Binary to ASCII, 16 bit to 5 digits (1 at a time) no temp register (!)
; by Rich Leggitt with tweaks by Scott Dattalo and bugfix by Dmitry Kiryashov and Nikolai Golovchenko
; given 16 bit data in HI and LO, extract decimal digits
; requires one Output register called temp, HI and LO are destroyed.
; 42 instructions and less than 269 (or 252 with known_zero) instructions executed
clrf temp
skp
sub10k incf temp,f
movlw 10000 & 255
subwf LO,f
;Scott Dattalo says:
;If you have a ram location that's known to be zero, then
;the following [the IF] can be replaced with [the ELSE]
IFNDEF known_zero
movlw 10000 >> 8
skpc
addlw 1 ; this sucks
subwf HI,f
ELSE
rlf known_zero,W
sublw (10000>>8)+1 ;bugfix by Dmitry Kiryashov and Nikolai Golovchenko
subwf Hi,F
ENDIF
bc sub10k ;9*7=63/8*7=56 inst in loop for 60900 (worst)
output(temp);
movlw 10
movwf temp
add1K decf temp,f
movlw 1000 & 255
addwf LO,f
;Scott Dattalo says:
;If you have a ram location that's known to be zero, then
;the following [the IF] can be replaced with [the ELSE]
IFNDEF known_zero
movlw 1000 >> 8
skpnc
addlw 1
addwf HI,f
ELSE
rlf known_zero,w
addlw 1000 >> 8
addwf HI,f
ENDIF
bnc add1k ;9*10=90/8*10=80 inst in loop for 60900
output(temp);
;Scott takes over here
clrf temp
movlw 100
skp ;is this a valid macro? I'd write goto $+2 ...
sub100
incf temp,f
subwf LO,f
skpc
goto sub100
decf HI,f
btfss HI,7 ;Check msb instead of carry for underflow.
goto sub100 ;4 inst per loop to 200 then 7 per loop to 900.
;Total 64(?) in loop for worst case
;at this point, HI = 0xff, and 0 <= LO <= 99
output(temp)
movlw 10
movwf temp
add10 decf temp,f
addwf LO,f
bnc add10 ;40 inst in loop for worst case.
output(temp);
output(LO);
return