if I may...

Code:
RES_VECT  CODE    0x0000            ; processor reset vector
    GOTO    START                   ; go to beginning of program
; TODO ADD INTERRUPTS HERE IF USED
MAIN_PROG CODE                      ; let linker place main program
START
 

        MOVLW   0f
        MOVWF   control
        MOVLW   3
        MOVWF   LATB,A
lopo
        BANKSEL control
        incf    control,F       ; control = control + 1
        bcf     control,4       ; control = control mod 15
  
        swapf   control,W       ; B7..B4 <- control
        xorwf   LATB,W          ; wreg = differences
        andlw   0xF0            ; ignore B3..B0 bits
        xorwf   LATB,F          ; update B7..B4 bits
 
        GOTO    lopo