drivers/FPU-emu/errors.c

/* */
This source file includes following definitions.
Un_impl
emu_printall
exception
real_2op_NaN
arith_invalid
divide_by_zero
set_precision_flag
set_precision_flag_up
set_precision_flag_down
denormal_operand
arith_overflow
arith_underflow
stack_overflow
stack_underflow
stack_underflow_i
stack_underflow_pop
   1 /*---------------------------------------------------------------------------+
   2  |  errors.c                                                                 |
   3  |                                                                           |
   4  |  The error handling functions for wm-FPU-emu                              |
   5  |                                                                           |
   6  | Copyright (C) 1992,1993,1994                                              |
   7  |                       W. Metzenthen, 22 Parker St, Ormond, Vic 3163,      |
   8  |                       Australia.  E-mail   billm@vaxc.cc.monash.edu.au    |
   9  |                                                                           |
  10  |                                                                           |
  11  +---------------------------------------------------------------------------*/
  12 
  13 /*---------------------------------------------------------------------------+
  14  | Note:                                                                     |
  15  |    The file contains code which accesses user memory.                     |
  16  |    Emulator static data may change when user memory is accessed, due to   |
  17  |    other processes using the emulator while swapping is in progress.      |
  18  +---------------------------------------------------------------------------*/
  19 
  20 #include <linux/signal.h>
  21 
  22 #include <asm/segment.h>
  23 
  24 #include "fpu_system.h"
  25 #include "exception.h"
  26 #include "fpu_emu.h"
  27 #include "status_w.h"
  28 #include "control_w.h"
  29 #include "reg_constant.h"
  30 #include "version.h"
  31 
  32 /* */
  33 #undef PRINT_MESSAGES
  34 /* */
  35 
  36 
  37 void Un_impl(void)
     /*  */
  38 {
  39   unsigned char byte1, FPU_modrm;
  40 
  41   RE_ENTRANT_CHECK_OFF;
  42   /* No need to verify_area(), we have previously fetched these bytes. */
  43   byte1 = get_fs_byte((unsigned char *) FPU_ORIG_EIP);
  44   FPU_modrm = get_fs_byte(1 + (unsigned char *) FPU_ORIG_EIP);
  45 
  46   printk("Unimplemented FPU Opcode at eip=%p : %02x ",
  47          (void *) FPU_ORIG_EIP, byte1);
  48 
  49   if (FPU_modrm >= 0300)
  50     printk("%02x (%02x+%d)\n", FPU_modrm, FPU_modrm & 0xf8, FPU_modrm & 7);
  51   else
  52     printk("/%d\n", (FPU_modrm >> 3) & 7);
  53   RE_ENTRANT_CHECK_ON;
  54 
  55   EXCEPTION(EX_Invalid);
  56 
  57 }
  58 
  59 
  60 
  61 
  62 void emu_printall()
     /*  */
  63 {
  64   int i;
  65   static char *tag_desc[] = { "Valid", "Zero", "ERROR", "ERROR",
  66                               "DeNorm", "Inf", "NaN", "Empty" };
  67   unsigned char byte1, FPU_modrm;
  68 
  69   RE_ENTRANT_CHECK_OFF;
  70   /* No need to verify_area(), we have previously fetched these bytes. */
  71   byte1 = get_fs_byte((unsigned char *) FPU_ORIG_EIP);
  72   FPU_modrm = get_fs_byte(1 + (unsigned char *) FPU_ORIG_EIP);
  73   partial_status = status_word();
  74 
  75 #ifdef DEBUGGING
  76 if ( partial_status & SW_Backward )    printk("SW: backward compatibility\n");
  77 if ( partial_status & SW_C3 )          printk("SW: condition bit 3\n");
  78 if ( partial_status & SW_C2 )          printk("SW: condition bit 2\n");
  79 if ( partial_status & SW_C1 )          printk("SW: condition bit 1\n");
  80 if ( partial_status & SW_C0 )          printk("SW: condition bit 0\n");
  81 if ( partial_status & SW_Summary )     printk("SW: exception summary\n");
  82 if ( partial_status & SW_Stack_Fault ) printk("SW: stack fault\n");
  83 if ( partial_status & SW_Precision )   printk("SW: loss of precision\n");
  84 if ( partial_status & SW_Underflow )   printk("SW: underflow\n");
  85 if ( partial_status & SW_Overflow )    printk("SW: overflow\n");
  86 if ( partial_status & SW_Zero_Div )    printk("SW: divide by zero\n");
  87 if ( partial_status & SW_Denorm_Op )   printk("SW: denormalized operand\n");
  88 if ( partial_status & SW_Invalid )     printk("SW: invalid operation\n");
  89 #endif DEBUGGING
  90 
  91   printk("At %p: %02x ", (void *) FPU_ORIG_EIP, byte1);
  92   if (FPU_modrm >= 0300)
  93     printk("%02x (%02x+%d)\n", FPU_modrm, FPU_modrm & 0xf8, FPU_modrm & 7);
  94   else
  95     printk("/%d, mod=%d rm=%d\n",
  96            (FPU_modrm >> 3) & 7, (FPU_modrm >> 6) & 3, FPU_modrm & 7);
  97 
  98   printk(" SW: b=%d st=%ld es=%d sf=%d cc=%d%d%d%d ef=%d%d%d%d%d%d\n",
  99          partial_status & 0x8000 ? 1 : 0,   /* busy */
 100          (partial_status & 0x3800) >> 11,   /* stack top pointer */
 101          partial_status & 0x80 ? 1 : 0,     /* Error summary status */
 102          partial_status & 0x40 ? 1 : 0,     /* Stack flag */
 103          partial_status & SW_C3?1:0, partial_status & SW_C2?1:0, /* cc */
 104          partial_status & SW_C1?1:0, partial_status & SW_C0?1:0, /* cc */
 105          partial_status & SW_Precision?1:0, partial_status & SW_Underflow?1:0,
 106          partial_status & SW_Overflow?1:0, partial_status & SW_Zero_Div?1:0,
 107          partial_status & SW_Denorm_Op?1:0, partial_status & SW_Invalid?1:0);
 108   
 109 printk(" CW: ic=%d rc=%ld%ld pc=%ld%ld iem=%d     ef=%d%d%d%d%d%d\n",
 110          control_word & 0x1000 ? 1 : 0,
 111          (control_word & 0x800) >> 11, (control_word & 0x400) >> 10,
 112          (control_word & 0x200) >> 9, (control_word & 0x100) >> 8,
 113          control_word & 0x80 ? 1 : 0,
 114          control_word & SW_Precision?1:0, control_word & SW_Underflow?1:0,
 115          control_word & SW_Overflow?1:0, control_word & SW_Zero_Div?1:0,
 116          control_word & SW_Denorm_Op?1:0, control_word & SW_Invalid?1:0);
 117 
 118   for ( i = 0; i < 8; i++ )
 119     {
 120       FPU_REG *r = &st(i);
 121       switch (r->tag)
 122         {
 123         case TW_Empty:
 124           continue;
 125           break;
 126         case TW_Zero:
 127 #if 0
 128           printk("st(%d)  %c .0000 0000 0000 0000         ",
 129                  i, r->sign ? '-' : '+');
 130           break;
 131 #endif
 132         case TW_Valid:
 133         case TW_NaN:
 134 /*      case TW_Denormal: */
 135         case TW_Infinity:
 136           printk("st(%d)  %c .%04lx %04lx %04lx %04lx e%+-6ld ", i,
 137                  r->sign ? '-' : '+',
 138                  (long)(r->sigh >> 16),
 139                  (long)(r->sigh & 0xFFFF),
 140                  (long)(r->sigl >> 16),
 141                  (long)(r->sigl & 0xFFFF),
 142                  r->exp - EXP_BIAS + 1);
 143           break;
 144         default:
 145           printk("Whoops! Error in errors.c      ");
 146           break;
 147         }
 148       printk("%s\n", tag_desc[(int) (unsigned) r->tag]);
 149     }
 150 
 151   printk("[data] %c .%04lx %04lx %04lx %04lx e%+-6ld ",
 152          FPU_loaded_data.sign ? '-' : '+',
 153          (long)(FPU_loaded_data.sigh >> 16),
 154          (long)(FPU_loaded_data.sigh & 0xFFFF),
 155          (long)(FPU_loaded_data.sigl >> 16),
 156          (long)(FPU_loaded_data.sigl & 0xFFFF),
 157          FPU_loaded_data.exp - EXP_BIAS + 1);
 158   printk("%s\n", tag_desc[(int) (unsigned) FPU_loaded_data.tag]);
 159   RE_ENTRANT_CHECK_ON;
 160 
 161 }
 162 
 163 static struct {
 164   int type;
 165   char *name;
 166 } exception_names[] = {
 167   { EX_StackOver, "stack overflow" },
 168   { EX_StackUnder, "stack underflow" },
 169   { EX_Precision, "loss of precision" },
 170   { EX_Underflow, "underflow" },
 171   { EX_Overflow, "overflow" },
 172   { EX_ZeroDiv, "divide by zero" },
 173   { EX_Denormal, "denormalized operand" },
 174   { EX_Invalid, "invalid operation" },
 175   { EX_INTERNAL, "INTERNAL BUG in "FPU_VERSION },
 176   { 0, NULL }
 177 };
 178 
 179 /*
 180  EX_INTERNAL is always given with a code which indicates where the
 181  error was detected.
 182 
 183  Internal error types:
 184        0      in load_store.c
 185        0x14   in fpu_etc.c
 186        0x1nn  in a *.c file:
 187               0x101  in reg_add_sub.c
 188               0x102  in reg_mul.c
 189               0x103  in poly_sin.c
 190               0x104  in poly_atan.c
 191               0x105  in reg_mul.c
 192               0x106  in reg_ld_str.c
 193               0x107  in fpu_trig.c
 194               0x108  in reg_compare.c
 195               0x109  in reg_compare.c
 196               0x110  in reg_add_sub.c
 197               0x111  in fpe_entry.c
 198               0x112  in fpu_trig.c
 199               0x113  in errors.c
 200               0x114  in reg_ld_str.c
 201               0x115  in fpu_trig.c
 202               0x116  in fpu_trig.c
 203               0x117  in fpu_trig.c
 204               0x118  in fpu_trig.c
 205               0x119  in fpu_trig.c
 206               0x120  in poly_atan.c
 207               0x121  in reg_compare.c
 208               0x122  in reg_compare.c
 209               0x123  in reg_compare.c
 210               0x125  in fpu_trig.c
 211               0x126  in fpu_entry.c
 212               0x127  in poly_2xm1.c
 213        0x2nn  in an *.S file:
 214               0x201  in reg_u_add.S, reg_round.S
 215               0x202  in reg_u_div.S
 216               0x203  in reg_u_div.S
 217               0x204  in reg_u_div.S
 218               0x205  in reg_u_mul.S
 219               0x206  in reg_u_sub.S
 220               0x207  in wm_sqrt.S
 221               0x208  in reg_div.S
 222               0x209  in reg_u_sub.S
 223               0x210  in reg_u_sub.S
 224               0x211  in reg_u_sub.S
 225               0x212  in reg_u_sub.S
 226               0x213  in wm_sqrt.S
 227               0x214  in wm_sqrt.S
 228               0x215  in wm_sqrt.S
 229               0x216  in reg_round.S
 230               0x217  in reg_round.S
 231               0x218  in reg_round.S
 232               0x220  in reg_norm.S
 233               0x221  in reg_norm.S
 234  */
 235 
 236 void exception(int n)
     /*  */
 237 {
 238   int i, int_type;
 239 
 240   int_type = 0;         /* Needed only to stop compiler warnings */
 241   if ( n & EX_INTERNAL )
 242     {
 243       int_type = n - EX_INTERNAL;
 244       n = EX_INTERNAL;
 245       /* Set lots of exception bits! */
 246       partial_status |= (SW_Exc_Mask | SW_Summary | SW_Backward);
 247     }
 248   else
 249     {
 250       /* Extract only the bits which we use to set the status word */
 251       n &= (SW_Exc_Mask);
 252       /* Set the corresponding exception bit */
 253       partial_status |= n;
 254       /* Set summary bits iff exception isn't masked */
 255       if ( partial_status & ~control_word & CW_Exceptions )
 256         partial_status |= (SW_Summary | SW_Backward);
 257       if ( n & (SW_Stack_Fault | EX_Precision) )
 258         {
 259           if ( !(n & SW_C1) )
 260             /* This bit distinguishes over- from underflow for a stack fault,
 261                and roundup from round-down for precision loss. */
 262             partial_status &= ~SW_C1;
 263         }
 264     }
 265 
 266   RE_ENTRANT_CHECK_OFF;
 267   if ( (~control_word & n & CW_Exceptions) || (n == EX_INTERNAL) )
 268     {
 269 #ifdef PRINT_MESSAGES
 270       /* My message from the sponsor */
 271       printk(FPU_VERSION" "__DATE__" (C) W. Metzenthen.\n");
 272 #endif PRINT_MESSAGES
 273       
 274       /* Get a name string for error reporting */
 275       for (i=0; exception_names[i].type; i++)
 276         if ( (exception_names[i].type & n) == exception_names[i].type )
 277           break;
 278       
 279       if (exception_names[i].type)
 280         {
 281 #ifdef PRINT_MESSAGES
 282           printk("FP Exception: %s!\n", exception_names[i].name);
 283 #endif PRINT_MESSAGES
 284         }
 285       else
 286         printk("FP emulator: Unknown Exception: 0x%04x!\n", n);
 287       
 288       if ( n == EX_INTERNAL )
 289         {
 290           printk("FP emulator: Internal error type 0x%04x\n", int_type);
 291           emu_printall();
 292         }
 293 #ifdef PRINT_MESSAGES
 294       else
 295         emu_printall();
 296 #endif PRINT_MESSAGES
 297 
 298       /*
 299        * The 80486 generates an interrupt on the next non-control FPU
 300        * instruction. So we need some means of flagging it.
 301        * We use the ES (Error Summary) bit for this, assuming that
 302        * this is the way a real FPU does it (until I can check it out),
 303        * if not, then some method such as the following kludge might
 304        * be needed.
 305        */
 306 /*      regs[0].tag |= TW_FPU_Interrupt; */
 307     }
 308   RE_ENTRANT_CHECK_ON;
 309 
 310 #ifdef __DEBUG__
 311   math_abort(FPU_info,SIGFPE);
 312 #endif __DEBUG__
 313 
 314 }
 315 
 316 
 317 /* Real operation attempted on two operands, one a NaN. */
 318 /* Returns nz if the exception is unmasked */
 319 asmlinkage int real_2op_NaN(FPU_REG const *a, FPU_REG const *b, FPU_REG *dest)
     /*  */
 320 {
 321   FPU_REG const *x;
 322   int signalling;
 323 
 324   /* The default result for the case of two "equal" NaNs (signs may
 325      differ) is chosen to reproduce 80486 behaviour */
 326   x = a;
 327   if (a->tag == TW_NaN)
 328     {
 329       if (b->tag == TW_NaN)
 330         {
 331           signalling = !(a->sigh & b->sigh & 0x40000000);
 332           /* find the "larger" */
 333           if ( significand(a) < significand(b) )
 334             x = b;
 335         }
 336       else
 337         {
 338           /* return the quiet version of the NaN in a */
 339           signalling = !(a->sigh & 0x40000000);
 340         }
 341     }
 342   else
 343 #ifdef PARANOID
 344     if (b->tag == TW_NaN)
 345 #endif PARANOID
 346     {
 347       signalling = !(b->sigh & 0x40000000);
 348       x = b;
 349     }
 350 #ifdef PARANOID
 351   else
 352     {
 353       signalling = 0;
 354       EXCEPTION(EX_INTERNAL|0x113);
 355       x = &CONST_QNaN;
 356     }
 357 #endif PARANOID
 358 
 359   if ( !signalling )
 360     {
 361       if ( !(x->sigh & 0x80000000) )  /* pseudo-NaN ? */
 362         x = &CONST_QNaN;
 363       reg_move(x, dest);
 364       return 0;
 365     }
 366 
 367   if ( control_word & CW_Invalid )
 368     {
 369       /* The masked response */
 370       if ( !(x->sigh & 0x80000000) )  /* pseudo-NaN ? */
 371         x = &CONST_QNaN;
 372       reg_move(x, dest);
 373       /* ensure a Quiet NaN */
 374       dest->sigh |= 0x40000000;
 375     }
 376 
 377   EXCEPTION(EX_Invalid);
 378   
 379   return !(control_word & CW_Invalid);
 380 }
 381 
 382 
 383 /* Invalid arith operation on Valid registers */
 384 /* Returns nz if the exception is unmasked */
 385 asmlinkage int arith_invalid(FPU_REG *dest)
     /*  */
 386 {
 387 
 388   EXCEPTION(EX_Invalid);
 389   
 390   if ( control_word & CW_Invalid )
 391     {
 392       /* The masked response */
 393       reg_move(&CONST_QNaN, dest);
 394     }
 395   
 396   return !(control_word & CW_Invalid);
 397 
 398 }
 399 
 400 
 401 /* Divide a finite number by zero */
 402 asmlinkage int divide_by_zero(int sign, FPU_REG *dest)
     /*  */
 403 {
 404 
 405   if ( control_word & CW_ZeroDiv )
 406     {
 407       /* The masked response */
 408       reg_move(&CONST_INF, dest);
 409       dest->sign = (unsigned char)sign;
 410     }
 411  
 412   EXCEPTION(EX_ZeroDiv);
 413 
 414   return !(control_word & CW_ZeroDiv);
 415 
 416 }
 417 
 418 
 419 /* This may be called often, so keep it lean */
 420 int set_precision_flag(int flags)
     /*  */
 421 {
 422   if ( control_word & CW_Precision )
 423     {
 424       partial_status &= ~(SW_C1 & flags);
 425       partial_status |= flags;   /* The masked response */
 426       return 0;
 427     }
 428   else
 429     {
 430       exception(flags);
 431       return 1;
 432     }
 433 }
 434 
 435 
 436 /* This may be called often, so keep it lean */
 437 asmlinkage void set_precision_flag_up(void)
     /*  */
 438 {
 439   if ( control_word & CW_Precision )
 440     partial_status |= (SW_Precision | SW_C1);   /* The masked response */
 441   else
 442     exception(EX_Precision | SW_C1);
 443 
 444 }
 445 
 446 
 447 /* This may be called often, so keep it lean */
 448 asmlinkage void set_precision_flag_down(void)
     /*  */
 449 {
 450   if ( control_word & CW_Precision )
 451     {   /* The masked response */
 452       partial_status &= ~SW_C1;
 453       partial_status |= SW_Precision;
 454     }
 455   else
 456     exception(EX_Precision);
 457 }
 458 
 459 
 460 asmlinkage int denormal_operand(void)
     /*  */
 461 {
 462   if ( control_word & CW_Denormal )
 463     {   /* The masked response */
 464       partial_status |= SW_Denorm_Op;
 465       return 0;
 466     }
 467   else
 468     {
 469       exception(EX_Denormal);
 470       return 1;
 471     }
 472 }
 473 
 474 
 475 asmlinkage int arith_overflow(FPU_REG *dest)
     /*  */
 476 {
 477 
 478   if ( control_word & CW_Overflow )
 479     {
 480       char sign;
 481       /* The masked response */
 482 /* ###### The response here depends upon the rounding mode */
 483       sign = dest->sign;
 484       reg_move(&CONST_INF, dest);
 485       dest->sign = sign;
 486     }
 487   else
 488     {
 489       /* Subtract the magic number from the exponent */
 490       dest->exp -= (3 * (1 << 13));
 491     }
 492 
 493   EXCEPTION(EX_Overflow);
 494   if ( control_word & CW_Overflow )
 495     {
 496       /* The overflow exception is masked. */
 497       /* By definition, precision is lost.
 498          The roundup bit (C1) is also set because we have
 499          "rounded" upwards to Infinity. */
 500       EXCEPTION(EX_Precision | SW_C1);
 501       return !(control_word & CW_Precision);
 502     }
 503 
 504   return !(control_word & CW_Overflow);
 505 
 506 }
 507 
 508 
 509 asmlinkage int arith_underflow(FPU_REG *dest)
     /*  */
 510 {
 511 
 512   if ( control_word & CW_Underflow )
 513     {
 514       /* The masked response */
 515       if ( dest->exp <= EXP_UNDER - 63 )
 516         {
 517           reg_move(&CONST_Z, dest);
 518           partial_status &= ~SW_C1;       /* Round down. */
 519         }
 520     }
 521   else
 522     {
 523       /* Add the magic number to the exponent. */
 524       dest->exp += (3 * (1 << 13));
 525     }
 526 
 527   EXCEPTION(EX_Underflow);
 528   if ( control_word & CW_Underflow )
 529     {
 530       /* The underflow exception is masked. */
 531       EXCEPTION(EX_Precision);
 532       return !(control_word & CW_Precision);
 533     }
 534 
 535   return !(control_word & CW_Underflow);
 536 
 537 }
 538 
 539 
 540 void stack_overflow(void)
     /*  */
 541 {
 542 
 543  if ( control_word & CW_Invalid )
 544     {
 545       /* The masked response */
 546       top--;
 547       reg_move(&CONST_QNaN, FPU_st0_ptr = &st(0));
 548     }
 549 
 550   EXCEPTION(EX_StackOver);
 551 
 552   return;
 553 
 554 }
 555 
 556 
 557 void stack_underflow(void)
     /*  */
 558 {
 559 
 560  if ( control_word & CW_Invalid )
 561     {
 562       /* The masked response */
 563       reg_move(&CONST_QNaN, FPU_st0_ptr);
 564     }
 565 
 566   EXCEPTION(EX_StackUnder);
 567 
 568   return;
 569 
 570 }
 571 
 572 
 573 void stack_underflow_i(int i)
     /*  */
 574 {
 575 
 576  if ( control_word & CW_Invalid )
 577     {
 578       /* The masked response */
 579       reg_move(&CONST_QNaN, &(st(i)));
 580     }
 581 
 582   EXCEPTION(EX_StackUnder);
 583 
 584   return;
 585 
 586 }
 587 
 588 
 589 void stack_underflow_pop(int i)
     /*  */
 590 {
 591 
 592  if ( control_word & CW_Invalid )
 593     {
 594       /* The masked response */
 595       reg_move(&CONST_QNaN, &(st(i)));
 596       pop();
 597     }
 598 
 599   EXCEPTION(EX_StackUnder);
 600 
 601   return;
 602 
 603 }
 604
/* */
root/drivers/FPU-emu/errors.c

DEFINITIONS
