Datasheet

 2012 Microchip Technology Inc. DS30575A-page 195
PIC18F97J94 FAMILY
10.12 Context Saving During Interrupts
During interrupts, the return PC address is saved on
the stack. Additionally, the WREG, STATUS and BSR
registers are saved on the Fast Return Stack.
If a fast return from interrupt is not used (see
Section 6.3 “Data Memory Organization”), the user
may need to save the WREG, STATUS and BSR regis-
ters on entry to the Interrupt Service Routine (ISR).
Depending on the user’s application, other registers
also may need to be saved.
Example 10-1 saves and restores the WREG, STATUS
and BSR registers during an Interrupt Service Routine.
EXAMPLE 10-1: SAVING STATUS, WREG AND BSR REGISTERS IN RAM
MOVWF W_TEMP ; W_TEMP is in virtual bank
MOVFF STATUS, STATUS_TEMP ; STATUS_TEMP located anywhere
MOVFF BSR, BSR_TEMP ; BSR_TMEP located anywhere
;
; USER ISR CODE
;
MOVFF BSR_TEMP, BSR ; Restore BSR
MOVF W_TEMP, W ; Restore WREG
MOVFF STATUS_TEMP, STATUS ; Restore STATUS