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 \f
 344
 345 /* Handle FSAVE and FXSAVE formats.  */
 346
 347 /* FIXME: kettenis/20030927: The functions below should accept a
 348    `regcache' argument, but I don't want to change the function
 349    signature just yet.  There's some band-aid in the functions below
 350    in the form of the `regcache' local variables.  This will ease the
 351    transition later on.  */
 352
 353 /* At fsave_offset[REGNUM] you'll find the offset to the location in
 354    the data structure used by the "fsave" instruction where GDB
 355    register REGNUM is stored.  */
 356
 357 static int fsave_offset[] =
 358 {
 359   28 + 0 * 10,                  /* %st(0) ...  */
 360   28 + 1 * 10,
 361   28 + 2 * 10,
 362   28 + 3 * 10,
 363   28 + 4 * 10,
 364   28 + 5 * 10,
 365   28 + 6 * 10,
 366   28 + 7 * 10,                  /* ... %st(7).  */
 367   0,                            /* `fctrl' (16 bits).  */
 368   4,                            /* `fstat' (16 bits).  */
 369   8,                            /* `ftag' (16 bits).  */
 370   16,                           /* `fiseg' (16 bits).  */
 371   12,                           /* `fioff'.  */
 372   24,                           /* `foseg' (16 bits).  */
 373   20,                           /* `fooff'.  */
 374   18                            /* `fop' (bottom 11 bits).  */
 375 };
 376
 377 #define FSAVE_ADDR(fsave, regnum) \
 378   (fsave + fsave_offset[regnum - I387_ST0_REGNUM])
 379 \f
 380
 381 /* Fill register REGNUM in REGCACHE with the appropriate value from
 382    *FSAVE.  This function masks off any of the reserved bits in
 383    *FSAVE.  */
 384
 385 void
 386 i387_supply_fsave (struct regcache *regcache, int regnum, const void *fsave)
 387 {
 388   struct gdbarch_tdep *tdep = gdbarch_tdep (get_regcache_arch (regcache));
 389   const char *regs = fsave;
 390   int i;
 391
 392   gdb_assert (tdep->st0_regnum >= I386_ST0_REGNUM);
 393
 394   /* Define I387_ST0_REGNUM such that we use the proper definitions
 395      for REGCACHE's architecture.  */
 396 #define I387_ST0_REGNUM tdep->st0_regnum
 397
 398   for (i = I387_ST0_REGNUM; i < I387_XMM0_REGNUM; i++)
 399     if (regnum == -1 || regnum == i)
 400       {
 401         if (fsave == NULL)
 402           {
 403             regcache_raw_supply (regcache, i, NULL);
 404             continue;
 405           }
 406
 407         /* Most of the FPU control registers occupy only 16 bits in the
 408            fsave area.  Give those a special treatment.  */
 409         if (i >= I387_FCTRL_REGNUM
 410             && i != I387_FIOFF_REGNUM && i != I387_FOOFF_REGNUM)
 411           {
 412             unsigned char val[4];
 413
 414             memcpy (val, FSAVE_ADDR (regs, i), 2);
 415             val[2] = val[3] = 0;
 416             if (i == I387_FOP_REGNUM)
 417               val[1] &= ((1 << 3) - 1);
 418             regcache_raw_supply (regcache, i, val);
 419           }
 420         else
 421           regcache_raw_supply (regcache, i, FSAVE_ADDR (regs, i));
 422       }
 423 #undef I387_ST0_REGNUM
 424 }
 425
 426 /* Fill register REGNUM (if it is a floating-point register) in *FSAVE
 427    with the value from REGCACHE.  If REGNUM is -1, do this for all
 428    registers.  This function doesn't touch any of the reserved bits in
 429    *FSAVE.  */
 430
 431 void
 432 i387_collect_fsave (const struct regcache *regcache, int regnum, void *fsave)
 433 {
 434   struct gdbarch_tdep *tdep = gdbarch_tdep (current_gdbarch);
 435   char *regs = fsave;
 436   int i;
 437
 438   gdb_assert (tdep->st0_regnum >= I386_ST0_REGNUM);
 439
 440   /* Define I387_ST0_REGNUM such that we use the proper definitions
 441      for REGCACHE's architecture.  */
 442 #define I387_ST0_REGNUM tdep->st0_regnum
 443
 444   for (i = I387_ST0_REGNUM; i < I387_XMM0_REGNUM; i++)
 445     if (regnum == -1 || regnum == i)
 446       {
 447         /* Most of the FPU control registers occupy only 16 bits in
 448            the fsave area.  Give those a special treatment.  */
 449         if (i >= I387_FCTRL_REGNUM
 450             && i != I387_FIOFF_REGNUM && i != I387_FOOFF_REGNUM)
 451           {
 452             unsigned char buf[4];
 453
 454             regcache_raw_collect (regcache, i, buf);
 455
 456             if (i == I387_FOP_REGNUM)
 457               {
 458                 /* The opcode occupies only 11 bits.  Make sure we
 459                    don't touch the other bits.  */
 460                 buf[1] &= ((1 << 3) - 1);
 461                 buf[1] |= ((FSAVE_ADDR (regs, i))[1] & ~((1 << 3) - 1));
 462               }
 463             memcpy (FSAVE_ADDR (regs, i), buf, 2);
 464           }
 465         else
 466           regcache_raw_collect (regcache, i, FSAVE_ADDR (regs, i));
 467       }
 468 #undef I387_ST0_REGNUM
 469 }
 470
 471 /* Fill register REGNUM (if it is a floating-point register) in *FSAVE
 472    with the value in GDB's register cache.  If REGNUM is -1, do this
 473    for all registers.  This function doesn't touch any of the reserved
 474    bits in *FSAVE.  */
 475
 476 void
 477 i387_fill_fsave (void *fsave, int regnum)
 478 {
 479   i387_collect_fsave (current_regcache, regnum, fsave);
 480 }
 481 \f
 482
 483 /* At fxsave_offset[REGNUM] you'll find the offset to the location in
 484    the data structure used by the "fxsave" instruction where GDB
 485    register REGNUM is stored.  */
 486
 487 static int fxsave_offset[] =
 488 {
 489   32,                           /* %st(0) through ...  */
 490   48,
 491   64,
 492   80,
 493   96,
 494   112,
 495   128,
 496   144,                          /* ... %st(7) (80 bits each).  */
 497   0,                            /* `fctrl' (16 bits).  */
 498   2,                            /* `fstat' (16 bits).  */
 499   4,                            /* `ftag' (16 bits).  */
 500   12,                           /* `fiseg' (16 bits).  */
 501   8,                            /* `fioff'.  */
 502   20,                           /* `foseg' (16 bits).  */
 503   16,                           /* `fooff'.  */
 504   6,                            /* `fop' (bottom 11 bits).  */
 505   160 + 0 * 16,                 /* %xmm0 through ...  */
 506   160 + 1 * 16,
 507   160 + 2 * 16,
 508   160 + 3 * 16,
 509   160 + 4 * 16,
 510   160 + 5 * 16,
 511   160 + 6 * 16,
 512   160 + 7 * 16,
 513   160 + 8 * 16,
 514   160 + 9 * 16,
 515   160 + 10 * 16,
 516   160 + 11 * 16,
 517   160 + 12 * 16,
 518   160 + 13 * 16,
 519   160 + 14 * 16,
 520   160 + 15 * 16,                /* ... %xmm15 (128 bits each).  */
 521 };
 522
 523 #define FXSAVE_ADDR(fxsave, regnum) \
 524   (fxsave + fxsave_offset[regnum - I387_ST0_REGNUM])
 525
 526 /* We made an unfortunate choice in putting %mxcsr after the SSE
 527    registers %xmm0-%xmm7 instead of before, since it makes supporting
 528    the registers %xmm8-%xmm15 on AMD64 a bit involved.  Therefore we
 529    don't include the offset for %mxcsr here above.  */
 530
 531 #define FXSAVE_MXCSR_ADDR(fxsave) (fxsave + 24)
 532
 533 static int i387_tag (const unsigned char *raw);
 534 \f
 535
 536 /* Fill register REGNUM in REGCACHE with the appropriate
 537    floating-point or SSE register value from *FXSAVE.  This function
 538    masks off any of the reserved bits in *FXSAVE.  */
 539
 540 void
 541 i387_supply_fxsave (struct regcache *regcache, int regnum, const void *fxsave)
 542 {
 543   struct gdbarch_tdep *tdep = gdbarch_tdep (get_regcache_arch (regcache));
 544   const char *regs = fxsave;
 545   int i;
 546
 547   gdb_assert (tdep->st0_regnum >= I386_ST0_REGNUM);
 548   gdb_assert (tdep->num_xmm_regs > 0);
 549
 550   /* Define I387_ST0_REGNUM and I387_NUM_XMM_REGS such that we use the
 551      proper definitions for REGCACHE's architecture.  */
 552
 553 #define I387_ST0_REGNUM tdep->st0_regnum
 554 #define I387_NUM_XMM_REGS tdep->num_xmm_regs
 555
 556   for (i = I387_ST0_REGNUM; i < I387_MXCSR_REGNUM; i++)
 557     if (regnum == -1 || regnum == i)
 558       {
 559         if (regs == NULL)
 560           {
 561             regcache_raw_supply (regcache, i, NULL);
 562             continue;
 563           }
 564
 565         /* Most of the FPU control registers occupy only 16 bits in
 566            the fxsave area.  Give those a special treatment.  */
 567         if (i >= I387_FCTRL_REGNUM && i < I387_XMM0_REGNUM
 568             && i != I387_FIOFF_REGNUM && i != I387_FOOFF_REGNUM)
 569           {
 570             unsigned char val[4];
 571
 572             memcpy (val, FXSAVE_ADDR (regs, i), 2);
 573             val[2] = val[3] = 0;
 574             if (i == I387_FOP_REGNUM)
 575               val[1] &= ((1 << 3) - 1);
 576             else if (i== I387_FTAG_REGNUM)
 577               {
 578                 /* The fxsave area contains a simplified version of
 579                    the tag word.  We have to look at the actual 80-bit
 580                    FP data to recreate the traditional i387 tag word.  */
 581
 582                 unsigned long ftag = 0;
 583                 int fpreg;
 584                 int top;
 585
 586                 top = ((FXSAVE_ADDR (regs, I387_FSTAT_REGNUM))[1] >> 3);
 587                 top &= 0x7;
 588
 589                 for (fpreg = 7; fpreg >= 0; fpreg--)
 590                   {
 591                     int tag;
 592
 593                     if (val[0] & (1 << fpreg))
 594                       {
 595                         int regnum = (fpreg + 8 - top) % 8 + I387_ST0_REGNUM;
 596                         tag = i387_tag (FXSAVE_ADDR (regs, regnum));
 597                       }
 598                     else
 599                       tag = 3;          /* Empty */
 600
 601                     ftag |= tag << (2 * fpreg);
 602                   }
 603                 val[0] = ftag & 0xff;
 604                 val[1] = (ftag >> 8) & 0xff;
 605               }
 606             regcache_raw_supply (regcache, i, val);
 607           }
 608         else
 609           regcache_raw_supply (regcache, i, FXSAVE_ADDR (regs, i));
 610       }
 611
 612   if (regnum == I387_MXCSR_REGNUM || regnum == -1)
 613     {
 614       if (regs == NULL)
 615         regcache_raw_supply (regcache, I387_MXCSR_REGNUM, NULL);
 616       else
 617         regcache_raw_supply (regcache, I387_MXCSR_REGNUM,
 618                              FXSAVE_MXCSR_ADDR (regs));
 619     }
 620
 621 #undef I387_ST0_REGNUM
 622 #undef I387_NUM_XMM_REGS
 623 }
 624
 625 /* Fill register REGNUM (if it is a floating-point or SSE register) in
 626    *FXSAVE with the value from REGCACHE.  If REGNUM is -1, do this for
 627    all registers.  This function doesn't touch any of the reserved
 628    bits in *FXSAVE.  */
 629
 630 void
 631 i387_collect_fxsave (const struct regcache *regcache, int regnum, void *fxsave)
 632 {
 633   struct gdbarch_tdep *tdep = gdbarch_tdep (current_gdbarch);
 634   char *regs = fxsave;
 635   int i;
 636
 637   gdb_assert (tdep->st0_regnum >= I386_ST0_REGNUM);
 638   gdb_assert (tdep->num_xmm_regs > 0);
 639
 640   /* Define I387_ST0_REGNUM and I387_NUM_XMM_REGS such that we use the
 641      proper definitions for REGCACHE's architecture.  */
 642
 643 #define I387_ST0_REGNUM tdep->st0_regnum
 644 #define I387_NUM_XMM_REGS tdep->num_xmm_regs
 645
 646   for (i = I387_ST0_REGNUM; i < I387_MXCSR_REGNUM; i++)
 647     if (regnum == -1 || regnum == i)
 648       {
 649         /* Most of the FPU control registers occupy only 16 bits in
 650            the fxsave area.  Give those a special treatment.  */
 651         if (i >= I387_FCTRL_REGNUM && i < I387_XMM0_REGNUM
 652             && i != I387_FIOFF_REGNUM && i != I387_FOOFF_REGNUM)
 653           {
 654             unsigned char buf[4];
 655
 656             regcache_raw_collect (regcache, i, buf);
 657
 658             if (i == I387_FOP_REGNUM)
 659               {
 660                 /* The opcode occupies only 11 bits.  Make sure we
 661                    don't touch the other bits.  */
 662                 buf[1] &= ((1 << 3) - 1);
 663                 buf[1] |= ((FXSAVE_ADDR (regs, i))[1] & ~((1 << 3) - 1));
 664               }
 665             else if (i == I387_FTAG_REGNUM)
 666               {
 667                 /* Converting back is much easier.  */
 668
 669                 unsigned short ftag;
 670                 int fpreg;
 671
 672                 ftag = (buf[1] << 8) | buf[0];
 673                 buf[0] = 0;
 674                 buf[1] = 0;
 675
 676                 for (fpreg = 7; fpreg >= 0; fpreg--)
 677                   {
 678                     int tag = (ftag >> (fpreg * 2)) & 3;
 679
 680                     if (tag != 3)
 681                       buf[0] |= (1 << fpreg);
 682                   }
 683               }
 684             memcpy (FXSAVE_ADDR (regs, i), buf, 2);
 685           }
 686         else
 687           regcache_raw_collect (regcache, i, FXSAVE_ADDR (regs, i));
 688       }
 689
 690   if (regnum == I387_MXCSR_REGNUM || regnum == -1)
 691     regcache_raw_collect (regcache, I387_MXCSR_REGNUM,
 692                           FXSAVE_MXCSR_ADDR (regs));
 693
 694 #undef I387_ST0_REGNUM
 695 #undef I387_NUM_XMM_REGS
 696 }
 697
 698 /* Fill register REGNUM (if it is a floating-point or SSE register) in
 699    *FXSAVE with the value in GDB's register cache.  If REGNUM is -1, do
 700    this for all registers.  This function doesn't touch any of the
 701    reserved bits in *FXSAVE.  */
 702
 703 void
 704 i387_fill_fxsave (void *fxsave, int regnum)
 705 {
 706   i387_collect_fxsave (current_regcache, regnum, fxsave);
 707 }
 708
 709 /* Recreate the FTW (tag word) valid bits from the 80-bit FP data in
 710    *RAW.  */
 711
 712 static int
 713 i387_tag (const unsigned char *raw)
 714 {
 715   int integer;
 716   unsigned int exponent;
 717   unsigned long fraction[2];
 718
 719   integer = raw[7] & 0x80;
 720   exponent = (((raw[9] & 0x7f) << 8) | raw[8]);
 721   fraction[0] = ((raw[3] << 24) | (raw[2] << 16) | (raw[1] << 8) | raw[0]);
 722   fraction[1] = (((raw[7] & 0x7f) << 24) | (raw[6] << 16)
 723                  | (raw[5] << 8) | raw[4]);
 724
 725   if (exponent == 0x7fff)
 726     {
 727       /* Special.  */
 728       return (2);
 729     }
 730   else if (exponent == 0x0000)
 731     {
 732       if (fraction[0] == 0x0000 && fraction[1] == 0x0000 && !integer)
 733         {
 734           /* Zero.  */
 735           return (1);
 736         }
 737       else
 738         {
 739           /* Special.  */
 740           return (2);
 741         }
 742     }
 743   else
 744     {
 745       if (integer)
 746         {
 747           /* Valid.  */
 748           return (0);
 749         }
 750       else
 751         {
 752           /* Special.  */
 753           return (2);
 754         }
 755     }
 756 }
 757
 758 /* Prepare the FPU stack in REGCACHE for a function return.  */
 759
 760 void
 761 i387_return_value (struct gdbarch *gdbarch, struct regcache *regcache)
 762 {
 763   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 764   ULONGEST fstat;
 765
 766   /* Define I387_ST0_REGNUM such that we use the proper
 767      definitions for the architecture.  */
 768 #define I387_ST0_REGNUM tdep->st0_regnum
 769
 770   /* Set the top of the floating-point register stack to 7.  The
 771      actual value doesn't really matter, but 7 is what a normal
 772      function return would end up with if the program started out with
 773      a freshly initialized FPU.  */
 774   regcache_raw_read_unsigned (regcache, I387_FSTAT_REGNUM, &fstat);
 775   fstat |= (7 << 11);
 776   regcache_raw_write_unsigned (regcache, I387_FSTAT_REGNUM, fstat);
 777
 778   /* Mark %st(1) through %st(7) as empty.  Since we set the top of the
 779      floating-point register stack to 7, the appropriate value for the
 780      tag word is 0x3fff.  */
 781   regcache_raw_write_unsigned (regcache, I387_FTAG_REGNUM, 0x3fff);
 782
 783 #undef I387_ST0_REGNUM
 784 }