list b=4 list p=16F886 include cblock 0x20 acc: 2 work: 2 temp endc org 0x0000 goto Start org 0x0004 retfie Start movlw 0xAA movwf acc movlw 0x7F movwf acc+1 movlw 0x04 movwf work movlw 0x00 movwf work+1 call Add16 movlw 0xAA movwf acc movlw 0x7F movwf acc+1 movlw 0x04 movwf work movlw 0x00 movwf work+1 call Add16Sat movlw 0xAA movwf acc movlw 0x7F movwf acc+1 movlw 0xAA movwf work movlw 0x00 movwf work+1 call Add16 movlw 0xAA movwf acc movlw 0x7F movwf acc+1 movlw 0xAA movwf work movlw 0x00 movwf work+1 call Add16Sat ; sub movlw 0xAA movwf acc movlw 0x80 movwf acc+1 movlw 0x04 movwf work movlw 0x00 movwf work+1 call Sub16 movlw 0xAA movwf acc movlw 0x80 movwf acc+1 movlw 0x04 movwf work movlw 0x00 movwf work+1 call Sub16Sat movlw 0xAA movwf acc movlw 0x80 movwf acc+1 movlw 0xBB movwf work movlw 0x00 movwf work+1 call Sub16 movlw 0xAA movwf acc movlw 0x80 movwf acc+1 movlw 0xBB movwf work movlw 0x00 movwf work+1 call Sub16Sat goto Start Add16 movf work,w addwf acc,f btfsc STATUS,C incf acc+1,f movf work+1,w addwf acc+1,f return Add16Sat movf acc+1,w movwf temp movf work,w addwf acc,f btfsc STATUS,C incf acc+1,f movf work+1,w addwf acc+1,f movf temp,w xorwf acc+1,w andlw 0x80 btfss STATUS,Z btfss acc+1,7 return movlw 0xFF movwf acc movlw 0x7F movwf acc+1 return Sub16 movf work,w subwf acc,f btfss STATUS,C decf acc+1,f movf work+1,w subwf acc+1,f return Sub16Sat movf acc+1,w movwf temp movf work,w subwf acc,f btfss STATUS,C decf acc+1,f movf work+1,w subwf acc+1,f movf temp,w xorwf acc+1,w andlw 0x80 btfss STATUS,Z btfsc acc+1,7 return clrf acc movlw 0x80 movwf acc+1 return end