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($frame+4*(num+2))
  70         &neg    ("edi");
  71
  72         # minimize cache contention by arraning 2K window between stack
  73         # pointer and ap argument [np is also position sensitive vector,
  74         # but it's assumed to be near ap, as it's allocated at ~same
  75         # time].
  76         &mov    ("eax","esp");
  77         &sub    ("eax","edx");
  78         &and    ("eax",2047);
  79         &sub    ("esp","eax");          # this aligns sp and ap modulo 2048
  80
  81         &xor    ("edx","esp");
  82         &and    ("edx",2048);
  83         &xor    ("edx",2048);
  84         &sub    ("esp","edx");          # this splits them apart modulo 4096
  85
  86         &and    ("esp",-64);            # align to cache line
  87
  88         ################################# load argument block...
  89         &mov    ("eax",&DWP(0*4,"esi"));# BN_ULONG *rp
  90         &mov    ("ebx",&DWP(1*4,"esi"));# const BN_ULONG *ap
  91         &mov    ("ecx",&DWP(2*4,"esi"));# const BN_ULONG *bp
  92         &mov    ("edx",&DWP(3*4,"esi"));# const BN_ULONG *np
  93         &mov    ("esi",&DWP(4*4,"esi"));# const BN_ULONG *n0
  94         #&mov   ("edi",&DWP(5*4,"esi"));# int num
  95
  96         &mov    ("esi",&DWP(0,"esi"));  # pull n0[0]
  97         &mov    ($_rp,"eax");           # ... save a copy of argument block
  98         &mov    ($_ap,"ebx");
  99         &mov    ($_bp,"ecx");
 100         &mov    ($_np,"edx");
 101         &mov    ($_n0,"esi");
 102         &lea    ($num,&DWP(-3,"edi"));  # num=num-1 to assist modulo-scheduling
 103         #&mov   ($_num,$num);           # redundant as $num is not reused
 104         &mov    ($_sp,"ebp");           # saved stack pointer!
 105 \f
 106 if($sse2) {
 107 $acc0="mm0";    # mmx register bank layout
 108 $acc1="mm1";
 109 $car0="mm2";
 110 $car1="mm3";
 111 $mul0="mm4";
 112 $mul1="mm5";
 113 $temp="mm6";
 114 $mask="mm7";
 115
 116         &picmeup("eax","OPENSSL_ia32cap_P");
 117         &bt     (&DWP(0,"eax"),26);
 118         &jnc    (&label("non_sse2"));
 119
 120         &mov    ("eax",-1);
 121         &movd   ($mask,"eax");          # mask 32 lower bits
 122
 123         &mov    ($ap,$_ap);             # load input pointers
 124         &mov    ($bp,$_bp);
 125         &mov    ($np,$_np);
 126
 127         &xor    ($i,$i);                # i=0
 128         &xor    ($j,$j);                # j=0
 129
 130         &movd   ($mul0,&DWP(0,$bp));            # bp[0]
 131         &movd   ($mul1,&DWP(0,$ap));            # ap[0]
 132         &movd   ($car1,&DWP(0,$np));            # np[0]
 133
 134         &pmuludq($mul1,$mul0);                  # ap[0]*bp[0]
 135         &movq   ($car0,$mul1);
 136         &movq   ($acc0,$mul1);                  # I wish movd worked for
 137         &pand   ($acc0,$mask);                  # inter-register transfers
 138
 139         &pmuludq($mul1,$_n0q);                  # *=n0
 140
 141         &pmuludq($car1,$mul1);                  # "t[0]"*np[0]*n0
 142         &paddq  ($car1,$acc0);
 143
 144         &movd   ($acc1,&DWP(4,$np));            # np[1]
 145         &movd   ($acc0,&DWP(4,$ap));            # ap[1]
 146
 147         &psrlq  ($car0,32);
 148         &psrlq  ($car1,32);
 149
 150         &inc    ($j);                           # j++
 151 &set_label("1st",16);
 152         &pmuludq($acc0,$mul0);                  # ap[j]*bp[0]
 153         &pmuludq($acc1,$mul1);                  # np[j]*m1
 154         &paddq  ($car0,$acc0);                  # +=c0
 155         &paddq  ($car1,$acc1);                  # +=c1
 156
 157         &movq   ($acc0,$car0);
 158         &pand   ($acc0,$mask);
 159         &movd   ($acc1,&DWP(4,$np,$j,4));       # np[j+1]
 160         &paddq  ($car1,$acc0);                  # +=ap[j]*bp[0];
 161         &movd   ($acc0,&DWP(4,$ap,$j,4));       # ap[j+1]
 162         &psrlq  ($car0,32);
 163         &movd   (&DWP($frame-4,"esp",$j,4),$car1);      # tp[j-1]=
 164         &psrlq  ($car1,32);
 165
 166         &lea    ($j,&DWP(1,$j));
 167         &cmp    ($j,$num);
 168         &jl     (&label("1st"));
 169
 170         &pmuludq($acc0,$mul0);                  # ap[num-1]*bp[0]
 171         &pmuludq($acc1,$mul1);                  # np[num-1]*m1
 172         &paddq  ($car0,$acc0);                  # +=c0
 173         &paddq  ($car1,$acc1);                  # +=c1
 174
 175         &movq   ($acc0,$car0);
 176         &pand   ($acc0,$mask);
 177         &paddq  ($car1,$acc0);                  # +=ap[num-1]*bp[0];
 178         &movd   (&DWP($frame-4,"esp",$j,4),$car1);      # tp[num-2]=
 179
 180         &psrlq  ($car0,32);
 181         &psrlq  ($car1,32);
 182
 183         &paddq  ($car1,$car0);
 184         &movq   (&QWP($frame,"esp",$num,4),$car1);      # tp[num].tp[num-1]
 185 \f
 186         &inc    ($i);                           # i++
 187 &set_label("outer");
 188         &xor    ($j,$j);                        # j=0
 189
 190         &movd   ($mul0,&DWP(0,$bp,$i,4));       # bp[i]
 191         &movd   ($mul1,&DWP(0,$ap));            # ap[0]
 192         &movd   ($temp,&DWP($frame,"esp"));     # tp[0]
 193         &movd   ($car1,&DWP(0,$np));            # np[0]
 194         &pmuludq($mul1,$mul0);                  # ap[0]*bp[i]
 195
 196         &paddq  ($mul1,$temp);                  # +=tp[0]
 197         &movq   ($acc0,$mul1);
 198         &movq   ($car0,$mul1);
 199         &pand   ($acc0,$mask);
 200
 201         &pmuludq($mul1,$_n0q);                  # *=n0
 202
 203         &pmuludq($car1,$mul1);
 204         &paddq  ($car1,$acc0);
 205
 206         &movd   ($temp,&DWP($frame+4,"esp"));   # tp[1]
 207         &movd   ($acc1,&DWP(4,$np));            # np[1]
 208         &movd   ($acc0,&DWP(4,$ap));            # ap[1]
 209
 210         &psrlq  ($car0,32);
 211         &psrlq  ($car1,32);
 212         &paddq  ($car0,$temp);                  # +=tp[1]
 213
 214         &inc    ($j);                           # j++
 215         &dec    ($num);
 216 &set_label("inner");
 217         &pmuludq($acc0,$mul0);                  # ap[j]*bp[i]
 218         &pmuludq($acc1,$mul1);                  # np[j]*m1
 219         &paddq  ($car0,$acc0);                  # +=c0
 220         &paddq  ($car1,$acc1);                  # +=c1
 221
 222         &movq   ($acc0,$car0);
 223         &movd   ($temp,&DWP($frame+4,"esp",$j,4));# tp[j+1]
 224         &pand   ($acc0,$mask);
 225         &movd   ($acc1,&DWP(4,$np,$j,4));       # np[j+1]
 226         &paddq  ($car1,$acc0);                  # +=ap[j]*bp[i]+tp[j]
 227         &movd   ($acc0,&DWP(4,$ap,$j,4));       # ap[j+1]
 228         &psrlq  ($car0,32);
 229         &movd   (&DWP($frame-4,"esp",$j,4),$car1);# tp[j-1]=
 230         &psrlq  ($car1,32);
 231         &paddq  ($car0,$temp);                  # +=tp[j+1]
 232
 233         &dec    ($num);
 234         &lea    ($j,&DWP(1,$j));                # j++
 235         &jnz    (&label("inner"));
 236
 237         &mov    ($num,$j);
 238         &pmuludq($acc0,$mul0);                  # ap[num-1]*bp[i]
 239         &pmuludq($acc1,$mul1);                  # np[num-1]*m1
 240         &paddq  ($car0,$acc0);                  # +=c0
 241         &paddq  ($car1,$acc1);                  # +=c1
 242
 243         &movq   ($acc0,$car0);
 244         &pand   ($acc0,$mask);
 245         &paddq  ($car1,$acc0);                  # +=ap[num-1]*bp[i]+tp[num-1]
 246         &movd   (&DWP($frame-4,"esp",$j,4),$car1);      # tp[num-2]=
 247         &psrlq  ($car0,32);
 248         &psrlq  ($car1,32);
 249
 250         &movd   ($temp,&DWP($frame+4,"esp",$num,4));    # += tp[num]
 251         &paddq  ($car1,$car0);
 252         &paddq  ($car1,$temp);
 253         &movq   (&QWP($frame,"esp",$num,4),$car1);      # tp[num].tp[num-1]
 254
 255         &lea    ($i,&DWP(1,$i));                # i++
 256         &cmp    ($i,$num);
 257         &jle    (&label("outer"));
 258
 259         &emms   ();                             # done with mmx bank
 260         &jmp    (&label("common_tail"));
 261
 262 &set_label("non_sse2",16);
 263 }
 264 \f
 265 if (0) {
 266         &mov    ("esp",$_sp);
 267         &xor    ("eax","eax");  # signal "not fast enough [yet]"
 268         &jmp    (&label("just_leave"));
 269         # While the below code provides competitive performance for
 270         # all key lengthes on modern Intel cores, it's still more
 271         # than 10% slower for 4096-bit key elsewhere:-( "Competitive"
 272         # means compared to the original integer-only assembler.
 273         # 512-bit RSA sign is better by ~40%, but that's about all
 274         # one can say about all CPUs...
 275 } else {
 276 $inp="esi";     # integer path uses these registers differently
 277 $word="edi";
 278 $carry="ebp";
 279
 280         &mov    ($inp,$_ap);
 281         &lea    ($carry,&DWP(1,$num));
 282         &mov    ($word,$_bp);
 283         &xor    ($j,$j);                                # j=0
 284         &mov    ("edx",$inp);
 285         &and    ($carry,1);                             # see if num is even
 286         &sub    ("edx",$word);                          # see if ap==bp
 287         &lea    ("eax",&DWP(4,$word,$num,4));           # &bp[num]
 288         &or     ($carry,"edx");
 289         &mov    ($word,&DWP(0,$word));                  # bp[0]
 290         &jz     (&label("bn_sqr_mont"));
 291         &mov    ($_bpend,"eax");
 292         &mov    ("eax",&DWP(0,$inp));
 293         &xor    ("edx","edx");
 294
 295 &set_label("mull",16);
 296         &mov    ($carry,"edx");
 297         &mul    ($word);                                # ap[j]*bp[0]
 298         &add    ($carry,"eax");
 299         &lea    ($j,&DWP(1,$j));
 300         &adc    ("edx",0);
 301         &mov    ("eax",&DWP(0,$inp,$j,4));              # ap[j+1]
 302         &cmp    ($j,$num);
 303         &mov    (&DWP($frame-4,"esp",$j,4),$carry);     # tp[j]=
 304         &jl     (&label("mull"));
 305
 306         &mov    ($carry,"edx");
 307         &mul    ($word);                                # ap[num-1]*bp[0]
 308          &mov   ($word,$_n0);
 309         &add    ("eax",$carry);
 310          &mov   ($inp,$_np);
 311         &adc    ("edx",0);
 312          &imul  ($word,&DWP($frame,"esp"));             # n0*tp[0]
 313
 314         &mov    (&DWP($frame,"esp",$num,4),"eax");      # tp[num-1]=
 315         &xor    ($j,$j);
 316         &mov    (&DWP($frame+4,"esp",$num,4),"edx");    # tp[num]=
 317         &mov    (&DWP($frame+8,"esp",$num,4),$j);       # tp[num+1]=
 318
 319         &mov    ("eax",&DWP(0,$inp));                   # np[0]
 320         &mul    ($word);                                # np[0]*m
 321         &add    ("eax",&DWP($frame,"esp"));             # +=tp[0]
 322         &mov    ("eax",&DWP(4,$inp));                   # np[1]
 323         &adc    ("edx",0);
 324         &inc    ($j);
 325
 326         &jmp    (&label("2ndmadd"));
 327 \f\f
 328 &set_label("1stmadd",16);
 329         &mov    ($carry,"edx");
 330         &mul    ($word);                                # ap[j]*bp[i]
 331         &add    ($carry,&DWP($frame,"esp",$j,4));       # +=tp[j]
 332         &lea    ($j,&DWP(1,$j));
 333         &adc    ("edx",0);
 334         &add    ($carry,"eax");
 335         &mov    ("eax",&DWP(0,$inp,$j,4));              # ap[j+1]
 336         &adc    ("edx",0);
 337         &cmp    ($j,$num);
 338         &mov    (&DWP($frame-4,"esp",$j,4),$carry);     # tp[j]=
 339         &jl     (&label("1stmadd"));
 340
 341         &mov    ($carry,"edx");
 342         &mul    ($word);                                # ap[num-1]*bp[i]
 343         &add    ("eax",&DWP($frame,"esp",$num,4));      # +=tp[num-1]
 344          &mov   ($word,$_n0);
 345         &adc    ("edx",0);
 346          &mov   ($inp,$_np);
 347         &add    ($carry,"eax");
 348         &adc    ("edx",0);
 349          &imul  ($word,&DWP($frame,"esp"));             # n0*tp[0]
 350
 351         &xor    ($j,$j);
 352         &add    ("edx",&DWP($frame+4,"esp",$num,4));    # carry+=tp[num]
 353         &mov    (&DWP($frame,"esp",$num,4),$carry);     # tp[num-1]=
 354         &adc    ($j,0);
 355          &mov   ("eax",&DWP(0,$inp));                   # np[0]
 356         &mov    (&DWP($frame+4,"esp",$num,4),"edx");    # tp[num]=
 357         &mov    (&DWP($frame+8,"esp",$num,4),$j);       # tp[num+1]=
 358
 359         &mul    ($word);                                # np[0]*m
 360         &add    ("eax",&DWP($frame,"esp"));             # +=tp[0]
 361         &mov    ("eax",&DWP(4,$inp));                   # np[1]
 362         &adc    ("edx",0);
 363         &mov    ($j,1);
 364 \f
 365 &set_label("2ndmadd",16);
 366         &mov    ($carry,"edx");
 367         &mul    ($word);                                # np[j]*m
 368         &add    ($carry,&DWP($frame,"esp",$j,4));       # +=tp[j]
 369         &lea    ($j,&DWP(1,$j));
 370         &adc    ("edx",0);
 371         &add    ($carry,"eax");
 372         &mov    ("eax",&DWP(0,$inp,$j,4));              # np[j+1]
 373         &adc    ("edx",0);
 374         &cmp    ($j,$num);
 375         &mov    (&DWP($frame-8,"esp",$j,4),$carry);     # tp[j-1]=
 376         &jl     (&label("2ndmadd"));
 377
 378         &mov    ($carry,"edx");
 379         &mul    ($word);                                # np[j]*m
 380         &add    ($carry,&DWP($frame,"esp",$num,4));     # +=tp[num-1]
 381         &adc    ("edx",0);
 382         &add    ($carry,"eax");
 383         &adc    ("edx",0);
 384         &mov    (&DWP($frame-4,"esp",$num,4),$carry);   # tp[num-2]=
 385
 386         &xor    ("eax","eax");
 387          &mov   ($j,$_bp);                              # &bp[i]
 388         &add    ("edx",&DWP($frame+4,"esp",$num,4));    # carry+=tp[num]
 389         &adc    ("eax",&DWP($frame+8,"esp",$num,4));    # +=tp[num+1]
 390          &lea   ($j,&DWP(4,$j));
 391         &mov    (&DWP($frame,"esp",$num,4),"edx");      # tp[num-1]=
 392          &cmp   ($j,$_bpend);
 393         &mov    (&DWP($frame+4,"esp",$num,4),"eax");    # tp[num]=
 394         &je     (&label("common_tail"));
 395
 396         &mov    ($word,&DWP(0,$j));                     # bp[i+1]
 397         &mov    ($inp,$_ap);
 398         &mov    ($_bp,$j);                              # &bp[++i]
 399         &xor    ($j,$j);
 400         &xor    ("edx","edx");
 401         &mov    ("eax",&DWP(0,$inp));
 402         &jmp    (&label("1stmadd"));
 403 \f
 404 &set_label("bn_sqr_mont",16);
 405 $sbit=$num;
 406         &mov    ($_num,$num);
 407         &mov    ($_bp,$j);                              # i=0
 408
 409         &mov    ("eax",$word);                          # ap[0]
 410         &mul    ($word);                                # ap[0]*ap[0]
 411         &mov    (&DWP($frame,"esp"),"eax");             # tp[0]=
 412         &mov    ($sbit,"edx");
 413         &shr    ("edx",1);
 414         &and    ($sbit,1);
 415         &inc    ($j);
 416 &set_label("sqr",16);
 417         &mov    ("eax",&DWP(0,$inp,$j,4));              # ap[j]
 418         &mov    ($carry,"edx");
 419         &mul    ($word);                                # ap[j]*ap[0]
 420         &add    ("eax",$carry);
 421         &lea    ($j,&DWP(1,$j));
 422         &adc    ("edx",0);
 423         &lea    ($carry,&DWP(0,$sbit,"eax",2));
 424         &shr    ("eax",31);
 425         &cmp    ($j,$_num);
 426         &mov    ($sbit,"eax");
 427         &mov    (&DWP($frame-4,"esp",$j,4),$carry);     # tp[j]=
 428         &jl     (&label("sqr"));
 429
 430         &mov    ("eax",&DWP(0,$inp,$j,4));              # ap[num-1]
 431         &mov    ($carry,"edx");
 432         &mul    ($word);                                # ap[num-1]*ap[0]
 433         &add    ("eax",$carry);
 434          &mov   ($word,$_n0);
 435         &adc    ("edx",0);
 436          &mov   ($inp,$_np);
 437         &lea    ($carry,&DWP(0,$sbit,"eax",2));
 438          &imul  ($word,&DWP($frame,"esp"));             # n0*tp[0]
 439         &shr    ("eax",31);
 440         &mov    (&DWP($frame,"esp",$j,4),$carry);       # tp[num-1]=
 441
 442         &lea    ($carry,&DWP(0,"eax","edx",2));
 443          &mov   ("eax",&DWP(0,$inp));                   # np[0]
 444         &shr    ("edx",31);
 445         &mov    (&DWP($frame+4,"esp",$j,4),$carry);     # tp[num]=
 446         &mov    (&DWP($frame+8,"esp",$j,4),"edx");      # tp[num+1]=
 447
 448         &mul    ($word);                                # np[0]*m
 449         &add    ("eax",&DWP($frame,"esp"));             # +=tp[0]
 450         &mov    ($num,$j);
 451         &adc    ("edx",0);
 452         &mov    ("eax",&DWP(4,$inp));                   # np[1]
 453         &mov    ($j,1);
 454 \f\f
 455 &set_label("3rdmadd",16);
 456         &mov    ($carry,"edx");
 457         &mul    ($word);                                # np[j]*m
 458         &add    ($carry,&DWP($frame,"esp",$j,4));       # +=tp[j]
 459         &adc    ("edx",0);
 460         &add    ($carry,"eax");
 461         &mov    ("eax",&DWP(4,$inp,$j,4));              # np[j+1]
 462         &adc    ("edx",0);
 463         &mov    (&DWP($frame-4,"esp",$j,4),$carry);     # tp[j-1]=
 464
 465         &mov    ($carry,"edx");
 466         &mul    ($word);                                # np[j+1]*m
 467         &add    ($carry,&DWP($frame+4,"esp",$j,4));     # +=tp[j+1]
 468         &lea    ($j,&DWP(2,$j));
 469         &adc    ("edx",0);
 470         &add    ($carry,"eax");
 471         &mov    ("eax",&DWP(0,$inp,$j,4));              # np[j+2]
 472         &adc    ("edx",0);
 473         &cmp    ($j,$num);
 474         &mov    (&DWP($frame-8,"esp",$j,4),$carry);     # tp[j]=
 475         &jl     (&label("3rdmadd"));
 476
 477         &mov    ($carry,"edx");
 478         &mul    ($word);                                # np[j]*m
 479         &add    ($carry,&DWP($frame,"esp",$num,4));     # +=tp[num-1]
 480         &adc    ("edx",0);
 481         &add    ($carry,"eax");
 482         &adc    ("edx",0);
 483         &mov    (&DWP($frame-4,"esp",$num,4),$carry);   # tp[num-2]=
 484
 485         &mov    ($j,$_bp);                              # i
 486         &xor    ("eax","eax");
 487         &mov    ($inp,$_ap);
 488         &add    ("edx",&DWP($frame+4,"esp",$num,4));    # carry+=tp[num]
 489         &adc    ("eax",&DWP($frame+8,"esp",$num,4));    # +=tp[num+1]
 490         &mov    (&DWP($frame,"esp",$num,4),"edx");      # tp[num-1]=
 491         &cmp    ($j,$num);
 492         &mov    (&DWP($frame+4,"esp",$num,4),"eax");    # tp[num]=
 493         &je     (&label("common_tail"));
 494 \f
 495         &mov    ($word,&DWP(4,$inp,$j,4));              # ap[i]
 496         &lea    ($j,&DWP(1,$j));
 497         &mov    ("eax",$word);
 498         &mov    ($_bp,$j);                              # ++i
 499         &mul    ($word);                                # ap[i]*ap[i]
 500         &add    ("eax",&DWP($frame,"esp",$j,4));        # +=tp[i]
 501         &adc    ("edx",0);
 502         &mov    (&DWP($frame,"esp",$j,4),"eax");        # tp[i]=
 503         &xor    ($carry,$carry);
 504         &cmp    ($j,$num);
 505         &lea    ($j,&DWP(1,$j));
 506         &je     (&label("sqrlast"));
 507
 508         &mov    ($sbit,"edx");                          # zaps $num
 509         &shr    ("edx",1);
 510         &and    ($sbit,1);
 511 &set_label("sqradd",16);
 512         &mov    ("eax",&DWP(0,$inp,$j,4));              # ap[j]
 513         &mov    ($carry,"edx");
 514         &mul    ($word);                                # ap[j]*ap[i]
 515         &add    ("eax",$carry);
 516         &lea    ($carry,&DWP(0,"eax","eax"));
 517         &adc    ("edx",0);
 518         &shr    ("eax",31);
 519         &add    ($carry,&DWP($frame,"esp",$j,4));       # +=tp[j]
 520         &lea    ($j,&DWP(1,$j));
 521         &adc    ("eax",0);
 522         &add    ($carry,$sbit);
 523         &adc    ("eax",0);
 524         &cmp    ($j,$_num);
 525         &mov    (&DWP($frame-4,"esp",$j,4),$carry);     # tp[j]=
 526         &mov    ($sbit,"eax");
 527         &jle    (&label("sqradd"));
 528
 529         &mov    ($carry,"edx");
 530         &add    ("edx","edx");
 531         &shr    ($carry,31);
 532         &add    ("edx",$sbit);
 533         &adc    ($carry,0);
 534 &set_label("sqrlast");
 535         &mov    ($word,$_n0);
 536         &mov    ($inp,$_np);
 537         &imul   ($word,&DWP($frame,"esp"));             # n0*tp[0]
 538
 539         &add    ("edx",&DWP($frame,"esp",$j,4));        # +=tp[num]
 540         &mov    ("eax",&DWP(0,$inp));                   # np[0]
 541         &adc    ($carry,0);
 542         &mov    (&DWP($frame,"esp",$j,4),"edx");        # tp[num]=
 543         &mov    (&DWP($frame+4,"esp",$j,4),$carry);     # tp[num+1]=
 544
 545         &mul    ($word);                                # np[0]*m
 546         &add    ("eax",&DWP($frame,"esp"));             # +=tp[0]
 547         &lea    ($num,&DWP(-1,$j));
 548         &adc    ("edx",0);
 549         &mov    ($j,1);
 550         &mov    ("eax",&DWP(4,$inp));                   # np[1]
 551
 552         &jmp    (&label("3rdmadd"));
 553 }
 554 \f
 555 &set_label("common_tail",16);
 556         &mov    ($np,$_np);                     # load modulus pointer
 557         &mov    ($rp,$_rp);                     # load result pointer
 558         &lea    ($tp,&DWP($frame,"esp"));       # [$ap and $bp are zapped]
 559
 560         &mov    ("eax",&DWP(0,$tp));            # tp[0]
 561         &mov    ($j,$num);                      # j=num-1
 562         &xor    ($i,$i);                        # i=0 and clear CF!
 563
 564 &set_label("sub",16);
 565         &sbb    ("eax",&DWP(0,$np,$i,4));
 566         &mov    (&DWP(0,$rp,$i,4),"eax");       # rp[i]=tp[i]-np[i]
 567         &dec    ($j);                           # doesn't affect CF!
 568         &mov    ("eax",&DWP(4,$tp,$i,4));       # tp[i+1]
 569         &lea    ($i,&DWP(1,$i));                # i++
 570         &jge    (&label("sub"));
 571
 572         &sbb    ("eax",0);                      # handle upmost overflow bit
 573         &and    ($tp,"eax");
 574         &not    ("eax");
 575         &mov    ($np,$rp);
 576         &and    ($np,"eax");
 577         &or     ($tp,$np);                      # tp=carry?tp:rp
 578
 579 &set_label("copy",16);                          # copy or in-place refresh
 580         &mov    ("eax",&DWP(0,$tp,$num,4));
 581         &mov    (&DWP(0,$rp,$num,4),"eax");     # rp[i]=tp[i]
 582         &mov    (&DWP($frame,"esp",$num,4),$j); # zap temporary vector
 583         &dec    ($num);
 584         &jge    (&label("copy"));
 585
 586         &mov    ("esp",$_sp);           # pull saved stack pointer
 587         &mov    ("eax",1);
 588 &set_label("just_leave");
 589 &function_end("bn_mul_mont");
 590
 591 &asciz("Montgomery Multiplication for x86, CRYPTOGAMS by <appro\@openssl.org>");
 592
 593 &asm_finish();