www.pudn.com > AN-1256.zip > app_isr.s90

;******************************************************************************************************** 
;                                               uC/OS-II 
;                                         The Real-Time Kernel 
; 
;                                       ATmega256  Specific code 
; 
; 
; File     : APP_ISR.S90 
; By       : Jean J. Labrosse 
;******************************************************************************************************** 
 
#include         
 
 
                NAME    app_isr 
 
                RSEG    CSTACK:DATA:NOROOT(0) 
                RSEG    RSTACK:DATA:NOROOT(0) 
 
;******************************************************************************************************** 
;                                         EXTERNAL DECLARATIONS 
;******************************************************************************************************** 
 
                EXTERN  OSIntExit 
                EXTERN  OSIntNesting 
                EXTERN  OSTCBCur 
 
                EXTERN  BSP_TickISR_Handler 
 
;******************************************************************************************************** 
;                                          PUBLIC DECLARATIONS 
;******************************************************************************************************** 
 
                PUBLIC  BSP_TickISR 
 
;/*$PAGE*/ 
;******************************************************************************************************** 
;                                           SYSTEM TICK ISR 
; 
; Description : This function is the Tick ISR. 
; 
;               The following C-like pseudo-code describe the operation being performed in the code below. 
; 
;               Save all registers on the current task's stack: 
;                      Use the PUSH_ALL macro 
;                      Get the SREG, set Bit #7 and save onto the task's stack using -Y addressing 
;                      Use the PUSH_SP macro to save the task's hardware stack pointer onto the current task's stack 
;               OSIntNesting++; 
;               if (OSIntNesting == 1) { 
;                  OSTCBCur->OSTCBStkPtr = SP 
;               } 
;               Clear the interrupt;                  Not needed for the timer we used. 
;               OSTimeTick();                         Notify uC/OS-II that a tick has occured 
;               OSIntExit();                          Notify uC/OS-II about end of ISR 
;               Restore all registers that were save on the current task's stack: 
;                      Use the POP_SP macro to restore the task's hardware stack pointer 
;                      Use the POP_SREG macro to restore the SREG register 
;                      Use the POP_ALL macro to restore the remaining registers 
;               Return from interrupt 
;******************************************************************************************************** 
 
                RSEG FARCODE:CODE:NOROOT(1) 
 
BSP_TickISR: 
                PUSH_ALL                            ; Save all registers and status register 
                IN      R16,SREG                    ; Save the SREG but with interrupts enabled 
                SBR     R16,BIT07 
                ST      -Y,R16 
                PUSH_SP                             ; Save the task's hardware stack pointer onto task's stack 
 
                LDS     R16,OSIntNesting            ; Notify uC/OS-II of ISR 
                INC     R16                         ; 
                STS     OSIntNesting,R16            ; 
 
                CPI     R16,1                       ; if (OSIntNesting == 1) { 
                BRNE    BSP_TickISR_1 
 
                LDS     R30,OSTCBCur                ;     OSTCBCur->OSTCBStkPtr = Y 
                LDS     R31,OSTCBCur+1 
                ST      Z+,R28 
                ST      Z+,R29                      ; } 
 
BSP_TickISR_1: 
                CALL    BSP_TickISR_Handler         ; Call tick ISR Handler written in C 
 
                CALL    OSIntExit                   ; Notify uC/OS-II about end of ISR 
 
                POP_SP                              ; Restore the hardware stack pointer from task's stack 
                POP_SREG_INT 
                POP_ALL                             ; Restore all registers 
                RETI 
 
                END