X-Comment-To: tom ehlert
Hi!
13-���-2002 22:31 [EMAIL PROTECTED] (tom ehlert) wrote to
[EMAIL PROTECTED]:
>> - rdatclk.asm. Was:
te> rdatclk was linked earlier. now its '#if 0' code (to be deleted ASAP)
I seen this, but I don't know (yet) where similar code may be present.
>> In other files also may be applied similar small optmizations. For example,
>> rdpcclk.asm. Was:
te> was xor ah,ah
te> Should be: mov ah,0
te> WHY?
Looks nicer and sensible (`mov ah,0' reflects AH=0 action better). This
is question of taste, though.
te> was > mov ah,0
te> should be > ;mov ah,0
te> OK.
Note: commented line shouldn't be deleted. It is a compromise beteween
readability (there are no implicit assumptions), supportness (if you will
copy this code without previous MOV AH,0 or XOR AH,AH, then you will see
that there should be AH==0 and you may simply uncomment code) and efficiency
(no extra instructions).
te> was > mov ax,dx
te> > mov dx,cx
te> should be > xchg ax,cx
Here should be:
xchg ax,cx ; OPTIMIZE: instead MOV AX,CX
te> > xchg ax,dx
te> why?
Because this code (XCHG AX/reg) shorter (than MOV AX/reg).
te> so we save 2 bytes.
Plus two bytes above. At lower level (when only formal optimizations
applied) there harder to ger more (although in previous example I offer
more).
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