os_cpu_a.s

ucos ii 2.83的完整版,包含接口程序

        MOVS    PC,R0                   	; Restore PC and CPSR

                                        	; SAVE OLD TASKS CONTEXT ONTO OLD TASKS STACK
        STMFD   SP!,{R2}                	; Push tasks PC 
        STMFD   SP!,{R4-R12,LR}         	; Push tasks LR,R12-R4
        MOV     R4,R1                   	; Move R0-R3 from IRQ stack to SVC stack
        MOV     R5,R3
        LDMFD   R4!,{R0-R3}             	; Load R0-R3 from IRQ stack
        STMFD   SP!,{R0-R3}             	; Push R0-R3
        STMFD   SP!,{R5}                	; Push tasks CPSR
        MRS     R4,SPSR
        STMFD   SP!,{R4}                	; Push tasks SPSR
        
        LDR     R4,=OSTCBCur          		; OSTCBCur->OSTCBStkPtr = SP
        LDR     R5,[R4]
        STR     SP,[R5]

        BL      OSTaskSwHook            	; call Task Switch Hook

        LDR     R4,=OSPrioCur         		; OSPrioCur = OSPrioHighRdy
        LDR     R5,=OSPrioHighRdy
        LDRB    R6,[R5]
        STRB    R6,[R4]
        
        LDR     R4,=OSTCBCur          		; OSTCBCur = OSTCBHighRdy
        LDR     R6,=OSTCBHighRdy      
        LDR     R6,[R6]
        LDR     SP,[R6]

        STR     R6,[R4]                 

        LDMFD   SP!,{R4}                	; pop new task's SPSR
        MSR     SPSR_cxsf,R4
        LDMFD   SP!,{R4}                	; pop new task's PSR
        MSR     CPSR_cxsf,R4
        
        ;- Write in the IVR to support Protect Mode
		;- No effect in Normal Mode
		;- De-assert the NIRQ and clear the source in Protect Mode
        LDR     r14, =AT91C_BASE_AIC
        STR     r14, [r14, #AIC_IVR]
        
        ;- 读取定时器状态寄存器
        LDR     r12,=AT91C_BASE_TC0
        LDR     r12,[r12, #TC_SR]
        
        ;- Mark the End of Interrupt on the AIC
        LDR     r12, =AT91C_BASE_AIC
        STR		r12, [r12, #AIC_EOICR]

        LDMFD   SP!,{R0-R12,LR,PC}      	; pop new tasks R0-R12,LR & PC
        
TC_OSTickISR
		STMFD	SP!,{R0-R3,R12,LR}
		
		BL		OSIntEnter
		BL		OSTimeTick
		BL 		OSIntExit
		
		LDR		R0, =OSIntCtxSwFlag
        LDR		R1, [R0]
        CMP		R1, #1
        BEQ		TC_OS_IntCtxSw
        
        ;- Write in the IVR to support Protect Mode
		;- No effect in Normal Mode
		;- De-assert the NIRQ and clear the source in Protect Mode
        LDR     r14, =AT91C_BASE_AIC
        STR     r14, [r14, #AIC_IVR]
        
        ;- 读取定时器状态寄存器
        LDR     r12,=AT91C_BASE_TC0
        LDR     r12,[r12, #TC_SR]
        
        ;- Mark the End of Interrupt on the AIC
        LDR     r12, =AT91C_BASE_AIC
        STR		r12, [r12, #AIC_EOICR]
        
        LDMFD	SP!, {R0-R3, R12, LR}        
        
        SUBS	PC, LR, #4

PIT_OS_IntCtxSw
        LDR     R0,=OSIntCtxSwFlag    		; OSIntCtxSwFlag = FALSE
        MOV     R1,#0
        STR     R1,[R0]

        LDMFD   SP!,{R0-R3,R12,LR}      	; Clean up IRQ stack
        STMFD   SP!,{R0-R3}             	; We will use R0-R3 as temporary registers
        MOV     R1,SP
        ADD     SP,SP,#16
        SUB     R2,LR,#4

        MRS     R3,SPSR                 	; Disable interrupts for when we go back to SVC mode
        ORR     R0,R3,#NO_INT
        BIC		R0,R0,#0x00000020			;- 这一句很关键，是整个系统稳定运行的重要因素
        MSR     SPSR_c,R0					;- c 控制域屏蔽字节（PSR[7:0]）
        									;- x 扩展域屏蔽字节（PSR[15:8]）
        									;- s 状态域屏蔽字节（PSR[23:16]）
        									;- f 标志域屏蔽字节（PSR[31:24]）

        LDR     R0,=.+8                 	; Switch back to SVC mode (Code below, current location + 2 instructions)
        MOVS    PC,R0                   	; Restore PC and CPSR

                                        	; SAVE OLD TASKS CONTEXT ONTO OLD TASKS STACK
        STMFD   SP!,{R2}                	; Push tasks PC 
        STMFD   SP!,{R4-R12,LR}         	; Push tasks LR,R12-R4
        MOV     R4,R1                   	; Move R0-R3 from IRQ stack to SVC stack
        MOV     R5,R3
        LDMFD   R4!,{R0-R3}             	; Load R0-R3 from IRQ stack
        STMFD   SP!,{R0-R3}             	; Push R0-R3
        STMFD   SP!,{R5}                	; Push tasks CPSR
        MRS     R4,SPSR
        STMFD   SP!,{R4}                	; Push tasks SPSR
        
        LDR     R4,=OSTCBCur          		; OSTCBCur->OSTCBStkPtr = SP
        LDR     R5,[R4]
        STR     SP,[R5]

        BL      OSTaskSwHook            	; call Task Switch Hook

        LDR     R4,=OSPrioCur         		; OSPrioCur = OSPrioHighRdy
        LDR     R5,=OSPrioHighRdy
        LDRB    R6,[R5]
        STRB    R6,[R4]
        
        LDR     R4,=OSTCBCur          		; OSTCBCur = OSTCBHighRdy
        LDR     R6,=OSTCBHighRdy      
        LDR     R6,[R6]
        LDR     SP,[R6]

        STR     R6,[R4]                 

        LDMFD   SP!,{R4}                	; pop new task's SPSR
        MSR     SPSR_cxsf,R4
        LDMFD   SP!,{R4}                	; pop new task's PSR
        MSR     CPSR_cxsf,R4
        
        ;- Write in the IVR to support Protect Mode
		;- No effect in Normal Mode
		;- De-assert the NIRQ and clear the source in Protect Mode
        LDR     r14, =AT91C_BASE_AIC
        STR     r14, [r14, #AIC_IVR]
        
         ;- 读取PIT寄存器PIVR以确认中断
        LDR     r12,=AT91C_BASE_PITC       	
        LDR     r12,[r12, #PITC_PIVR]
        
        ;- Mark the End of Interrupt on the AIC
        LDR     r12, =AT91C_BASE_AIC
        STR		r12, [r12, #AIC_EOICR]

        LDMFD   SP!,{R0-R12,LR,PC}      	; pop new tasks R0-R12,LR & PC

PIT_OSTickISR
		STMFD	SP!,{R0-R3,R12,LR}
		
		BL		OSIntEnter
		BL		OSTimeTick
		BL		Uart_Debug_ISR		
		BL 		OSIntExit
		
		LDR		R0, =OSIntCtxSwFlag
        LDR		R1, [R0]
        CMP		R1, #1
        BEQ		PIT_OS_IntCtxSw
        
        ;- Write in the IVR to support Protect Mode
		;- No effect in Normal Mode
		;- De-assert the NIRQ and clear the source in Protect Mode
        LDR     r14, =AT91C_BASE_AIC
        STR     r14, [r14, #AIC_IVR]
        
        ;- 读取PIT寄存器PIVR以确认中断
        LDR     r12,=AT91C_BASE_PITC       	
        LDR     r12,[r12, #PITC_PIVR]
        
        ;- Mark the End of Interrupt on the AIC
        LDR     r12, =AT91C_BASE_AIC
        STR		r12, [r12, #AIC_EOICR]
        
        LDMFD	SP!, {R0-R3, R12, LR}        
        
        SUBS	PC, LR, #4
;- 临界处理函数
ARMCoreDisableIntExt
		MRS     R0,CPSR                     ;- 将CPSR寄存器的值传送到参数寄存器R0中

__DisableInt
        ORR     R1,R0,#I_BIT:OR:F_BIT
        
        MSR     CPSR_c,R1                   ;- 进行判断的目的是确认中断禁止操作已经成功后再开始临界处理
        MRS     R1,CPSR                     
        AND     R1,R1,#I_BIT:OR:F_BIT
        CMP     R1,#I_BIT:OR:F_BIT
        BNE     __DisableInt                
        BX		LR                          ;- 返回调用函数并返回原来的CPSR值

ARMCoreRestoreIntStatus
		MSR		CPSR_c, R0                  
		BX		LR        
        END