Re: All is right !


almas wrote:

Hi everybody hello world
Below, the solution of Wolfgang.... i again reduce the size of file. now
55 bytes.

Regards Almas

mov si,0082h ;;;;;; mov esi,0082h ; I assume space before parameters
; cmp byte [esi-2],0 ; a few buyes more, but perhaps useful
; jz error ;if commandline is empty
lodsw ;get both bytes at once
call convert ;modify AL set carry/NC on error/GOOD
jc error
shl al,4
xchg al,ah ;save first and use second yet
call convert ;call the same again
jc error
or al,ah
mov offset hexa,AL
; jmp short error ; display_quit

error:
mov dx, offset errtxt ; jmp short error_quit
; ;;;;;;; display_quit: ; mov dx, offset txt
error_quit:
mov AH,09
int 21h
;;;;;; ret ;it will work, even I'd always use:
;;;;;; The RET of the call will be used like an INT 20h
;;;;; If it go in convert routine, the only output is RET

Ok, even this is a rare seen method for saving on one byte :)
always comment things like this in deep detail for yourself
in case you may look at it again after some years.

convert:
; cmp al,30h ;I'd put this in ; jc oh_no ;jc == jb
cmp al,3ah
jc num
cmp al,41h
jc oh_no
cmp al,47h ;
cmc ;invert the carry-bit (error if NoCarry >46h)
jc oh_no
sub al,07h
num:
sub al,30h
oh_no:
ret ;the last SUB will always result in NoCarry
;while any error got a set Carry-flag now.

Because you ignore input <30h anyway, you could
shorten 'convert' and ignore 'all' wrong input

convert:
sub AL,30h
cmp AL,0Ah
jc done
sub AL,07h
done:
ret

and then you must also remove the 'jc error' lines after
the two CALLs (saved four more bytes).

; mov ax,4c00h ;because DOS will restore its stack and
; int21h ;segment-registers on termination then.

errtxt db: "A2H" ,9 ; information about usage here

; txt db: " "
hexa db: " " ,36 ; old value ,10,36
; wolfgang

Oh, I became out-commented :)
__
wolfgang



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