.main           movlw 0x1
                movwf 0x21
                movlw 0x1
                movwf 0x22
.while1         movlw 0x1
                iorlw 0x0
                btfsc STATUS,2
.mul1           addwf 0x20,0
                decfsz 0xc,1
                goto .mul1
                movwf 0x22
                movf 0x21,0
                movwf 0x20
                movlw 0x4
                subwf 0x20,0
                btfss STATUS,0
                clrw
                iorlw 0x0
                btfsc STATUS,2
                goto .while1
                goto .endwh1
.else1          goto .while1
.endwh1         nop

    Source: geocities.com/gnupic