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#!/usr/bin/perl
# At some point it became apparent that the original SSLeay RC4
# assembler implementation performs suboptimaly on latest IA-32
# microarchitectures. After re-tuning performance has changed as
# following:
#
# Pentium +0%
# Pentium III +17%
# AMD +52%(*)
# P4 +180%(**)
#
# (*) This number is actually a trade-off:-) It's possible to
# achieve +72%, but at the cost of -48% off PIII performance.
# In other words code performing further 13% faster on AMD
# would perform almost 2 times slower on Intel PIII...
# For reference! This code delivers ~80% of rc4-amd64.pl
# performance on the same Opteron machine.
# (**) This number requires compressed key schedule set up by
# RC4_set_key and therefore doesn't apply to 0.9.7 [option for
# compressed key schedule is implemented in 0.9.8 and later,
# see commentary section in rc4_skey.c for further details].
#
# <appro@fy.chalmers.se>
push(@INC,"perlasm","../../perlasm");
require "x86asm.pl";
&asm_init($ARGV[0],"rc4-586.pl");
$x="eax";
$y="ebx";
$tx="ecx";
$ty="edx";
$in="esi";
$out="edi";
$d="ebp";
&RC4("RC4");
&asm_finish();
sub RC4_loop
{
local($n,$p,$char)=@_;
&comment("Round $n");
if ($char)
{
if ($p >= 0)
{
&mov($ty, &swtmp(2));
&cmp($ty, $in);
&jbe(&label("finished"));
&inc($in);
}
else
{
&add($ty, 8);
&inc($in);
&cmp($ty, $in);
&jb(&label("finished"));
&mov(&swtmp(2), $ty);
}
}
# Moved out
# &mov( $tx, &DWP(0,$d,$x,4)) if $p < 0;
&add( &LB($y), &LB($tx));
&mov( $ty, &DWP(0,$d,$y,4));
# XXX
&mov( &DWP(0,$d,$x,4),$ty);
&add( $ty, $tx);
&mov( &DWP(0,$d,$y,4),$tx);
&and( $ty, 0xff);
&inc( &LB($x)); # NEXT ROUND
&mov( $tx, &DWP(0,$d,$x,4)) if $p < 1; # NEXT ROUND
&mov( $ty, &DWP(0,$d,$ty,4));
if (!$char)
{
#moved up into last round
if ($p >= 1)
{
&add( $out, 8)
}
&movb( &BP($n,"esp","",0), &LB($ty));
}
else
{
# Note in+=8 has occured
&movb( &HB($ty), &BP(-1,$in,"",0));
# XXX
&xorb(&LB($ty), &HB($ty));
# XXX
&movb(&BP($n,$out,"",0),&LB($ty));
}
}
sub RC4
{
local($name)=@_;
&function_begin_B($name,"");
&mov($ty,&wparam(1)); # len
&cmp($ty,0);
&jne(&label("proceed"));
&ret();
&set_label("proceed");
&comment("");
&push("ebp");
&push("ebx");
&push("esi");
&xor( $x, $x); # avoid partial register stalls
&push("edi");
&xor( $y, $y); # avoid partial register stalls
&mov( $d, &wparam(0)); # key
&mov( $in, &wparam(2));
&movb( &LB($x), &BP(0,$d,"",1));
&movb( &LB($y), &BP(4,$d,"",1));
&mov( $out, &wparam(3));
&inc( &LB($x));
&stack_push(3); # 3 temp variables
&add( $d, 8);
# detect compressed schedule, see commentary section in rc4_skey.c...
# in 0.9.7 context ~50 bytes below RC4_CHAR label remain redundant,
# as compressed key schedule is set up in 0.9.8 and later.
&cmp(&DWP(256,$d),-1);
&je(&label("RC4_CHAR"));
&lea( $ty, &DWP(-8,$ty,$in));
# check for 0 length input
&mov( &swtmp(2), $ty); # this is now address to exit at
&mov( $tx, &DWP(0,$d,$x,4));
&cmp( $ty, $in);
&jb( &label("end")); # less than 8 bytes
&set_label("start");
# filling DELAY SLOT
&add( $in, 8);
&RC4_loop(0,-1,0);
&RC4_loop(1,0,0);
&RC4_loop(2,0,0);
&RC4_loop(3,0,0);
&RC4_loop(4,0,0);
&RC4_loop(5,0,0);
&RC4_loop(6,0,0);
&RC4_loop(7,1,0);
&comment("apply the cipher text");
# xor the cipher data with input
#&add( $out, 8); #moved up into last round
&mov( $tx, &swtmp(0));
&mov( $ty, &DWP(-8,$in,"",0));
&xor( $tx, $ty);
&mov( $ty, &DWP(-4,$in,"",0));
&mov( &DWP(-8,$out,"",0), $tx);
&mov( $tx, &swtmp(1));
&xor( $tx, $ty);
&mov( $ty, &swtmp(2)); # load end ptr;
&mov( &DWP(-4,$out,"",0), $tx);
&mov( $tx, &DWP(0,$d,$x,4));
&cmp($in, $ty);
&jbe(&label("start"));
&set_label("end");
# There is quite a bit of extra crap in RC4_loop() for this
# first round
&RC4_loop(0,-1,1);
&RC4_loop(1,0,1);
&RC4_loop(2,0,1);
&RC4_loop(3,0,1);
&RC4_loop(4,0,1);
&RC4_loop(5,0,1);
&RC4_loop(6,1,1);
&jmp(&label("finished"));
&align(16);
# this is essentially Intel P4 specific codepath, see rc4_skey.c,
# and is engaged in 0.9.8 and later context...
&set_label("RC4_CHAR");
&lea ($ty,&DWP(0,$in,$ty));
&mov (&swtmp(2),$ty);
&movz ($tx,&BP(0,$d,$x));
# strangely enough unrolled loop performs over 20% slower...
&set_label("RC4_CHAR_loop");
&add (&LB($y),&LB($tx));
&movz ($ty,&BP(0,$d,$y));
&movb (&BP(0,$d,$y),&LB($tx));
&movb (&BP(0,$d,$x),&LB($ty));
&add (&LB($ty),&LB($tx));
&movz ($ty,&BP(0,$d,$ty));
&add (&LB($x),1);
&xorb (&LB($ty),&BP(0,$in));
&lea ($in,&DWP(1,$in));
&movz ($tx,&BP(0,$d,$x));
&cmp ($in,&swtmp(2));
&movb (&BP(0,$out),&LB($ty));
&lea ($out,&DWP(1,$out));
&jb (&label("RC4_CHAR_loop"));
&set_label("finished");
&dec( $x);
&stack_pop(3);
&movb( &BP(-4,$d,"",0),&LB($y));
&movb( &BP(-8,$d,"",0),&LB($x));
&function_end($name);
}
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