#define     SDO     PORTA,0     ;RA0 is Serial Data Out
#define     SCK     PORTA,1     ;RA1 is Serial Clock


SEND        EQU     0x20        ;GP RAM 0x20 is serial send buffer

        movfw       RCREG       ;move received data byte into SPI send register
        movwf       SEND
        call        DATA_OUT    ;send data on SPI buss

DATA_OUT    movlw       0x08        ;initialize bit counter
        movwf       BITCOUNT

SEND_BIT    btfss       SEND,7      ;is MSB of send register high or low?
        goto        SEND_LO     ;low, send 0
        goto        SEND_HI     ;high, send 1

SEND_LO     bcf     SDO     ;send 0
        goto        SHIFT

SEND_HI     bsf     SDO     ;send 1
        goto        SHIFT

SHIFT       bsf     SCK     ;clock hi
        bcf     SCK     ;clock lo
        rlf     SEND,F      ;shift bits in send register
        decfsz      BITCOUNT,F  ;decriment bit counter
        goto        SEND_BIT    ;bit counter > 0, send next bit
        return              ;bit counter = 0, return