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

;******************************************************************************************************** 
;                                               uC/OS-II 
;                                         The Real-Time Kernel 
; 
;                                       ATmega256  Specific code 
; 
; 
; File     : APP_ISR.S 
; By       : Jean J. Labrosse 
;******************************************************************************************************** 
 
                .include   "os_cpu_i.h" 
 
;/*$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 
;******************************************************************************************************** 
 
                .area   text(rel) 
                 
_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        ; Handle the tick ISR 
 
                CALL    _OSIntExit                  ; Notify uC/OS-II about end of ISR 
 
                POP_SP                              ; Restore the hardware stack pointer from task's stack 
                POP_SREG_INT                        ; Restore the SREG register 
                POP_ALL                             ; Restore all registers 
 
                RETI