>http://home.netcom.com/~fastfwd/answers.html#PIC00094 from Andrew
>Warren: 16-bit by 8 - site unreachable

Here is the info from Andrew's site:
I saw the 8-bit divide routine in Question #64, but I can't figure out how
to extend it to divide one 16-bit number by another. How do you do a 16-bit
divide?

Like this. The following routine is written for clarity, not absolute
speed, but it should still perform relatively quickly:

            ; 16-Bit Divide.  Written by Andy Warren.
            ;
            ; Copyright (C) 1996 Fast Forward Engineering.  All rights
reserved.
            ; Permission is hereby granted for any non-commercial use,
            ; so long as this copyright notice remains intact.
            ;
            ; Enter with Dividend in DIVIDENDHI:DIVIDENDLO, divisor in
            ; DIVISORHI:DIVISORLO.
            ;
            ; Exits with quotient in QUOTIENTHI:QUOTIENTLO, remainder in
            ; REMAINDERHI:REMAINDERLO.

            DIVIDE16:

                    CLRF    REMAINDERHI     ;CLEAR THE REMAINDER.
                    CLRF    REMAINDERLO     ;

                    MOVLW   16              ;WE'RE DIVIDING BY A 16-BIT
DIVISOR.
                    MOVWF   COUNT           ;

            DIVLOOP:

                    RLF     DIVIDENDLO      ;SHIFT DIVIDEND LEFT 1 BIT INTO
                    RLF     DIVIDENDHI      ;REMAINDERHI:REMAINDERLO.
                    RLF     REMAINDERLO     ;
                    RLF     REMAINDERHI     ;

                    MOVF    DIVISORHI,W     ;COMPARE THE DIVISOR TO THE
PORTION OF THE
                    SUBWF   REMAINDERHI,W   ;DIVIDEND THAT'S BEEN SHIFTED
INTO REMHI.

                    BNZ     CHECKLESS       ;IF THE TWO HI-BYTES AREN'T THE
SAME, JUMP
                                            ;AHEAD.

                    MOVF    DIVISORLO,W     ;OTHERWISE, WE HAVE TO COMPARE
THE
                    SUBWF   REMAINDERLO,W   ;LO-BYTES.

            CHECKLESS:

                    BNC     NOSUB           ;IF THE SHIFTED PORTION OF THE
DIVIDEND WAS
                                            ;LESS THAN THE DIVISOR, JUMP
AHEAD.

                    MOVF    DIVISORLO,W     ;OTHERWISE, REMAINDER =
REMAINDER - DIVISOR.
                    SUBWF   REMAINDERLO     ;
                    MOVF    DIVISORHI,W     ;
                    SKPC                    ;
                    INCFSZ  DIVISORHI       ;
                    SUBWF   REMAINDERHI     ; (CARRY'S ALWAYS SET AT THIS
POINT.)

            NOSUB:

                    RLF     QUOTIENTLO      ;IF WE JUST SUBTRACTED, SHIFT A
"1" INTO
                    RLF     QUOTIENTHI      ;THE QUOTIENT.  OTHERWISE,
SHIFT A "0".

                    DECFSZ  COUNT           ;HAVE WE SHIFTED ENOUGH BITS?
                    GOTO    DIVLOOP         ;IF NOT, LOOP BACK.

            ; AT THIS POINT, THE QUOTIENT IS IN QUOTIENTHI:LO AND THE
REMAINDER IS
            ; IN REMAINDERHI:LO.

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