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

   1 #!/usr/bin/env perl
   2
   3 # ====================================================================
   4 # Written by Andy Polyakov <appro@fy.chalmers.se> for the OpenSSL
   5 # project. The module is, however, dual licensed under OpenSSL and
   6 # CRYPTOGAMS licenses depending on where you obtain it. For further
   7 # details see http://www.openssl.org/~appro/cryptogams/.
   8 # ====================================================================
   9
  10 # October 2005
  11 #
  12 # This is a "teaser" code, as it can be improved in several ways...
  13 # First of all non-SSE2 path should be implemented (yes, for now it
  14 # performs Montgomery multiplication/convolution only on SSE2-capable
  15 # CPUs such as P4, others fall down to original code). Then inner loop
  16 # can be unrolled and modulo-scheduled to improve ILP and possibly
  17 # moved to 128-bit XMM register bank (though it would require input
  18 # rearrangement and/or increase bus bandwidth utilization). Dedicated
  19 # squaring procedure should give further performance improvement...
  20 # Yet, for being draft, the code improves rsa512 *sign* benchmark by
  21 # 110%(!), rsa1024 one - by 70% and rsa4096 - by 20%:-)
  22
  23 # December 2006
  24 #
  25 # Modulo-scheduling SSE2 loops results in further 15-20% improvement.
  26 # Integer-only code [being equipped with dedicated squaring procedure]
  27 # gives ~40% on rsa512 sign benchmark...
  28
  29 $0 =~ m/(.*[\/\\])[^\/\\]+$/; $dir=$1;
  30 push(@INC,"${dir}","${dir}../../perlasm");
  31 require "x86asm.pl";
  32
  33 &asm_init($ARGV[0],$0);
  34
  35 $sse2=0;
  36 for (@ARGV) { $sse2=1 if (/-DOPENSSL_IA32_SSE2/); }
  37
  38 &external_label("OPENSSL_ia32cap_P") if ($sse2);
  39
  40 &function_begin("bn_mul_mont");
  41
  42 $i="edx";
  43 $j="ecx";
  44 $ap="esi";      $tp="esi";              # overlapping variables!!!
  45 $rp="edi";      $bp="edi";              # overlapping variables!!!
  46 $np="ebp";
  47 $num="ebx";
  48
  49 $_num=&DWP(4*0,"esp");                  # stack top layout
  50 $_rp=&DWP(4*1,"esp");
  51 $_ap=&DWP(4*2,"esp");
  52 $_bp=&DWP(4*3,"esp");
  53 $_np=&DWP(4*4,"esp");
  54 $_n0=&DWP(4*5,"esp");   $_n0q=&QWP(4*5,"esp");
  55 $_sp=&DWP(4*6,"esp");
  56 $_bpend=&DWP(4*7,"esp");
  57 $frame=32;                              # size of above frame rounded up to 16n
  58
  59         &xor    ("eax","eax");
  60         &mov    ("edi",&wparam(5));     # int num
  61         &cmp    ("edi",4);
  62         &jl     (&label("just_leave"));
  63
  64         &lea    ("esi",&wparam(0));     # put aside pointer to argument block
  65         &lea    ("edx",&wparam(1));     # load ap
  66         &mov    ("ebp","esp");          # saved stack pointer!
  67         &add    ("edi",2);              # extra two words on top of tp
  68         &neg    ("edi");
  69         &lea    ("esp",&DWP(-$frame,"esp","edi",4));    # alloca($frame+4*(num+2))
  70         &neg    ("edi");
  71
  72         # minimize cache contention by arraning 2K window between stack
  73         # pointer and ap argument [np is also position sensitive vector,
  74         # but it's assumed to be near ap, as it's allocated at ~same
  75         # time].
  76         &mov    ("eax","esp");
  77         &sub    ("eax","edx");
  78         &and    ("eax",2047);
  79         &sub    ("esp","eax");          # this aligns sp and ap modulo 2048
  80
  81         &xor    ("edx","esp");
  82         &and    ("edx",2048);
  83         &xor    ("edx",2048);
  84         &sub    ("esp","edx");          # this splits them apart modulo 4096
  85
  86         &and    ("esp",-64);            # align to cache line
  87
  88         # Some OSes, *cough*-dows, insist on stack being "wired" to
  89         # physical memory in strictly sequential manner, i.e. if stack
  90         # allocation spans two pages, then reference to farmost one can
  91         # be punishable by SEGV. But page walking can do good even on
  92         # other OSes, because it guarantees that villain thread hits
  93         # the guard page before it can make damage to innocent one...
  94         &mov    ("eax","ebp");
  95         &sub    ("eax","esp");
  96         &and    ("eax",-4096);
  97 &set_label("page_walk");
  98         &mov    ("edx",&DWP(0,"esp","eax"));
  99         &sub    ("eax",4096);
 100         &data_byte(0x2e);
 101         &jnc    (&label("page_walk"));
 102
 103         ################################# load argument block...
 104         &mov    ("eax",&DWP(0*4,"esi"));# BN_ULONG *rp
 105         &mov    ("ebx",&DWP(1*4,"esi"));# const BN_ULONG *ap
 106         &mov    ("ecx",&DWP(2*4,"esi"));# const BN_ULONG *bp
 107         &mov    ("edx",&DWP(3*4,"esi"));# const BN_ULONG *np
 108         &mov    ("esi",&DWP(4*4,"esi"));# const BN_ULONG *n0
 109         #&mov   ("edi",&DWP(5*4,"esi"));# int num
 110
 111         &mov    ("esi",&DWP(0,"esi"));  # pull n0[0]
 112         &mov    ($_rp,"eax");           # ... save a copy of argument block
 113         &mov    ($_ap,"ebx");
 114         &mov    ($_bp,"ecx");
 115         &mov    ($_np,"edx");
 116         &mov    ($_n0,"esi");
 117         &lea    ($num,&DWP(-3,"edi"));  # num=num-1 to assist modulo-scheduling
 118         #&mov   ($_num,$num);           # redundant as $num is not reused
 119         &mov    ($_sp,"ebp");           # saved stack pointer!
 120 \f
 121 if($sse2) {
 122 $acc0="mm0";    # mmx register bank layout
 123 $acc1="mm1";
 124 $car0="mm2";
 125 $car1="mm3";
 126 $mul0="mm4";
 127 $mul1="mm5";
 128 $temp="mm6";
 129 $mask="mm7";
 130
 131         &picmeup("eax","OPENSSL_ia32cap_P");
 132         &bt     (&DWP(0,"eax"),26);
 133         &jnc    (&label("non_sse2"));
 134
 135         &mov    ("eax",-1);
 136         &movd   ($mask,"eax");          # mask 32 lower bits
 137
 138         &mov    ($ap,$_ap);             # load input pointers
 139         &mov    ($bp,$_bp);
 140         &mov    ($np,$_np);
 141
 142         &xor    ($i,$i);                # i=0
 143         &xor    ($j,$j);                # j=0
 144
 145         &movd   ($mul0,&DWP(0,$bp));            # bp[0]
 146         &movd   ($mul1,&DWP(0,$ap));            # ap[0]
 147         &movd   ($car1,&DWP(0,$np));            # np[0]
 148
 149         &pmuludq($mul1,$mul0);                  # ap[0]*bp[0]
 150         &movq   ($car0,$mul1);
 151         &movq   ($acc0,$mul1);                  # I wish movd worked for
 152         &pand   ($acc0,$mask);                  # inter-register transfers
 153
 154         &pmuludq($mul1,$_n0q);                  # *=n0
 155
 156         &pmuludq($car1,$mul1);                  # "t[0]"*np[0]*n0
 157         &paddq  ($car1,$acc0);
 158
 159         &movd   ($acc1,&DWP(4,$np));            # np[1]
 160         &movd   ($acc0,&DWP(4,$ap));            # ap[1]
 161
 162         &psrlq  ($car0,32);
 163         &psrlq  ($car1,32);
 164
 165         &inc    ($j);                           # j++
 166 &set_label("1st",16);
 167         &pmuludq($acc0,$mul0);                  # ap[j]*bp[0]
 168         &pmuludq($acc1,$mul1);                  # np[j]*m1
 169         &paddq  ($car0,$acc0);                  # +=c0
 170         &paddq  ($car1,$acc1);                  # +=c1
 171
 172         &movq   ($acc0,$car0);
 173         &pand   ($acc0,$mask);
 174         &movd   ($acc1,&DWP(4,$np,$j,4));       # np[j+1]
 175         &paddq  ($car1,$acc0);                  # +=ap[j]*bp[0];
 176         &movd   ($acc0,&DWP(4,$ap,$j,4));       # ap[j+1]
 177         &psrlq  ($car0,32);
 178         &movd   (&DWP($frame-4,"esp",$j,4),$car1);      # tp[j-1]=
 179         &psrlq  ($car1,32);
 180
 181         &lea    ($j,&DWP(1,$j));
 182         &cmp    ($j,$num);
 183         &jl     (&label("1st"));
 184
 185         &pmuludq($acc0,$mul0);                  # ap[num-1]*bp[0]
 186         &pmuludq($acc1,$mul1);                  # np[num-1]*m1
 187         &paddq  ($car0,$acc0);                  # +=c0
 188         &paddq  ($car1,$acc1);                  # +=c1
 189
 190         &movq   ($acc0,$car0);
 191         &pand   ($acc0,$mask);
 192         &paddq  ($car1,$acc0);                  # +=ap[num-1]*bp[0];
 193         &movd   (&DWP($frame-4,"esp",$j,4),$car1);      # tp[num-2]=
 194
 195         &psrlq  ($car0,32);
 196         &psrlq  ($car1,32);
 197
 198         &paddq  ($car1,$car0);
 199         &movq   (&QWP($frame,"esp",$num,4),$car1);      # tp[num].tp[num-1]
 200 \f
 201         &inc    ($i);                           # i++
 202 &set_label("outer");
 203         &xor    ($j,$j);                        # j=0
 204
 205         &movd   ($mul0,&DWP(0,$bp,$i,4));       # bp[i]
 206         &movd   ($mul1,&DWP(0,$ap));            # ap[0]
 207         &movd   ($temp,&DWP($frame,"esp"));     # tp[0]
 208         &movd   ($car1,&DWP(0,$np));            # np[0]
 209         &pmuludq($mul1,$mul0);                  # ap[0]*bp[i]
 210
 211         &paddq  ($mul1,$temp);                  # +=tp[0]
 212         &movq   ($acc0,$mul1);
 213         &movq   ($car0,$mul1);
 214         &pand   ($acc0,$mask);
 215
 216         &pmuludq($mul1,$_n0q);                  # *=n0
 217
 218         &pmuludq($car1,$mul1);
 219         &paddq  ($car1,$acc0);
 220
 221         &movd   ($temp,&DWP($frame+4,"esp"));   # tp[1]
 222         &movd   ($acc1,&DWP(4,$np));            # np[1]
 223         &movd   ($acc0,&DWP(4,$ap));            # ap[1]
 224
 225         &psrlq  ($car0,32);
 226         &psrlq  ($car1,32);
 227         &paddq  ($car0,$temp);                  # +=tp[1]
 228
 229         &inc    ($j);                           # j++
 230         &dec    ($num);
 231 &set_label("inner");
 232         &pmuludq($acc0,$mul0);                  # ap[j]*bp[i]
 233         &pmuludq($acc1,$mul1);                  # np[j]*m1
 234         &paddq  ($car0,$acc0);                  # +=c0
 235         &paddq  ($car1,$acc1);                  # +=c1
 236
 237         &movq   ($acc0,$car0);
 238         &movd   ($temp,&DWP($frame+4,"esp",$j,4));# tp[j+1]
 239         &pand   ($acc0,$mask);
 240         &movd   ($acc1,&DWP(4,$np,$j,4));       # np[j+1]
 241         &paddq  ($car1,$acc0);                  # +=ap[j]*bp[i]+tp[j]
 242         &movd   ($acc0,&DWP(4,$ap,$j,4));       # ap[j+1]
 243         &psrlq  ($car0,32);
 244         &movd   (&DWP($frame-4,"esp",$j,4),$car1);# tp[j-1]=
 245         &psrlq  ($car1,32);
 246         &paddq  ($car0,$temp);                  # +=tp[j+1]
 247
 248         &dec    ($num);
 249         &lea    ($j,&DWP(1,$j));                # j++
 250         &jnz    (&label("inner"));
 251
 252         &mov    ($num,$j);
 253         &pmuludq($acc0,$mul0);                  # ap[num-1]*bp[i]
 254         &pmuludq($acc1,$mul1);                  # np[num-1]*m1
 255         &paddq  ($car0,$acc0);                  # +=c0
 256         &paddq  ($car1,$acc1);                  # +=c1
 257
 258         &movq   ($acc0,$car0);
 259         &pand   ($acc0,$mask);
 260         &paddq  ($car1,$acc0);                  # +=ap[num-1]*bp[i]+tp[num-1]
 261         &movd   (&DWP($frame-4,"esp",$j,4),$car1);      # tp[num-2]=
 262         &psrlq  ($car0,32);
 263         &psrlq  ($car1,32);
 264
 265         &movd   ($temp,&DWP($frame+4,"esp",$num,4));    # += tp[num]
 266         &paddq  ($car1,$car0);
 267         &paddq  ($car1,$temp);
 268         &movq   (&QWP($frame,"esp",$num,4),$car1);      # tp[num].tp[num-1]
 269
 270         &lea    ($i,&DWP(1,$i));                # i++
 271         &cmp    ($i,$num);
 272         &jle    (&label("outer"));
 273
 274         &emms   ();                             # done with mmx bank
 275         &jmp    (&label("common_tail"));
 276
 277 &set_label("non_sse2",16);
 278 }
 279 \f
 280 if (0) {
 281         &mov    ("esp",$_sp);
 282         &xor    ("eax","eax");  # signal "not fast enough [yet]"
 283         &jmp    (&label("just_leave"));
 284         # While the below code provides competitive performance for
 285         # all key lengthes on modern Intel cores, it's still more
 286         # than 10% slower for 4096-bit key elsewhere:-( "Competitive"
 287         # means compared to the original integer-only assembler.
 288         # 512-bit RSA sign is better by ~40%, but that's about all
 289         # one can say about all CPUs...
 290 } else {
 291 $inp="esi";     # integer path uses these registers differently
 292 $word="edi";
 293 $carry="ebp";
 294
 295         &mov    ($inp,$_ap);
 296         &lea    ($carry,&DWP(1,$num));
 297         &mov    ($word,$_bp);
 298         &xor    ($j,$j);                                # j=0
 299         &mov    ("edx",$inp);
 300         &and    ($carry,1);                             # see if num is even
 301         &sub    ("edx",$word);                          # see if ap==bp
 302         &lea    ("eax",&DWP(4,$word,$num,4));           # &bp[num]
 303         &or     ($carry,"edx");
 304         &mov    ($word,&DWP(0,$word));                  # bp[0]
 305         &jz     (&label("bn_sqr_mont"));
 306         &mov    ($_bpend,"eax");
 307         &mov    ("eax",&DWP(0,$inp));
 308         &xor    ("edx","edx");
 309
 310 &set_label("mull",16);
 311         &mov    ($carry,"edx");
 312         &mul    ($word);                                # ap[j]*bp[0]
 313         &add    ($carry,"eax");
 314         &lea    ($j,&DWP(1,$j));
 315         &adc    ("edx",0);
 316         &mov    ("eax",&DWP(0,$inp,$j,4));              # ap[j+1]
 317         &cmp    ($j,$num);
 318         &mov    (&DWP($frame-4,"esp",$j,4),$carry);     # tp[j]=
 319         &jl     (&label("mull"));
 320
 321         &mov    ($carry,"edx");
 322         &mul    ($word);                                # ap[num-1]*bp[0]
 323          &mov   ($word,$_n0);
 324         &add    ("eax",$carry);
 325          &mov   ($inp,$_np);
 326         &adc    ("edx",0);
 327          &imul  ($word,&DWP($frame,"esp"));             # n0*tp[0]
 328
 329         &mov    (&DWP($frame,"esp",$num,4),"eax");      # tp[num-1]=
 330         &xor    ($j,$j);
 331         &mov    (&DWP($frame+4,"esp",$num,4),"edx");    # tp[num]=
 332         &mov    (&DWP($frame+8,"esp",$num,4),$j);       # tp[num+1]=
 333
 334         &mov    ("eax",&DWP(0,$inp));                   # np[0]
 335         &mul    ($word);                                # np[0]*m
 336         &add    ("eax",&DWP($frame,"esp"));             # +=tp[0]
 337         &mov    ("eax",&DWP(4,$inp));                   # np[1]
 338         &adc    ("edx",0);
 339         &inc    ($j);
 340
 341         &jmp    (&label("2ndmadd"));
 342 \f\f
 343 &set_label("1stmadd",16);
 344         &mov    ($carry,"edx");
 345         &mul    ($word);                                # ap[j]*bp[i]
 346         &add    ($carry,&DWP($frame,"esp",$j,4));       # +=tp[j]
 347         &lea    ($j,&DWP(1,$j));
 348         &adc    ("edx",0);
 349         &add    ($carry,"eax");
 350         &mov    ("eax",&DWP(0,$inp,$j,4));              # ap[j+1]
 351         &adc    ("edx",0);
 352         &cmp    ($j,$num);
 353         &mov    (&DWP($frame-4,"esp",$j,4),$carry);     # tp[j]=
 354         &jl     (&label("1stmadd"));
 355
 356         &mov    ($carry,"edx");
 357         &mul    ($word);                                # ap[num-1]*bp[i]
 358         &add    ("eax",&DWP($frame,"esp",$num,4));      # +=tp[num-1]
 359          &mov   ($word,$_n0);
 360         &adc    ("edx",0);
 361          &mov   ($inp,$_np);
 362         &add    ($carry,"eax");
 363         &adc    ("edx",0);
 364          &imul  ($word,&DWP($frame,"esp"));             # n0*tp[0]
 365
 366         &xor    ($j,$j);
 367         &add    ("edx",&DWP($frame+4,"esp",$num,4));    # carry+=tp[num]
 368         &mov    (&DWP($frame,"esp",$num,4),$carry);     # tp[num-1]=
 369         &adc    ($j,0);
 370          &mov   ("eax",&DWP(0,$inp));                   # np[0]
 371         &mov    (&DWP($frame+4,"esp",$num,4),"edx");    # tp[num]=
 372         &mov    (&DWP($frame+8,"esp",$num,4),$j);       # tp[num+1]=
 373
 374         &mul    ($word);                                # np[0]*m
 375         &add    ("eax",&DWP($frame,"esp"));             # +=tp[0]
 376         &mov    ("eax",&DWP(4,$inp));                   # np[1]
 377         &adc    ("edx",0);
 378         &mov    ($j,1);
 379 \f
 380 &set_label("2ndmadd",16);
 381         &mov    ($carry,"edx");
 382         &mul    ($word);                                # np[j]*m
 383         &add    ($carry,&DWP($frame,"esp",$j,4));       # +=tp[j]
 384         &lea    ($j,&DWP(1,$j));
 385         &adc    ("edx",0);
 386         &add    ($carry,"eax");
 387         &mov    ("eax",&DWP(0,$inp,$j,4));              # np[j+1]
 388         &adc    ("edx",0);
 389         &cmp    ($j,$num);
 390         &mov    (&DWP($frame-8,"esp",$j,4),$carry);     # tp[j-1]=
 391         &jl     (&label("2ndmadd"));
 392
 393         &mov    ($carry,"edx");
 394         &mul    ($word);                                # np[j]*m
 395         &add    ($carry,&DWP($frame,"esp",$num,4));     # +=tp[num-1]
 396         &adc    ("edx",0);
 397         &add    ($carry,"eax");
 398         &adc    ("edx",0);
 399         &mov    (&DWP($frame-4,"esp",$num,4),$carry);   # tp[num-2]=
 400
 401         &xor    ("eax","eax");
 402          &mov   ($j,$_bp);                              # &bp[i]
 403         &add    ("edx",&DWP($frame+4,"esp",$num,4));    # carry+=tp[num]
 404         &adc    ("eax",&DWP($frame+8,"esp",$num,4));    # +=tp[num+1]
 405          &lea   ($j,&DWP(4,$j));
 406         &mov    (&DWP($frame,"esp",$num,4),"edx");      # tp[num-1]=
 407          &cmp   ($j,$_bpend);
 408         &mov    (&DWP($frame+4,"esp",$num,4),"eax");    # tp[num]=
 409         &je     (&label("common_tail"));
 410
 411         &mov    ($word,&DWP(0,$j));                     # bp[i+1]
 412         &mov    ($inp,$_ap);
 413         &mov    ($_bp,$j);                              # &bp[++i]
 414         &xor    ($j,$j);
 415         &xor    ("edx","edx");
 416         &mov    ("eax",&DWP(0,$inp));
 417         &jmp    (&label("1stmadd"));
 418 \f
 419 &set_label("bn_sqr_mont",16);
 420 $sbit=$num;
 421         &mov    ($_num,$num);
 422         &mov    ($_bp,$j);                              # i=0
 423
 424         &mov    ("eax",$word);                          # ap[0]
 425         &mul    ($word);                                # ap[0]*ap[0]
 426         &mov    (&DWP($frame,"esp"),"eax");             # tp[0]=
 427         &mov    ($sbit,"edx");
 428         &shr    ("edx",1);
 429         &and    ($sbit,1);
 430         &inc    ($j);
 431 &set_label("sqr",16);
 432         &mov    ("eax",&DWP(0,$inp,$j,4));              # ap[j]
 433         &mov    ($carry,"edx");
 434         &mul    ($word);                                # ap[j]*ap[0]
 435         &add    ("eax",$carry);
 436         &lea    ($j,&DWP(1,$j));
 437         &adc    ("edx",0);
 438         &lea    ($carry,&DWP(0,$sbit,"eax",2));
 439         &shr    ("eax",31);
 440         &cmp    ($j,$_num);
 441         &mov    ($sbit,"eax");
 442         &mov    (&DWP($frame-4,"esp",$j,4),$carry);     # tp[j]=
 443         &jl     (&label("sqr"));
 444
 445         &mov    ("eax",&DWP(0,$inp,$j,4));              # ap[num-1]
 446         &mov    ($carry,"edx");
 447         &mul    ($word);                                # ap[num-1]*ap[0]
 448         &add    ("eax",$carry);
 449          &mov   ($word,$_n0);
 450         &adc    ("edx",0);
 451          &mov   ($inp,$_np);
 452         &lea    ($carry,&DWP(0,$sbit,"eax",2));
 453          &imul  ($word,&DWP($frame,"esp"));             # n0*tp[0]
 454         &shr    ("eax",31);
 455         &mov    (&DWP($frame,"esp",$j,4),$carry);       # tp[num-1]=
 456
 457         &lea    ($carry,&DWP(0,"eax","edx",2));
 458          &mov   ("eax",&DWP(0,$inp));                   # np[0]
 459         &shr    ("edx",31);
 460         &mov    (&DWP($frame+4,"esp",$j,4),$carry);     # tp[num]=
 461         &mov    (&DWP($frame+8,"esp",$j,4),"edx");      # tp[num+1]=
 462
 463         &mul    ($word);                                # np[0]*m
 464         &add    ("eax",&DWP($frame,"esp"));             # +=tp[0]
 465         &mov    ($num,$j);
 466         &adc    ("edx",0);
 467         &mov    ("eax",&DWP(4,$inp));                   # np[1]
 468         &mov    ($j,1);
 469 \f\f
 470 &set_label("3rdmadd",16);
 471         &mov    ($carry,"edx");
 472         &mul    ($word);                                # np[j]*m
 473         &add    ($carry,&DWP($frame,"esp",$j,4));       # +=tp[j]
 474         &adc    ("edx",0);
 475         &add    ($carry,"eax");
 476         &mov    ("eax",&DWP(4,$inp,$j,4));              # np[j+1]
 477         &adc    ("edx",0);
 478         &mov    (&DWP($frame-4,"esp",$j,4),$carry);     # tp[j-1]=
 479
 480         &mov    ($carry,"edx");
 481         &mul    ($word);                                # np[j+1]*m
 482         &add    ($carry,&DWP($frame+4,"esp",$j,4));     # +=tp[j+1]
 483         &lea    ($j,&DWP(2,$j));
 484         &adc    ("edx",0);
 485         &add    ($carry,"eax");
 486         &mov    ("eax",&DWP(0,$inp,$j,4));              # np[j+2]
 487         &adc    ("edx",0);
 488         &cmp    ($j,$num);
 489         &mov    (&DWP($frame-8,"esp",$j,4),$carry);     # tp[j]=
 490         &jl     (&label("3rdmadd"));
 491
 492         &mov    ($carry,"edx");
 493         &mul    ($word);                                # np[j]*m
 494         &add    ($carry,&DWP($frame,"esp",$num,4));     # +=tp[num-1]
 495         &adc    ("edx",0);
 496         &add    ($carry,"eax");
 497         &adc    ("edx",0);
 498         &mov    (&DWP($frame-4,"esp",$num,4),$carry);   # tp[num-2]=
 499
 500         &mov    ($j,$_bp);                              # i
 501         &xor    ("eax","eax");
 502         &mov    ($inp,$_ap);
 503         &add    ("edx",&DWP($frame+4,"esp",$num,4));    # carry+=tp[num]
 504         &adc    ("eax",&DWP($frame+8,"esp",$num,4));    # +=tp[num+1]
 505         &mov    (&DWP($frame,"esp",$num,4),"edx");      # tp[num-1]=
 506         &cmp    ($j,$num);
 507         &mov    (&DWP($frame+4,"esp",$num,4),"eax");    # tp[num]=
 508         &je     (&label("common_tail"));
 509 \f
 510         &mov    ($word,&DWP(4,$inp,$j,4));              # ap[i]
 511         &lea    ($j,&DWP(1,$j));
 512         &mov    ("eax",$word);
 513         &mov    ($_bp,$j);                              # ++i
 514         &mul    ($word);                                # ap[i]*ap[i]
 515         &add    ("eax",&DWP($frame,"esp",$j,4));        # +=tp[i]
 516         &adc    ("edx",0);
 517         &mov    (&DWP($frame,"esp",$j,4),"eax");        # tp[i]=
 518         &xor    ($carry,$carry);
 519         &cmp    ($j,$num);
 520         &lea    ($j,&DWP(1,$j));
 521         &je     (&label("sqrlast"));
 522
 523         &mov    ($sbit,"edx");                          # zaps $num
 524         &shr    ("edx",1);
 525         &and    ($sbit,1);
 526 &set_label("sqradd",16);
 527         &mov    ("eax",&DWP(0,$inp,$j,4));              # ap[j]
 528         &mov    ($carry,"edx");
 529         &mul    ($word);                                # ap[j]*ap[i]
 530         &add    ("eax",$carry);
 531         &lea    ($carry,&DWP(0,"eax","eax"));
 532         &adc    ("edx",0);
 533         &shr    ("eax",31);
 534         &add    ($carry,&DWP($frame,"esp",$j,4));       # +=tp[j]
 535         &lea    ($j,&DWP(1,$j));
 536         &adc    ("eax",0);
 537         &add    ($carry,$sbit);
 538         &adc    ("eax",0);
 539         &cmp    ($j,$_num);
 540         &mov    (&DWP($frame-4,"esp",$j,4),$carry);     # tp[j]=
 541         &mov    ($sbit,"eax");
 542         &jle    (&label("sqradd"));
 543
 544         &mov    ($carry,"edx");
 545         &add    ("edx","edx");
 546         &shr    ($carry,31);
 547         &add    ("edx",$sbit);
 548         &adc    ($carry,0);
 549 &set_label("sqrlast");
 550         &mov    ($word,$_n0);
 551         &mov    ($inp,$_np);
 552         &imul   ($word,&DWP($frame,"esp"));             # n0*tp[0]
 553
 554         &add    ("edx",&DWP($frame,"esp",$j,4));        # +=tp[num]
 555         &mov    ("eax",&DWP(0,$inp));                   # np[0]
 556         &adc    ($carry,0);
 557         &mov    (&DWP($frame,"esp",$j,4),"edx");        # tp[num]=
 558         &mov    (&DWP($frame+4,"esp",$j,4),$carry);     # tp[num+1]=
 559
 560         &mul    ($word);                                # np[0]*m
 561         &add    ("eax",&DWP($frame,"esp"));             # +=tp[0]
 562         &lea    ($num,&DWP(-1,$j));
 563         &adc    ("edx",0);
 564         &mov    ($j,1);
 565         &mov    ("eax",&DWP(4,$inp));                   # np[1]
 566
 567         &jmp    (&label("3rdmadd"));
 568 }
 569 \f
 570 &set_label("common_tail",16);
 571         &mov    ($np,$_np);                     # load modulus pointer
 572         &mov    ($rp,$_rp);                     # load result pointer
 573         &lea    ($tp,&DWP($frame,"esp"));       # [$ap and $bp are zapped]
 574
 575         &mov    ("eax",&DWP(0,$tp));            # tp[0]
 576         &mov    ($j,$num);                      # j=num-1
 577         &xor    ($i,$i);                        # i=0 and clear CF!
 578
 579 &set_label("sub",16);
 580         &sbb    ("eax",&DWP(0,$np,$i,4));
 581         &mov    (&DWP(0,$rp,$i,4),"eax");       # rp[i]=tp[i]-np[i]
 582         &dec    ($j);                           # doesn't affect CF!
 583         &mov    ("eax",&DWP(4,$tp,$i,4));       # tp[i+1]
 584         &lea    ($i,&DWP(1,$i));                # i++
 585         &jge    (&label("sub"));
 586
 587         &sbb    ("eax",0);                      # handle upmost overflow bit
 588         &and    ($tp,"eax");
 589         &not    ("eax");
 590         &mov    ($np,$rp);
 591         &and    ($np,"eax");
 592         &or     ($tp,$np);                      # tp=carry?tp:rp
 593
 594 &set_label("copy",16);                          # copy or in-place refresh
 595         &mov    ("eax",&DWP(0,$tp,$num,4));
 596         &mov    (&DWP(0,$rp,$num,4),"eax");     # rp[i]=tp[i]
 597         &mov    (&DWP($frame,"esp",$num,4),$j); # zap temporary vector
 598         &dec    ($num);
 599         &jge    (&label("copy"));
 600
 601         &mov    ("esp",$_sp);           # pull saved stack pointer
 602         &mov    ("eax",1);
 603 &set_label("just_leave");
 604 &function_end("bn_mul_mont");
 605
 606 &asciz("Montgomery Multiplication for x86, CRYPTOGAMS by <appro\@openssl.org>");
 607
 608 &asm_finish();