[MiNT] C bit

["Konrad M. Kokoszkiewicz" <draco@obta.uw.edu.pl>]

Hello,

here something about how the gcc 2.8.1 can optimize code. The original
code comes from older versions of MiNT (now this part is inlined in one of
the assembly modules):

C listing:

ulong	uptime = 0;
short	uptimetick = 200;

void calc_load_average()
{
	/* snip */

	uptime++;
	uptimetick += 200;
	if (uptime % 5) return;

	/* snip */
	...

Compiler output (-m68030 -O3):

_calc_load_average:
	...
	move.l	_uptime,a0
	lea	$0001(a0),a1
	move.l	a1,_uptime
	add.w	#$00c8,_uptimetick
	move.l	a0,d1
	addq.l	#$01,d1
	move.l	d1,d2
	mulu.l	#$cccccccd,d0-d2
	lsr.l	#$02,d0
	move.l	d0,a1
	lea	(a1,d0.l*4),a1
	move.l	a1,d0
	cmp.l	d1,d0
	bne.s	L459
	...

Comments?

--
Konrad M.Kokoszkiewicz
|mail: draco@atari.org                  |  Atari Falcon030 user   |
|http://www.obta.uw.edu.pl/~draco/      | Moderator gregis LATINE |
|http://draco.atari.org                 |       (loquentium)      |

** Ea natura multitudinis est,
** aut servit humiliter, aut superbe dominatur (Liv. XXIV,25)
*************************************************************
** U pospolstwa normalne jest, ze albo sluzy ono unizenie,
** albo bezczelnie sie panoszy.