----- Original Message -----
From: Scott Dattalo <scott@DATTALO.COM>

The following section may be shortened slightly in one of two ways:

>
>         ; carry propagation, if set then make sure if 'follows' through
>
>         MOVLW   0x01            ; preload with 1
>         BTFSC   STATUS,C        ; check carry for overflow
>         ADDWF   Product+2,F     ; add one to next byte
>
>         BTFSC   STATUS,C        ; check carry for overflow
>         ADDWF   Product+1,F     ; add one to next byte
>
>         BTFSC   STATUS,C        ; check carry for overflow
>         ADDWF   Product,F       ; add one to next byte

   rlf   known_zero,w    ;a trick learned from payson
   addwf Product+2,f
   rlf   known_zero,w
   addwf Product+1,f
   rlf   known_zero,w
   addwf Product+0,f

OR:

   skpnc
    incf  Product+2,f
   skpnc
    incf  Product+1,f
   skpnc
    incf  Product+0,f

Uh, this last snippet will _not_ work.
If carry is clear on entry, then no bytes will be touched, this is fine.
But, if carry is set on entry, then all three bytes will be incremented.
This is an error.

This occurs because the carry bit is _not_ set by the "incf" instruction.

Bob Ammerman
RAm Systems
(contract development of high performance, high function, low-level
software)

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