1 /* Intel 387 floating point stuff.
3 Copyright 1988, 1989, 1991, 1992, 1993, 1994, 1998, 1999, 2000,
4 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
6 This file is part of GDB.
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.
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.
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. */
25 #include "floatformat.h"
33 #include "gdb_assert.h"
34 #include "gdb_string.h"
36 #include "i386-tdep.h"
37 #include "i387-tdep.h"
39 /* Implement the `info float' layout based on the register definitions
42 /* Print the floating point number specified by RAW. */
45 print_i387_value (char *raw
, struct ui_file
*file
)
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
);
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
);
62 fprintf_filtered (file
, " %-+27.19g", (double) value
);
66 /* Print the classification for the register contents RAW. */
69 print_i387_ext (unsigned char *raw
, struct ui_file
*file
)
73 unsigned int exponent
;
74 unsigned long fraction
[2];
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]);
83 if (exponent
== 0x7fff && integer
)
85 if (fraction
[0] == 0x00000000 && fraction
[1] == 0x00000000)
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)
93 fputs_filtered (" QNaN", file
);
96 fputs_filtered (" SNaN", file
);
98 else if (exponent
< 0x7fff && exponent
> 0x0000 && integer
)
100 print_i387_value (raw
, file
);
101 else if (exponent
== 0x0000)
103 /* Denormal or zero. */
104 print_i387_value (raw
, file
);
107 /* Pseudo-denormal. */
108 fputs_filtered (" Pseudo-denormal", file
);
109 else if (fraction
[0] || fraction
[1])
111 fputs_filtered (" Denormal", file
);
115 fputs_filtered (" Unsupported", file
);
118 /* Print the status word STATUS. */
121 print_i387_status_word (unsigned int status
, struct ui_file
*file
)
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" : " ");
142 fputs_filtered ("\n", file
);
144 fprintf_filtered (file
,
145 " TOP: %d\n", ((status
>> 11) & 7));
148 /* Print the control word CONTROL. */
151 print_i387_control_word (unsigned int control
, struct ui_file
*file
)
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" : " ");
163 fputs_filtered ("\n", file
);
165 fputs_filtered (" PC: ", file
);
166 switch ((control
>> 8) & 3)
169 fputs_filtered ("Single Precision (24-bits)\n", file
);
172 fputs_filtered ("Reserved\n", file
);
175 fputs_filtered ("Double Precision (53-bits)\n", file
);
178 fputs_filtered ("Extended Precision (64-bits)\n", file
);
182 fputs_filtered (" RC: ", file
);
183 switch ((control
>> 10) & 3)
186 fputs_filtered ("Round to nearest\n", file
);
189 fputs_filtered ("Round down\n", file
);
192 fputs_filtered ("Round up\n", file
);
195 fputs_filtered ("Round toward zero\n", file
);
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. */
205 i387_print_float_info (struct gdbarch
*gdbarch
, struct ui_file
*file
,
206 struct frame_info
*frame
, const char *args
)
208 struct gdbarch_tdep
*tdep
= gdbarch_tdep (get_frame_arch (frame
));
221 gdb_assert (gdbarch
== get_frame_arch (frame
));
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
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
);
236 top
= ((fstat
>> 11) & 7);
238 for (fpreg
= 7; fpreg
>= 0; fpreg
--)
240 unsigned char raw
[I386_MAX_REGISTER_SIZE
];
241 int tag
= (ftag
>> (fpreg
* 2)) & 3;
244 fprintf_filtered (file
, "%sR%d: ", fpreg
== top
? "=>" : " ", fpreg
);
249 fputs_filtered ("Valid ", file
);
252 fputs_filtered ("Zero ", file
);
255 fputs_filtered ("Special ", file
);
258 fputs_filtered ("Empty ", file
);
262 get_frame_register (frame
, (fpreg
+ 8 - top
) % 8 + I387_ST0_REGNUM
, raw
);
264 fputs_filtered ("0x", file
);
265 for (i
= 9; i
>= 0; i
--)
266 fprintf_filtered (file
, "%02x", raw
[i
]);
269 print_i387_ext (raw
, file
);
271 fputs_filtered ("\n", file
);
274 fputs_filtered ("\n", file
);
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"));
289 #undef I387_ST0_REGNUM
293 /* Read a value of type TYPE from register REGNUM in frame FRAME, and
294 return its contents in TO. */
297 i387_register_to_value (struct frame_info
*frame
, int regnum
,
298 struct type
*type
, void *to
)
300 char from
[I386_MAX_REGISTER_SIZE
];
302 gdb_assert (i386_fp_regnum_p (regnum
));
304 /* We only support floating-point values. */
305 if (TYPE_CODE (type
) != TYPE_CODE_FLT
)
307 warning ("Cannot convert floating-point register value "
308 "to non-floating-point type.");
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
);
318 /* Write the contents FROM of a value of type TYPE into register
319 REGNUM in frame FRAME. */
322 i387_value_to_register (struct frame_info
*frame
, int regnum
,
323 struct type
*type
, const void *from
)
325 char to
[I386_MAX_REGISTER_SIZE
];
327 gdb_assert (i386_fp_regnum_p (regnum
));
329 /* We only support floating-point values. */
330 if (TYPE_CODE (type
) != TYPE_CODE_FLT
)
332 warning ("Cannot convert non-floating-point type "
333 "to floating-point register value.");
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
);
345 /* Handle FSAVE and FXSAVE formats. */
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. */
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. */
357 static int fsave_offset
[] =
359 28 + 0 * 10, /* %st(0) ... */
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). */
372 24, /* `foseg' (16 bits). */
374 18 /* `fop' (bottom 11 bits). */
377 #define FSAVE_ADDR(fsave, regnum) \
378 (fsave + fsave_offset[regnum - I387_ST0_REGNUM])
381 /* Fill register REGNUM in REGCACHE with the appropriate value from
382 *FSAVE. This function masks off any of the reserved bits in
386 i387_supply_fsave (struct regcache
*regcache
, int regnum
, const void *fsave
)
388 struct gdbarch_tdep
*tdep
= gdbarch_tdep (get_regcache_arch (regcache
));
389 const char *regs
= fsave
;
392 gdb_assert (tdep
->st0_regnum
>= I386_ST0_REGNUM
);
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
398 for (i
= I387_ST0_REGNUM
; i
< I387_XMM0_REGNUM
; i
++)
399 if (regnum
== -1 || regnum
== i
)
403 regcache_raw_supply (regcache
, i
, NULL
);
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
)
412 unsigned char val
[4];
414 memcpy (val
, FSAVE_ADDR (regs
, i
), 2);
416 if (i
== I387_FOP_REGNUM
)
417 val
[1] &= ((1 << 3) - 1);
418 regcache_raw_supply (regcache
, i
, val
);
421 regcache_raw_supply (regcache
, i
, FSAVE_ADDR (regs
, i
));
423 #undef I387_ST0_REGNUM
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
432 i387_collect_fsave (const struct regcache
*regcache
, int regnum
, void *fsave
)
434 struct gdbarch_tdep
*tdep
= gdbarch_tdep (current_gdbarch
);
438 gdb_assert (tdep
->st0_regnum
>= I386_ST0_REGNUM
);
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
444 for (i
= I387_ST0_REGNUM
; i
< I387_XMM0_REGNUM
; i
++)
445 if (regnum
== -1 || regnum
== i
)
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
)
452 unsigned char buf
[4];
454 regcache_raw_collect (regcache
, i
, buf
);
456 if (i
== I387_FOP_REGNUM
)
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));
463 memcpy (FSAVE_ADDR (regs
, i
), buf
, 2);
466 regcache_raw_collect (regcache
, i
, FSAVE_ADDR (regs
, i
));
468 #undef I387_ST0_REGNUM
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
477 i387_fill_fsave (void *fsave
, int regnum
)
479 i387_collect_fsave (current_regcache
, regnum
, fsave
);
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. */
487 static int fxsave_offset
[] =
489 32, /* %st(0) through ... */
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). */
502 20, /* `foseg' (16 bits). */
504 6, /* `fop' (bottom 11 bits). */
505 160 + 0 * 16, /* %xmm0 through ... */
520 160 + 15 * 16, /* ... %xmm15 (128 bits each). */
523 #define FXSAVE_ADDR(fxsave, regnum) \
524 (fxsave + fxsave_offset[regnum - I387_ST0_REGNUM])
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. */
531 #define FXSAVE_MXCSR_ADDR(fxsave) (fxsave + 24)
533 static int i387_tag (const unsigned char *raw
);
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. */
541 i387_supply_fxsave (struct regcache
*regcache
, int regnum
, const void *fxsave
)
543 struct gdbarch_tdep
*tdep
= gdbarch_tdep (get_regcache_arch (regcache
));
544 const char *regs
= fxsave
;
547 gdb_assert (tdep
->st0_regnum
>= I386_ST0_REGNUM
);
548 gdb_assert (tdep
->num_xmm_regs
> 0);
550 /* Define I387_ST0_REGNUM and I387_NUM_XMM_REGS such that we use the
551 proper definitions for REGCACHE's architecture. */
553 #define I387_ST0_REGNUM tdep->st0_regnum
554 #define I387_NUM_XMM_REGS tdep->num_xmm_regs
556 for (i
= I387_ST0_REGNUM
; i
< I387_MXCSR_REGNUM
; i
++)
557 if (regnum
== -1 || regnum
== i
)
561 regcache_raw_supply (regcache
, i
, NULL
);
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
)
570 unsigned char val
[4];
572 memcpy (val
, FXSAVE_ADDR (regs
, i
), 2);
574 if (i
== I387_FOP_REGNUM
)
575 val
[1] &= ((1 << 3) - 1);
576 else if (i
== I387_FTAG_REGNUM
)
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. */
582 unsigned long ftag
= 0;
586 top
= ((FXSAVE_ADDR (regs
, I387_FSTAT_REGNUM
))[1] >> 3);
589 for (fpreg
= 7; fpreg
>= 0; fpreg
--)
593 if (val
[0] & (1 << fpreg
))
595 int regnum
= (fpreg
+ 8 - top
) % 8 + I387_ST0_REGNUM
;
596 tag
= i387_tag (FXSAVE_ADDR (regs
, regnum
));
601 ftag
|= tag
<< (2 * fpreg
);
603 val
[0] = ftag
& 0xff;
604 val
[1] = (ftag
>> 8) & 0xff;
606 regcache_raw_supply (regcache
, i
, val
);
609 regcache_raw_supply (regcache
, i
, FXSAVE_ADDR (regs
, i
));
612 if (regnum
== I387_MXCSR_REGNUM
|| regnum
== -1)
615 regcache_raw_supply (regcache
, I387_MXCSR_REGNUM
, NULL
);
617 regcache_raw_supply (regcache
, I387_MXCSR_REGNUM
,
618 FXSAVE_MXCSR_ADDR (regs
));
621 #undef I387_ST0_REGNUM
622 #undef I387_NUM_XMM_REGS
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
631 i387_collect_fxsave (const struct regcache
*regcache
, int regnum
, void *fxsave
)
633 struct gdbarch_tdep
*tdep
= gdbarch_tdep (current_gdbarch
);
637 gdb_assert (tdep
->st0_regnum
>= I386_ST0_REGNUM
);
638 gdb_assert (tdep
->num_xmm_regs
> 0);
640 /* Define I387_ST0_REGNUM and I387_NUM_XMM_REGS such that we use the
641 proper definitions for REGCACHE's architecture. */
643 #define I387_ST0_REGNUM tdep->st0_regnum
644 #define I387_NUM_XMM_REGS tdep->num_xmm_regs
646 for (i
= I387_ST0_REGNUM
; i
< I387_MXCSR_REGNUM
; i
++)
647 if (regnum
== -1 || regnum
== i
)
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
)
654 unsigned char buf
[4];
656 regcache_raw_collect (regcache
, i
, buf
);
658 if (i
== I387_FOP_REGNUM
)
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));
665 else if (i
== I387_FTAG_REGNUM
)
667 /* Converting back is much easier. */
672 ftag
= (buf
[1] << 8) | buf
[0];
676 for (fpreg
= 7; fpreg
>= 0; fpreg
--)
678 int tag
= (ftag
>> (fpreg
* 2)) & 3;
681 buf
[0] |= (1 << fpreg
);
684 memcpy (FXSAVE_ADDR (regs
, i
), buf
, 2);
687 regcache_raw_collect (regcache
, i
, FXSAVE_ADDR (regs
, i
));
690 if (regnum
== I387_MXCSR_REGNUM
|| regnum
== -1)
691 regcache_raw_collect (regcache
, I387_MXCSR_REGNUM
,
692 FXSAVE_MXCSR_ADDR (regs
));
694 #undef I387_ST0_REGNUM
695 #undef I387_NUM_XMM_REGS
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. */
704 i387_fill_fxsave (void *fxsave
, int regnum
)
706 i387_collect_fxsave (current_regcache
, regnum
, fxsave
);
709 /* Recreate the FTW (tag word) valid bits from the 80-bit FP data in
713 i387_tag (const unsigned char *raw
)
716 unsigned int exponent
;
717 unsigned long fraction
[2];
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]);
725 if (exponent
== 0x7fff)
730 else if (exponent
== 0x0000)
732 if (fraction
[0] == 0x0000 && fraction
[1] == 0x0000 && !integer
)
758 /* Prepare the FPU stack in REGCACHE for a function return. */
761 i387_return_value (struct gdbarch
*gdbarch
, struct regcache
*regcache
)
763 struct gdbarch_tdep
*tdep
= gdbarch_tdep (gdbarch
);
766 /* Define I387_ST0_REGNUM such that we use the proper
767 definitions for the architecture. */
768 #define I387_ST0_REGNUM tdep->st0_regnum
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
);
776 regcache_raw_write_unsigned (regcache
, I387_FSTAT_REGNUM
, fstat
);
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);
783 #undef I387_ST0_REGNUM
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