contrib/gdb-6.2.1/gdb/i387-tdep.c

   1 /* Intel 387 floating point stuff.
   2
   3    Copyright 1988, 1989, 1991, 1992, 1993, 1994, 1998, 1999, 2000,
   4    2001, 2002, 2003, 2004 Free Software Foundation, Inc.
   5
   6    This file is part of GDB.
   7
   8    This program is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 2 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program; if not, write to the Free Software
  20    Foundation, Inc., 59 Temple Place - Suite 330,
  21    Boston, MA 02111-1307, USA.  */
  22
  23 #include "defs.h"
  24 #include "doublest.h"
  25 #include "floatformat.h"
  26 #include "frame.h"
  27 #include "gdbcore.h"
  28 #include "inferior.h"
  29 #include "language.h"
  30 #include "regcache.h"
  31 #include "value.h"
  32
  33 #include "gdb_assert.h"
  34 #include "gdb_string.h"
  35
  36 #include "i386-tdep.h"
  37 #include "i387-tdep.h"
  38
  39 /* Implement the `info float' layout based on the register definitions
  40    in `tm-i386.h'.  */
  41
  42 /* Print the floating point number specified by RAW.  */
  43
  44 static void
  45 print_i387_value (char *raw, struct ui_file *file)
  46 {
  47   DOUBLEST value;
  48
  49   /* Using extract_typed_floating here might affect the representation
  50      of certain numbers such as NaNs, even if GDB is running natively.
  51      This is fine since our caller already detects such special
  52      numbers and we print the hexadecimal representation anyway.  */
  53   value = extract_typed_floating (raw, builtin_type_i387_ext);
  54
  55   /* We try to print 19 digits.  The last digit may or may not contain
  56      garbage, but we'd better print one too many.  We need enough room
  57      to print the value, 1 position for the sign, 1 for the decimal
  58      point, 19 for the digits and 6 for the exponent adds up to 27.  */
  59 #ifdef PRINTF_HAS_LONG_DOUBLE
  60   fprintf_filtered (file, " %-+27.19Lg", (long double) value);
  61 #else
  62   fprintf_filtered (file, " %-+27.19g", (double) value);
  63 #endif
  64 }
  65
  66 /* Print the classification for the register contents RAW.  */
  67
  68 static void
  69 print_i387_ext (unsigned char *raw, struct ui_file *file)
  70 {
  71   int sign;
  72   int integer;
  73   unsigned int exponent;
  74   unsigned long fraction[2];
  75
  76   sign = raw[9] & 0x80;
  77   integer = raw[7] & 0x80;
  78   exponent = (((raw[9] & 0x7f) << 8) | raw[8]);
  79   fraction[0] = ((raw[3] << 24) | (raw[2] << 16) | (raw[1] << 8) | raw[0]);
  80   fraction[1] = (((raw[7] & 0x7f) << 24) | (raw[6] << 16)
  81                  | (raw[5] << 8) | raw[4]);
  82
  83   if (exponent == 0x7fff && integer)
  84     {
  85       if (fraction[0] == 0x00000000 && fraction[1] == 0x00000000)
  86         /* Infinity.  */
  87         fprintf_filtered (file, " %cInf", (sign ? '-' : '+'));
  88       else if (sign && fraction[0] == 0x00000000 && fraction[1] == 0x40000000)
  89         /* Real Indefinite (QNaN).  */
  90         fputs_unfiltered (" Real Indefinite (QNaN)", file);
  91       else if (fraction[1] & 0x40000000)
  92         /* QNaN.  */
  93         fputs_filtered (" QNaN", file);
  94       else
  95         /* SNaN.  */
  96         fputs_filtered (" SNaN", file);
  97     }
  98   else if (exponent < 0x7fff && exponent > 0x0000 && integer)
  99     /* Normal.  */
 100     print_i387_value (raw, file);
 101   else if (exponent == 0x0000)
 102     {
 103       /* Denormal or zero.  */
 104       print_i387_value (raw, file);
 105
 106       if (integer)
 107         /* Pseudo-denormal.  */
 108         fputs_filtered (" Pseudo-denormal", file);
 109       else if (fraction[0] || fraction[1])
 110         /* Denormal.  */
 111         fputs_filtered (" Denormal", file);
 112     }
 113   else
 114     /* Unsupported.  */
 115     fputs_filtered (" Unsupported", file);
 116 }
 117
 118 /* Print the status word STATUS.  */
 119
 120 static void
 121 print_i387_status_word (unsigned int status, struct ui_file *file)
 122 {
 123   fprintf_filtered (file, "Status Word:         %s",
 124                    local_hex_string_custom (status, "04"));
 125   fputs_filtered ("  ", file);
 126   fprintf_filtered (file, " %s", (status & 0x0001) ? "IE" : "  ");
 127   fprintf_filtered (file, " %s", (status & 0x0002) ? "DE" : "  ");
 128   fprintf_filtered (file, " %s", (status & 0x0004) ? "ZE" : "  ");
 129   fprintf_filtered (file, " %s", (status & 0x0008) ? "OE" : "  ");
 130   fprintf_filtered (file, " %s", (status & 0x0010) ? "UE" : "  ");
 131   fprintf_filtered (file, " %s", (status & 0x0020) ? "PE" : "  ");
 132   fputs_filtered ("  ", file);
 133   fprintf_filtered (file, " %s", (status & 0x0080) ? "ES" : "  ");
 134   fputs_filtered ("  ", file);
 135   fprintf_filtered (file, " %s", (status & 0x0040) ? "SF" : "  ");
 136   fputs_filtered ("  ", file);
 137   fprintf_filtered (file, " %s", (status & 0x0100) ? "C0" : "  ");
 138   fprintf_filtered (file, " %s", (status & 0x0200) ? "C1" : "  ");
 139   fprintf_filtered (file, " %s", (status & 0x0400) ? "C2" : "  ");
 140   fprintf_filtered (file, " %s", (status & 0x4000) ? "C3" : "  ");
 141
 142   fputs_filtered ("\n", file);
 143
 144   fprintf_filtered (file,
 145                     "                       TOP: %d\n", ((status >> 11) & 7));
 146 }
 147
 148 /* Print the control word CONTROL.  */
 149
 150 static void
 151 print_i387_control_word (unsigned int control, struct ui_file *file)
 152 {
 153   fprintf_filtered (file, "Control Word:        %s",
 154                    local_hex_string_custom (control, "04"));
 155   fputs_filtered ("  ", file);
 156   fprintf_filtered (file, " %s", (control & 0x0001) ? "IM" : "  ");
 157   fprintf_filtered (file, " %s", (control & 0x0002) ? "DM" : "  ");
 158   fprintf_filtered (file, " %s", (control & 0x0004) ? "ZM" : "  ");
 159   fprintf_filtered (file, " %s", (control & 0x0008) ? "OM" : "  ");
 160   fprintf_filtered (file, " %s", (control & 0x0010) ? "UM" : "  ");
 161   fprintf_filtered (file, " %s", (control & 0x0020) ? "PM" : "  ");
 162
 163   fputs_filtered ("\n", file);
 164
 165   fputs_filtered ("                       PC: ", file);
 166   switch ((control >> 8) & 3)
 167     {
 168     case 0:
 169       fputs_filtered ("Single Precision (24-bits)\n", file);
 170       break;
 171     case 1:
 172       fputs_filtered ("Reserved\n", file);
 173       break;
 174     case 2:
 175       fputs_filtered ("Double Precision (53-bits)\n", file);
 176       break;
 177     case 3:
 178       fputs_filtered ("Extended Precision (64-bits)\n", file);
 179       break;
 180     }
 181
 182   fputs_filtered ("                       RC: ", file);
 183   switch ((control >> 10) & 3)
 184     {
 185     case 0:
 186       fputs_filtered ("Round to nearest\n", file);
 187       break;
 188     case 1:
 189       fputs_filtered ("Round down\n", file);
 190       break;
 191     case 2:
 192       fputs_filtered ("Round up\n", file);
 193       break;
 194     case 3:
 195       fputs_filtered ("Round toward zero\n", file);
 196       break;
 197     }
 198 }
 199
 200 /* Print out the i387 floating point state.  Note that we ignore FRAME
 201    in the code below.  That's OK since floating-point registers are
 202    never saved on the stack.  */
 203
 204 void
 205 i387_print_float_info (struct gdbarch *gdbarch, struct ui_file *file,
 206                        struct frame_info *frame, const char *args)
 207 {
 208   struct gdbarch_tdep *tdep = gdbarch_tdep (get_frame_arch (frame));
 209   char buf[4];
 210   ULONGEST fctrl;
 211   ULONGEST fstat;
 212   ULONGEST ftag;
 213   ULONGEST fiseg;
 214   ULONGEST fioff;
 215   ULONGEST foseg;
 216   ULONGEST fooff;
 217   ULONGEST fop;
 218   int fpreg;
 219   int top;
 220
 221   gdb_assert (gdbarch == get_frame_arch (frame));
 222
 223   /* Define I387_ST0_REGNUM such that we use the proper definitions
 224      for FRAME's architecture.  */
 225 #define I387_ST0_REGNUM tdep->st0_regnum
 226
 227   fctrl = get_frame_register_unsigned (frame, I387_FCTRL_REGNUM);
 228   fstat = get_frame_register_unsigned (frame, I387_FSTAT_REGNUM);
 229   ftag = get_frame_register_unsigned (frame, I387_FTAG_REGNUM);
 230   fiseg = get_frame_register_unsigned (frame, I387_FISEG_REGNUM);
 231   fioff = get_frame_register_unsigned (frame, I387_FIOFF_REGNUM);
 232   foseg = get_frame_register_unsigned (frame, I387_FOSEG_REGNUM);
 233   fooff = get_frame_register_unsigned (frame, I387_FOOFF_REGNUM);
 234   fop = get_frame_register_unsigned (frame, I387_FOP_REGNUM);
 235
 236   top = ((fstat >> 11) & 7);
 237
 238   for (fpreg = 7; fpreg >= 0; fpreg--)
 239     {
 240       unsigned char raw[I386_MAX_REGISTER_SIZE];
 241       int tag = (ftag >> (fpreg * 2)) & 3;
 242       int i;
 243
 244       fprintf_filtered (file, "%sR%d: ", fpreg == top ? "=>" : "  ", fpreg);
 245
 246       switch (tag)
 247         {
 248         case 0:
 249           fputs_filtered ("Valid   ", file);
 250           break;
 251         case 1:
 252           fputs_filtered ("Zero    ", file);
 253           break;
 254         case 2:
 255           fputs_filtered ("Special ", file);
 256           break;
 257         case 3:
 258           fputs_filtered ("Empty   ", file);
 259           break;
 260         }
 261
 262       get_frame_register (frame, (fpreg + 8 - top) % 8 + I387_ST0_REGNUM, raw);
 263
 264       fputs_filtered ("0x", file);
 265       for (i = 9; i >= 0; i--)
 266         fprintf_filtered (file, "%02x", raw[i]);
 267
 268       if (tag != 3)
 269         print_i387_ext (raw, file);
 270
 271       fputs_filtered ("\n", file);
 272     }
 273
 274   fputs_filtered ("\n", file);
 275
 276   print_i387_status_word (fstat, file);
 277   print_i387_control_word (fctrl, file);
 278   fprintf_filtered (file, "Tag Word:            %s\n",
 279                     local_hex_string_custom (ftag, "04"));
 280   fprintf_filtered (file, "Instruction Pointer: %s:",
 281                     local_hex_string_custom (fiseg, "02"));
 282   fprintf_filtered (file, "%s\n", local_hex_string_custom (fioff, "08"));
 283   fprintf_filtered (file, "Operand Pointer:     %s:",
 284                     local_hex_string_custom (foseg, "02"));
 285   fprintf_filtered (file, "%s\n", local_hex_string_custom (fooff, "08"));
 286   fprintf_filtered (file, "Opcode:              %s\n",
 287                     local_hex_string_custom (fop ? (fop | 0xd800) : 0, "04"));
 288
 289 #undef I387_ST0_REGNUM
 290 }
 291 \f
 292
 293 /* Read a value of type TYPE from register REGNUM in frame FRAME, and
 294    return its contents in TO.  */
 295
 296 void
 297 i387_register_to_value (struct frame_info *frame, int regnum,
 298                         struct type *type, void *to)
 299 {
 300   char from[I386_MAX_REGISTER_SIZE];
 301
 302   gdb_assert (i386_fp_regnum_p (regnum));
 303
 304   /* We only support floating-point values.  */
 305   if (TYPE_CODE (type) != TYPE_CODE_FLT)
 306     {
 307       warning ("Cannot convert floating-point register value "
 308                "to non-floating-point type.");
 309       return;
 310     }
 311
 312   /* Convert to TYPE.  This should be a no-op if TYPE is equivalent to
 313      the extended floating-point format used by the FPU.  */
 314   get_frame_register (frame, regnum, from);
 315   convert_typed_floating (from, builtin_type_i387_ext, to, type);
 316 }
 317
 318 /* Write the contents FROM of a value of type TYPE into register
 319    REGNUM in frame FRAME.  */
 320
 321 void
 322 i387_value_to_register (struct frame_info *frame, int regnum,
 323                         struct type *type, const void *from)
 324 {
 325   char to[I386_MAX_REGISTER_SIZE];
 326
 327   gdb_assert (i386_fp_regnum_p (regnum));
 328
 329   /* We only support floating-point values.  */
 330   if (TYPE_CODE (type) != TYPE_CODE_FLT)
 331     {
 332       warning ("Cannot convert non-floating-point type "
 333                "to floating-point register value.");
 334       return;
 335     }
 336
 337   /* Convert from TYPE.  This should be a no-op if TYPE is equivalent
 338      to the extended floating-point format used by the FPU.  */
 339   convert_typed_floating (from, type, to, builtin_type_i387_ext);
 340   put_frame_register (frame, regnum, to);
 341 }
 342 \f
 343
 344 /* Handle FSAVE and FXSAVE formats.  */
 345
 346 /* FIXME: kettenis/20030927: The functions below should accept a
 347    `regcache' argument, but I don't want to change the function
 348    signature just yet.  There's some band-aid in the functions below
 349    in the form of the `regcache' local variables.  This will ease the
 350    transition later on.  */
 351
 352 /* At fsave_offset[REGNUM] you'll find the offset to the location in
 353    the data structure used by the "fsave" instruction where GDB
 354    register REGNUM is stored.  */
 355
 356 static int fsave_offset[] =
 357 {
 358   28 + 0 * 10,                  /* %st(0) ...  */
 359   28 + 1 * 10,
 360   28 + 2 * 10,
 361   28 + 3 * 10,
 362   28 + 4 * 10,
 363   28 + 5 * 10,
 364   28 + 6 * 10,
 365   28 + 7 * 10,                  /* ... %st(7).  */
 366   0,                            /* `fctrl' (16 bits).  */
 367   4,                            /* `fstat' (16 bits).  */
 368   8,                            /* `ftag' (16 bits).  */
 369   16,                           /* `fiseg' (16 bits).  */
 370   12,                           /* `fioff'.  */
 371   24,                           /* `foseg' (16 bits).  */
 372   20,                           /* `fooff'.  */
 373   18                            /* `fop' (bottom 11 bits).  */
 374 };
 375
 376 #define FSAVE_ADDR(fsave, regnum) \
 377   (fsave + fsave_offset[regnum - I387_ST0_REGNUM])
 378 \f
 379
 380 /* Fill register REGNUM in REGCACHE with the appropriate value from
 381    *FSAVE.  This function masks off any of the reserved bits in
 382    *FSAVE.  */
 383
 384 void
 385 i387_supply_fsave (struct regcache *regcache, int regnum, const void *fsave)
 386 {
 387   struct gdbarch_tdep *tdep = gdbarch_tdep (get_regcache_arch (regcache));
 388   const char *regs = fsave;
 389   int i;
 390
 391   gdb_assert (tdep->st0_regnum >= I386_ST0_REGNUM);
 392
 393   /* Define I387_ST0_REGNUM such that we use the proper definitions
 394      for REGCACHE's architecture.  */
 395 #define I387_ST0_REGNUM tdep->st0_regnum
 396
 397   for (i = I387_ST0_REGNUM; i < I387_XMM0_REGNUM; i++)
 398     if (regnum == -1 || regnum == i)
 399       {
 400         if (fsave == NULL)
 401           {
 402             regcache_raw_supply (regcache, i, NULL);
 403             continue;
 404           }
 405
 406         /* Most of the FPU control registers occupy only 16 bits in the
 407            fsave area.  Give those a special treatment.  */
 408         if (i >= I387_FCTRL_REGNUM
 409             && i != I387_FIOFF_REGNUM && i != I387_FOOFF_REGNUM)
 410           {
 411             unsigned char val[4];
 412
 413             memcpy (val, FSAVE_ADDR (regs, i), 2);
 414             val[2] = val[3] = 0;
 415             if (i == I387_FOP_REGNUM)
 416               val[1] &= ((1 << 3) - 1);
 417             regcache_raw_supply (regcache, i, val);
 418           }
 419         else
 420           regcache_raw_supply (regcache, i, FSAVE_ADDR (regs, i));
 421       }
 422 #undef I387_ST0_REGNUM
 423 }
 424
 425 /* Fill register REGNUM (if it is a floating-point register) in *FSAVE
 426    with the value from REGCACHE.  If REGNUM is -1, do this for all
 427    registers.  This function doesn't touch any of the reserved bits in
 428    *FSAVE.  */
 429
 430 void
 431 i387_collect_fsave (const struct regcache *regcache, int regnum, void *fsave)
 432 {
 433   struct gdbarch_tdep *tdep = gdbarch_tdep (current_gdbarch);
 434   char *regs = fsave;
 435   int i;
 436
 437   gdb_assert (tdep->st0_regnum >= I386_ST0_REGNUM);
 438
 439   /* Define I387_ST0_REGNUM such that we use the proper definitions
 440      for REGCACHE's architecture.  */
 441 #define I387_ST0_REGNUM tdep->st0_regnum
 442
 443   for (i = I387_ST0_REGNUM; i < I387_XMM0_REGNUM; i++)
 444     if (regnum == -1 || regnum == i)
 445       {
 446         /* Most of the FPU control registers occupy only 16 bits in
 447            the fsave area.  Give those a special treatment.  */
 448         if (i >= I387_FCTRL_REGNUM
 449             && i != I387_FIOFF_REGNUM && i != I387_FOOFF_REGNUM)
 450           {
 451             unsigned char buf[4];
 452
 453             regcache_raw_collect (regcache, i, buf);
 454
 455             if (i == I387_FOP_REGNUM)
 456               {
 457                 /* The opcode occupies only 11 bits.  Make sure we
 458                    don't touch the other bits.  */
 459                 buf[1] &= ((1 << 3) - 1);
 460                 buf[1] |= ((FSAVE_ADDR (regs, i))[1] & ~((1 << 3) - 1));
 461               }
 462             memcpy (FSAVE_ADDR (regs, i), buf, 2);
 463           }
 464         else
 465           regcache_raw_collect (regcache, i, FSAVE_ADDR (regs, i));
 466       }
 467 #undef I387_ST0_REGNUM
 468 }
 469
 470 /* Fill register REGNUM (if it is a floating-point register) in *FSAVE
 471    with the value in GDB's register cache.  If REGNUM is -1, do this
 472    for all registers.  This function doesn't touch any of the reserved
 473    bits in *FSAVE.  */
 474
 475 void
 476 i387_fill_fsave (void *fsave, int regnum)
 477 {
 478   i387_collect_fsave (current_regcache, regnum, fsave);
 479 }
 480 \f
 481
 482 /* At fxsave_offset[REGNUM] you'll find the offset to the location in
 483    the data structure used by the "fxsave" instruction where GDB
 484    register REGNUM is stored.  */
 485
 486 static int fxsave_offset[] =
 487 {
 488   32,                           /* %st(0) through ...  */
 489   48,
 490   64,
 491   80,
 492   96,
 493   112,
 494   128,
 495   144,                          /* ... %st(7) (80 bits each).  */
 496   0,                            /* `fctrl' (16 bits).  */
 497   2,                            /* `fstat' (16 bits).  */
 498   4,                            /* `ftag' (16 bits).  */
 499   12,                           /* `fiseg' (16 bits).  */
 500   8,                            /* `fioff'.  */
 501   20,                           /* `foseg' (16 bits).  */
 502   16,                           /* `fooff'.  */
 503   6,                            /* `fop' (bottom 11 bits).  */
 504   160 + 0 * 16,                 /* %xmm0 through ...  */
 505   160 + 1 * 16,
 506   160 + 2 * 16,
 507   160 + 3 * 16,
 508   160 + 4 * 16,
 509   160 + 5 * 16,
 510   160 + 6 * 16,
 511   160 + 7 * 16,
 512   160 + 8 * 16,
 513   160 + 9 * 16,
 514   160 + 10 * 16,
 515   160 + 11 * 16,
 516   160 + 12 * 16,
 517   160 + 13 * 16,
 518   160 + 14 * 16,
 519   160 + 15 * 16,                /* ... %xmm15 (128 bits each).  */
 520 };
 521
 522 #define FXSAVE_ADDR(fxsave, regnum) \
 523   (fxsave + fxsave_offset[regnum - I387_ST0_REGNUM])
 524
 525 /* We made an unfortunate choice in putting %mxcsr after the SSE
 526    registers %xmm0-%xmm7 instead of before, since it makes supporting
 527    the registers %xmm8-%xmm15 on AMD64 a bit involved.  Therefore we
 528    don't include the offset for %mxcsr here above.  */
 529
 530 #define FXSAVE_MXCSR_ADDR(fxsave) (fxsave + 24)
 531
 532 static int i387_tag (const unsigned char *raw);
 533 \f
 534
 535 /* Fill register REGNUM in REGCACHE with the appropriate
 536    floating-point or SSE register value from *FXSAVE.  This function
 537    masks off any of the reserved bits in *FXSAVE.  */
 538
 539 void
 540 i387_supply_fxsave (struct regcache *regcache, int regnum, const void *fxsave)
 541 {
 542   struct gdbarch_tdep *tdep = gdbarch_tdep (get_regcache_arch (regcache));
 543   const char *regs = fxsave;
 544   int i;
 545
 546   gdb_assert (tdep->st0_regnum >= I386_ST0_REGNUM);
 547   gdb_assert (tdep->num_xmm_regs > 0);
 548
 549   /* Define I387_ST0_REGNUM and I387_NUM_XMM_REGS such that we use the
 550      proper definitions for REGCACHE's architecture.  */
 551
 552 #define I387_ST0_REGNUM tdep->st0_regnum
 553 #define I387_NUM_XMM_REGS tdep->num_xmm_regs
 554
 555   for (i = I387_ST0_REGNUM; i < I387_MXCSR_REGNUM; i++)
 556     if (regnum == -1 || regnum == i)
 557       {
 558         if (regs == NULL)
 559           {
 560             regcache_raw_supply (regcache, i, NULL);
 561             continue;
 562           }
 563
 564         /* Most of the FPU control registers occupy only 16 bits in
 565            the fxsave area.  Give those a special treatment.  */
 566         if (i >= I387_FCTRL_REGNUM && i < I387_XMM0_REGNUM
 567             && i != I387_FIOFF_REGNUM && i != I387_FOOFF_REGNUM)
 568           {
 569             unsigned char val[4];
 570
 571             memcpy (val, FXSAVE_ADDR (regs, i), 2);
 572             val[2] = val[3] = 0;
 573             if (i == I387_FOP_REGNUM)
 574               val[1] &= ((1 << 3) - 1);
 575             else if (i== I387_FTAG_REGNUM)
 576               {
 577                 /* The fxsave area contains a simplified version of
 578                    the tag word.  We have to look at the actual 80-bit
 579                    FP data to recreate the traditional i387 tag word.  */
 580
 581                 unsigned long ftag = 0;
 582                 int fpreg;
 583                 int top;
 584
 585                 top = ((FXSAVE_ADDR (regs, I387_FSTAT_REGNUM))[1] >> 3);
 586                 top &= 0x7;
 587
 588                 for (fpreg = 7; fpreg >= 0; fpreg--)
 589                   {
 590                     int tag;
 591
 592                     if (val[0] & (1 << fpreg))
 593                       {
 594                         int regnum = (fpreg + 8 - top) % 8 + I387_ST0_REGNUM;
 595                         tag = i387_tag (FXSAVE_ADDR (regs, regnum));
 596                       }
 597                     else
 598                       tag = 3;          /* Empty */
 599
 600                     ftag |= tag << (2 * fpreg);
 601                   }
 602                 val[0] = ftag & 0xff;
 603                 val[1] = (ftag >> 8) & 0xff;
 604               }
 605             regcache_raw_supply (regcache, i, val);
 606           }
 607         else
 608           regcache_raw_supply (regcache, i, FXSAVE_ADDR (regs, i));
 609       }
 610
 611   if (regnum == I387_MXCSR_REGNUM || regnum == -1)
 612     {
 613       if (regs == NULL)
 614         regcache_raw_supply (regcache, I387_MXCSR_REGNUM, NULL);
 615       else
 616         regcache_raw_supply (regcache, I387_MXCSR_REGNUM,
 617                              FXSAVE_MXCSR_ADDR (regs));
 618     }
 619
 620 #undef I387_ST0_REGNUM
 621 #undef I387_NUM_XMM_REGS
 622 }
 623
 624 /* Fill register REGNUM (if it is a floating-point or SSE register) in
 625    *FXSAVE with the value from REGCACHE.  If REGNUM is -1, do this for
 626    all registers.  This function doesn't touch any of the reserved
 627    bits in *FXSAVE.  */
 628
 629 void
 630 i387_collect_fxsave (const struct regcache *regcache, int regnum, void *fxsave)
 631 {
 632   struct gdbarch_tdep *tdep = gdbarch_tdep (current_gdbarch);
 633   char *regs = fxsave;
 634   int i;
 635
 636   gdb_assert (tdep->st0_regnum >= I386_ST0_REGNUM);
 637   gdb_assert (tdep->num_xmm_regs > 0);
 638
 639   /* Define I387_ST0_REGNUM and I387_NUM_XMM_REGS such that we use the
 640      proper definitions for REGCACHE's architecture.  */
 641
 642 #define I387_ST0_REGNUM tdep->st0_regnum
 643 #define I387_NUM_XMM_REGS tdep->num_xmm_regs
 644
 645   for (i = I387_ST0_REGNUM; i < I387_MXCSR_REGNUM; i++)
 646     if (regnum == -1 || regnum == i)
 647       {
 648         /* Most of the FPU control registers occupy only 16 bits in
 649            the fxsave area.  Give those a special treatment.  */
 650         if (i >= I387_FCTRL_REGNUM && i < I387_XMM0_REGNUM
 651             && i != I387_FIOFF_REGNUM && i != I387_FOOFF_REGNUM)
 652           {
 653             unsigned char buf[4];
 654
 655             regcache_raw_collect (regcache, i, buf);
 656
 657             if (i == I387_FOP_REGNUM)
 658               {
 659                 /* The opcode occupies only 11 bits.  Make sure we
 660                    don't touch the other bits.  */
 661                 buf[1] &= ((1 << 3) - 1);
 662                 buf[1] |= ((FXSAVE_ADDR (regs, i))[1] & ~((1 << 3) - 1));
 663               }
 664             else if (i == I387_FTAG_REGNUM)
 665               {
 666                 /* Converting back is much easier.  */
 667
 668                 unsigned short ftag;
 669                 int fpreg;
 670
 671                 ftag = (buf[1] << 8) | buf[0];
 672                 buf[0] = 0;
 673                 buf[1] = 0;
 674
 675                 for (fpreg = 7; fpreg >= 0; fpreg--)
 676                   {
 677                     int tag = (ftag >> (fpreg * 2)) & 3;
 678
 679                     if (tag != 3)
 680                       buf[0] |= (1 << fpreg);
 681                   }
 682               }
 683             memcpy (FXSAVE_ADDR (regs, i), buf, 2);
 684           }
 685         else
 686           regcache_raw_collect (regcache, i, FXSAVE_ADDR (regs, i));
 687       }
 688
 689   if (regnum == I387_MXCSR_REGNUM || regnum == -1)
 690     regcache_raw_collect (regcache, I387_MXCSR_REGNUM,
 691                           FXSAVE_MXCSR_ADDR (regs));
 692
 693 #undef I387_ST0_REGNUM
 694 #undef I387_NUM_XMM_REGS
 695 }
 696
 697 /* Fill register REGNUM (if it is a floating-point or SSE register) in
 698    *FXSAVE with the value in GDB's register cache.  If REGNUM is -1, do
 699    this for all registers.  This function doesn't touch any of the
 700    reserved bits in *FXSAVE.  */
 701
 702 void
 703 i387_fill_fxsave (void *fxsave, int regnum)
 704 {
 705   i387_collect_fxsave (current_regcache, regnum, fxsave);
 706 }
 707
 708 /* Recreate the FTW (tag word) valid bits from the 80-bit FP data in
 709    *RAW.  */
 710
 711 static int
 712 i387_tag (const unsigned char *raw)
 713 {
 714   int integer;
 715   unsigned int exponent;
 716   unsigned long fraction[2];
 717
 718   integer = raw[7] & 0x80;
 719   exponent = (((raw[9] & 0x7f) << 8) | raw[8]);
 720   fraction[0] = ((raw[3] << 24) | (raw[2] << 16) | (raw[1] << 8) | raw[0]);
 721   fraction[1] = (((raw[7] & 0x7f) << 24) | (raw[6] << 16)
 722                  | (raw[5] << 8) | raw[4]);
 723
 724   if (exponent == 0x7fff)
 725     {
 726       /* Special.  */
 727       return (2);
 728     }
 729   else if (exponent == 0x0000)
 730     {
 731       if (fraction[0] == 0x0000 && fraction[1] == 0x0000 && !integer)
 732         {
 733           /* Zero.  */
 734           return (1);
 735         }
 736       else
 737         {
 738           /* Special.  */
 739           return (2);
 740         }
 741     }
 742   else
 743     {
 744       if (integer)
 745         {
 746           /* Valid.  */
 747           return (0);
 748         }
 749       else
 750         {
 751           /* Special.  */
 752           return (2);
 753         }
 754     }
 755 }
 756
 757 /* Prepare the FPU stack in REGCACHE for a function return.  */
 758
 759 void
 760 i387_return_value (struct gdbarch *gdbarch, struct regcache *regcache)
 761 {
 762   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 763   ULONGEST fstat;
 764
 765   /* Define I387_ST0_REGNUM such that we use the proper
 766      definitions for the architecture.  */
 767 #define I387_ST0_REGNUM tdep->st0_regnum
 768
 769   /* Set the top of the floating-point register stack to 7.  The
 770      actual value doesn't really matter, but 7 is what a normal
 771      function return would end up with if the program started out with
 772      a freshly initialized FPU.  */
 773   regcache_raw_read_unsigned (regcache, I387_FSTAT_REGNUM, &fstat);
 774   fstat |= (7 << 11);
 775   regcache_raw_write_unsigned (regcache, I387_FSTAT_REGNUM, fstat);
 776
 777   /* Mark %st(1) through %st(7) as empty.  Since we set the top of the
 778      floating-point register stack to 7, the appropriate value for the
 779      tag word is 0x3fff.  */
 780   regcache_raw_write_unsigned (regcache, I387_FTAG_REGNUM, 0x3fff);
 781
 782 #undef I387_ST0_REGNUM
 783 }