arch/x86/math-emu/reg_compare.c

   1 /*---------------------------------------------------------------------------+
   2  |  reg_compare.c                                                            |
   3  |                                                                           |
   4  | Compare two floating point registers                                      |
   5  |                                                                           |
   6  | Copyright (C) 1992,1993,1994,1997                                         |
   7  |                  W. Metzenthen, 22 Parker St, Ormond, Vic 3163, Australia |
   8  |                  E-mail   billm@suburbia.net                              |
   9  |                                                                           |
  10  |                                                                           |
  11  +---------------------------------------------------------------------------*/
  12
  13 /*---------------------------------------------------------------------------+
  14  | compare() is the core FPU_REG comparison function                         |
  15  +---------------------------------------------------------------------------*/
  16
  17 #include "fpu_system.h"
  18 #include "exception.h"
  19 #include "fpu_emu.h"
  20 #include "control_w.h"
  21 #include "status_w.h"
  22
  23 static int compare(FPU_REG const *b, int tagb)
  24 {
  25         int diff, exp0, expb;
  26         u_char st0_tag;
  27         FPU_REG *st0_ptr;
  28         FPU_REG x, y;
  29         u_char st0_sign, signb = getsign(b);
  30
  31         st0_ptr = &st(0);
  32         st0_tag = FPU_gettag0();
  33         st0_sign = getsign(st0_ptr);
  34
  35         if (tagb == TAG_Special)
  36                 tagb = FPU_Special(b);
  37         if (st0_tag == TAG_Special)
  38                 st0_tag = FPU_Special(st0_ptr);
  39
  40         if (((st0_tag != TAG_Valid) && (st0_tag != TW_Denormal))
  41             || ((tagb != TAG_Valid) && (tagb != TW_Denormal))) {
  42                 if (st0_tag == TAG_Zero) {
  43                         if (tagb == TAG_Zero)
  44                                 return COMP_A_eq_B;
  45                         if (tagb == TAG_Valid)
  46                                 return ((signb ==
  47                                          SIGN_POS) ? COMP_A_lt_B : COMP_A_gt_B);
  48                         if (tagb == TW_Denormal)
  49                                 return ((signb ==
  50                                          SIGN_POS) ? COMP_A_lt_B : COMP_A_gt_B)
  51                                     | COMP_Denormal;
  52                 } else if (tagb == TAG_Zero) {
  53                         if (st0_tag == TAG_Valid)
  54                                 return ((st0_sign ==
  55                                          SIGN_POS) ? COMP_A_gt_B : COMP_A_lt_B);
  56                         if (st0_tag == TW_Denormal)
  57                                 return ((st0_sign ==
  58                                          SIGN_POS) ? COMP_A_gt_B : COMP_A_lt_B)
  59                                     | COMP_Denormal;
  60                 }
  61
  62                 if (st0_tag == TW_Infinity) {
  63                         if ((tagb == TAG_Valid) || (tagb == TAG_Zero))
  64                                 return ((st0_sign ==
  65                                          SIGN_POS) ? COMP_A_gt_B : COMP_A_lt_B);
  66                         else if (tagb == TW_Denormal)
  67                                 return ((st0_sign ==
  68                                          SIGN_POS) ? COMP_A_gt_B : COMP_A_lt_B)
  69                                     | COMP_Denormal;
  70                         else if (tagb == TW_Infinity) {
  71                                 /* The 80486 book says that infinities can be equal! */
  72                                 return (st0_sign == signb) ? COMP_A_eq_B :
  73                                     ((st0_sign ==
  74                                       SIGN_POS) ? COMP_A_gt_B : COMP_A_lt_B);
  75                         }
  76                         /* Fall through to the NaN code */
  77                 } else if (tagb == TW_Infinity) {
  78                         if ((st0_tag == TAG_Valid) || (st0_tag == TAG_Zero))
  79                                 return ((signb ==
  80                                          SIGN_POS) ? COMP_A_lt_B : COMP_A_gt_B);
  81                         if (st0_tag == TW_Denormal)
  82                                 return ((signb ==
  83                                          SIGN_POS) ? COMP_A_lt_B : COMP_A_gt_B)
  84                                     | COMP_Denormal;
  85                         /* Fall through to the NaN code */
  86                 }
  87
  88                 /* The only possibility now should be that one of the arguments
  89                    is a NaN */
  90                 if ((st0_tag == TW_NaN) || (tagb == TW_NaN)) {
  91                         int signalling = 0, unsupported = 0;
  92                         if (st0_tag == TW_NaN) {
  93                                 signalling =
  94                                     (st0_ptr->sigh & 0xc0000000) == 0x80000000;
  95                                 unsupported = !((exponent(st0_ptr) == EXP_OVER)
  96                                                 && (st0_ptr->
  97                                                     sigh & 0x80000000));
  98                         }
  99                         if (tagb == TW_NaN) {
 100                                 signalling |=
 101                                     (b->sigh & 0xc0000000) == 0x80000000;
 102                                 unsupported |= !((exponent(b) == EXP_OVER)
 103                                                  && (b->sigh & 0x80000000));
 104                         }
 105                         if (signalling || unsupported)
 106                                 return COMP_No_Comp | COMP_SNaN | COMP_NaN;
 107                         else
 108                                 /* Neither is a signaling NaN */
 109                                 return COMP_No_Comp | COMP_NaN;
 110                 }
 111
 112                 EXCEPTION(EX_Invalid);
 113         }
 114
 115         if (st0_sign != signb) {
 116                 return ((st0_sign == SIGN_POS) ? COMP_A_gt_B : COMP_A_lt_B)
 117                     | (((st0_tag == TW_Denormal) || (tagb == TW_Denormal)) ?
 118                        COMP_Denormal : 0);
 119         }
 120
 121         if ((st0_tag == TW_Denormal) || (tagb == TW_Denormal)) {
 122                 FPU_to_exp16(st0_ptr, &x);
 123                 FPU_to_exp16(b, &y);
 124                 st0_ptr = &x;
 125                 b = &y;
 126                 exp0 = exponent16(st0_ptr);
 127                 expb = exponent16(b);
 128         } else {
 129                 exp0 = exponent(st0_ptr);
 130                 expb = exponent(b);
 131         }
 132
 133 #ifdef PARANOID
 134         if (!(st0_ptr->sigh & 0x80000000))
 135                 EXCEPTION(EX_Invalid);
 136         if (!(b->sigh & 0x80000000))
 137                 EXCEPTION(EX_Invalid);
 138 #endif /* PARANOID */
 139
 140         diff = exp0 - expb;
 141         if (diff == 0) {
 142                 diff = st0_ptr->sigh - b->sigh; /* Works only if ms bits are
 143                                                    identical */
 144                 if (diff == 0) {
 145                         diff = st0_ptr->sigl > b->sigl;
 146                         if (diff == 0)
 147                                 diff = -(st0_ptr->sigl < b->sigl);
 148                 }
 149         }
 150
 151         if (diff > 0) {
 152                 return ((st0_sign == SIGN_POS) ? COMP_A_gt_B : COMP_A_lt_B)
 153                     | (((st0_tag == TW_Denormal) || (tagb == TW_Denormal)) ?
 154                        COMP_Denormal : 0);
 155         }
 156         if (diff < 0) {
 157                 return ((st0_sign == SIGN_POS) ? COMP_A_lt_B : COMP_A_gt_B)
 158                     | (((st0_tag == TW_Denormal) || (tagb == TW_Denormal)) ?
 159                        COMP_Denormal : 0);
 160         }
 161
 162         return COMP_A_eq_B
 163             | (((st0_tag == TW_Denormal) || (tagb == TW_Denormal)) ?
 164                COMP_Denormal : 0);
 165
 166 }
 167
 168 /* This function requires that st(0) is not empty */
 169 int FPU_compare_st_data(FPU_REG const *loaded_data, u_char loaded_tag)
 170 {
 171         int f, c;
 172
 173         c = compare(loaded_data, loaded_tag);
 174
 175         if (c & COMP_NaN) {
 176                 EXCEPTION(EX_Invalid);
 177                 f = SW_C3 | SW_C2 | SW_C0;
 178         } else
 179                 switch (c & 7) {
 180                 case COMP_A_lt_B:
 181                         f = SW_C0;
 182                         break;
 183                 case COMP_A_eq_B:
 184                         f = SW_C3;
 185                         break;
 186                 case COMP_A_gt_B:
 187                         f = 0;
 188                         break;
 189                 case COMP_No_Comp:
 190                         f = SW_C3 | SW_C2 | SW_C0;
 191                         break;
 192                 default:
 193 #ifdef PARANOID
 194                         EXCEPTION(EX_INTERNAL | 0x121);
 195 #endif /* PARANOID */
 196                         f = SW_C3 | SW_C2 | SW_C0;
 197                         break;
 198                 }
 199         setcc(f);
 200         if (c & COMP_Denormal) {
 201                 return denormal_operand() < 0;
 202         }
 203         return 0;
 204 }
 205
 206 static int compare_st_st(int nr)
 207 {
 208         int f, c;
 209         FPU_REG *st_ptr;
 210
 211         if (!NOT_EMPTY(0) || !NOT_EMPTY(nr)) {
 212                 setcc(SW_C3 | SW_C2 | SW_C0);
 213                 /* Stack fault */
 214                 EXCEPTION(EX_StackUnder);
 215                 return !(control_word & CW_Invalid);
 216         }
 217
 218         st_ptr = &st(nr);
 219         c = compare(st_ptr, FPU_gettagi(nr));
 220         if (c & COMP_NaN) {
 221                 setcc(SW_C3 | SW_C2 | SW_C0);
 222                 EXCEPTION(EX_Invalid);
 223                 return !(control_word & CW_Invalid);
 224         } else
 225                 switch (c & 7) {
 226                 case COMP_A_lt_B:
 227                         f = SW_C0;
 228                         break;
 229                 case COMP_A_eq_B:
 230                         f = SW_C3;
 231                         break;
 232                 case COMP_A_gt_B:
 233                         f = 0;
 234                         break;
 235                 case COMP_No_Comp:
 236                         f = SW_C3 | SW_C2 | SW_C0;
 237                         break;
 238                 default:
 239 #ifdef PARANOID
 240                         EXCEPTION(EX_INTERNAL | 0x122);
 241 #endif /* PARANOID */
 242                         f = SW_C3 | SW_C2 | SW_C0;
 243                         break;
 244                 }
 245         setcc(f);
 246         if (c & COMP_Denormal) {
 247                 return denormal_operand() < 0;
 248         }
 249         return 0;
 250 }
 251
 252 static int compare_i_st_st(int nr)
 253 {
 254         int f, c;
 255         FPU_REG *st_ptr;
 256
 257         if (!NOT_EMPTY(0) || !NOT_EMPTY(nr)) {
 258                 FPU_EFLAGS |= (X86_EFLAGS_ZF | X86_EFLAGS_PF | X86_EFLAGS_CF);
 259                 /* Stack fault */
 260                 EXCEPTION(EX_StackUnder);
 261                 return !(control_word & CW_Invalid);
 262         }
 263
 264         partial_status &= ~SW_C0;
 265         st_ptr = &st(nr);
 266         c = compare(st_ptr, FPU_gettagi(nr));
 267         if (c & COMP_NaN) {
 268                 FPU_EFLAGS |= (X86_EFLAGS_ZF | X86_EFLAGS_PF | X86_EFLAGS_CF);
 269                 EXCEPTION(EX_Invalid);
 270                 return !(control_word & CW_Invalid);
 271         }
 272
 273         switch (c & 7) {
 274         case COMP_A_lt_B:
 275                 f = X86_EFLAGS_CF;
 276                 break;
 277         case COMP_A_eq_B:
 278                 f = X86_EFLAGS_ZF;
 279                 break;
 280         case COMP_A_gt_B:
 281                 f = 0;
 282                 break;
 283         case COMP_No_Comp:
 284                 f = X86_EFLAGS_ZF | X86_EFLAGS_PF | X86_EFLAGS_CF;
 285                 break;
 286         default:
 287 #ifdef PARANOID
 288                 EXCEPTION(EX_INTERNAL | 0x122);
 289 #endif /* PARANOID */
 290                 f = 0;
 291                 break;
 292         }
 293         FPU_EFLAGS = (FPU_EFLAGS & ~(X86_EFLAGS_ZF | X86_EFLAGS_PF | X86_EFLAGS_CF)) | f;
 294         if (c & COMP_Denormal) {
 295                 return denormal_operand() < 0;
 296         }
 297         return 0;
 298 }
 299
 300 static int compare_u_st_st(int nr)
 301 {
 302         int f = 0, c;
 303         FPU_REG *st_ptr;
 304
 305         if (!NOT_EMPTY(0) || !NOT_EMPTY(nr)) {
 306                 setcc(SW_C3 | SW_C2 | SW_C0);
 307                 /* Stack fault */
 308                 EXCEPTION(EX_StackUnder);
 309                 return !(control_word & CW_Invalid);
 310         }
 311
 312         st_ptr = &st(nr);
 313         c = compare(st_ptr, FPU_gettagi(nr));
 314         if (c & COMP_NaN) {
 315                 setcc(SW_C3 | SW_C2 | SW_C0);
 316                 if (c & COMP_SNaN) {    /* This is the only difference between
 317                                            un-ordered and ordinary comparisons */
 318                         EXCEPTION(EX_Invalid);
 319                         return !(control_word & CW_Invalid);
 320                 }
 321                 return 0;
 322         } else
 323                 switch (c & 7) {
 324                 case COMP_A_lt_B:
 325                         f = SW_C0;
 326                         break;
 327                 case COMP_A_eq_B:
 328                         f = SW_C3;
 329                         break;
 330                 case COMP_A_gt_B:
 331                         f = 0;
 332                         break;
 333                 case COMP_No_Comp:
 334                         f = SW_C3 | SW_C2 | SW_C0;
 335                         break;
 336 #ifdef PARANOID
 337                 default:
 338                         EXCEPTION(EX_INTERNAL | 0x123);
 339                         f = SW_C3 | SW_C2 | SW_C0;
 340                         break;
 341 #endif /* PARANOID */
 342                 }
 343         setcc(f);
 344         if (c & COMP_Denormal) {
 345                 return denormal_operand() < 0;
 346         }
 347         return 0;
 348 }
 349
 350 static int compare_ui_st_st(int nr)
 351 {
 352         int f = 0, c;
 353         FPU_REG *st_ptr;
 354
 355         if (!NOT_EMPTY(0) || !NOT_EMPTY(nr)) {
 356                 FPU_EFLAGS |= (X86_EFLAGS_ZF | X86_EFLAGS_PF | X86_EFLAGS_CF);
 357                 /* Stack fault */
 358                 EXCEPTION(EX_StackUnder);
 359                 return !(control_word & CW_Invalid);
 360         }
 361
 362         partial_status &= ~SW_C0;
 363         st_ptr = &st(nr);
 364         c = compare(st_ptr, FPU_gettagi(nr));
 365         if (c & COMP_NaN) {
 366                 FPU_EFLAGS |= (X86_EFLAGS_ZF | X86_EFLAGS_PF | X86_EFLAGS_CF);
 367                 if (c & COMP_SNaN) {    /* This is the only difference between
 368                                            un-ordered and ordinary comparisons */
 369                         EXCEPTION(EX_Invalid);
 370                         return !(control_word & CW_Invalid);
 371                 }
 372                 return 0;
 373         }
 374
 375         switch (c & 7) {
 376         case COMP_A_lt_B:
 377                 f = X86_EFLAGS_CF;
 378                 break;
 379         case COMP_A_eq_B:
 380                 f = X86_EFLAGS_ZF;
 381                 break;
 382         case COMP_A_gt_B:
 383                 f = 0;
 384                 break;
 385         case COMP_No_Comp:
 386                 f = X86_EFLAGS_ZF | X86_EFLAGS_PF | X86_EFLAGS_CF;
 387                 break;
 388 #ifdef PARANOID
 389         default:
 390                 EXCEPTION(EX_INTERNAL | 0x123);
 391                 f = 0;
 392                 break;
 393 #endif /* PARANOID */
 394         }
 395         FPU_EFLAGS = (FPU_EFLAGS & ~(X86_EFLAGS_ZF | X86_EFLAGS_PF | X86_EFLAGS_CF)) | f;
 396         if (c & COMP_Denormal) {
 397                 return denormal_operand() < 0;
 398         }
 399         return 0;
 400 }
 401
 402 /*---------------------------------------------------------------------------*/
 403
 404 void fcom_st(void)
 405 {
 406         /* fcom st(i) */
 407         compare_st_st(FPU_rm);
 408 }
 409
 410 void fcompst(void)
 411 {
 412         /* fcomp st(i) */
 413         if (!compare_st_st(FPU_rm))
 414                 FPU_pop();
 415 }
 416
 417 void fcompp(void)
 418 {
 419         /* fcompp */
 420         if (FPU_rm != 1) {
 421                 FPU_illegal();
 422                 return;
 423         }
 424         if (!compare_st_st(1))
 425                 poppop();
 426 }
 427
 428 void fucom_(void)
 429 {
 430         /* fucom st(i) */
 431         compare_u_st_st(FPU_rm);
 432
 433 }
 434
 435 void fucomp(void)
 436 {
 437         /* fucomp st(i) */
 438         if (!compare_u_st_st(FPU_rm))
 439                 FPU_pop();
 440 }
 441
 442 void fucompp(void)
 443 {
 444         /* fucompp */
 445         if (FPU_rm == 1) {
 446                 if (!compare_u_st_st(1))
 447                         poppop();
 448         } else
 449                 FPU_illegal();
 450 }
 451
 452 /* P6+ compare-to-EFLAGS ops */
 453
 454 void fcomi_(void)
 455 {
 456         /* fcomi st(i) */
 457         compare_i_st_st(FPU_rm);
 458 }
 459
 460 void fcomip(void)
 461 {
 462         /* fcomip st(i) */
 463         if (!compare_i_st_st(FPU_rm))
 464                 FPU_pop();
 465 }
 466
 467 void fucomi_(void)
 468 {
 469         /* fucomi st(i) */
 470         compare_ui_st_st(FPU_rm);
 471 }
 472
 473 void fucomip(void)
 474 {
 475         /* fucomip st(i) */
 476         if (!compare_ui_st_st(FPU_rm))
 477                 FPU_pop();
 478 }