rc4-586.pl: optimize even further...

# Pentium III	7.8(*)

# Intel P4	7.5

#

# Opteron	6.4/+14%		# new MMX numbers

# Core2		5.8/+50%(**)

# Westmere	5.5/+80%(**)

# Sandy Bridge	5.4/0%

# Opteron	6.1/+20%		# new MMX numbers

# Core2		5.3/+67%(**)

# Westmere	5.1/+94%(**)

# Sandy Bridge	5.0/+8%

#

# (*)	PIII can actually deliver 6.6 cycles per byte with MMX code,

#	but this specific code performs poorly on Core2. And vice

  $RC4_loop_mmx = sub {

    my $i=shift;

	&add	($yy,$tx);

	&movz	($yy,&LB($yy));				# (*)

	&add	(&LB($yy),&LB($tx));

	&psllq	("mm1",8*(($i-1)&7))			if (abs($i)!=1);

	&mov	($ty,&DWP(0,$dat,$yy,4));

	&mov	(&DWP(0,$dat,$yy,4),$tx);

		&$RC4_loop_mmx(0);

	&set_label("loop_mmx_enter");

		for 	($i=1;$i<8;$i++) { &$RC4_loop_mmx($i); }

		&mov	($ty,$yy);

		&xor	($yy,$yy);		# this is second key to Core2

		&mov	(&LB($yy),&LB($ty));	# and Westmere performance...

		&cmp	($inp,&DWP(-4,$dat));

		&lea	($inp,&DWP(8,$inp));

	&jb	(&label("loop_mmx"));