ghash-x86.pl: "528B" variant of gcm_ghash_4bit_mmx gives 20-40%
[openssl.git] / crypto / modes / asm / ghash-x86.pl
index 0222ede585941e0066a62e1167298046346b20dc..9fa4da1e915302e4fa0b8ab9b82c40fa337dd3fc 100644 (file)
 # details see http://www.openssl.org/~appro/cryptogams/.
 # ====================================================================
 #
-# The module implements "4-bit" Galois field multiplication and
-# streamed GHASH function. "4-bit" means that it uses 256 bytes
-# per-key table [+128/256 bytes fixed table]. It has two code paths:
-# vanilla x86 and vanilla MMX. Former will be executed on 486 and
-# Pentium, latter on all others. Performance results are for streamed
-# GHASH subroutine and are expressed in cycles per processed byte,
-# less is better:
+# March, May, June 2010
+#
+# The module implements "4-bit" GCM GHASH function and underlying
+# single multiplication operation in GF(2^128). "4-bit" means that it
+# uses 256 bytes per-key table [+64/128 bytes fixed table]. It has two
+# code paths: vanilla x86 and vanilla MMX. Former will be executed on
+# 486 and Pentium, latter on all others. MMX GHASH features so called
+# "528B" variant of "4-bit" method utilizing additional 256+16 bytes
+# of per-key storage [+512 bytes shared table]. Performance results
+# are for streamed GHASH subroutine and are expressed in cycles per
+# processed byte, less is better:
 #
 #              gcc 2.95.3(*)   MMX assembler   x86 assembler
 #
 # Pentium      100/112(**)     -               50
-# PIII         63 /77          17              24
-# P4           96 /122         33              84(***)
-# Opteron      50 /71          22              30
-# Core2                63 /102         21              28
+# PIII         63 /77          12.2            24
+# P4           96 /122         18.0            84(***)
+# Opteron      50 /71          10.1            30
+# Core2                54 /68          8.6             18
 #
 # (*)  gcc 3.4.x was observed to generate few percent slower code,
-#      which is one of reasons why 2.95.3 result were chosen;
+#      which is one of reasons why 2.95.3 results were chosen,
 #      another reason is lack of 3.4.x results for older CPUs;
 # (**) second number is result for code compiled with -fPIC flag,
 #      which is actually more relevant, because assembler code is
 #      position-independent;
 # (***)        see comment in non-MMX routine for further details;
 #
-# To summarize, it's 2-3 times faster than gcc-generated code. To
-# anchor it to something else SHA1 assembler processes single byte
-# in 11-13 cycles.
+# To summarize, it's >2-5 times faster than gcc-generated code. To
+# anchor it to something else SHA1 assembler processes one byte in
+# 11-13 cycles on contemporary x86 cores. As for choice of MMX in
+# particular, see comment at the end of the file...
+
+# May 2010
+#
+# Add PCLMULQDQ version performing at 2.13 cycles per processed byte.
+# The question is how close is it to theoretical limit? The pclmulqdq
+# instruction latency appears to be 14 cycles and there can't be more
+# than 2 of them executing at any given time. This means that single
+# Karatsuba multiplication would take 28 cycles *plus* few cycles for
+# pre- and post-processing. Then multiplication has to be followed by
+# modulo-reduction. Given that aggregated reduction method [see
+# "Carry-less Multiplication and Its Usage for Computing the GCM Mode"
+# white paper by Intel] allows you to perform reduction only once in
+# a while we can assume that asymptotic performance can be estimated
+# as (28+Tmod/Naggr)/16, where Tmod is time to perform reduction
+# and Naggr is the aggregation factor.
+#
+# Before we proceed to this implementation let's have closer look at
+# the best-performing code suggested by Intel in their white paper.
+# By tracing inter-register dependencies Tmod is estimated as ~19
+# cycles and Naggr is 4, resulting in 2.05 cycles per processed byte.
+# As implied, this is quite optimistic estimate, because it does not
+# account for Karatsuba pre- and post-processing, which for a single
+# multiplication is ~5 cycles. Unfortunately Intel does not provide
+# performance data for GHASH alone, only for fused GCM mode. But
+# we can estimate it by subtracting CTR performance result provided
+# in "AES Instruction Set" white paper: 3.54-1.38=2.16 cycles per
+# processed byte or 5% off the estimate. It should be noted though
+# that 3.54 is GCM result for 16KB block size, while 1.38 is CTR for
+# 1KB block size, meaning that real number is likely to be a bit
+# further from estimate.
+#
+# Moving on to the implementation in question. Tmod is estimated as
+# ~13 cycles and Naggr is 2, giving asymptotic performance of ...
+# 2.16. How is it possible that measured performance is better than
+# optimistic theoretical estimate? There is one thing Intel failed
+# to recognize. By fusing GHASH with CTR former's performance is
+# really limited to above (Tmul + Tmod/Naggr) equation. But if GHASH
+# procedure is detached, the modulo-reduction can be interleaved with
+# Naggr-1 multiplications and under ideal conditions even disappear
+# from the equation. So that optimistic theoretical estimate for this
+# implementation is ... 28/16=1.75, and not 2.16. Well, it's probably
+# way too optimistic, at least for such small Naggr. I'd argue that
+# (28+Tproc/Naggr), where Tproc is time required for Karatsuba pre-
+# and post-processing, is more realistic estimate. In this case it
+# gives ... 1.91 cycles per processed byte. Or in other words,
+# depending on how well we can interleave reduction and one of the
+# two multiplications the performance should be betwen 1.91 and 2.16.
+# As already mentioned, this implementation processes one byte [out
+# of 1KB buffer] in 2.13 cycles, while x86_64 counterpart - in 2.07.
+# x86_64 performance is better, because larger register bank allows
+# to interleave reduction and multiplication better.
+#
+# Does it make sense to increase Naggr? To start with it's virtually
+# impossible in 32-bit mode, because of limited register bank
+# capacity. Otherwise improvement has to be weighed agiainst slower
+# setup, as well as code size and complexity increase. As even
+# optimistic estimate doesn't promise 30% performance improvement,
+# there are currently no plans to increase Naggr.
+#
+# Special thanks to David Woodhouse <dwmw2@infradead.org> for
+# providing access to a Westmere-based system on behalf of Intel
+# Open Source Technology Centre.
 
 $0 =~ m/(.*[\/\\])[^\/\\]+$/; $dir=$1;
 push(@INC,"${dir}","${dir}../../perlasm");
 require "x86asm.pl";
 
-&asm_init($ARGV[0],"gcm-x86.pl",$x86only = $ARGV[$#ARGV] eq "386");
+&asm_init($ARGV[0],"ghash-x86.pl",$x86only = $ARGV[$#ARGV] eq "386");
 
-&static_label("rem_4bit") if (!$x86only);
+$sse2=0;
+for (@ARGV) { $sse2=1 if (/-DOPENSSL_IA32_SSE2/); }
 
-$Zhh  = "ebp";
-$Zhl  = "edx";
-$Zlh  = "ecx";
-$Zll  = "ebx";
+($Zhh,$Zhl,$Zlh,$Zll) = ("ebp","edx","ecx","ebx");
 $inp  = "edi";
 $Htbl = "esi";
-
+\f
 $unroll = 0;   # Affects x86 loop. Folded loop performs ~7% worse
                # than unrolled, which has to be weighted against
-               # almost 2x code size reduction. Well, *overall*
-               # code size. x86-specific code shrinks by 7.5x...
-
-sub mmx_loop() {
-# MMX version performs 2.5 times better on P4 (see comment in non-MMX
-# routine for further details), 35% better on Opteron and Core2, 40%
-# better on PIII... In other words effort is considered to be well
-# spent...
-    my $inp = shift;
-    my $rem_4bit = shift;
-    my $cnt = $Zhh;
-    my $nhi = $Zhl;
-    my $nlo = $Zlh;
-    my $rem = $Zll;
-
-    my $Zlo = "mm0";
-    my $Zhi = "mm1";
-    my $tmp = "mm2";
-
-       &xor    ($nlo,$nlo);    # avoid partial register stalls on PIII
-       &mov    ($nhi,$Zll);
-       &mov    (&LB($nlo),&LB($nhi));
-       &mov    ($cnt,15);
-       &shl    (&LB($nlo),4);
-       &and    ($nhi,0xf0);
-       &movq   ($Zlo,&QWP(8,$Htbl,$nlo));
-       &movq   ($Zhi,&QWP(0,$Htbl,$nlo));
-       &movd   ($rem,$Zlo);
-       &jmp    (&label("mmx_loop"));
-
-    &set_label("mmx_loop",16);
-       &psrlq  ($Zlo,4);
-       &and    ($rem,0xf);
-       &movq   ($tmp,$Zhi);
-       &psrlq  ($Zhi,4);
-       &dec    ($cnt);
-       &pxor   ($Zlo,&QWP(8,$Htbl,$nhi));
-       &psllq  ($tmp,60);
-       &pxor   ($Zhi,&QWP(0,$rem_4bit,$rem,8));
-       &movd   ($rem,$Zlo);
-       &pxor   ($Zhi,&QWP(0,$Htbl,$nhi));
-       &pxor   ($Zlo,$tmp);
-       &js     (&label("mmx_break"));
-
-       &movz   ($nhi,&BP(0,$inp,$cnt));
-       &psrlq  ($Zlo,4);
-       &mov    (&LB($nlo),&LB($nhi));
-       &movq   ($tmp,$Zhi);
-       &shl    (&LB($nlo),4);
-       &psrlq  ($Zhi,4);
-       &and    ($rem,0xf);
-       &pxor   ($Zlo,&QWP(8,$Htbl,$nlo));
-       &psllq  ($tmp,60);
-       &pxor   ($Zhi,&QWP(0,$rem_4bit,$rem,8));
-       &movd   ($rem,$Zlo);
-       &pxor   ($Zhi,&QWP(0,$Htbl,$nlo));
-       &pxor   ($Zlo,$tmp);
-       &and    ($nhi,0xf0);
-       &jmp    (&label("mmx_loop"));
-
-    &set_label("mmx_break",16);
-       &psrlq  ($Zlo,32);      # lower part of Zlo is already there
-       &movd   ($Zhl,$Zhi);
-       &psrlq  ($Zhi,32);
-       &movd   ($Zlh,$Zlo);
-       &movd   ($Zhh,$Zhi);
-
-       &bswap  ($Zll);
-       &bswap  ($Zhl);
-       &bswap  ($Zlh);
-       &bswap  ($Zhh);
-}
+               # 2.5x x86-specific code size reduction.
 
 sub x86_loop {
     my $off = shift;
@@ -218,33 +212,30 @@ if ($unroll) {
     &function_end_B("_x86_gmult_4bit_inner");
 }
 
-&function_begin("gcm_gmult_4bit");
-    if (!$x86only) {
-       &call   (&label("pic_point"));
-       &set_label("pic_point");
-       &blindpop("eax");
-       &picmeup("ebp","OPENSSL_ia32cap_P","eax",&label("pic_point"));
-       &bt     (&DWP(0,"ebp"),23);     # check for MMX bit
-       &jnc    (&label("x86"));
-
-       &lea    ("eax",&DWP(&label("rem_4bit")."-".&label("pic_point"),"eax"));
-
-       &mov    ($inp,&wparam(0));      # load Xi
-       &mov    ($Htbl,&wparam(1));     # load Htable
-
-       &movz   ($Zll,&BP(15,$inp));
-
-       &mmx_loop($inp,"eax");
+sub deposit_rem_4bit {
+    my $bias = shift;
 
-       &emms   ();
-       &mov    (&DWP(12,$inp),$Zll);
-       &mov    (&DWP(4,$inp),$Zhl);
-       &mov    (&DWP(8,$inp),$Zlh);
-       &mov    (&DWP(0,$inp),$Zhh);
+       &mov    (&DWP($bias+0, "esp"),0x0000<<16);
+       &mov    (&DWP($bias+4, "esp"),0x1C20<<16);
+       &mov    (&DWP($bias+8, "esp"),0x3840<<16);
+       &mov    (&DWP($bias+12,"esp"),0x2460<<16);
+       &mov    (&DWP($bias+16,"esp"),0x7080<<16);
+       &mov    (&DWP($bias+20,"esp"),0x6CA0<<16);
+       &mov    (&DWP($bias+24,"esp"),0x48C0<<16);
+       &mov    (&DWP($bias+28,"esp"),0x54E0<<16);
+       &mov    (&DWP($bias+32,"esp"),0xE100<<16);
+       &mov    (&DWP($bias+36,"esp"),0xFD20<<16);
+       &mov    (&DWP($bias+40,"esp"),0xD940<<16);
+       &mov    (&DWP($bias+44,"esp"),0xC560<<16);
+       &mov    (&DWP($bias+48,"esp"),0x9180<<16);
+       &mov    (&DWP($bias+52,"esp"),0x8DA0<<16);
+       &mov    (&DWP($bias+56,"esp"),0xA9C0<<16);
+       &mov    (&DWP($bias+60,"esp"),0xB5E0<<16);
+}
+\f
+$suffix = $x86only ? "" : "_x86";
 
-       &function_end_A();
-    &set_label("x86",16);
-    }
+&function_begin("gcm_gmult_4bit".$suffix);
        &stack_push(16+4+1);                    # +1 for stack alignment
        &mov    ($inp,&wparam(0));              # load Xi
        &mov    ($Htbl,&wparam(1));             # load Htable
@@ -275,52 +266,202 @@ if ($unroll) {
        &mov    (&DWP(4,$inp),$Zhl);
        &mov    (&DWP(0,$inp),$Zhh);
        &stack_pop(16+4+1);
-&function_end("gcm_gmult_4bit");
+&function_end("gcm_gmult_4bit".$suffix);
+
+&function_begin("gcm_ghash_4bit".$suffix);
+       &stack_push(16+4+1);                    # +1 for 64-bit alignment
+       &mov    ($Zll,&wparam(0));              # load Xi
+       &mov    ($Htbl,&wparam(1));             # load Htable
+       &mov    ($inp,&wparam(2));              # load in
+       &mov    ("ecx",&wparam(3));             # load len
+       &add    ("ecx",$inp);
+       &mov    (&wparam(3),"ecx");
+
+       &mov    ($Zhh,&DWP(0,$Zll));            # load Xi[16]
+       &mov    ($Zhl,&DWP(4,$Zll));
+       &mov    ($Zlh,&DWP(8,$Zll));
+       &mov    ($Zll,&DWP(12,$Zll));
+
+       &deposit_rem_4bit(16);
+
+    &set_label("x86_outer_loop",16);
+       &xor    ($Zll,&DWP(12,$inp));           # xor with input
+       &xor    ($Zlh,&DWP(8,$inp));
+       &xor    ($Zhl,&DWP(4,$inp));
+       &xor    ($Zhh,&DWP(0,$inp));
+       &mov    (&DWP(12,"esp"),$Zll);          # dump it on stack
+       &mov    (&DWP(8,"esp"),$Zlh);
+       &mov    (&DWP(4,"esp"),$Zhl);
+       &mov    (&DWP(0,"esp"),$Zhh);
+
+       &shr    ($Zll,20);
+       &and    ($Zll,0xf0);
+
+       if ($unroll) {
+               &call   ("_x86_gmult_4bit_inner");
+       } else {
+               &x86_loop(0);
+               &mov    ($inp,&wparam(2));
+       }
+       &lea    ($inp,&DWP(16,$inp));
+       &cmp    ($inp,&wparam(3));
+       &mov    (&wparam(2),$inp)       if (!$unroll);
+       &jb     (&label("x86_outer_loop"));
+
+       &mov    ($inp,&wparam(0));      # load Xi
+       &mov    (&DWP(12,$inp),$Zll);
+       &mov    (&DWP(8,$inp),$Zlh);
+       &mov    (&DWP(4,$inp),$Zhl);
+       &mov    (&DWP(0,$inp),$Zhh);
+       &stack_pop(16+4+1);
+&function_end("gcm_ghash_4bit".$suffix);
+\f
+if (!$x86only) {{{
+
+&static_label("rem_4bit");
+
+if (0) {{      # "May" MMX version is kept for reference...
+
+$S=12;         # shift factor for rem_4bit
 
+&function_begin_B("_mmx_gmult_4bit_inner");
+# MMX version performs 3.5 times better on P4 (see comment in non-MMX
+# routine for further details), 100% better on Opteron, ~70% better
+# on Core2 and PIII... In other words effort is considered to be well
+# spent... Since initial release the loop was unrolled in order to
+# "liberate" register previously used as loop counter. Instead it's
+# used to optimize critical path in 'Z.hi ^= rem_4bit[Z.lo&0xf]'.
+# The path involves move of Z.lo from MMX to integer register,
+# effective address calculation and finally merge of value to Z.hi.
+# Reference to rem_4bit is scheduled so late that I had to >>4
+# rem_4bit elements. This resulted in 20-45% procent improvement
+# on contemporary ยต-archs.
+{
+    my $cnt;
+    my $rem_4bit = "eax";
+    my @rem = ($Zhh,$Zll);
+    my $nhi = $Zhl;
+    my $nlo = $Zlh;
+
+    my ($Zlo,$Zhi) = ("mm0","mm1");
+    my $tmp = "mm2";
+
+       &xor    ($nlo,$nlo);    # avoid partial register stalls on PIII
+       &mov    ($nhi,$Zll);
+       &mov    (&LB($nlo),&LB($nhi));
+       &shl    (&LB($nlo),4);
+       &and    ($nhi,0xf0);
+       &movq   ($Zlo,&QWP(8,$Htbl,$nlo));
+       &movq   ($Zhi,&QWP(0,$Htbl,$nlo));
+       &movd   ($rem[0],$Zlo);
+
+       for ($cnt=28;$cnt>=-2;$cnt--) {
+           my $odd = $cnt&1;
+           my $nix = $odd ? $nlo : $nhi;
+
+               &shl    (&LB($nlo),4)                   if ($odd);
+               &psrlq  ($Zlo,4);
+               &movq   ($tmp,$Zhi);
+               &psrlq  ($Zhi,4);
+               &pxor   ($Zlo,&QWP(8,$Htbl,$nix));
+               &mov    (&LB($nlo),&BP($cnt/2,$inp))    if (!$odd && $cnt>=0);
+               &psllq  ($tmp,60);
+               &and    ($nhi,0xf0)                     if ($odd);
+               &pxor   ($Zhi,&QWP(0,$rem_4bit,$rem[1],8)) if ($cnt<28);
+               &and    ($rem[0],0xf);
+               &pxor   ($Zhi,&QWP(0,$Htbl,$nix));
+               &mov    ($nhi,$nlo)                     if (!$odd && $cnt>=0);
+               &movd   ($rem[1],$Zlo);
+               &pxor   ($Zlo,$tmp);
+
+               push    (@rem,shift(@rem));             # "rotate" registers
+       }
+
+       &mov    ($inp,&DWP(4,$rem_4bit,$rem[1],8));     # last rem_4bit[rem]
+
+       &psrlq  ($Zlo,32);      # lower part of Zlo is already there
+       &movd   ($Zhl,$Zhi);
+       &psrlq  ($Zhi,32);
+       &movd   ($Zlh,$Zlo);
+       &movd   ($Zhh,$Zhi);
+       &shl    ($inp,4);       # compensate for rem_4bit[i] being >>4
+
+       &bswap  ($Zll);
+       &bswap  ($Zhl);
+       &bswap  ($Zlh);
+       &xor    ($Zhh,$inp);
+       &bswap  ($Zhh);
+
+       &ret    ();
+}
+&function_end_B("_mmx_gmult_4bit_inner");
+
+&function_begin("gcm_gmult_4bit_mmx");
+       &mov    ($inp,&wparam(0));      # load Xi
+       &mov    ($Htbl,&wparam(1));     # load Htable
+
+       &call   (&label("pic_point"));
+       &set_label("pic_point");
+       &blindpop("eax");
+       &lea    ("eax",&DWP(&label("rem_4bit")."-".&label("pic_point"),"eax"));
+
+       &movz   ($Zll,&BP(15,$inp));
+
+       &call   ("_mmx_gmult_4bit_inner");
+
+       &mov    ($inp,&wparam(0));      # load Xi
+       &emms   ();
+       &mov    (&DWP(12,$inp),$Zll);
+       &mov    (&DWP(4,$inp),$Zhl);
+       &mov    (&DWP(8,$inp),$Zlh);
+       &mov    (&DWP(0,$inp),$Zhh);
+&function_end("gcm_gmult_4bit_mmx");
+\f
 # Streamed version performs 20% better on P4, 7% on Opteron,
 # 10% on Core2 and PIII...
-&function_begin("gcm_ghash_4bit");
-    if (!$x86only) {
+&function_begin("gcm_ghash_4bit_mmx");
+       &mov    ($Zhh,&wparam(0));      # load Xi
+       &mov    ($Htbl,&wparam(1));     # load Htable
+       &mov    ($inp,&wparam(2));      # load in
+       &mov    ($Zlh,&wparam(3));      # load len
+
        &call   (&label("pic_point"));
        &set_label("pic_point");
        &blindpop("eax");
-       &picmeup("ebp","OPENSSL_ia32cap_P","eax",&label("pic_point"));
-       &bt     (&DWP(0,"ebp"),23);     # check for MMX bit
-       &jnc    (&label("x86"));
-
        &lea    ("eax",&DWP(&label("rem_4bit")."-".&label("pic_point"),"eax"));
 
-       &mov    ($inp,&wparam(0));      # load in
-       &mov    ($Zlh,&wparam(1));      # load len
-       &mov    ($Zhh,&wparam(2));      # load Xi
-       &mov    ($Htbl,&wparam(3));     # load Htable
        &add    ($Zlh,$inp);
-       &mov    (&wparam(1),$Zlh);      # len to point at the end of input
+       &mov    (&wparam(3),$Zlh);      # len to point at the end of input
        &stack_push(4+1);               # +1 for stack alignment
+
        &mov    ($Zll,&DWP(12,$Zhh));   # load Xi[16]
        &mov    ($Zhl,&DWP(4,$Zhh));
        &mov    ($Zlh,&DWP(8,$Zhh));
        &mov    ($Zhh,&DWP(0,$Zhh));
+       &jmp    (&label("mmx_outer_loop"));
 
     &set_label("mmx_outer_loop",16);
        &xor    ($Zll,&DWP(12,$inp));
        &xor    ($Zhl,&DWP(4,$inp));
        &xor    ($Zlh,&DWP(8,$inp));
        &xor    ($Zhh,&DWP(0,$inp));
+       &mov    (&wparam(2),$inp);
        &mov    (&DWP(12,"esp"),$Zll);
        &mov    (&DWP(4,"esp"),$Zhl);
        &mov    (&DWP(8,"esp"),$Zlh);
        &mov    (&DWP(0,"esp"),$Zhh);
 
+       &mov    ($inp,"esp");
        &shr    ($Zll,24);
 
-       &mmx_loop("esp","eax");
+       &call   ("_mmx_gmult_4bit_inner");
 
+       &mov    ($inp,&wparam(2));
        &lea    ($inp,&DWP(16,$inp));
-       &cmp    ($inp,&wparam(1));
+       &cmp    ($inp,&wparam(3));
        &jb     (&label("mmx_outer_loop"));
 
-       &mov    ($inp,&wparam(2));      # load Xi
+       &mov    ($inp,&wparam(0));      # load Xi
        &emms   ();
        &mov    (&DWP(12,$inp),$Zll);
        &mov    (&DWP(4,$inp),$Zhl);
@@ -328,83 +469,862 @@ if ($unroll) {
        &mov    (&DWP(0,$inp),$Zhh);
 
        &stack_pop(4+1);
-       &function_end_A();
-    &set_label("x86",16);
-    }
-       &stack_push(16+4+1);                    # +1 for 64-bit alignment
-       &mov    ($inp,&wparam(0));              # load in
-       &mov    ("ecx",&wparam(1));             # load len
-       &mov    ($Zll,&wparam(2));              # load Xi
-       &mov    ($Htbl,&wparam(3));             # load Htable
-       &add    ("ecx",$inp);
-       &mov    (&wparam(1),"ecx");
+&function_end("gcm_ghash_4bit_mmx");
+\f
+}} else {{     # "June" MMX version...
+               # ... has "April" gcm_gmult_4bit_mmx with folded loop.
+               # This is done to conserve code size...
+$S=16;         # shift factor for rem_4bit
 
-       &mov    ($Zhh,&DWP(0,$Zll));            # load Xi[16]
-       &mov    ($Zhl,&DWP(4,$Zll));
-       &mov    ($Zlh,&DWP(8,$Zll));
-       &mov    ($Zll,&DWP(12,$Zll));
+sub mmx_loop() {
+# MMX version performs 2.8 times better on P4 (see comment in non-MMX
+# routine for further details), 40% better on Opteron and Core2, 50%
+# better on PIII... In other words effort is considered to be well
+# spent...
+    my $inp = shift;
+    my $rem_4bit = shift;
+    my $cnt = $Zhh;
+    my $nhi = $Zhl;
+    my $nlo = $Zlh;
+    my $rem = $Zll;
 
-       &deposit_rem_4bit(16);
+    my ($Zlo,$Zhi) = ("mm0","mm1");
+    my $tmp = "mm2";
 
-    &set_label("x86_outer_loop",16);
-       &xor    ($Zll,&DWP(12,$inp));           # xor with input
-       &xor    ($Zlh,&DWP(8,$inp));
-       &xor    ($Zhl,&DWP(4,$inp));
-       &xor    ($Zhh,&DWP(0,$inp));
-       &mov    (&DWP(12,"esp"),$Zll);          # dump it on stack
-       &mov    (&DWP(8,"esp"),$Zlh);
-       &mov    (&DWP(4,"esp"),$Zhl);
-       &mov    (&DWP(0,"esp"),$Zhh);
+       &xor    ($nlo,$nlo);    # avoid partial register stalls on PIII
+       &mov    ($nhi,$Zll);
+       &mov    (&LB($nlo),&LB($nhi));
+       &mov    ($cnt,14);
+       &shl    (&LB($nlo),4);
+       &and    ($nhi,0xf0);
+       &movq   ($Zlo,&QWP(8,$Htbl,$nlo));
+       &movq   ($Zhi,&QWP(0,$Htbl,$nlo));
+       &movd   ($rem,$Zlo);
+       &jmp    (&label("mmx_loop"));
 
-       &shr    ($Zll,20);
-       &and    ($Zll,0xf0);
+    &set_label("mmx_loop",16);
+       &psrlq  ($Zlo,4);
+       &and    ($rem,0xf);
+       &movq   ($tmp,$Zhi);
+       &psrlq  ($Zhi,4);
+       &pxor   ($Zlo,&QWP(8,$Htbl,$nhi));
+       &mov    (&LB($nlo),&BP(0,$inp,$cnt));
+       &psllq  ($tmp,60);
+       &pxor   ($Zhi,&QWP(0,$rem_4bit,$rem,8));
+       &dec    ($cnt);
+       &movd   ($rem,$Zlo);
+       &pxor   ($Zhi,&QWP(0,$Htbl,$nhi));
+       &mov    ($nhi,$nlo);
+       &pxor   ($Zlo,$tmp);
+       &js     (&label("mmx_break"));
 
-       if ($unroll) {
-               &call   ("_x86_gmult_4bit_inner");
-       } else {
-               &x86_loop(0);
-               &mov    ($inp,&wparam(0));
-       }
-       &lea    ($inp,&DWP(16,$inp));
-       &cmp    ($inp,&wparam(1));
-       &mov    (&wparam(0),$inp)       if (!$unroll);
-       &jb     (&label("x86_outer_loop"));
+       &shl    (&LB($nlo),4);
+       &and    ($rem,0xf);
+       &psrlq  ($Zlo,4);
+       &and    ($nhi,0xf0);
+       &movq   ($tmp,$Zhi);
+       &psrlq  ($Zhi,4);
+       &pxor   ($Zlo,&QWP(8,$Htbl,$nlo));
+       &psllq  ($tmp,60);
+       &pxor   ($Zhi,&QWP(0,$rem_4bit,$rem,8));
+       &movd   ($rem,$Zlo);
+       &pxor   ($Zhi,&QWP(0,$Htbl,$nlo));
+       &pxor   ($Zlo,$tmp);
+       &jmp    (&label("mmx_loop"));
+
+    &set_label("mmx_break",16);
+       &shl    (&LB($nlo),4);
+       &and    ($rem,0xf);
+       &psrlq  ($Zlo,4);
+       &and    ($nhi,0xf0);
+       &movq   ($tmp,$Zhi);
+       &psrlq  ($Zhi,4);
+       &pxor   ($Zlo,&QWP(8,$Htbl,$nlo));
+       &psllq  ($tmp,60);
+       &pxor   ($Zhi,&QWP(0,$rem_4bit,$rem,8));
+       &movd   ($rem,$Zlo);
+       &pxor   ($Zhi,&QWP(0,$Htbl,$nlo));
+       &pxor   ($Zlo,$tmp);
+
+       &psrlq  ($Zlo,4);
+       &and    ($rem,0xf);
+       &movq   ($tmp,$Zhi);
+       &psrlq  ($Zhi,4);
+       &pxor   ($Zlo,&QWP(8,$Htbl,$nhi));
+       &psllq  ($tmp,60);
+       &pxor   ($Zhi,&QWP(0,$rem_4bit,$rem,8));
+       &movd   ($rem,$Zlo);
+       &pxor   ($Zhi,&QWP(0,$Htbl,$nhi));
+       &pxor   ($Zlo,$tmp);
 
-       &mov    ($inp,&wparam(2));      # load Xi
+       &psrlq  ($Zlo,32);      # lower part of Zlo is already there
+       &movd   ($Zhl,$Zhi);
+       &psrlq  ($Zhi,32);
+       &movd   ($Zlh,$Zlo);
+       &movd   ($Zhh,$Zhi);
+
+       &bswap  ($Zll);
+       &bswap  ($Zhl);
+       &bswap  ($Zlh);
+       &bswap  ($Zhh);
+}
+
+&function_begin("gcm_gmult_4bit_mmx");
+       &mov    ($inp,&wparam(0));      # load Xi
+       &mov    ($Htbl,&wparam(1));     # load Htable
+
+       &call   (&label("pic_point"));
+       &set_label("pic_point");
+       &blindpop("eax");
+       &lea    ("eax",&DWP(&label("rem_4bit")."-".&label("pic_point"),"eax"));
+
+       &movz   ($Zll,&BP(15,$inp));
+
+       &mmx_loop($inp,"eax");
+
+       &emms   ();
        &mov    (&DWP(12,$inp),$Zll);
-       &mov    (&DWP(8,$inp),$Zlh);
        &mov    (&DWP(4,$inp),$Zhl);
+       &mov    (&DWP(8,$inp),$Zlh);
        &mov    (&DWP(0,$inp),$Zhh);
-       &stack_pop(16+4+1);
-&function_end("gcm_ghash_4bit");
+&function_end("gcm_gmult_4bit_mmx");
+\f
+######################################################################
+# Below subroutine is "528B" variant of "4-bit" GCM GHASH function
+# (see gcm128.c for details). It provides further 20-40% performance
+# improvement over *previous* version of this module.
 
-sub deposit_rem_4bit {
-    my $bias = shift;
+&static_label("rem_8bit");
 
-       &mov    (&DWP($bias+0, "esp"),0x0000<<16);
-       &mov    (&DWP($bias+4, "esp"),0x1C20<<16);
-       &mov    (&DWP($bias+8, "esp"),0x3840<<16);
-       &mov    (&DWP($bias+12,"esp"),0x2460<<16);
-       &mov    (&DWP($bias+16,"esp"),0x7080<<16);
-       &mov    (&DWP($bias+20,"esp"),0x6CA0<<16);
-       &mov    (&DWP($bias+24,"esp"),0x48C0<<16);
-       &mov    (&DWP($bias+28,"esp"),0x54E0<<16);
-       &mov    (&DWP($bias+32,"esp"),0xE100<<16);
-       &mov    (&DWP($bias+36,"esp"),0xFD20<<16);
-       &mov    (&DWP($bias+40,"esp"),0xD940<<16);
-       &mov    (&DWP($bias+44,"esp"),0xC560<<16);
-       &mov    (&DWP($bias+48,"esp"),0x9180<<16);
-       &mov    (&DWP($bias+52,"esp"),0x8DA0<<16);
-       &mov    (&DWP($bias+56,"esp"),0xA9C0<<16);
-       &mov    (&DWP($bias+60,"esp"),0xB5E0<<16);
+&function_begin("gcm_ghash_4bit_mmx");
+{ my ($Zlo,$Zhi) = ("mm7","mm6");
+  my $rem_8bit = "esi";
+  my $Htbl = "ebx";
+
+    # parameter block
+    &mov       ("eax",&wparam(0));             # Xi
+    &mov       ("ebx",&wparam(1));             # Htable
+    &mov       ("ecx",&wparam(2));             # inp
+    &mov       ("edx",&wparam(3));             # len
+    &mov       ("ebp","esp");                  # original %esp
+    &call      (&label("pic_point"));
+    &set_label ("pic_point");
+    &blindpop  ($rem_8bit);
+    &lea       ($rem_8bit,&DWP(&label("rem_8bit")."-".&label("pic_point"),$rem_8bit));
+
+    &sub       ("esp",512+16+16);              # allocate stack frame...
+    &and       ("esp",-64);                    # ...and align it
+    &sub       ("esp",16);                     # place for (u8)(H[]<<4)
+
+    &add       ("edx","ecx");                  # pointer to the end of input
+    &mov       (&DWP(528+16+0,"esp"),"eax");   # save Xi
+    &mov       (&DWP(528+16+8,"esp"),"edx");   # save inp+len
+    &mov       (&DWP(528+16+12,"esp"),"ebp");  # save original %esp
+
+    { my @lo  = ("mm0","mm1","mm2");
+      my @hi  = ("mm3","mm4","mm5");
+      my @tmp = ("mm6","mm7");
+      my $off1=0,$off2=0,$i;
+
+      &add     ($Htbl,128);                    # optimize for size
+      &lea     ("edi",&DWP(16+128,"esp"));
+      &lea     ("ebp",&DWP(16+256+128,"esp"));
+
+      # decompose Htable (low and high parts are kept separately),
+      # generate Htable>>4, save to stack...
+      for ($i=0;$i<18;$i++) {
+
+       &mov    ("edx",&DWP(16*$i+8-128,$Htbl))         if ($i<16);
+       &movq   ($lo[0],&QWP(16*$i+8-128,$Htbl))        if ($i<16);
+       &psllq  ($tmp[1],60)                            if ($i>1);
+       &movq   ($hi[0],&QWP(16*$i+0-128,$Htbl))        if ($i<16);
+       &por    ($lo[2],$tmp[1])                        if ($i>1);
+       &movq   (&QWP($off1-128,"edi"),$lo[1])          if ($i>0 && $i<17);
+       &psrlq  ($lo[1],4)                              if ($i>0 && $i<17);
+       &movq   (&QWP($off1,"edi"),$hi[1])              if ($i>0 && $i<17);
+       &movq   ($tmp[0],$hi[1])                        if ($i>0 && $i<17);
+       &movq   (&QWP($off2-128,"ebp"),$lo[2])          if ($i>1);
+       &psrlq  ($hi[1],4)                              if ($i>0 && $i<17);
+       &movq   (&QWP($off2,"ebp"),$hi[2])              if ($i>1);
+       &shl    ("edx",4)                               if ($i<16);
+       &mov    (&BP($i,"esp"),&LB("edx"))              if ($i<16);
+
+       unshift (@lo,pop(@lo));                 # "rotate" registers
+       unshift (@hi,pop(@hi));
+       unshift (@tmp,pop(@tmp));
+       $off1 += 8      if ($i>0);
+       $off2 += 8      if ($i>1);
+      }
+    }
+
+    &movq      ($Zhi,&QWP(0,"eax"));
+    &mov       ("ebx",&DWP(8,"eax"));
+    &mov       ("edx",&DWP(12,"eax"));         # load Xi
+
+&set_label("outer",16);
+  { my $nlo = "eax";
+    my $dat = "edx";
+    my @nhi = ("edi","ebp");
+    my @rem = ("ebx","ecx");
+    my @red = ("mm0","mm1","mm2");
+    my $tmp = "mm3";
+
+    &xor       ($dat,&DWP(12,"ecx"));          # merge input
+    &xor       ("ebx",&DWP(8,"ecx"));
+    &pxor      ($Zhi,&QWP(0,"ecx"));
+    &lea       ("ecx",&DWP(16,"ecx"));         # inp+=16
+    #&mov      (&DWP(528+12,"esp"),$dat);      # save inp^Xi
+    &mov       (&DWP(528+8,"esp"),"ebx");
+    &movq      (&QWP(528+0,"esp"),$Zhi);
+    &mov       (&DWP(528+16+4,"esp"),"ecx");   # save inp
+
+    &xor       ($nlo,$nlo);
+    &rol       ($dat,8);
+    &mov       (&LB($nlo),&LB($dat));
+    &mov       ($nhi[1],$nlo);
+    &and       (&LB($nlo),0x0f);
+    &shr       ($nhi[1],4);
+    &pxor      ($red[0],$red[0]);
+    &rol       ($dat,8);                               # next byte
+    &pxor      ($red[1],$red[1]);
+    &pxor      ($red[2],$red[2]);
+
+    # Just like in "May" verson modulo-schedule for critical path in
+    # 'Z.hi ^= rem_8bit[Z.lo&0xff^((u8)H[nhi]<<4)]<<48'. Final xor
+    # is scheduled so late that rem_8bit is shifted *right* by 16,
+    # which is why last argument to pinsrw is 2, which corresponds to
+    # <<32...
+    for ($j=11,$i=0;$i<15;$i++) {
+
+      if ($i>0) {
+       &pxor   ($Zlo,&QWP(16,"esp",$nlo,8));           # Z^=H[nlo]
+       &rol    ($dat,8);                               # next byte
+       &pxor   ($Zhi,&QWP(16+128,"esp",$nlo,8));
+
+       &pxor   ($Zlo,$tmp);
+       &pxor   ($Zhi,&QWP(16+256+128,"esp",$nhi[0],8));
+       &xor    (&LB($rem[1]),&BP(0,"esp",$nhi[0]));    # rem^H[nhi]<<4
+      } else {
+       &movq   ($Zlo,&QWP(16,"esp",$nlo,8));
+       &movq   ($Zhi,&QWP(16+128,"esp",$nlo,8));
+      }
+
+       &mov    (&LB($nlo),&LB($dat));
+       &mov    ($dat,&DWP(528+$j,"esp"))       if (--$j%4==0);
+
+       &movd   ($rem[0],$Zlo);
+       &movz   ($rem[1],&LB($rem[1]))          if ($i>0);
+       &psrlq  ($Zlo,8);
+
+       &movq   ($tmp,$Zhi);
+       &mov    ($nhi[0],$nlo);
+       &psrlq  ($Zhi,8);
+
+       &pxor   ($Zlo,&QWP(16+256+0,"esp",$nhi[1],8));  # Z^=H[nhi]>>4
+       &and    (&LB($nlo),0x0f);
+       &psllq  ($tmp,56);
+
+       &pxor   ($Zhi,$red[1])                          if ($i>1);
+       &shr    ($nhi[0],4);
+       &pinsrw ($red[0],&WP(0,$rem_8bit,$rem[1],2),2)  if ($i>0);
+
+       unshift (@red,pop(@red));                       # "rotate" registers
+       unshift (@rem,pop(@rem));
+       unshift (@nhi,pop(@nhi));
+    }
+
+    &pxor      ($Zlo,&QWP(16,"esp",$nlo,8));           # Z^=H[nlo]
+    &pxor      ($Zhi,&QWP(16+128,"esp",$nlo,8));
+    &xor       (&LB($rem[1]),&BP(0,"esp",$nhi[0]));    #$rem[0]);                      # rem^H[nhi]<<4
+
+    &pxor      ($Zlo,$tmp);
+    &pxor      ($Zhi,&QWP(16+256+128,"esp",$nhi[0],8));
+    &movz      ($rem[1],&LB($rem[1]));
+
+    &pxor      ($red[2],$red[2]);                      # clear 2nd word
+    &psllq     ($red[1],4);
+
+    &movd      ($rem[0],$Zlo);
+    &psrlq     ($Zlo,4);
+
+    &movq      ($tmp,$Zhi);
+    &psrlq     ($Zhi,4);
+    &shl       ($rem[0],4);
+
+    &pxor      ($Zlo,&QWP(16,"esp",$nhi[1],8));        # Z^=H[nhi]
+    &psllq     ($tmp,60);
+    &movz      ($rem[0],&LB($rem[0]));
+
+    &pxor      ($Zlo,$tmp);
+    &pxor      ($Zhi,&QWP(16+128,"esp",$nhi[1],8));
+
+    &pinsrw    ($red[0],&WP(0,$rem_8bit,$rem[1],2),2);
+    &pxor      ($Zhi,$red[1]);
+
+    &movd      ($dat,$Zlo);
+    &pinsrw    ($red[2],&WP(0,$rem_8bit,$rem[0],2),3);
+
+    &psllq     ($red[0],12);
+    &pxor      ($Zhi,$red[0]);
+    &psrlq     ($Zlo,32);
+    &pxor      ($Zhi,$red[2]);
+
+    &mov       ("ecx",&DWP(528+16+4,"esp"));   # restore inp
+    &movd      ("ebx",$Zlo);
+    &movq      ($tmp,$Zhi);                    # 01234567
+    &psllw     ($Zhi,8);                       # 1.3.5.7.
+    &psrlw     ($tmp,8);                       # .0.2.4.6
+    &por       ($Zhi,$tmp);                    # 10325476
+    &bswap     ($dat);
+    &pshufw    ($Zhi,$Zhi,0b00011011);         # 76543210
+    &bswap     ("ebx");
+    
+    &cmp       ("ecx",&DWP(528+16+8,"esp"));   # are we done?
+    &jne       (&label("outer"));
+  }
+
+    &mov       ("eax",&DWP(528+16+0,"esp"));   # restore Xi
+    &mov       (&DWP(12,"eax"),"edx");
+    &mov       (&DWP(8,"eax"),"ebx");
+    &movq      (&QWP(0,"eax"),$Zhi);
+
+    &mov       ("esp",&DWP(528+16+12,"esp"));  # restore original %esp
+    &emms      ();
 }
+&function_end("gcm_ghash_4bit_mmx");
+}}
+\f
+if ($sse2) {{
+######################################################################
+# PCLMULQDQ version.
 
-if (!$x86only) {
-&set_label("rem_4bit",64);
-       &data_word(0,0x0000<<16,0,0x1C20<<16,0,0x3840<<16,0,0x2460<<16);
-       &data_word(0,0x7080<<16,0,0x6CA0<<16,0,0x48C0<<16,0,0x54E0<<16);
-       &data_word(0,0xE100<<16,0,0xFD20<<16,0,0xD940<<16,0,0xC560<<16);
-       &data_word(0,0x9180<<16,0,0x8DA0<<16,0,0xA9C0<<16,0,0xB5E0<<16);
+$Xip="eax";
+$Htbl="edx";
+$const="ecx";
+$inp="esi";
+$len="ebx";
+
+($Xi,$Xhi)=("xmm0","xmm1");    $Hkey="xmm2";
+($T1,$T2,$T3)=("xmm3","xmm4","xmm5");
+($Xn,$Xhn)=("xmm6","xmm7");
+
+&static_label("bswap");
+
+sub clmul64x64_T2 {    # minimal "register" pressure
+my ($Xhi,$Xi,$Hkey)=@_;
+
+       &movdqa         ($Xhi,$Xi);             #
+       &pshufd         ($T1,$Xi,0b01001110);
+       &pshufd         ($T2,$Hkey,0b01001110);
+       &pxor           ($T1,$Xi);              #
+       &pxor           ($T2,$Hkey);
+
+       &pclmulqdq      ($Xi,$Hkey,0x00);       #######
+       &pclmulqdq      ($Xhi,$Hkey,0x11);      #######
+       &pclmulqdq      ($T1,$T2,0x00);         #######
+       &pxor           ($T1,$Xi);              #
+       &pxor           ($T1,$Xhi);             #
+
+       &movdqa         ($T2,$T1);              #
+       &psrldq         ($T1,8);
+       &pslldq         ($T2,8);                #
+       &pxor           ($Xhi,$T1);
+       &pxor           ($Xi,$T2);              #
 }
+
+sub clmul64x64_T3 {
+# Even though this subroutine offers visually better ILP, it
+# was empirically found to be a tad slower than above version.
+# At least in gcm_ghash_clmul context. But it's just as well,
+# because loop modulo-scheduling is possible only thanks to
+# minimized "register" pressure...
+my ($Xhi,$Xi,$Hkey)=@_;
+
+       &movdqa         ($T1,$Xi);              #
+       &movdqa         ($Xhi,$Xi);
+       &pclmulqdq      ($Xi,$Hkey,0x00);       #######
+       &pclmulqdq      ($Xhi,$Hkey,0x11);      #######
+       &pshufd         ($T2,$T1,0b01001110);   #
+       &pshufd         ($T3,$Hkey,0b01001110);
+       &pxor           ($T2,$T1);              #
+       &pxor           ($T3,$Hkey);
+       &pclmulqdq      ($T2,$T3,0x00);         #######
+       &pxor           ($T2,$Xi);              #
+       &pxor           ($T2,$Xhi);             #
+
+       &movdqa         ($T3,$T2);              #
+       &psrldq         ($T2,8);
+       &pslldq         ($T3,8);                #
+       &pxor           ($Xhi,$T2);
+       &pxor           ($Xi,$T3);              #
+}
+\f
+if (1) {               # Algorithm 9 with <<1 twist.
+                       # Reduction is shorter and uses only two
+                       # temporary registers, which makes it better
+                       # candidate for interleaving with 64x64
+                       # multiplication. Pre-modulo-scheduled loop
+                       # was found to be ~20% faster than Algorithm 5
+                       # below. Algorithm 9 was therefore chosen for
+                       # further optimization...
+
+sub reduction_alg9 {   # 17/13 times faster than Intel version
+my ($Xhi,$Xi) = @_;
+
+       # 1st phase
+       &movdqa         ($T1,$Xi)               #
+       &psllq          ($Xi,1);
+       &pxor           ($Xi,$T1);              #
+       &psllq          ($Xi,5);                #
+       &pxor           ($Xi,$T1);              #
+       &psllq          ($Xi,57);               #
+       &movdqa         ($T2,$Xi);              #
+       &pslldq         ($Xi,8);
+       &psrldq         ($T2,8);                #
+       &pxor           ($Xi,$T1);
+       &pxor           ($Xhi,$T2);             #
+
+       # 2nd phase
+       &movdqa         ($T2,$Xi);
+       &psrlq          ($Xi,5);
+       &pxor           ($Xi,$T2);              #
+       &psrlq          ($Xi,1);                #
+       &pxor           ($Xi,$T2);              #
+       &pxor           ($T2,$Xhi);
+       &psrlq          ($Xi,1);                #
+       &pxor           ($Xi,$T2);              #
+}
+
+&function_begin_B("gcm_init_clmul");
+       &mov            ($Htbl,&wparam(0));
+       &mov            ($Xip,&wparam(1));
+
+       &call           (&label("pic"));
+&set_label("pic");
+       &blindpop       ($const);
+       &lea            ($const,&DWP(&label("bswap")."-".&label("pic"),$const));
+
+       &movdqu         ($Hkey,&QWP(0,$Xip));
+       &pshufd         ($Hkey,$Hkey,0b01001110);# dword swap
+
+       # <<1 twist
+       &pshufd         ($T2,$Hkey,0b11111111); # broadcast uppermost dword
+       &movdqa         ($T1,$Hkey);
+       &psllq          ($Hkey,1);
+       &pxor           ($T3,$T3);              #
+       &psrlq          ($T1,63);
+       &pcmpgtd        ($T3,$T2);              # broadcast carry bit
+       &pslldq         ($T1,8);
+       &por            ($Hkey,$T1);            # H<<=1
+
+       # magic reduction
+       &pand           ($T3,&QWP(16,$const));  # 0x1c2_polynomial
+       &pxor           ($Hkey,$T3);            # if(carry) H^=0x1c2_polynomial
+
+       # calculate H^2
+       &movdqa         ($Xi,$Hkey);
+       &clmul64x64_T2  ($Xhi,$Xi,$Hkey);
+       &reduction_alg9 ($Xhi,$Xi);
+
+       &movdqu         (&QWP(0,$Htbl),$Hkey);  # save H
+       &movdqu         (&QWP(16,$Htbl),$Xi);   # save H^2
+
+       &ret            ();
+&function_end_B("gcm_init_clmul");
+
+&function_begin_B("gcm_gmult_clmul");
+       &mov            ($Xip,&wparam(0));
+       &mov            ($Htbl,&wparam(1));
+
+       &call           (&label("pic"));
+&set_label("pic");
+       &blindpop       ($const);
+       &lea            ($const,&DWP(&label("bswap")."-".&label("pic"),$const));
+
+       &movdqu         ($Xi,&QWP(0,$Xip));
+       &movdqa         ($T3,&QWP(0,$const));
+       &movdqu         ($Hkey,&QWP(0,$Htbl));
+       &pshufb         ($Xi,$T3);
+
+       &clmul64x64_T2  ($Xhi,$Xi,$Hkey);
+       &reduction_alg9 ($Xhi,$Xi);
+
+       &pshufb         ($Xi,$T3);
+       &movdqu         (&QWP(0,$Xip),$Xi);
+
+       &ret    ();
+&function_end_B("gcm_gmult_clmul");
+
+&function_begin("gcm_ghash_clmul");
+       &mov            ($Xip,&wparam(0));
+       &mov            ($Htbl,&wparam(1));
+       &mov            ($inp,&wparam(2));
+       &mov            ($len,&wparam(3));
+
+       &call           (&label("pic"));
+&set_label("pic");
+       &blindpop       ($const);
+       &lea            ($const,&DWP(&label("bswap")."-".&label("pic"),$const));
+
+       &movdqu         ($Xi,&QWP(0,$Xip));
+       &movdqa         ($T3,&QWP(0,$const));
+       &movdqu         ($Hkey,&QWP(0,$Htbl));
+       &pshufb         ($Xi,$T3);
+
+       &sub            ($len,0x10);
+       &jz             (&label("odd_tail"));
+
+       #######
+       # Xi+2 =[H*(Ii+1 + Xi+1)] mod P =
+       #       [(H*Ii+1) + (H*Xi+1)] mod P =
+       #       [(H*Ii+1) + H^2*(Ii+Xi)] mod P
+       #
+       &movdqu         ($T1,&QWP(0,$inp));     # Ii
+       &movdqu         ($Xn,&QWP(16,$inp));    # Ii+1
+       &pshufb         ($T1,$T3);
+       &pshufb         ($Xn,$T3);
+       &pxor           ($Xi,$T1);              # Ii+Xi
+
+       &clmul64x64_T2  ($Xhn,$Xn,$Hkey);       # H*Ii+1
+       &movdqu         ($Hkey,&QWP(16,$Htbl)); # load H^2
+
+       &lea            ($inp,&DWP(32,$inp));   # i+=2
+       &sub            ($len,0x20);
+       &jbe            (&label("even_tail"));
+
+&set_label("mod_loop");
+       &clmul64x64_T2  ($Xhi,$Xi,$Hkey);       # H^2*(Ii+Xi)
+       &movdqu         ($T1,&QWP(0,$inp));     # Ii
+       &movdqu         ($Hkey,&QWP(0,$Htbl));  # load H
+
+       &pxor           ($Xi,$Xn);              # (H*Ii+1) + H^2*(Ii+Xi)
+       &pxor           ($Xhi,$Xhn);
+
+       &movdqu         ($Xn,&QWP(16,$inp));    # Ii+1
+       &pshufb         ($T1,$T3);
+       &pshufb         ($Xn,$T3);
+
+       &movdqa         ($T3,$Xn);              #&clmul64x64_TX ($Xhn,$Xn,$Hkey); H*Ii+1
+       &movdqa         ($Xhn,$Xn);
+        &pxor          ($Xhi,$T1);             # "Ii+Xi", consume early
+
+         &movdqa       ($T1,$Xi)               #&reduction_alg9($Xhi,$Xi); 1st phase
+         &psllq        ($Xi,1);
+         &pxor         ($Xi,$T1);              #
+         &psllq        ($Xi,5);                #
+         &pxor         ($Xi,$T1);              #
+       &pclmulqdq      ($Xn,$Hkey,0x00);       #######
+         &psllq        ($Xi,57);               #
+         &movdqa       ($T2,$Xi);              #
+         &pslldq       ($Xi,8);
+         &psrldq       ($T2,8);                #       
+         &pxor         ($Xi,$T1);
+       &pshufd         ($T1,$T3,0b01001110);
+         &pxor         ($Xhi,$T2);             #
+       &pxor           ($T1,$T3);
+       &pshufd         ($T3,$Hkey,0b01001110);
+       &pxor           ($T3,$Hkey);            #
+
+       &pclmulqdq      ($Xhn,$Hkey,0x11);      #######
+         &movdqa       ($T2,$Xi);              # 2nd phase
+         &psrlq        ($Xi,5);
+         &pxor         ($Xi,$T2);              #
+         &psrlq        ($Xi,1);                #
+         &pxor         ($Xi,$T2);              #
+         &pxor         ($T2,$Xhi);
+         &psrlq        ($Xi,1);                #
+         &pxor         ($Xi,$T2);              #
+
+       &pclmulqdq      ($T1,$T3,0x00);         #######
+       &movdqu         ($Hkey,&QWP(16,$Htbl)); # load H^2
+       &pxor           ($T1,$Xn);              #
+       &pxor           ($T1,$Xhn);             #
+
+       &movdqa         ($T3,$T1);              #
+       &psrldq         ($T1,8);
+       &pslldq         ($T3,8);                #
+       &pxor           ($Xhn,$T1);
+       &pxor           ($Xn,$T3);              #
+       &movdqa         ($T3,&QWP(0,$const));
+
+       &lea            ($inp,&DWP(32,$inp));
+       &sub            ($len,0x20);
+       &ja             (&label("mod_loop"));
+
+&set_label("even_tail");
+       &clmul64x64_T2  ($Xhi,$Xi,$Hkey);       # H^2*(Ii+Xi)
+
+       &pxor           ($Xi,$Xn);              # (H*Ii+1) + H^2*(Ii+Xi)
+       &pxor           ($Xhi,$Xhn);
+
+       &reduction_alg9 ($Xhi,$Xi);
+
+       &test           ($len,$len);
+       &jnz            (&label("done"));
+
+       &movdqu         ($Hkey,&QWP(0,$Htbl));  # load H
+&set_label("odd_tail");
+       &movdqu         ($T1,&QWP(0,$inp));     # Ii
+       &pshufb         ($T1,$T3);
+       &pxor           ($Xi,$T1);              # Ii+Xi
+
+       &clmul64x64_T2  ($Xhi,$Xi,$Hkey);       # H*(Ii+Xi)
+       &reduction_alg9 ($Xhi,$Xi);
+
+&set_label("done");
+       &pshufb         ($Xi,$T3);
+       &movdqu         (&QWP(0,$Xip),$Xi);
+&function_end("gcm_ghash_clmul");
+\f
+} else {               # Algorith 5. Kept for reference purposes.
+
+sub reduction_alg5 {   # 19/16 times faster than Intel version
+my ($Xhi,$Xi)=@_;
+
+       # <<1
+       &movdqa         ($T1,$Xi);              #
+       &movdqa         ($T2,$Xhi);
+       &pslld          ($Xi,1);
+       &pslld          ($Xhi,1);               #
+       &psrld          ($T1,31);
+       &psrld          ($T2,31);               #
+       &movdqa         ($T3,$T1);
+       &pslldq         ($T1,4);
+       &psrldq         ($T3,12);               #
+       &pslldq         ($T2,4);
+       &por            ($Xhi,$T3);             #
+       &por            ($Xi,$T1);
+       &por            ($Xhi,$T2);             #
+
+       # 1st phase
+       &movdqa         ($T1,$Xi);
+       &movdqa         ($T2,$Xi);
+       &movdqa         ($T3,$Xi);              #
+       &pslld          ($T1,31);
+       &pslld          ($T2,30);
+       &pslld          ($Xi,25);               #
+       &pxor           ($T1,$T2);
+       &pxor           ($T1,$Xi);              #
+       &movdqa         ($T2,$T1);              #
+       &pslldq         ($T1,12);
+       &psrldq         ($T2,4);                #
+       &pxor           ($T3,$T1);
+
+       # 2nd phase
+       &pxor           ($Xhi,$T3);             #
+       &movdqa         ($Xi,$T3);
+       &movdqa         ($T1,$T3);
+       &psrld          ($Xi,1);                #
+       &psrld          ($T1,2);
+       &psrld          ($T3,7);                #
+       &pxor           ($Xi,$T1);
+       &pxor           ($Xhi,$T2);
+       &pxor           ($Xi,$T3);              #
+       &pxor           ($Xi,$Xhi);             #
+}
+
+&function_begin_B("gcm_init_clmul");
+       &mov            ($Htbl,&wparam(0));
+       &mov            ($Xip,&wparam(1));
+
+       &call           (&label("pic"));
+&set_label("pic");
+       &blindpop       ($const);
+       &lea            ($const,&DWP(&label("bswap")."-".&label("pic"),$const));
+
+       &movdqu         ($Hkey,&QWP(0,$Xip));
+       &pshufd         ($Hkey,$Hkey,0b01001110);# dword swap
+
+       # calculate H^2
+       &movdqa         ($Xi,$Hkey);
+       &clmul64x64_T3  ($Xhi,$Xi,$Hkey);
+       &reduction_alg5 ($Xhi,$Xi);
+
+       &movdqu         (&QWP(0,$Htbl),$Hkey);  # save H
+       &movdqu         (&QWP(16,$Htbl),$Xi);   # save H^2
+
+       &ret            ();
+&function_end_B("gcm_init_clmul");
+
+&function_begin_B("gcm_gmult_clmul");
+       &mov            ($Xip,&wparam(0));
+       &mov            ($Htbl,&wparam(1));
+
+       &call           (&label("pic"));
+&set_label("pic");
+       &blindpop       ($const);
+       &lea            ($const,&DWP(&label("bswap")."-".&label("pic"),$const));
+
+       &movdqu         ($Xi,&QWP(0,$Xip));
+       &movdqa         ($Xn,&QWP(0,$const));
+       &movdqu         ($Hkey,&QWP(0,$Htbl));
+       &pshufb         ($Xi,$Xn);
+
+       &clmul64x64_T3  ($Xhi,$Xi,$Hkey);
+       &reduction_alg5 ($Xhi,$Xi);
+
+       &pshufb         ($Xi,$Xn);
+       &movdqu         (&QWP(0,$Xip),$Xi);
+
+       &ret    ();
+&function_end_B("gcm_gmult_clmul");
+
+&function_begin("gcm_ghash_clmul");
+       &mov            ($Xip,&wparam(0));
+       &mov            ($Htbl,&wparam(1));
+       &mov            ($inp,&wparam(2));
+       &mov            ($len,&wparam(3));
+
+       &call           (&label("pic"));
+&set_label("pic");
+       &blindpop       ($const);
+       &lea            ($const,&DWP(&label("bswap")."-".&label("pic"),$const));
+
+       &movdqu         ($Xi,&QWP(0,$Xip));
+       &movdqa         ($T3,&QWP(0,$const));
+       &movdqu         ($Hkey,&QWP(0,$Htbl));
+       &pshufb         ($Xi,$T3);
+
+       &sub            ($len,0x10);
+       &jz             (&label("odd_tail"));
+
+       #######
+       # Xi+2 =[H*(Ii+1 + Xi+1)] mod P =
+       #       [(H*Ii+1) + (H*Xi+1)] mod P =
+       #       [(H*Ii+1) + H^2*(Ii+Xi)] mod P
+       #
+       &movdqu         ($T1,&QWP(0,$inp));     # Ii
+       &movdqu         ($Xn,&QWP(16,$inp));    # Ii+1
+       &pshufb         ($T1,$T3);
+       &pshufb         ($Xn,$T3);
+       &pxor           ($Xi,$T1);              # Ii+Xi
+
+       &clmul64x64_T3  ($Xhn,$Xn,$Hkey);       # H*Ii+1
+       &movdqu         ($Hkey,&QWP(16,$Htbl)); # load H^2
+
+       &sub            ($len,0x20);
+       &lea            ($inp,&DWP(32,$inp));   # i+=2
+       &jbe            (&label("even_tail"));
+
+&set_label("mod_loop");
+       &clmul64x64_T3  ($Xhi,$Xi,$Hkey);       # H^2*(Ii+Xi)
+       &movdqu         ($Hkey,&QWP(0,$Htbl));  # load H
+
+       &pxor           ($Xi,$Xn);              # (H*Ii+1) + H^2*(Ii+Xi)
+       &pxor           ($Xhi,$Xhn);
+
+       &reduction_alg5 ($Xhi,$Xi);
+
+       #######
+       &movdqa         ($T3,&QWP(0,$const));
+       &movdqu         ($T1,&QWP(0,$inp));     # Ii
+       &movdqu         ($Xn,&QWP(16,$inp));    # Ii+1
+       &pshufb         ($T1,$T3);
+       &pshufb         ($Xn,$T3);
+       &pxor           ($Xi,$T1);              # Ii+Xi
+
+       &clmul64x64_T3  ($Xhn,$Xn,$Hkey);       # H*Ii+1
+       &movdqu         ($Hkey,&QWP(16,$Htbl)); # load H^2
+
+       &sub            ($len,0x20);
+       &lea            ($inp,&DWP(32,$inp));
+       &ja             (&label("mod_loop"));
+
+&set_label("even_tail");
+       &clmul64x64_T3  ($Xhi,$Xi,$Hkey);       # H^2*(Ii+Xi)
+
+       &pxor           ($Xi,$Xn);              # (H*Ii+1) + H^2*(Ii+Xi)
+       &pxor           ($Xhi,$Xhn);
+
+       &reduction_alg5 ($Xhi,$Xi);
+
+       &movdqa         ($T3,&QWP(0,$const));
+       &test           ($len,$len);
+       &jnz            (&label("done"));
+
+       &movdqu         ($Hkey,&QWP(0,$Htbl));  # load H
+&set_label("odd_tail");
+       &movdqu         ($T1,&QWP(0,$inp));     # Ii
+       &pshufb         ($T1,$T3);
+       &pxor           ($Xi,$T1);              # Ii+Xi
+
+       &clmul64x64_T3  ($Xhi,$Xi,$Hkey);       # H*(Ii+Xi)
+       &reduction_alg5 ($Xhi,$Xi);
+
+       &movdqa         ($T3,&QWP(0,$const));
+&set_label("done");
+       &pshufb         ($Xi,$T3);
+       &movdqu         (&QWP(0,$Xip),$Xi);
+&function_end("gcm_ghash_clmul");
+
+}
+\f
+&set_label("bswap",64);
+       &data_byte(15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,0);
+       &data_byte(1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0xc2); # 0x1c2_polynomial
+}}     # $sse2
+
+&set_label("rem_4bit",64);
+       &data_word(0,0x0000<<$S,0,0x1C20<<$S,0,0x3840<<$S,0,0x2460<<$S);
+       &data_word(0,0x7080<<$S,0,0x6CA0<<$S,0,0x48C0<<$S,0,0x54E0<<$S);
+       &data_word(0,0xE100<<$S,0,0xFD20<<$S,0,0xD940<<$S,0,0xC560<<$S);
+       &data_word(0,0x9180<<$S,0,0x8DA0<<$S,0,0xA9C0<<$S,0,0xB5E0<<$S);
+&set_label("rem_8bit",64);
+       &data_short(0x0000,0x01C2,0x0384,0x0246,0x0708,0x06CA,0x048C,0x054E);
+       &data_short(0x0E10,0x0FD2,0x0D94,0x0C56,0x0918,0x08DA,0x0A9C,0x0B5E);
+       &data_short(0x1C20,0x1DE2,0x1FA4,0x1E66,0x1B28,0x1AEA,0x18AC,0x196E);
+       &data_short(0x1230,0x13F2,0x11B4,0x1076,0x1538,0x14FA,0x16BC,0x177E);
+       &data_short(0x3840,0x3982,0x3BC4,0x3A06,0x3F48,0x3E8A,0x3CCC,0x3D0E);
+       &data_short(0x3650,0x3792,0x35D4,0x3416,0x3158,0x309A,0x32DC,0x331E);
+       &data_short(0x2460,0x25A2,0x27E4,0x2626,0x2368,0x22AA,0x20EC,0x212E);
+       &data_short(0x2A70,0x2BB2,0x29F4,0x2836,0x2D78,0x2CBA,0x2EFC,0x2F3E);
+       &data_short(0x7080,0x7142,0x7304,0x72C6,0x7788,0x764A,0x740C,0x75CE);
+       &data_short(0x7E90,0x7F52,0x7D14,0x7CD6,0x7998,0x785A,0x7A1C,0x7BDE);
+       &data_short(0x6CA0,0x6D62,0x6F24,0x6EE6,0x6BA8,0x6A6A,0x682C,0x69EE);
+       &data_short(0x62B0,0x6372,0x6134,0x60F6,0x65B8,0x647A,0x663C,0x67FE);
+       &data_short(0x48C0,0x4902,0x4B44,0x4A86,0x4FC8,0x4E0A,0x4C4C,0x4D8E);
+       &data_short(0x46D0,0x4712,0x4554,0x4496,0x41D8,0x401A,0x425C,0x439E);
+       &data_short(0x54E0,0x5522,0x5764,0x56A6,0x53E8,0x522A,0x506C,0x51AE);
+       &data_short(0x5AF0,0x5B32,0x5974,0x58B6,0x5DF8,0x5C3A,0x5E7C,0x5FBE);
+       &data_short(0xE100,0xE0C2,0xE284,0xE346,0xE608,0xE7CA,0xE58C,0xE44E);
+       &data_short(0xEF10,0xEED2,0xEC94,0xED56,0xE818,0xE9DA,0xEB9C,0xEA5E);
+       &data_short(0xFD20,0xFCE2,0xFEA4,0xFF66,0xFA28,0xFBEA,0xF9AC,0xF86E);
+       &data_short(0xF330,0xF2F2,0xF0B4,0xF176,0xF438,0xF5FA,0xF7BC,0xF67E);
+       &data_short(0xD940,0xD882,0xDAC4,0xDB06,0xDE48,0xDF8A,0xDDCC,0xDC0E);
+       &data_short(0xD750,0xD692,0xD4D4,0xD516,0xD058,0xD19A,0xD3DC,0xD21E);
+       &data_short(0xC560,0xC4A2,0xC6E4,0xC726,0xC268,0xC3AA,0xC1EC,0xC02E);
+       &data_short(0xCB70,0xCAB2,0xC8F4,0xC936,0xCC78,0xCDBA,0xCFFC,0xCE3E);
+       &data_short(0x9180,0x9042,0x9204,0x93C6,0x9688,0x974A,0x950C,0x94CE);
+       &data_short(0x9F90,0x9E52,0x9C14,0x9DD6,0x9898,0x995A,0x9B1C,0x9ADE);
+       &data_short(0x8DA0,0x8C62,0x8E24,0x8FE6,0x8AA8,0x8B6A,0x892C,0x88EE);
+       &data_short(0x83B0,0x8272,0x8034,0x81F6,0x84B8,0x857A,0x873C,0x86FE);
+       &data_short(0xA9C0,0xA802,0xAA44,0xAB86,0xAEC8,0xAF0A,0xAD4C,0xAC8E);
+       &data_short(0xA7D0,0xA612,0xA454,0xA596,0xA0D8,0xA11A,0xA35C,0xA29E);
+       &data_short(0xB5E0,0xB422,0xB664,0xB7A6,0xB2E8,0xB32A,0xB16C,0xB0AE);
+       &data_short(0xBBF0,0xBA32,0xB874,0xB9B6,0xBCF8,0xBD3A,0xBF7C,0xBEBE);
+}}}    # !$x86only
+
 &asciz("GHASH for x86, CRYPTOGAMS by <appro\@openssl.org>");
 &asm_finish();
+
+# A question was risen about choice of vanilla MMX. Or rather why wasn't
+# SSE2 chosen instead? In addition to the fact that MMX runs on legacy
+# CPUs such as PIII, "4-bit" MMX version was observed to provide better
+# performance than *corresponding* SSE2 one even on contemporary CPUs.
+# SSE2 results were provided by Peter-Michael Hager. He maintains SSE2
+# implementation featuring full range of lookup-table sizes, but with
+# per-invocation lookup table setup. Latter means that table size is
+# chosen depending on how much data is to be hashed in every given call,
+# more data - larger table. Best reported result for Core2 is ~4 cycles
+# per processed byte out of 64KB block. Recall that this number accounts
+# even for 64KB table setup overhead. As discussed in gcm128.c we choose
+# to be more conservative in respect to lookup table sizes, but how
+# do the results compare? Minimalistic "256B" MMX version delivers ~11
+# cycles on same platform. As also discussed in gcm128.c, next in line
+# "8-bit Shoup's" method should deliver twice the performance of "4-bit"
+# one. It should be also be noted that in SSE2 case improvement can be
+# "super-linear," i.e. more than twice, mostly because >>8 maps to
+# single instruction on SSE2 register. This is unlike "4-bit" case when
+# >>4 maps to same amount of instructions in both MMX and SSE2 cases.
+# Bottom line is that switch to SSE2 is considered to be justifiable
+# only in case we choose to implement "8-bit" method...