crypto/bn/asm/x86-mont.pl

   1 #! /usr/bin/env perl
   2 # Copyright 2005-2016 The OpenSSL Project Authors. All Rights Reserved.
   3 #
   4 # Licensed under the OpenSSL license (the "License").  You may not use
   5 # this file except in compliance with the License.  You can obtain a copy
   6 # in the file LICENSE in the source distribution or at
   7 # https://www.openssl.org/source/license.html
   8
   9
  10 # ====================================================================
  11 # Written by Andy Polyakov <appro@openssl.org> for the OpenSSL
  12 # project. The module is, however, dual licensed under OpenSSL and
  13 # CRYPTOGAMS licenses depending on where you obtain it. For further
  14 # details see http://www.openssl.org/~appro/cryptogams/.
  15 # ====================================================================
  16
  17 # October 2005
  18 #
  19 # This is a "teaser" code, as it can be improved in several ways...
  20 # First of all non-SSE2 path should be implemented (yes, for now it
  21 # performs Montgomery multiplication/convolution only on SSE2-capable
  22 # CPUs such as P4, others fall down to original code). Then inner loop
  23 # can be unrolled and modulo-scheduled to improve ILP and possibly
  24 # moved to 128-bit XMM register bank (though it would require input
  25 # rearrangement and/or increase bus bandwidth utilization). Dedicated
  26 # squaring procedure should give further performance improvement...
  27 # Yet, for being draft, the code improves rsa512 *sign* benchmark by
  28 # 110%(!), rsa1024 one - by 70% and rsa4096 - by 20%:-)
  29
  30 # December 2006
  31 #
  32 # Modulo-scheduling SSE2 loops results in further 15-20% improvement.
  33 # Integer-only code [being equipped with dedicated squaring procedure]
  34 # gives ~40% on rsa512 sign benchmark...
  35
  36 $0 =~ m/(.*[\/\\])[^\/\\]+$/; $dir=$1;
  37 push(@INC,"${dir}","${dir}../../perlasm");
  38 require "x86asm.pl";
  39
  40 $output = pop;
  41 open STDOUT,">$output";
  42
  43 &asm_init($ARGV[0]);
  44
  45 $sse2=0;
  46 for (@ARGV) { $sse2=1 if (/-DOPENSSL_IA32_SSE2/); }
  47
  48 &external_label("OPENSSL_ia32cap_P") if ($sse2);
  49
  50 &function_begin("bn_mul_mont");
  51
  52 $i="edx";
  53 $j="ecx";
  54 $ap="esi";      $tp="esi";              # overlapping variables!!!
  55 $rp="edi";      $bp="edi";              # overlapping variables!!!
  56 $np="ebp";
  57 $num="ebx";
  58
  59 $_num=&DWP(4*0,"esp");                  # stack top layout
  60 $_rp=&DWP(4*1,"esp");
  61 $_ap=&DWP(4*2,"esp");
  62 $_bp=&DWP(4*3,"esp");
  63 $_np=&DWP(4*4,"esp");
  64 $_n0=&DWP(4*5,"esp");   $_n0q=&QWP(4*5,"esp");
  65 $_sp=&DWP(4*6,"esp");
  66 $_bpend=&DWP(4*7,"esp");
  67 $frame=32;                              # size of above frame rounded up to 16n
  68
  69         &xor    ("eax","eax");
  70         &mov    ("edi",&wparam(5));     # int num
  71         &cmp    ("edi",4);
  72         &jl     (&label("just_leave"));
  73
  74         &lea    ("esi",&wparam(0));     # put aside pointer to argument block
  75         &lea    ("edx",&wparam(1));     # load ap
  76         &add    ("edi",2);              # extra two words on top of tp
  77         &neg    ("edi");
  78         &lea    ("ebp",&DWP(-$frame,"esp","edi",4));    # future alloca($frame+4*(num+2))
  79         &neg    ("edi");
  80
  81         # minimize cache contention by arraning 2K window between stack
  82         # pointer and ap argument [np is also position sensitive vector,
  83         # but it's assumed to be near ap, as it's allocated at ~same
  84         # time].
  85         &mov    ("eax","ebp");
  86         &sub    ("eax","edx");
  87         &and    ("eax",2047);
  88         &sub    ("ebp","eax");          # this aligns sp and ap modulo 2048
  89
  90         &xor    ("edx","ebp");
  91         &and    ("edx",2048);
  92         &xor    ("edx",2048);
  93         &sub    ("ebp","edx");          # this splits them apart modulo 4096
  94
  95         &and    ("ebp",-64);            # align to cache line
  96
  97         # An OS-agnostic version of __chkstk.
  98         #
  99         # Some OSes (Windows) insist on stack being "wired" to
 100         # physical memory in strictly sequential manner, i.e. if stack
 101         # allocation spans two pages, then reference to farmost one can
 102         # be punishable by SEGV. But page walking can do good even on
 103         # other OSes, because it guarantees that villain thread hits
 104         # the guard page before it can make damage to innocent one...
 105         &mov    ("eax","esp");
 106         &sub    ("eax","ebp");
 107         &and    ("eax",-4096);
 108         &mov    ("edx","esp");          # saved stack pointer!
 109         &lea    ("esp",&DWP(0,"ebp","eax"));
 110         &mov    ("eax",&DWP(0,"esp"));
 111         &cmp    ("esp","ebp");
 112         &ja     (&label("page_walk"));
 113         &jmp    (&label("page_walk_done"));
 114
 115 &set_label("page_walk",16);
 116         &lea    ("esp",&DWP(-4096,"esp"));
 117         &mov    ("eax",&DWP(0,"esp"));
 118         &cmp    ("esp","ebp");
 119         &ja     (&label("page_walk"));
 120 &set_label("page_walk_done");
 121
 122         ################################# load argument block...
 123         &mov    ("eax",&DWP(0*4,"esi"));# BN_ULONG *rp
 124         &mov    ("ebx",&DWP(1*4,"esi"));# const BN_ULONG *ap
 125         &mov    ("ecx",&DWP(2*4,"esi"));# const BN_ULONG *bp
 126         &mov    ("ebp",&DWP(3*4,"esi"));# const BN_ULONG *np
 127         &mov    ("esi",&DWP(4*4,"esi"));# const BN_ULONG *n0
 128         #&mov   ("edi",&DWP(5*4,"esi"));# int num
 129
 130         &mov    ("esi",&DWP(0,"esi"));  # pull n0[0]
 131         &mov    ($_rp,"eax");           # ... save a copy of argument block
 132         &mov    ($_ap,"ebx");
 133         &mov    ($_bp,"ecx");
 134         &mov    ($_np,"ebp");
 135         &mov    ($_n0,"esi");
 136         &lea    ($num,&DWP(-3,"edi"));  # num=num-1 to assist modulo-scheduling
 137         #&mov   ($_num,$num);           # redundant as $num is not reused
 138         &mov    ($_sp,"edx");           # saved stack pointer!
 139 \f
 140 if($sse2) {
 141 $acc0="mm0";    # mmx register bank layout
 142 $acc1="mm1";
 143 $car0="mm2";
 144 $car1="mm3";
 145 $mul0="mm4";
 146 $mul1="mm5";
 147 $temp="mm6";
 148 $mask="mm7";
 149
 150         &picmeup("eax","OPENSSL_ia32cap_P");
 151         &bt     (&DWP(0,"eax"),26);
 152         &jnc    (&label("non_sse2"));
 153
 154         &mov    ("eax",-1);
 155         &movd   ($mask,"eax");          # mask 32 lower bits
 156
 157         &mov    ($ap,$_ap);             # load input pointers
 158         &mov    ($bp,$_bp);
 159         &mov    ($np,$_np);
 160
 161         &xor    ($i,$i);                # i=0
 162         &xor    ($j,$j);                # j=0
 163
 164         &movd   ($mul0,&DWP(0,$bp));            # bp[0]
 165         &movd   ($mul1,&DWP(0,$ap));            # ap[0]
 166         &movd   ($car1,&DWP(0,$np));            # np[0]
 167
 168         &pmuludq($mul1,$mul0);                  # ap[0]*bp[0]
 169         &movq   ($car0,$mul1);
 170         &movq   ($acc0,$mul1);                  # I wish movd worked for
 171         &pand   ($acc0,$mask);                  # inter-register transfers
 172
 173         &pmuludq($mul1,$_n0q);                  # *=n0
 174
 175         &pmuludq($car1,$mul1);                  # "t[0]"*np[0]*n0
 176         &paddq  ($car1,$acc0);
 177
 178         &movd   ($acc1,&DWP(4,$np));            # np[1]
 179         &movd   ($acc0,&DWP(4,$ap));            # ap[1]
 180
 181         &psrlq  ($car0,32);
 182         &psrlq  ($car1,32);
 183
 184         &inc    ($j);                           # j++
 185 &set_label("1st",16);
 186         &pmuludq($acc0,$mul0);                  # ap[j]*bp[0]
 187         &pmuludq($acc1,$mul1);                  # np[j]*m1
 188         &paddq  ($car0,$acc0);                  # +=c0
 189         &paddq  ($car1,$acc1);                  # +=c1
 190
 191         &movq   ($acc0,$car0);
 192         &pand   ($acc0,$mask);
 193         &movd   ($acc1,&DWP(4,$np,$j,4));       # np[j+1]
 194         &paddq  ($car1,$acc0);                  # +=ap[j]*bp[0];
 195         &movd   ($acc0,&DWP(4,$ap,$j,4));       # ap[j+1]
 196         &psrlq  ($car0,32);
 197         &movd   (&DWP($frame-4,"esp",$j,4),$car1);      # tp[j-1]=
 198         &psrlq  ($car1,32);
 199
 200         &lea    ($j,&DWP(1,$j));
 201         &cmp    ($j,$num);
 202         &jl     (&label("1st"));
 203
 204         &pmuludq($acc0,$mul0);                  # ap[num-1]*bp[0]
 205         &pmuludq($acc1,$mul1);                  # np[num-1]*m1
 206         &paddq  ($car0,$acc0);                  # +=c0
 207         &paddq  ($car1,$acc1);                  # +=c1
 208
 209         &movq   ($acc0,$car0);
 210         &pand   ($acc0,$mask);
 211         &paddq  ($car1,$acc0);                  # +=ap[num-1]*bp[0];
 212         &movd   (&DWP($frame-4,"esp",$j,4),$car1);      # tp[num-2]=
 213
 214         &psrlq  ($car0,32);
 215         &psrlq  ($car1,32);
 216
 217         &paddq  ($car1,$car0);
 218         &movq   (&QWP($frame,"esp",$num,4),$car1);      # tp[num].tp[num-1]
 219 \f
 220         &inc    ($i);                           # i++
 221 &set_label("outer");
 222         &xor    ($j,$j);                        # j=0
 223
 224         &movd   ($mul0,&DWP(0,$bp,$i,4));       # bp[i]
 225         &movd   ($mul1,&DWP(0,$ap));            # ap[0]
 226         &movd   ($temp,&DWP($frame,"esp"));     # tp[0]
 227         &movd   ($car1,&DWP(0,$np));            # np[0]
 228         &pmuludq($mul1,$mul0);                  # ap[0]*bp[i]
 229
 230         &paddq  ($mul1,$temp);                  # +=tp[0]
 231         &movq   ($acc0,$mul1);
 232         &movq   ($car0,$mul1);
 233         &pand   ($acc0,$mask);
 234
 235         &pmuludq($mul1,$_n0q);                  # *=n0
 236
 237         &pmuludq($car1,$mul1);
 238         &paddq  ($car1,$acc0);
 239
 240         &movd   ($temp,&DWP($frame+4,"esp"));   # tp[1]
 241         &movd   ($acc1,&DWP(4,$np));            # np[1]
 242         &movd   ($acc0,&DWP(4,$ap));            # ap[1]
 243
 244         &psrlq  ($car0,32);
 245         &psrlq  ($car1,32);
 246         &paddq  ($car0,$temp);                  # +=tp[1]
 247
 248         &inc    ($j);                           # j++
 249         &dec    ($num);
 250 &set_label("inner");
 251         &pmuludq($acc0,$mul0);                  # ap[j]*bp[i]
 252         &pmuludq($acc1,$mul1);                  # np[j]*m1
 253         &paddq  ($car0,$acc0);                  # +=c0
 254         &paddq  ($car1,$acc1);                  # +=c1
 255
 256         &movq   ($acc0,$car0);
 257         &movd   ($temp,&DWP($frame+4,"esp",$j,4));# tp[j+1]
 258         &pand   ($acc0,$mask);
 259         &movd   ($acc1,&DWP(4,$np,$j,4));       # np[j+1]
 260         &paddq  ($car1,$acc0);                  # +=ap[j]*bp[i]+tp[j]
 261         &movd   ($acc0,&DWP(4,$ap,$j,4));       # ap[j+1]
 262         &psrlq  ($car0,32);
 263         &movd   (&DWP($frame-4,"esp",$j,4),$car1);# tp[j-1]=
 264         &psrlq  ($car1,32);
 265         &paddq  ($car0,$temp);                  # +=tp[j+1]
 266
 267         &dec    ($num);
 268         &lea    ($j,&DWP(1,$j));                # j++
 269         &jnz    (&label("inner"));
 270
 271         &mov    ($num,$j);
 272         &pmuludq($acc0,$mul0);                  # ap[num-1]*bp[i]
 273         &pmuludq($acc1,$mul1);                  # np[num-1]*m1
 274         &paddq  ($car0,$acc0);                  # +=c0
 275         &paddq  ($car1,$acc1);                  # +=c1
 276
 277         &movq   ($acc0,$car0);
 278         &pand   ($acc0,$mask);
 279         &paddq  ($car1,$acc0);                  # +=ap[num-1]*bp[i]+tp[num-1]
 280         &movd   (&DWP($frame-4,"esp",$j,4),$car1);      # tp[num-2]=
 281         &psrlq  ($car0,32);
 282         &psrlq  ($car1,32);
 283
 284         &movd   ($temp,&DWP($frame+4,"esp",$num,4));    # += tp[num]
 285         &paddq  ($car1,$car0);
 286         &paddq  ($car1,$temp);
 287         &movq   (&QWP($frame,"esp",$num,4),$car1);      # tp[num].tp[num-1]
 288
 289         &lea    ($i,&DWP(1,$i));                # i++
 290         &cmp    ($i,$num);
 291         &jle    (&label("outer"));
 292
 293         &emms   ();                             # done with mmx bank
 294         &jmp    (&label("common_tail"));
 295
 296 &set_label("non_sse2",16);
 297 }
 298 \f
 299 if (0) {
 300         &mov    ("esp",$_sp);
 301         &xor    ("eax","eax");  # signal "not fast enough [yet]"
 302         &jmp    (&label("just_leave"));
 303         # While the below code provides competitive performance for
 304         # all key lengths on modern Intel cores, it's still more
 305         # than 10% slower for 4096-bit key elsewhere:-( "Competitive"
 306         # means compared to the original integer-only assembler.
 307         # 512-bit RSA sign is better by ~40%, but that's about all
 308         # one can say about all CPUs...
 309 } else {
 310 $inp="esi";     # integer path uses these registers differently
 311 $word="edi";
 312 $carry="ebp";
 313
 314         &mov    ($inp,$_ap);
 315         &lea    ($carry,&DWP(1,$num));
 316         &mov    ($word,$_bp);
 317         &xor    ($j,$j);                                # j=0
 318         &mov    ("edx",$inp);
 319         &and    ($carry,1);                             # see if num is even
 320         &sub    ("edx",$word);                          # see if ap==bp
 321         &lea    ("eax",&DWP(4,$word,$num,4));           # &bp[num]
 322         &or     ($carry,"edx");
 323         &mov    ($word,&DWP(0,$word));                  # bp[0]
 324         &jz     (&label("bn_sqr_mont"));
 325         &mov    ($_bpend,"eax");
 326         &mov    ("eax",&DWP(0,$inp));
 327         &xor    ("edx","edx");
 328
 329 &set_label("mull",16);
 330         &mov    ($carry,"edx");
 331         &mul    ($word);                                # ap[j]*bp[0]
 332         &add    ($carry,"eax");
 333         &lea    ($j,&DWP(1,$j));
 334         &adc    ("edx",0);
 335         &mov    ("eax",&DWP(0,$inp,$j,4));              # ap[j+1]
 336         &cmp    ($j,$num);
 337         &mov    (&DWP($frame-4,"esp",$j,4),$carry);     # tp[j]=
 338         &jl     (&label("mull"));
 339
 340         &mov    ($carry,"edx");
 341         &mul    ($word);                                # ap[num-1]*bp[0]
 342          &mov   ($word,$_n0);
 343         &add    ("eax",$carry);
 344          &mov   ($inp,$_np);
 345         &adc    ("edx",0);
 346          &imul  ($word,&DWP($frame,"esp"));             # n0*tp[0]
 347
 348         &mov    (&DWP($frame,"esp",$num,4),"eax");      # tp[num-1]=
 349         &xor    ($j,$j);
 350         &mov    (&DWP($frame+4,"esp",$num,4),"edx");    # tp[num]=
 351         &mov    (&DWP($frame+8,"esp",$num,4),$j);       # tp[num+1]=
 352
 353         &mov    ("eax",&DWP(0,$inp));                   # np[0]
 354         &mul    ($word);                                # np[0]*m
 355         &add    ("eax",&DWP($frame,"esp"));             # +=tp[0]
 356         &mov    ("eax",&DWP(4,$inp));                   # np[1]
 357         &adc    ("edx",0);
 358         &inc    ($j);
 359
 360         &jmp    (&label("2ndmadd"));
 361 \f\f
 362 &set_label("1stmadd",16);
 363         &mov    ($carry,"edx");
 364         &mul    ($word);                                # ap[j]*bp[i]
 365         &add    ($carry,&DWP($frame,"esp",$j,4));       # +=tp[j]
 366         &lea    ($j,&DWP(1,$j));
 367         &adc    ("edx",0);
 368         &add    ($carry,"eax");
 369         &mov    ("eax",&DWP(0,$inp,$j,4));              # ap[j+1]
 370         &adc    ("edx",0);
 371         &cmp    ($j,$num);
 372         &mov    (&DWP($frame-4,"esp",$j,4),$carry);     # tp[j]=
 373         &jl     (&label("1stmadd"));
 374
 375         &mov    ($carry,"edx");
 376         &mul    ($word);                                # ap[num-1]*bp[i]
 377         &add    ("eax",&DWP($frame,"esp",$num,4));      # +=tp[num-1]
 378          &mov   ($word,$_n0);
 379         &adc    ("edx",0);
 380          &mov   ($inp,$_np);
 381         &add    ($carry,"eax");
 382         &adc    ("edx",0);
 383          &imul  ($word,&DWP($frame,"esp"));             # n0*tp[0]
 384
 385         &xor    ($j,$j);
 386         &add    ("edx",&DWP($frame+4,"esp",$num,4));    # carry+=tp[num]
 387         &mov    (&DWP($frame,"esp",$num,4),$carry);     # tp[num-1]=
 388         &adc    ($j,0);
 389          &mov   ("eax",&DWP(0,$inp));                   # np[0]
 390         &mov    (&DWP($frame+4,"esp",$num,4),"edx");    # tp[num]=
 391         &mov    (&DWP($frame+8,"esp",$num,4),$j);       # tp[num+1]=
 392
 393         &mul    ($word);                                # np[0]*m
 394         &add    ("eax",&DWP($frame,"esp"));             # +=tp[0]
 395         &mov    ("eax",&DWP(4,$inp));                   # np[1]
 396         &adc    ("edx",0);
 397         &mov    ($j,1);
 398 \f
 399 &set_label("2ndmadd",16);
 400         &mov    ($carry,"edx");
 401         &mul    ($word);                                # np[j]*m
 402         &add    ($carry,&DWP($frame,"esp",$j,4));       # +=tp[j]
 403         &lea    ($j,&DWP(1,$j));
 404         &adc    ("edx",0);
 405         &add    ($carry,"eax");
 406         &mov    ("eax",&DWP(0,$inp,$j,4));              # np[j+1]
 407         &adc    ("edx",0);
 408         &cmp    ($j,$num);
 409         &mov    (&DWP($frame-8,"esp",$j,4),$carry);     # tp[j-1]=
 410         &jl     (&label("2ndmadd"));
 411
 412         &mov    ($carry,"edx");
 413         &mul    ($word);                                # np[j]*m
 414         &add    ($carry,&DWP($frame,"esp",$num,4));     # +=tp[num-1]
 415         &adc    ("edx",0);
 416         &add    ($carry,"eax");
 417         &adc    ("edx",0);
 418         &mov    (&DWP($frame-4,"esp",$num,4),$carry);   # tp[num-2]=
 419
 420         &xor    ("eax","eax");
 421          &mov   ($j,$_bp);                              # &bp[i]
 422         &add    ("edx",&DWP($frame+4,"esp",$num,4));    # carry+=tp[num]
 423         &adc    ("eax",&DWP($frame+8,"esp",$num,4));    # +=tp[num+1]
 424          &lea   ($j,&DWP(4,$j));
 425         &mov    (&DWP($frame,"esp",$num,4),"edx");      # tp[num-1]=
 426          &cmp   ($j,$_bpend);
 427         &mov    (&DWP($frame+4,"esp",$num,4),"eax");    # tp[num]=
 428         &je     (&label("common_tail"));
 429
 430         &mov    ($word,&DWP(0,$j));                     # bp[i+1]
 431         &mov    ($inp,$_ap);
 432         &mov    ($_bp,$j);                              # &bp[++i]
 433         &xor    ($j,$j);
 434         &xor    ("edx","edx");
 435         &mov    ("eax",&DWP(0,$inp));
 436         &jmp    (&label("1stmadd"));
 437 \f
 438 &set_label("bn_sqr_mont",16);
 439 $sbit=$num;
 440         &mov    ($_num,$num);
 441         &mov    ($_bp,$j);                              # i=0
 442
 443         &mov    ("eax",$word);                          # ap[0]
 444         &mul    ($word);                                # ap[0]*ap[0]
 445         &mov    (&DWP($frame,"esp"),"eax");             # tp[0]=
 446         &mov    ($sbit,"edx");
 447         &shr    ("edx",1);
 448         &and    ($sbit,1);
 449         &inc    ($j);
 450 &set_label("sqr",16);
 451         &mov    ("eax",&DWP(0,$inp,$j,4));              # ap[j]
 452         &mov    ($carry,"edx");
 453         &mul    ($word);                                # ap[j]*ap[0]
 454         &add    ("eax",$carry);
 455         &lea    ($j,&DWP(1,$j));
 456         &adc    ("edx",0);
 457         &lea    ($carry,&DWP(0,$sbit,"eax",2));
 458         &shr    ("eax",31);
 459         &cmp    ($j,$_num);
 460         &mov    ($sbit,"eax");
 461         &mov    (&DWP($frame-4,"esp",$j,4),$carry);     # tp[j]=
 462         &jl     (&label("sqr"));
 463
 464         &mov    ("eax",&DWP(0,$inp,$j,4));              # ap[num-1]
 465         &mov    ($carry,"edx");
 466         &mul    ($word);                                # ap[num-1]*ap[0]
 467         &add    ("eax",$carry);
 468          &mov   ($word,$_n0);
 469         &adc    ("edx",0);
 470          &mov   ($inp,$_np);
 471         &lea    ($carry,&DWP(0,$sbit,"eax",2));
 472          &imul  ($word,&DWP($frame,"esp"));             # n0*tp[0]
 473         &shr    ("eax",31);
 474         &mov    (&DWP($frame,"esp",$j,4),$carry);       # tp[num-1]=
 475
 476         &lea    ($carry,&DWP(0,"eax","edx",2));
 477          &mov   ("eax",&DWP(0,$inp));                   # np[0]
 478         &shr    ("edx",31);
 479         &mov    (&DWP($frame+4,"esp",$j,4),$carry);     # tp[num]=
 480         &mov    (&DWP($frame+8,"esp",$j,4),"edx");      # tp[num+1]=
 481
 482         &mul    ($word);                                # np[0]*m
 483         &add    ("eax",&DWP($frame,"esp"));             # +=tp[0]
 484         &mov    ($num,$j);
 485         &adc    ("edx",0);
 486         &mov    ("eax",&DWP(4,$inp));                   # np[1]
 487         &mov    ($j,1);
 488 \f\f
 489 &set_label("3rdmadd",16);
 490         &mov    ($carry,"edx");
 491         &mul    ($word);                                # np[j]*m
 492         &add    ($carry,&DWP($frame,"esp",$j,4));       # +=tp[j]
 493         &adc    ("edx",0);
 494         &add    ($carry,"eax");
 495         &mov    ("eax",&DWP(4,$inp,$j,4));              # np[j+1]
 496         &adc    ("edx",0);
 497         &mov    (&DWP($frame-4,"esp",$j,4),$carry);     # tp[j-1]=
 498
 499         &mov    ($carry,"edx");
 500         &mul    ($word);                                # np[j+1]*m
 501         &add    ($carry,&DWP($frame+4,"esp",$j,4));     # +=tp[j+1]
 502         &lea    ($j,&DWP(2,$j));
 503         &adc    ("edx",0);
 504         &add    ($carry,"eax");
 505         &mov    ("eax",&DWP(0,$inp,$j,4));              # np[j+2]
 506         &adc    ("edx",0);
 507         &cmp    ($j,$num);
 508         &mov    (&DWP($frame-8,"esp",$j,4),$carry);     # tp[j]=
 509         &jl     (&label("3rdmadd"));
 510
 511         &mov    ($carry,"edx");
 512         &mul    ($word);                                # np[j]*m
 513         &add    ($carry,&DWP($frame,"esp",$num,4));     # +=tp[num-1]
 514         &adc    ("edx",0);
 515         &add    ($carry,"eax");
 516         &adc    ("edx",0);
 517         &mov    (&DWP($frame-4,"esp",$num,4),$carry);   # tp[num-2]=
 518
 519         &mov    ($j,$_bp);                              # i
 520         &xor    ("eax","eax");
 521         &mov    ($inp,$_ap);
 522         &add    ("edx",&DWP($frame+4,"esp",$num,4));    # carry+=tp[num]
 523         &adc    ("eax",&DWP($frame+8,"esp",$num,4));    # +=tp[num+1]
 524         &mov    (&DWP($frame,"esp",$num,4),"edx");      # tp[num-1]=
 525         &cmp    ($j,$num);
 526         &mov    (&DWP($frame+4,"esp",$num,4),"eax");    # tp[num]=
 527         &je     (&label("common_tail"));
 528 \f
 529         &mov    ($word,&DWP(4,$inp,$j,4));              # ap[i]
 530         &lea    ($j,&DWP(1,$j));
 531         &mov    ("eax",$word);
 532         &mov    ($_bp,$j);                              # ++i
 533         &mul    ($word);                                # ap[i]*ap[i]
 534         &add    ("eax",&DWP($frame,"esp",$j,4));        # +=tp[i]
 535         &adc    ("edx",0);
 536         &mov    (&DWP($frame,"esp",$j,4),"eax");        # tp[i]=
 537         &xor    ($carry,$carry);
 538         &cmp    ($j,$num);
 539         &lea    ($j,&DWP(1,$j));
 540         &je     (&label("sqrlast"));
 541
 542         &mov    ($sbit,"edx");                          # zaps $num
 543         &shr    ("edx",1);
 544         &and    ($sbit,1);
 545 &set_label("sqradd",16);
 546         &mov    ("eax",&DWP(0,$inp,$j,4));              # ap[j]
 547         &mov    ($carry,"edx");
 548         &mul    ($word);                                # ap[j]*ap[i]
 549         &add    ("eax",$carry);
 550         &lea    ($carry,&DWP(0,"eax","eax"));
 551         &adc    ("edx",0);
 552         &shr    ("eax",31);
 553         &add    ($carry,&DWP($frame,"esp",$j,4));       # +=tp[j]
 554         &lea    ($j,&DWP(1,$j));
 555         &adc    ("eax",0);
 556         &add    ($carry,$sbit);
 557         &adc    ("eax",0);
 558         &cmp    ($j,$_num);
 559         &mov    (&DWP($frame-4,"esp",$j,4),$carry);     # tp[j]=
 560         &mov    ($sbit,"eax");
 561         &jle    (&label("sqradd"));
 562
 563         &mov    ($carry,"edx");
 564         &add    ("edx","edx");
 565         &shr    ($carry,31);
 566         &add    ("edx",$sbit);
 567         &adc    ($carry,0);
 568 &set_label("sqrlast");
 569         &mov    ($word,$_n0);
 570         &mov    ($inp,$_np);
 571         &imul   ($word,&DWP($frame,"esp"));             # n0*tp[0]
 572
 573         &add    ("edx",&DWP($frame,"esp",$j,4));        # +=tp[num]
 574         &mov    ("eax",&DWP(0,$inp));                   # np[0]
 575         &adc    ($carry,0);
 576         &mov    (&DWP($frame,"esp",$j,4),"edx");        # tp[num]=
 577         &mov    (&DWP($frame+4,"esp",$j,4),$carry);     # tp[num+1]=
 578
 579         &mul    ($word);                                # np[0]*m
 580         &add    ("eax",&DWP($frame,"esp"));             # +=tp[0]
 581         &lea    ($num,&DWP(-1,$j));
 582         &adc    ("edx",0);
 583         &mov    ($j,1);
 584         &mov    ("eax",&DWP(4,$inp));                   # np[1]
 585
 586         &jmp    (&label("3rdmadd"));
 587 }
 588 \f
 589 &set_label("common_tail",16);
 590         &mov    ($np,$_np);                     # load modulus pointer
 591         &mov    ($rp,$_rp);                     # load result pointer
 592         &lea    ($tp,&DWP($frame,"esp"));       # [$ap and $bp are zapped]
 593
 594         &mov    ("eax",&DWP(0,$tp));            # tp[0]
 595         &mov    ($j,$num);                      # j=num-1
 596         &xor    ($i,$i);                        # i=0 and clear CF!
 597
 598 &set_label("sub",16);
 599         &sbb    ("eax",&DWP(0,$np,$i,4));
 600         &mov    (&DWP(0,$rp,$i,4),"eax");       # rp[i]=tp[i]-np[i]
 601         &dec    ($j);                           # doesn't affect CF!
 602         &mov    ("eax",&DWP(4,$tp,$i,4));       # tp[i+1]
 603         &lea    ($i,&DWP(1,$i));                # i++
 604         &jge    (&label("sub"));
 605
 606         &sbb    ("eax",0);                      # handle upmost overflow bit
 607         &and    ($tp,"eax");
 608         &not    ("eax");
 609         &mov    ($np,$rp);
 610         &and    ($np,"eax");
 611         &or     ($tp,$np);                      # tp=carry?tp:rp
 612
 613 &set_label("copy",16);                          # copy or in-place refresh
 614         &mov    ("eax",&DWP(0,$tp,$num,4));
 615         &mov    (&DWP(0,$rp,$num,4),"eax");     # rp[i]=tp[i]
 616         &mov    (&DWP($frame,"esp",$num,4),$j); # zap temporary vector
 617         &dec    ($num);
 618         &jge    (&label("copy"));
 619
 620         &mov    ("esp",$_sp);           # pull saved stack pointer
 621         &mov    ("eax",1);
 622 &set_label("just_leave");
 623 &function_end("bn_mul_mont");
 624
 625 &asciz("Montgomery Multiplication for x86, CRYPTOGAMS by <appro\@openssl.org>");
 626
 627 &asm_finish();
 628
 629 close STDOUT;