Hi,

I thought of something like this solution (which COULD work in SOME special
circumstances). This one uses Wouter idea about stop bit, but stores bits in
reverse order to be able to use DECFSZ to check if only stop bit is in the
byte. It is also 12 instruction solution, so not even smaller than previous
codes but maybe somebody could get another idea how to shrink it further -
for example leaving out the return :-)

morse_output:
    movwf    tmp
loop:
    bcf      STATUS,C        ; make sure no 1 is in C
     rrf      tmp, f          ; 0 or 1 to C
    call     comp_portb0     ; set portb,0 to high and wait 1 or 3 dots
    call     comp_portb0     ; set low and wait 1 dot
    decfsz   tmp, w          ; check if tmp is zero and skip if it is
    goto     loop
    return          ;!!!!    ; we may can leave it out as it does not hurt
                             ; if it waits an extra dot after the letter...
comp_portb0:
    rlf      dit_count,f     ; first of all save C into count variable (C=1
if dash)
    bsf      STATUS,C        ; this one is for replacing incf dit_count
    rlf      dit_count,f     ; multiplying dash to length 3 or dot to 1
                             ; now C is 0 for sure so next time comp_portb0
                             ; gets called it will wait only 1 dot...
    comp     portb, 0        ; instr 12

dit_delay:
    clrf     inner_count      ; set up inner loop count
dit_inner_loop:
    decfsz   inner_count
    goto     dit_inner_loop
    decfsz   dit_count,f
    goto     dit_delay
    return

Tamas


On 3/19/07, Robert Ammerman <rammerman@verizon.net> wrote:
>
> Here is another flavor that really does get down to 12 instructions, but
> with the restriction that the delay routine cannot modify W
>
> morse_output:
>     movwf        morse_bits
>     addwf        morse_bits,w
>     skpnz
>     return
>     skpnc
>     bsf            dit_count,1
>     bsf            portb,0
>     call            dit_delay_plus_1
>     bcf            portb,0
>     call            dit_delay_plus_1
>     bra            more_output
>
> ; This delay routine must preserve W.
>
> dit_delay_plus_1:
>     incf        dit_count,f        ; instruction number 12
>
> dit_delay:
>     clrf         inner_count      ; set up inner loop count
> ;    bsf        inner_count,?   ; alternate set up (assumes zero to start)
> dit_inner_loop:
>     decfsz    inner_count
>     goto      dit_inner_loop
>     decfsz    dit_count,f
>     goto        dit_delay
>     return
>
> --
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