xC0   ; Interrupt lockout mask value

	IMPORT	STD_Idle_Count
	IMPORT	TCD_Interrupt_Level

Idle_Count	DCD	STD_Idle_Count
Int_Level	DCD	TCD_Interrupt_Level

;
;void STT_Lock_Interrupt(void);
;
	EXPORT	STT_Lock_Interrupt
STT_Lock_Interrupt
	;close arm interrupt
        MRS     a1,CPSR                     ; Pickup current CPSR
        ORR     a1,a1,#LOCKOUT              ; Build interrupt lockout value
        MSR     CPSR_cxsf,a1                ; Lockout interrupts
	
	BX	lr			    ;return

;
;void STT_Restore_Interrupt()
;

	EXPORT STT_Restore_Interrupt
STT_Restore_Interrupt
	;restore interrupt according to TCD_Interrupt_Level	
        LDR     a2,[pc, #Int_Level-.-8]     ; Pickup address of interrupt 
                                            ; lockout
	MRS	a1,CPSR
        BIC     a1,a1,#LOCK_MSK             ; Clear lockout mask
        LDR     a3,[a2, #0]                 ; Pickup interrupt lockout mask
        ORR     a1,a1,a3                    ; Build new interrupt lockout mask
        MSR     CPSR_cxsf,a1                ; Place it into the SPSR 
	
	BX	lr			    ;return


;
;idle task:just do counting, the interrupt MUST be disabled during counting
;
	EXPORT	STT_Idle_Loop
STT_Idle_Loop

	;BL	STT_Lock_Interrupt		;lock interrupt

	;close arm interrupt
        MRS     a1,CPSR                     ; Pickup current CPSR
        ORR     a1,a1,#LOCKOUT              ; Build interrupt lockout value
        MSR     CPSR_cxsf,a1                ; Lockout interrupts
	
	;do counting
        LDR     a2,[pc,#Idle_Count-.-8] 	; Pickup idle count address
        LDR     a1,[a2, #0]             	; Pickup current count
	ADD	a1,a1,#1
	STR	a1,[a2,#0]

	;BL	STT_Restore_Interrupt		;restore interrupt

	;restore interrupt according to TCD_Interrupt_Level	
        LDR     a2,[pc, #Int_Level-.-8]     ; Pickup address of interrupt 
                                            ; lockout
	MRS	a1,CPSR
        BIC     a1,a1,#LOCK_MSK             ; Clear lockout mask
        LDR     a3,[a2, #0]                 ; Pickup interrupt lockout mask
        ORR     a1,a1,a3                    ; Build new interrupt lockout mask
        MSR     CPSR_cxsf,a1                ; Place it into the SPSR 


	B	STT_Idle_Loop		   	 ;loop again
	
	END