#include p16f887.inc


RegA equ 0x25   ; bank0
RegB equ 0x26   ;
aux equ 0x27
RegC equ 0xB0   ; 0x30 bank 1
RegD equ 0xB1   ; 0x31 bank 1
M equ 0x125 ;0x25 bank 2

main:
    BCF STATUS,RP1
    BCF STATUS,RP0
    MOVLW D'100'
    MOVWF RegA
    MOVLW D'50'
    MOVWF RegB

    BSF STATUS,RP0  ;{01} bank1
    MOVLW D'200'
    MOVWF RegC
    MOVLW D'20'
    MOVWF RegD
    ADDWF RegC,0    ;d=0 w=D

    BSF STATUS,RP1
    BCF STATUS,RP0  ;{10} bank2
    MOVWF M ; M=RegC+RegD
    RRF M,1 ; M=M/2


    BCF STATUS,RP0
    BCF STATUS,RP1  ;{00} bank0
    MOVF RegA,0 ;d=0 w=A
    ADDWF RegB,0    ;d=0 w=w+RegB
    MOVWF aux
    RRF aux,0; d=0 w=(A+B)/2

    BSF STATUS,RP1  ;{10} bank2
    ADDWF M,1   ;d=1 M=w+M
    RRF M,1 ;d=1 M=M/2

    NOP
end