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openssl/crypto/bn/asm/x86-mont.pl

Index: openssl/crypto/bn/asm/x86-mont.pl
===================================================================
--- openssl/crypto/bn/asm/x86-mont.pl	(revision 0)
+++ openssl/crypto/bn/asm/x86-mont.pl	(revision 0)
@@ -0,0 +1,593 @@
+#!/usr/bin/env perl
+
+# ====================================================================
+# Written by Andy Polyakov <appro@fy.chalmers.se> for the OpenSSL
+# project. The module is, however, dual licensed under OpenSSL and
+# CRYPTOGAMS licenses depending on where you obtain it. For further
+# details see http://www.openssl.org/~appro/cryptogams/.
+# ====================================================================
+
+# October 2005
+#
+# This is a "teaser" code, as it can be improved in several ways...
+# First of all non-SSE2 path should be implemented (yes, for now it
+# performs Montgomery multiplication/convolution only on SSE2-capable
+# CPUs such as P4, others fall down to original code). Then inner loop
+# can be unrolled and modulo-scheduled to improve ILP and possibly
+# moved to 128-bit XMM register bank (though it would require input
+# rearrangement and/or increase bus bandwidth utilization). Dedicated
+# squaring procedure should give further performance improvement...
+# Yet, for being draft, the code improves rsa512 *sign* benchmark by
+# 110%(!), rsa1024 one - by 70% and rsa4096 - by 20%:-)
+
+# December 2006
+#
+# Modulo-scheduling SSE2 loops results in further 15-20% improvement.
+# Integer-only code [being equipped with dedicated squaring procedure]
+# gives ~40% on rsa512 sign benchmark...
+
+$0 =~ m/(.*[\/\\])[^\/\\]+$/; $dir=$1;
+push(@INC,"${dir}","${dir}../../perlasm");
+require "x86asm.pl";
+
+&asm_init($ARGV[0],$0);
+
+$sse2=0;
+for (@ARGV) { $sse2=1 if (/-DOPENSSL_IA32_SSE2/); }
+
+&external_label("OPENSSL_ia32cap_P") if ($sse2);
+
+&function_begin("bn_mul_mont");
+
+$i="edx";
+$j="ecx";
+$ap="esi";	$tp="esi";		# overlapping variables!!!
+$rp="edi";	$bp="edi";		# overlapping variables!!!
+$np="ebp";
+$num="ebx";
+
+$_num=&DWP(4*0,"esp");			# stack top layout
+$_rp=&DWP(4*1,"esp");
+$_ap=&DWP(4*2,"esp");
+$_bp=&DWP(4*3,"esp");
+$_np=&DWP(4*4,"esp");
+$_n0=&DWP(4*5,"esp");	$_n0q=&QWP(4*5,"esp");
+$_sp=&DWP(4*6,"esp");
+$_bpend=&DWP(4*7,"esp");
+$frame=32;				# size of above frame rounded up to 16n
+
+	&xor	("eax","eax");
+	&mov	("edi",&wparam(5));	# int num
+	&cmp	("edi",4);
+	&jl	(&label("just_leave"));
+
+	&lea	("esi",&wparam(0));	# put aside pointer to argument block
+	&lea	("edx",&wparam(1));	# load ap
+	&mov	("ebp","esp");		# saved stack pointer!
+	&add	("edi",2);		# extra two words on top of tp
+	&neg	("edi");
+	&lea	("esp",&DWP(-$frame,"esp","edi",4));	# alloca($frame+4*(num+2))
+	&neg	("edi");
+
+	# minimize cache contention by arraning 2K window between stack
+	# pointer and ap argument [np is also position sensitive vector,
+	# but it's assumed to be near ap, as it's allocated at ~same
+	# time].
+	&mov	("eax","esp");
+	&sub	("eax","edx");
+	&and	("eax",2047);
+	&sub	("esp","eax");		# this aligns sp and ap modulo 2048
+
+	&xor	("edx","esp");
+	&and	("edx",2048);
+	&xor	("edx",2048);
+	&sub	("esp","edx");		# this splits them apart modulo 4096
+
+	&and	("esp",-64);		# align to cache line
+
+	################################# load argument block...
+	&mov	("eax",&DWP(0*4,"esi"));# BN_ULONG *rp
+	&mov	("ebx",&DWP(1*4,"esi"));# const BN_ULONG *ap
+	&mov	("ecx",&DWP(2*4,"esi"));# const BN_ULONG *bp
+	&mov	("edx",&DWP(3*4,"esi"));# const BN_ULONG *np
+	&mov	("esi",&DWP(4*4,"esi"));# const BN_ULONG *n0
+	#&mov	("edi",&DWP(5*4,"esi"));# int num
+
+	&mov	("esi",&DWP(0,"esi"));	# pull n0[0]
+	&mov	($_rp,"eax");		# ... save a copy of argument block
+	&mov	($_ap,"ebx");
+	&mov	($_bp,"ecx");
+	&mov	($_np,"edx");
+	&mov	($_n0,"esi");
+	&lea	($num,&DWP(-3,"edi"));	# num=num-1 to assist modulo-scheduling
+	#&mov	($_num,$num);		# redundant as $num is not reused
+	&mov	($_sp,"ebp");		# saved stack pointer!
+
+if($sse2) {
+$acc0="mm0";	# mmx register bank layout
+$acc1="mm1";
+$car0="mm2";
+$car1="mm3";
+$mul0="mm4";
+$mul1="mm5";
+$temp="mm6";
+$mask="mm7";
+
+	&picmeup("eax","OPENSSL_ia32cap_P");
+	&bt	(&DWP(0,"eax"),26);
+	&jnc	(&label("non_sse2"));
+
+	&mov	("eax",-1);
+	&movd	($mask,"eax");		# mask 32 lower bits
+
+	&mov	($ap,$_ap);		# load input pointers
+	&mov	($bp,$_bp);
+	&mov	($np,$_np);
+
+	&xor	($i,$i);		# i=0
+	&xor	($j,$j);		# j=0
+
+	&movd	($mul0,&DWP(0,$bp));		# bp[0]
+	&movd	($mul1,&DWP(0,$ap));		# ap[0]
+	&movd	($car1,&DWP(0,$np));		# np[0]
+
+	&pmuludq($mul1,$mul0);			# ap[0]*bp[0]
+	&movq	($car0,$mul1);
+	&movq	($acc0,$mul1);			# I wish movd worked for
+	&pand	($acc0,$mask);			# inter-register transfers
+
+	&pmuludq($mul1,$_n0q);			# *=n0
+
+	&pmuludq($car1,$mul1);			# "t[0]"*np[0]*n0
+	&paddq	($car1,$acc0);
+
+	&movd	($acc1,&DWP(4,$np));		# np[1]
+	&movd	($acc0,&DWP(4,$ap));		# ap[1]
+
+	&psrlq	($car0,32);
+	&psrlq	($car1,32);
+
+	&inc	($j);				# j++
+&set_label("1st",16);
+	&pmuludq($acc0,$mul0);			# ap[j]*bp[0]
+	&pmuludq($acc1,$mul1);			# np[j]*m1
+	&paddq	($car0,$acc0);			# +=c0
+	&paddq	($car1,$acc1);			# +=c1
+
+	&movq	($acc0,$car0);
+	&pand	($acc0,$mask);
+	&movd	($acc1,&DWP(4,$np,$j,4));	# np[j+1]
+	&paddq	($car1,$acc0);			# +=ap[j]*bp[0];
+	&movd	($acc0,&DWP(4,$ap,$j,4));	# ap[j+1]
+	&psrlq	($car0,32);
+	&movd	(&DWP($frame-4,"esp",$j,4),$car1);	# tp[j-1]=
+	&psrlq	($car1,32);
+
+	&lea	($j,&DWP(1,$j));
+	&cmp	($j,$num);
+	&jl	(&label("1st"));
+
+	&pmuludq($acc0,$mul0);			# ap[num-1]*bp[0]
+	&pmuludq($acc1,$mul1);			# np[num-1]*m1
+	&paddq	($car0,$acc0);			# +=c0
+	&paddq	($car1,$acc1);			# +=c1
+
+	&movq	($acc0,$car0);
+	&pand	($acc0,$mask);
+	&paddq	($car1,$acc0);			# +=ap[num-1]*bp[0];
+	&movd	(&DWP($frame-4,"esp",$j,4),$car1);	# tp[num-2]=
+
+	&psrlq	($car0,32);
+	&psrlq	($car1,32);
+
+	&paddq	($car1,$car0);
+	&movq	(&QWP($frame,"esp",$num,4),$car1);	# tp[num].tp[num-1]
+
+	&inc	($i);				# i++
+&set_label("outer");
+	&xor	($j,$j);			# j=0
+
+	&movd	($mul0,&DWP(0,$bp,$i,4));	# bp[i]
+	&movd	($mul1,&DWP(0,$ap));		# ap[0]
+	&movd	($temp,&DWP($frame,"esp"));	# tp[0]
+	&movd	($car1,&DWP(0,$np));		# np[0]
+	&pmuludq($mul1,$mul0);			# ap[0]*bp[i]
+
+	&paddq	($mul1,$temp);			# +=tp[0]
+	&movq	($acc0,$mul1);
+	&movq	($car0,$mul1);
+	&pand	($acc0,$mask);
+
+	&pmuludq($mul1,$_n0q);			# *=n0
+
+	&pmuludq($car1,$mul1);
+	&paddq	($car1,$acc0);
+
+	&movd	($temp,&DWP($frame+4,"esp"));	# tp[1]
+	&movd	($acc1,&DWP(4,$np));		# np[1]
+	&movd	($acc0,&DWP(4,$ap));		# ap[1]
+
+	&psrlq	($car0,32);
+	&psrlq	($car1,32);
+	&paddq	($car0,$temp);			# +=tp[1]
+
+	&inc	($j);				# j++
+	&dec	($num);
+&set_label("inner");
+	&pmuludq($acc0,$mul0);			# ap[j]*bp[i]
+	&pmuludq($acc1,$mul1);			# np[j]*m1
+	&paddq	($car0,$acc0);			# +=c0
+	&paddq	($car1,$acc1);			# +=c1
+
+	&movq	($acc0,$car0);
+	&movd	($temp,&DWP($frame+4,"esp",$j,4));# tp[j+1]
+	&pand	($acc0,$mask);
+	&movd	($acc1,&DWP(4,$np,$j,4));	# np[j+1]
+	&paddq	($car1,$acc0);			# +=ap[j]*bp[i]+tp[j]
+	&movd	($acc0,&DWP(4,$ap,$j,4));	# ap[j+1]
+	&psrlq	($car0,32);
+	&movd	(&DWP($frame-4,"esp",$j,4),$car1);# tp[j-1]=
+	&psrlq	($car1,32);
+	&paddq	($car0,$temp);			# +=tp[j+1]
+
+	&dec	($num);
+	&lea	($j,&DWP(1,$j));		# j++
+	&jnz	(&label("inner"));
+
+	&mov	($num,$j);
+	&pmuludq($acc0,$mul0);			# ap[num-1]*bp[i]
+	&pmuludq($acc1,$mul1);			# np[num-1]*m1
+	&paddq	($car0,$acc0);			# +=c0
+	&paddq	($car1,$acc1);			# +=c1
+
+	&movq	($acc0,$car0);
+	&pand	($acc0,$mask);
+	&paddq	($car1,$acc0);			# +=ap[num-1]*bp[i]+tp[num-1]
+	&movd	(&DWP($frame-4,"esp",$j,4),$car1);	# tp[num-2]=
+	&psrlq	($car0,32);
+	&psrlq	($car1,32);
+
+	&movd	($temp,&DWP($frame+4,"esp",$num,4));	# += tp[num]
+	&paddq	($car1,$car0);
+	&paddq	($car1,$temp);
+	&movq	(&QWP($frame,"esp",$num,4),$car1);	# tp[num].tp[num-1]
+
+	&lea	($i,&DWP(1,$i));		# i++
+	&cmp	($i,$num);
+	&jle	(&label("outer"));
+
+	&emms	();				# done with mmx bank
+	&jmp	(&label("common_tail"));
+
+&set_label("non_sse2",16);
+}
+
+if (0) {
+	&mov	("esp",$_sp);
+	&xor	("eax","eax");	# signal "not fast enough [yet]"
+	&jmp	(&label("just_leave"));
+	# While the below code provides competitive performance for
+	# all key lengthes on modern Intel cores, it's still more
+	# than 10% slower for 4096-bit key elsewhere:-( "Competitive"
+	# means compared to the original integer-only assembler.
+	# 512-bit RSA sign is better by ~40%, but that's about all
+	# one can say about all CPUs...
+} else {
+$inp="esi";	# integer path uses these registers differently
+$word="edi";
+$carry="ebp";
+
+	&mov	($inp,$_ap);
+	&lea	($carry,&DWP(1,$num));
+	&mov	($word,$_bp);
+	&xor	($j,$j);				# j=0
+	&mov	("edx",$inp);
+	&and	($carry,1);				# see if num is even
+	&sub	("edx",$word);				# see if ap==bp
+	&lea	("eax",&DWP(4,$word,$num,4));		# &bp[num]
+	&or	($carry,"edx");
+	&mov	($word,&DWP(0,$word));			# bp[0]
+	&jz	(&label("bn_sqr_mont"));
+	&mov	($_bpend,"eax");
+	&mov	("eax",&DWP(0,$inp));
+	&xor	("edx","edx");
+
+&set_label("mull",16);
+	&mov	($carry,"edx");
+	&mul	($word);				# ap[j]*bp[0]
+	&add	($carry,"eax");
+	&lea	($j,&DWP(1,$j));
+	&adc	("edx",0);
+	&mov	("eax",&DWP(0,$inp,$j,4));		# ap[j+1]
+	&cmp	($j,$num);
+	&mov	(&DWP($frame-4,"esp",$j,4),$carry);	# tp[j]=
+	&jl	(&label("mull"));
+
+	&mov	($carry,"edx");
+	&mul	($word);				# ap[num-1]*bp[0]
+	 &mov	($word,$_n0);
+	&add	("eax",$carry);
+	 &mov	($inp,$_np);
+	&adc	("edx",0);
+	 &imul	($word,&DWP($frame,"esp"));		# n0*tp[0]
+
+	&mov	(&DWP($frame,"esp",$num,4),"eax");	# tp[num-1]=
+	&xor	($j,$j);
+	&mov	(&DWP($frame+4,"esp",$num,4),"edx");	# tp[num]=
+	&mov	(&DWP($frame+8,"esp",$num,4),$j);	# tp[num+1]=
+
+	&mov	("eax",&DWP(0,$inp));			# np[0]
+	&mul	($word);				# np[0]*m
+	&add	("eax",&DWP($frame,"esp"));		# +=tp[0]
+	&mov	("eax",&DWP(4,$inp));			# np[1]
+	&adc	("edx",0);
+	&inc	($j);
+
+	&jmp	(&label("2ndmadd"));
+
+&set_label("1stmadd",16);
+	&mov	($carry,"edx");
+	&mul	($word);				# ap[j]*bp[i]
+	&add	($carry,&DWP($frame,"esp",$j,4));	# +=tp[j]
+	&lea	($j,&DWP(1,$j));
+	&adc	("edx",0);
+	&add	($carry,"eax");
+	&mov	("eax",&DWP(0,$inp,$j,4));		# ap[j+1]
+	&adc	("edx",0);
+	&cmp	($j,$num);
+	&mov	(&DWP($frame-4,"esp",$j,4),$carry);	# tp[j]=
+	&jl	(&label("1stmadd"));
+
+	&mov	($carry,"edx");
+	&mul	($word);				# ap[num-1]*bp[i]
+	&add	("eax",&DWP($frame,"esp",$num,4));	# +=tp[num-1]
+	 &mov	($word,$_n0);
+	&adc	("edx",0);
+	 &mov	($inp,$_np);
+	&add	($carry,"eax");
+	&adc	("edx",0);
+	 &imul	($word,&DWP($frame,"esp"));		# n0*tp[0]
+
+	&xor	($j,$j);
+	&add	("edx",&DWP($frame+4,"esp",$num,4));	# carry+=tp[num]
+	&mov	(&DWP($frame,"esp",$num,4),$carry);	# tp[num-1]=
+	&adc	($j,0);
+	 &mov	("eax",&DWP(0,$inp));			# np[0]
+	&mov	(&DWP($frame+4,"esp",$num,4),"edx");	# tp[num]=
+	&mov	(&DWP($frame+8,"esp",$num,4),$j);	# tp[num+1]=
+
+	&mul	($word);				# np[0]*m
+	&add	("eax",&DWP($frame,"esp"));		# +=tp[0]
+	&mov	("eax",&DWP(4,$inp));			# np[1]
+	&adc	("edx",0);
+	&mov	($j,1);
+
+&set_label("2ndmadd",16);
+	&mov	($carry,"edx");
+	&mul	($word);				# np[j]*m
+	&add	($carry,&DWP($frame,"esp",$j,4));	# +=tp[j]
+	&lea	($j,&DWP(1,$j));
+	&adc	("edx",0);
+	&add	($carry,"eax");
+	&mov	("eax",&DWP(0,$inp,$j,4));		# np[j+1]
+	&adc	("edx",0);
+	&cmp	($j,$num);
+	&mov	(&DWP($frame-8,"esp",$j,4),$carry);	# tp[j-1]=
+	&jl	(&label("2ndmadd"));
+
+	&mov	($carry,"edx");
+	&mul	($word);				# np[j]*m
+	&add	($carry,&DWP($frame,"esp",$num,4));	# +=tp[num-1]
+	&adc	("edx",0);
+	&add	($carry,"eax");
+	&adc	("edx",0);
+	&mov	(&DWP($frame-4,"esp",$num,4),$carry);	# tp[num-2]=
+
+	&xor	("eax","eax");
+	 &mov	($j,$_bp);				# &bp[i]
+	&add	("edx",&DWP($frame+4,"esp",$num,4));	# carry+=tp[num]
+	&adc	("eax",&DWP($frame+8,"esp",$num,4));	# +=tp[num+1]
+	 &lea	($j,&DWP(4,$j));
+	&mov	(&DWP($frame,"esp",$num,4),"edx");	# tp[num-1]=
+	 &cmp	($j,$_bpend);
+	&mov	(&DWP($frame+4,"esp",$num,4),"eax");	# tp[num]=
+	&je	(&label("common_tail"));
+
+	&mov	($word,&DWP(0,$j));			# bp[i+1]
+	&mov	($inp,$_ap);
+	&mov	($_bp,$j);				# &bp[++i]
+	&xor	($j,$j);
+	&xor	("edx","edx");
+	&mov	("eax",&DWP(0,$inp));
+	&jmp	(&label("1stmadd"));
+
+&set_label("bn_sqr_mont",16);
+$sbit=$num;
+	&mov	($_num,$num);
+	&mov	($_bp,$j);				# i=0
+
+	&mov	("eax",$word);				# ap[0]
+	&mul	($word);				# ap[0]*ap[0]
+	&mov	(&DWP($frame,"esp"),"eax");		# tp[0]=
+	&mov	($sbit,"edx");
+	&shr	("edx",1);
+	&and	($sbit,1);
+	&inc	($j);
+&set_label("sqr",16);
+	&mov	("eax",&DWP(0,$inp,$j,4));		# ap[j]
+	&mov	($carry,"edx");
+	&mul	($word);				# ap[j]*ap[0]
+	&add	("eax",$carry);
+	&lea	($j,&DWP(1,$j));
+	&adc	("edx",0);
+	&lea	($carry,&DWP(0,$sbit,"eax",2));
+	&shr	("eax",31);
+	&cmp	($j,$_num);
+	&mov	($sbit,"eax");
+	&mov	(&DWP($frame-4,"esp",$j,4),$carry);	# tp[j]=
+	&jl	(&label("sqr"));
+
+	&mov	("eax",&DWP(0,$inp,$j,4));		# ap[num-1]
+	&mov	($carry,"edx");
+	&mul	($word);				# ap[num-1]*ap[0]
+	&add	("eax",$carry);
+	 &mov	($word,$_n0);
+	&adc	("edx",0);
+	 &mov	($inp,$_np);
+	&lea	($carry,&DWP(0,$sbit,"eax",2));
+	 &imul	($word,&DWP($frame,"esp"));		# n0*tp[0]
+	&shr	("eax",31);
+	&mov	(&DWP($frame,"esp",$j,4),$carry);	# tp[num-1]=
+
+	&lea	($carry,&DWP(0,"eax","edx",2));
+	 &mov	("eax",&DWP(0,$inp));			# np[0]
+	&shr	("edx",31);
+	&mov	(&DWP($frame+4,"esp",$j,4),$carry);	# tp[num]=
+	&mov	(&DWP($frame+8,"esp",$j,4),"edx");	# tp[num+1]=
+
+	&mul	($word);				# np[0]*m
+	&add	("eax",&DWP($frame,"esp"));		# +=tp[0]
+	&mov	($num,$j);
+	&adc	("edx",0);
+	&mov	("eax",&DWP(4,$inp));			# np[1]
+	&mov	($j,1);
+
+&set_label("3rdmadd",16);
+	&mov	($carry,"edx");
+	&mul	($word);				# np[j]*m
+	&add	($carry,&DWP($frame,"esp",$j,4));	# +=tp[j]
+	&adc	("edx",0);
+	&add	($carry,"eax");
+	&mov	("eax",&DWP(4,$inp,$j,4));		# np[j+1]
+	&adc	("edx",0);
+	&mov	(&DWP($frame-4,"esp",$j,4),$carry);	# tp[j-1]=
+
+	&mov	($carry,"edx");
+	&mul	($word);				# np[j+1]*m
+	&add	($carry,&DWP($frame+4,"esp",$j,4));	# +=tp[j+1]
+	&lea	($j,&DWP(2,$j));
+	&adc	("edx",0);
+	&add	($carry,"eax");
+	&mov	("eax",&DWP(0,$inp,$j,4));		# np[j+2]
+	&adc	("edx",0);
+	&cmp	($j,$num);
+	&mov	(&DWP($frame-8,"esp",$j,4),$carry);	# tp[j]=
+	&jl	(&label("3rdmadd"));
+
+	&mov	($carry,"edx");
+	&mul	($word);				# np[j]*m
+	&add	($carry,&DWP($frame,"esp",$num,4));	# +=tp[num-1]
+	&adc	("edx",0);
+	&add	($carry,"eax");
+	&adc	("edx",0);
+	&mov	(&DWP($frame-4,"esp",$num,4),$carry);	# tp[num-2]=
+
+	&mov	($j,$_bp);				# i
+	&xor	("eax","eax");
+	&mov	($inp,$_ap);
+	&add	("edx",&DWP($frame+4,"esp",$num,4));	# carry+=tp[num]
+	&adc	("eax",&DWP($frame+8,"esp",$num,4));	# +=tp[num+1]
+	&mov	(&DWP($frame,"esp",$num,4),"edx");	# tp[num-1]=
+	&cmp	($j,$num);
+	&mov	(&DWP($frame+4,"esp",$num,4),"eax");	# tp[num]=
+	&je	(&label("common_tail"));
+
+	&mov	($word,&DWP(4,$inp,$j,4));		# ap[i]
+	&lea	($j,&DWP(1,$j));
+	&mov	("eax",$word);
+	&mov	($_bp,$j);				# ++i
+	&mul	($word);				# ap[i]*ap[i]
+	&add	("eax",&DWP($frame,"esp",$j,4));	# +=tp[i]
+	&adc	("edx",0);
+	&mov	(&DWP($frame,"esp",$j,4),"eax");	# tp[i]=
+	&xor	($carry,$carry);
+	&cmp	($j,$num);
+	&lea	($j,&DWP(1,$j));
+	&je	(&label("sqrlast"));
+
+	&mov	($sbit,"edx");				# zaps $num
+	&shr	("edx",1);
+	&and	($sbit,1);
+&set_label("sqradd",16);
+	&mov	("eax",&DWP(0,$inp,$j,4));		# ap[j]
+	&mov	($carry,"edx");
+	&mul	($word);				# ap[j]*ap[i]
+	&add	("eax",$carry);
+	&lea	($carry,&DWP(0,"eax","eax"));
+	&adc	("edx",0);
+	&shr	("eax",31);
+	&add	($carry,&DWP($frame,"esp",$j,4));	# +=tp[j]
+	&lea	($j,&DWP(1,$j));
+	&adc	("eax",0);
+	&add	($carry,$sbit);
+	&adc	("eax",0);
+	&cmp	($j,$_num);
+	&mov	(&DWP($frame-4,"esp",$j,4),$carry);	# tp[j]=
+	&mov	($sbit,"eax");
+	&jle	(&label("sqradd"));
+
+	&mov	($carry,"edx");
+	&add	("edx","edx");
+	&shr	($carry,31);
+	&add	("edx",$sbit);
+	&adc	($carry,0);
+&set_label("sqrlast");
+	&mov	($word,$_n0);
+	&mov	($inp,$_np);
+	&imul	($word,&DWP($frame,"esp"));		# n0*tp[0]
+
+	&add	("edx",&DWP($frame,"esp",$j,4));	# +=tp[num]
+	&mov	("eax",&DWP(0,$inp));			# np[0]
+	&adc	($carry,0);
+	&mov	(&DWP($frame,"esp",$j,4),"edx");	# tp[num]=
+	&mov	(&DWP($frame+4,"esp",$j,4),$carry);	# tp[num+1]=
+
+	&mul	($word);				# np[0]*m
+	&add	("eax",&DWP($frame,"esp"));		# +=tp[0]
+	&lea	($num,&DWP(-1,$j));
+	&adc	("edx",0);
+	&mov	($j,1);
+	&mov	("eax",&DWP(4,$inp));			# np[1]
+
+	&jmp	(&label("3rdmadd"));
+}
+
+&set_label("common_tail",16);
+	&mov	($np,$_np);			# load modulus pointer
+	&mov	($rp,$_rp);			# load result pointer
+	&lea	($tp,&DWP($frame,"esp"));	# [$ap and $bp are zapped]
+
+	&mov	("eax",&DWP(0,$tp));		# tp[0]
+	&mov	($j,$num);			# j=num-1
+	&xor	($i,$i);			# i=0 and clear CF!
+
+&set_label("sub",16);
+	&sbb	("eax",&DWP(0,$np,$i,4));
+	&mov	(&DWP(0,$rp,$i,4),"eax");	# rp[i]=tp[i]-np[i]
+	&dec	($j);				# doesn't affect CF!
+	&mov	("eax",&DWP(4,$tp,$i,4));	# tp[i+1]
+	&lea	($i,&DWP(1,$i));		# i++
+	&jge	(&label("sub"));
+
+	&sbb	("eax",0);			# handle upmost overflow bit
+	&and	($tp,"eax");
+	&not	("eax");
+	&mov	($np,$rp);
+	&and	($np,"eax");
+	&or	($tp,$np);			# tp=carry?tp:rp
+
+&set_label("copy",16);				# copy or in-place refresh
+	&mov	("eax",&DWP(0,$tp,$num,4));
+	&mov	(&DWP(0,$rp,$num,4),"eax");	# rp[i]=tp[i]
+	&mov	(&DWP($frame,"esp",$num,4),$j);	# zap temporary vector
+	&dec	($num);
+	&jge	(&label("copy"));
+
+	&mov	("esp",$_sp);		# pull saved stack pointer
+	&mov	("eax",1);
+&set_label("just_leave");
+&function_end("bn_mul_mont");
+
+&asciz("Montgomery Multiplication for x86, CRYPTOGAMS by <appro\@openssl.org>");
+
+&asm_finish();