gdb: add target_ops::supports_displaced_step
[deliverable/binutils-gdb.git] / libiberty / floatformat.c
CommitLineData
252b5132 1/* IEEE floating point support routines, for GDB, the GNU Debugger.
533da483 2 Copyright (C) 1991-2020 Free Software Foundation, Inc.
252b5132
RH
3
4This file is part of GDB.
5
6This program is free software; you can redistribute it and/or modify
7it under the terms of the GNU General Public License as published by
8the Free Software Foundation; either version 2 of the License, or
9(at your option) any later version.
10
11This program is distributed in the hope that it will be useful,
12but WITHOUT ANY WARRANTY; without even the implied warranty of
13MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14GNU General Public License for more details.
15
16You should have received a copy of the GNU General Public License
17along with this program; if not, write to the Free Software
979c05d3 18Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA. */
252b5132 19
b52927b7 20/* This is needed to pick up the NAN macro on some systems. */
f91ca6bc 21#ifndef _GNU_SOURCE
b52927b7 22#define _GNU_SOURCE
f91ca6bc 23#endif
b52927b7
DD
24
25#ifdef HAVE_CONFIG_H
26#include "config.h"
27#endif
28
29#include <math.h>
30
31#ifdef HAVE_STRING_H
32#include <string.h>
33#endif
34
e27d251e
DD
35/* On some platforms, <float.h> provides DBL_QNAN. */
36#ifdef STDC_HEADERS
37#include <float.h>
38#endif
39
1ea16ec5 40#include "ansidecl.h"
b52927b7 41#include "libiberty.h"
252b5132 42#include "floatformat.h"
b52927b7
DD
43
44#ifndef INFINITY
45#ifdef HUGE_VAL
46#define INFINITY HUGE_VAL
252b5132 47#else
b52927b7
DD
48#define INFINITY (1.0 / 0.0)
49#endif
50#endif
51
52#ifndef NAN
e27d251e
DD
53#ifdef DBL_QNAN
54#define NAN DBL_QNAN
55#else
b52927b7 56#define NAN (0.0 / 0.0)
252b5132 57#endif
e27d251e 58#endif
252b5132 59
b14d30e1 60static int mant_bits_set (const struct floatformat *, const unsigned char *);
49b1fae4
DD
61static unsigned long get_field (const unsigned char *,
62 enum floatformat_byteorders,
63 unsigned int,
64 unsigned int,
65 unsigned int);
66static int floatformat_always_valid (const struct floatformat *fmt,
3b6940c0 67 const void *from);
5324d185
AC
68
69static int
49b1fae4 70floatformat_always_valid (const struct floatformat *fmt ATTRIBUTE_UNUSED,
3b6940c0 71 const void *from ATTRIBUTE_UNUSED)
5324d185
AC
72{
73 return 1;
74}
75
252b5132
RH
76/* The odds that CHAR_BIT will be anything but 8 are low enough that I'm not
77 going to bother with trying to muck around with whether it is defined in
78 a system header, what we do if not, etc. */
79#define FLOATFORMAT_CHAR_BIT 8
80
f9e9243a
UW
81/* floatformats for IEEE half, single and double, big and little endian. */
82const struct floatformat floatformat_ieee_half_big =
83{
84 floatformat_big, 16, 0, 1, 5, 15, 31, 6, 10,
85 floatformat_intbit_no,
86 "floatformat_ieee_half_big",
87 floatformat_always_valid,
88 NULL
89};
90const struct floatformat floatformat_ieee_half_little =
91{
92 floatformat_little, 16, 0, 1, 5, 15, 31, 6, 10,
93 floatformat_intbit_no,
94 "floatformat_ieee_half_little",
95 floatformat_always_valid,
96 NULL
97};
252b5132
RH
98const struct floatformat floatformat_ieee_single_big =
99{
f03aa80d
AC
100 floatformat_big, 32, 0, 1, 8, 127, 255, 9, 23,
101 floatformat_intbit_no,
5324d185 102 "floatformat_ieee_single_big",
b14d30e1
JM
103 floatformat_always_valid,
104 NULL
252b5132
RH
105};
106const struct floatformat floatformat_ieee_single_little =
107{
f03aa80d
AC
108 floatformat_little, 32, 0, 1, 8, 127, 255, 9, 23,
109 floatformat_intbit_no,
5324d185 110 "floatformat_ieee_single_little",
b14d30e1
JM
111 floatformat_always_valid,
112 NULL
252b5132
RH
113};
114const struct floatformat floatformat_ieee_double_big =
115{
f03aa80d
AC
116 floatformat_big, 64, 0, 1, 11, 1023, 2047, 12, 52,
117 floatformat_intbit_no,
5324d185 118 "floatformat_ieee_double_big",
b14d30e1
JM
119 floatformat_always_valid,
120 NULL
252b5132
RH
121};
122const struct floatformat floatformat_ieee_double_little =
123{
f03aa80d
AC
124 floatformat_little, 64, 0, 1, 11, 1023, 2047, 12, 52,
125 floatformat_intbit_no,
5324d185 126 "floatformat_ieee_double_little",
b14d30e1
JM
127 floatformat_always_valid,
128 NULL
252b5132
RH
129};
130
131/* floatformat for IEEE double, little endian byte order, with big endian word
132 ordering, as on the ARM. */
133
134const struct floatformat floatformat_ieee_double_littlebyte_bigword =
135{
f03aa80d
AC
136 floatformat_littlebyte_bigword, 64, 0, 1, 11, 1023, 2047, 12, 52,
137 floatformat_intbit_no,
5324d185 138 "floatformat_ieee_double_littlebyte_bigword",
b14d30e1
JM
139 floatformat_always_valid,
140 NULL
252b5132
RH
141};
142
fb10537e
DD
143/* floatformat for VAX. Not quite IEEE, but close enough. */
144
145const struct floatformat floatformat_vax_f =
146{
147 floatformat_vax, 32, 0, 1, 8, 129, 0, 9, 23,
148 floatformat_intbit_no,
149 "floatformat_vax_f",
b14d30e1
JM
150 floatformat_always_valid,
151 NULL
fb10537e
DD
152};
153const struct floatformat floatformat_vax_d =
154{
155 floatformat_vax, 64, 0, 1, 8, 129, 0, 9, 55,
156 floatformat_intbit_no,
157 "floatformat_vax_d",
b14d30e1
JM
158 floatformat_always_valid,
159 NULL
fb10537e
DD
160};
161const struct floatformat floatformat_vax_g =
162{
163 floatformat_vax, 64, 0, 1, 11, 1025, 0, 12, 52,
164 floatformat_intbit_no,
165 "floatformat_vax_g",
b14d30e1
JM
166 floatformat_always_valid,
167 NULL
fb10537e
DD
168};
169
3b6940c0
DD
170static int floatformat_i387_ext_is_valid (const struct floatformat *fmt,
171 const void *from);
5324d185
AC
172
173static int
3b6940c0 174floatformat_i387_ext_is_valid (const struct floatformat *fmt, const void *from)
5324d185
AC
175{
176 /* In the i387 double-extended format, if the exponent is all ones,
177 then the integer bit must be set. If the exponent is neither 0
178 nor ~0, the intbit must also be set. Only if the exponent is
179 zero can it be zero, and then it must be zero. */
180 unsigned long exponent, int_bit;
648c3dc0 181 const unsigned char *ufrom = (const unsigned char *) from;
3b6940c0 182
5324d185
AC
183 exponent = get_field (ufrom, fmt->byteorder, fmt->totalsize,
184 fmt->exp_start, fmt->exp_len);
185 int_bit = get_field (ufrom, fmt->byteorder, fmt->totalsize,
186 fmt->man_start, 1);
3b6940c0 187
5324d185
AC
188 if ((exponent == 0) != (int_bit == 0))
189 return 0;
190 else
191 return 1;
192}
193
252b5132
RH
194const struct floatformat floatformat_i387_ext =
195{
196 floatformat_little, 80, 0, 1, 15, 0x3fff, 0x7fff, 16, 64,
f03aa80d 197 floatformat_intbit_yes,
5324d185 198 "floatformat_i387_ext",
b14d30e1
JM
199 floatformat_i387_ext_is_valid,
200 NULL
252b5132
RH
201};
202const struct floatformat floatformat_m68881_ext =
203{
204 /* Note that the bits from 16 to 31 are unused. */
f03aa80d
AC
205 floatformat_big, 96, 0, 1, 15, 0x3fff, 0x7fff, 32, 64,
206 floatformat_intbit_yes,
5324d185 207 "floatformat_m68881_ext",
b14d30e1
JM
208 floatformat_always_valid,
209 NULL
252b5132
RH
210};
211const struct floatformat floatformat_i960_ext =
212{
213 /* Note that the bits from 0 to 15 are unused. */
214 floatformat_little, 96, 16, 17, 15, 0x3fff, 0x7fff, 32, 64,
f03aa80d 215 floatformat_intbit_yes,
5324d185 216 "floatformat_i960_ext",
b14d30e1
JM
217 floatformat_always_valid,
218 NULL
252b5132
RH
219};
220const struct floatformat floatformat_m88110_ext =
221{
eb828599
AC
222 floatformat_big, 80, 0, 1, 15, 0x3fff, 0x7fff, 16, 64,
223 floatformat_intbit_yes,
5324d185 224 "floatformat_m88110_ext",
b14d30e1
JM
225 floatformat_always_valid,
226 NULL
eb828599
AC
227};
228const struct floatformat floatformat_m88110_harris_ext =
229{
252b5132
RH
230 /* Harris uses raw format 128 bytes long, but the number is just an ieee
231 double, and the last 64 bits are wasted. */
232 floatformat_big,128, 0, 1, 11, 0x3ff, 0x7ff, 12, 52,
f03aa80d 233 floatformat_intbit_no,
5324d185 234 "floatformat_m88110_ext_harris",
b14d30e1
JM
235 floatformat_always_valid,
236 NULL
252b5132 237};
eb828599
AC
238const struct floatformat floatformat_arm_ext_big =
239{
240 /* Bits 1 to 16 are unused. */
241 floatformat_big, 96, 0, 17, 15, 0x3fff, 0x7fff, 32, 64,
242 floatformat_intbit_yes,
5324d185 243 "floatformat_arm_ext_big",
b14d30e1
JM
244 floatformat_always_valid,
245 NULL
eb828599
AC
246};
247const struct floatformat floatformat_arm_ext_littlebyte_bigword =
248{
249 /* Bits 1 to 16 are unused. */
250 floatformat_littlebyte_bigword, 96, 0, 17, 15, 0x3fff, 0x7fff, 32, 64,
251 floatformat_intbit_yes,
5324d185 252 "floatformat_arm_ext_littlebyte_bigword",
b14d30e1
JM
253 floatformat_always_valid,
254 NULL
eb828599
AC
255};
256const struct floatformat floatformat_ia64_spill_big =
257{
258 floatformat_big, 128, 0, 1, 17, 65535, 0x1ffff, 18, 64,
259 floatformat_intbit_yes,
5324d185 260 "floatformat_ia64_spill_big",
b14d30e1
JM
261 floatformat_always_valid,
262 NULL
eb828599
AC
263};
264const struct floatformat floatformat_ia64_spill_little =
265{
266 floatformat_little, 128, 0, 1, 17, 65535, 0x1ffff, 18, 64,
267 floatformat_intbit_yes,
5324d185 268 "floatformat_ia64_spill_little",
b14d30e1
JM
269 floatformat_always_valid,
270 NULL
eb828599
AC
271};
272const struct floatformat floatformat_ia64_quad_big =
273{
274 floatformat_big, 128, 0, 1, 15, 16383, 0x7fff, 16, 112,
275 floatformat_intbit_no,
5324d185 276 "floatformat_ia64_quad_big",
b14d30e1
JM
277 floatformat_always_valid,
278 NULL
eb828599
AC
279};
280const struct floatformat floatformat_ia64_quad_little =
281{
282 floatformat_little, 128, 0, 1, 15, 16383, 0x7fff, 16, 112,
283 floatformat_intbit_no,
5324d185 284 "floatformat_ia64_quad_little",
b14d30e1
JM
285 floatformat_always_valid,
286 NULL
287};
288
289static int
290floatformat_ibm_long_double_is_valid (const struct floatformat *fmt,
291 const void *from)
292{
293 const unsigned char *ufrom = (const unsigned char *) from;
294 const struct floatformat *hfmt = fmt->split_half;
295 long top_exp, bot_exp;
296 int top_nan = 0;
297
298 top_exp = get_field (ufrom, hfmt->byteorder, hfmt->totalsize,
299 hfmt->exp_start, hfmt->exp_len);
300 bot_exp = get_field (ufrom + 8, hfmt->byteorder, hfmt->totalsize,
301 hfmt->exp_start, hfmt->exp_len);
302
38e654e2 303 if ((unsigned long) top_exp == hfmt->exp_nan)
b14d30e1
JM
304 top_nan = mant_bits_set (hfmt, ufrom);
305
306 /* A NaN is valid with any low part. */
307 if (top_nan)
308 return 1;
309
310 /* An infinity, zero or denormal requires low part 0 (positive or
311 negative). */
38e654e2 312 if ((unsigned long) top_exp == hfmt->exp_nan || top_exp == 0)
b14d30e1 313 {
b14d30e1
JM
314 if (bot_exp != 0)
315 return 0;
316
317 return !mant_bits_set (hfmt, ufrom + 8);
318 }
319
320 /* The top part is now a finite normal value. The long double value
321 is the sum of the two parts, and the top part must equal the
322 result of rounding the long double value to nearest double. Thus
323 the bottom part must be <= 0.5ulp of the top part in absolute
324 value, and if it is < 0.5ulp then the long double is definitely
325 valid. */
326 if (bot_exp < top_exp - 53)
327 return 1;
328 if (bot_exp > top_exp - 53 && bot_exp != 0)
329 return 0;
330 if (bot_exp == 0)
331 {
332 /* The bottom part is 0 or denormal. Determine which, and if
333 denormal the first two set bits. */
334 int first_bit = -1, second_bit = -1, cur_bit;
38e654e2 335 for (cur_bit = 0; (unsigned int) cur_bit < hfmt->man_len; cur_bit++)
b14d30e1
JM
336 if (get_field (ufrom + 8, hfmt->byteorder, hfmt->totalsize,
337 hfmt->man_start + cur_bit, 1))
338 {
339 if (first_bit == -1)
340 first_bit = cur_bit;
341 else
342 {
343 second_bit = cur_bit;
344 break;
345 }
346 }
347 /* Bottom part 0 is OK. */
348 if (first_bit == -1)
349 return 1;
350 /* The real exponent of the bottom part is -first_bit. */
351 if (-first_bit < top_exp - 53)
352 return 1;
353 if (-first_bit > top_exp - 53)
354 return 0;
355 /* The bottom part is at least 0.5ulp of the top part. For this
356 to be OK, the bottom part must be exactly 0.5ulp (i.e. no
357 more bits set) and the top part must have last bit 0. */
358 if (second_bit != -1)
359 return 0;
360 return !get_field (ufrom, hfmt->byteorder, hfmt->totalsize,
361 hfmt->man_start + hfmt->man_len - 1, 1);
362 }
363 else
364 {
365 /* The bottom part is at least 0.5ulp of the top part. For this
366 to be OK, it must be exactly 0.5ulp (i.e. no explicit bits
367 set) and the top part must have last bit 0. */
368 if (get_field (ufrom, hfmt->byteorder, hfmt->totalsize,
369 hfmt->man_start + hfmt->man_len - 1, 1))
370 return 0;
371 return !mant_bits_set (hfmt, ufrom + 8);
372 }
373}
374
21290977 375const struct floatformat floatformat_ibm_long_double_big =
b14d30e1
JM
376{
377 floatformat_big, 128, 0, 1, 11, 1023, 2047, 12, 52,
378 floatformat_intbit_no,
21290977 379 "floatformat_ibm_long_double_big",
38e654e2 380 floatformat_ibm_long_double_is_valid,
b14d30e1 381 &floatformat_ieee_double_big
eb828599 382};
21290977
DD
383
384const struct floatformat floatformat_ibm_long_double_little =
385{
386 floatformat_little, 128, 0, 1, 11, 1023, 2047, 12, 52,
387 floatformat_intbit_no,
388 "floatformat_ibm_long_double_little",
389 floatformat_ibm_long_double_is_valid,
390 &floatformat_ieee_double_little
391};
252b5132 392\f
9e59254c
JB
393
394#ifndef min
395#define min(a, b) ((a) < (b) ? (a) : (b))
396#endif
397
b14d30e1
JM
398/* Return 1 if any bits are explicitly set in the mantissa of UFROM,
399 format FMT, 0 otherwise. */
400static int
401mant_bits_set (const struct floatformat *fmt, const unsigned char *ufrom)
402{
403 unsigned int mant_bits, mant_off;
404 int mant_bits_left;
405
406 mant_off = fmt->man_start;
407 mant_bits_left = fmt->man_len;
408 while (mant_bits_left > 0)
409 {
410 mant_bits = min (mant_bits_left, 32);
411
412 if (get_field (ufrom, fmt->byteorder, fmt->totalsize,
413 mant_off, mant_bits) != 0)
414 return 1;
415
416 mant_off += mant_bits;
417 mant_bits_left -= mant_bits;
418 }
419 return 0;
420}
421
3f2aacaf 422/* Extract a field which starts at START and is LEN bits long. DATA and
252b5132
RH
423 TOTAL_LEN are the thing we are extracting it from, in byteorder ORDER. */
424static unsigned long
49b1fae4
DD
425get_field (const unsigned char *data, enum floatformat_byteorders order,
426 unsigned int total_len, unsigned int start, unsigned int len)
252b5132 427{
9e59254c 428 unsigned long result = 0;
252b5132 429 unsigned int cur_byte;
9e59254c
JB
430 int lo_bit, hi_bit, cur_bitshift = 0;
431 int nextbyte = (order == floatformat_little) ? 1 : -1;
432
433 /* Start is in big-endian bit order! Fix that first. */
434 start = total_len - (start + len);
252b5132
RH
435
436 /* Start at the least significant part of the field. */
252b5132 437 if (order == floatformat_little)
9e59254c 438 cur_byte = start / FLOATFORMAT_CHAR_BIT;
252b5132 439 else
9e59254c 440 cur_byte = (total_len - start - 1) / FLOATFORMAT_CHAR_BIT;
252b5132 441
9e59254c
JB
442 lo_bit = start % FLOATFORMAT_CHAR_BIT;
443 hi_bit = min (lo_bit + len, FLOATFORMAT_CHAR_BIT);
444
445 do
252b5132 446 {
9e59254c
JB
447 unsigned int shifted = *(data + cur_byte) >> lo_bit;
448 unsigned int bits = hi_bit - lo_bit;
449 unsigned int mask = (1 << bits) - 1;
450 result |= (shifted & mask) << cur_bitshift;
451 len -= bits;
452 cur_bitshift += bits;
453 cur_byte += nextbyte;
454 lo_bit = 0;
455 hi_bit = min (len, FLOATFORMAT_CHAR_BIT);
252b5132 456 }
9e59254c
JB
457 while (len != 0);
458
252b5132
RH
459 return result;
460}
461
252b5132
RH
462/* Convert from FMT to a double.
463 FROM is the address of the extended float.
464 Store the double in *TO. */
465
466void
49b1fae4 467floatformat_to_double (const struct floatformat *fmt,
3b6940c0 468 const void *from, double *to)
252b5132 469{
648c3dc0 470 const unsigned char *ufrom = (const unsigned char *) from;
252b5132
RH
471 double dto;
472 long exponent;
473 unsigned long mant;
474 unsigned int mant_bits, mant_off;
475 int mant_bits_left;
252b5132 476
b14d30e1
JM
477 /* Split values are not handled specially, since the top half has
478 the correctly rounded double value (in the only supported case of
479 split values). */
480
252b5132
RH
481 exponent = get_field (ufrom, fmt->byteorder, fmt->totalsize,
482 fmt->exp_start, fmt->exp_len);
b52927b7
DD
483
484 /* If the exponent indicates a NaN, we don't have information to
485 decide what to do. So we handle it like IEEE, except that we
486 don't try to preserve the type of NaN. FIXME. */
487 if ((unsigned long) exponent == fmt->exp_nan)
488 {
b14d30e1 489 int nan = mant_bits_set (fmt, ufrom);
b52927b7 490
f2942ea4 491 /* On certain systems (such as GNU/Linux), the use of the
07ffcfec 492 INFINITY macro below may generate a warning that cannot be
f2942ea4
DD
493 silenced due to a bug in GCC (PR preprocessor/11931). The
494 preprocessor fails to recognise the __extension__ keyword in
495 conjunction with the GNU/C99 extension for hexadecimal
496 floating point constants and will issue a warning when
497 compiling with -pedantic. */
b52927b7
DD
498 if (nan)
499 dto = NAN;
500 else
501 dto = INFINITY;
502
503 if (get_field (ufrom, fmt->byteorder, fmt->totalsize, fmt->sign_start, 1))
504 dto = -dto;
505
506 *to = dto;
507
508 return;
509 }
252b5132
RH
510
511 mant_bits_left = fmt->man_len;
512 mant_off = fmt->man_start;
513 dto = 0.0;
514
252b5132
RH
515 /* Build the result algebraically. Might go infinite, underflow, etc;
516 who cares. */
517
e372c21c
AS
518 /* For denorms use minimum exponent. */
519 if (exponent == 0)
520 exponent = 1 - fmt->exp_bias;
521 else
252b5132 522 {
e372c21c
AS
523 exponent -= fmt->exp_bias;
524
525 /* If this format uses a hidden bit, explicitly add it in now.
526 Otherwise, increment the exponent by one to account for the
527 integer bit. */
528
252b5132
RH
529 if (fmt->intbit == floatformat_intbit_no)
530 dto = ldexp (1.0, exponent);
531 else
532 exponent++;
533 }
534
535 while (mant_bits_left > 0)
536 {
537 mant_bits = min (mant_bits_left, 32);
538
539 mant = get_field (ufrom, fmt->byteorder, fmt->totalsize,
540 mant_off, mant_bits);
541
e372c21c
AS
542 dto += ldexp ((double) mant, exponent - mant_bits);
543 exponent -= mant_bits;
252b5132
RH
544 mant_off += mant_bits;
545 mant_bits_left -= mant_bits;
546 }
547
548 /* Negate it if negative. */
549 if (get_field (ufrom, fmt->byteorder, fmt->totalsize, fmt->sign_start, 1))
550 dto = -dto;
551 *to = dto;
552}
553\f
49b1fae4
DD
554static void put_field (unsigned char *, enum floatformat_byteorders,
555 unsigned int,
556 unsigned int,
557 unsigned int,
558 unsigned long);
252b5132 559
3f2aacaf 560/* Set a field which starts at START and is LEN bits long. DATA and
252b5132
RH
561 TOTAL_LEN are the thing we are extracting it from, in byteorder ORDER. */
562static void
49b1fae4
DD
563put_field (unsigned char *data, enum floatformat_byteorders order,
564 unsigned int total_len, unsigned int start, unsigned int len,
565 unsigned long stuff_to_put)
252b5132
RH
566{
567 unsigned int cur_byte;
9e59254c
JB
568 int lo_bit, hi_bit;
569 int nextbyte = (order == floatformat_little) ? 1 : -1;
570
571 /* Start is in big-endian bit order! Fix that first. */
572 start = total_len - (start + len);
252b5132
RH
573
574 /* Start at the least significant part of the field. */
252b5132 575 if (order == floatformat_little)
9e59254c 576 cur_byte = start / FLOATFORMAT_CHAR_BIT;
252b5132 577 else
9e59254c 578 cur_byte = (total_len - start - 1) / FLOATFORMAT_CHAR_BIT;
252b5132 579
9e59254c
JB
580 lo_bit = start % FLOATFORMAT_CHAR_BIT;
581 hi_bit = min (lo_bit + len, FLOATFORMAT_CHAR_BIT);
582
583 do
252b5132 584 {
9e59254c
JB
585 unsigned char *byte_ptr = data + cur_byte;
586 unsigned int bits = hi_bit - lo_bit;
587 unsigned int mask = ((1 << bits) - 1) << lo_bit;
588 *byte_ptr = (*byte_ptr & ~mask) | ((stuff_to_put << lo_bit) & mask);
589 stuff_to_put >>= bits;
590 len -= bits;
591 cur_byte += nextbyte;
592 lo_bit = 0;
593 hi_bit = min (len, FLOATFORMAT_CHAR_BIT);
252b5132 594 }
9e59254c 595 while (len != 0);
252b5132
RH
596}
597
598/* The converse: convert the double *FROM to an extended float
599 and store where TO points. Neither FROM nor TO have any alignment
600 restrictions. */
601
602void
49b1fae4 603floatformat_from_double (const struct floatformat *fmt,
3b6940c0 604 const double *from, void *to)
252b5132
RH
605{
606 double dfrom;
607 int exponent;
608 double mant;
609 unsigned int mant_bits, mant_off;
610 int mant_bits_left;
648c3dc0 611 unsigned char *uto = (unsigned char *) to;
252b5132 612
b52927b7 613 dfrom = *from;
252b5132 614 memset (uto, 0, fmt->totalsize / FLOATFORMAT_CHAR_BIT);
b52927b7 615
b14d30e1
JM
616 /* Split values are not handled specially, since a bottom half of
617 zero is correct for any value representable as double (in the
618 only supported case of split values). */
619
b52927b7
DD
620 /* If negative, set the sign bit. */
621 if (dfrom < 0)
622 {
623 put_field (uto, fmt->byteorder, fmt->totalsize, fmt->sign_start, 1, 1);
624 dfrom = -dfrom;
625 }
626
252b5132 627 if (dfrom == 0)
b52927b7
DD
628 {
629 /* 0.0. */
630 return;
631 }
632
252b5132
RH
633 if (dfrom != dfrom)
634 {
b52927b7 635 /* NaN. */
252b5132
RH
636 put_field (uto, fmt->byteorder, fmt->totalsize, fmt->exp_start,
637 fmt->exp_len, fmt->exp_nan);
b52927b7 638 /* Be sure it's not infinity, but NaN value is irrelevant. */
252b5132
RH
639 put_field (uto, fmt->byteorder, fmt->totalsize, fmt->man_start,
640 32, 1);
641 return;
642 }
643
b52927b7 644 if (dfrom + dfrom == dfrom)
252b5132 645 {
b52927b7
DD
646 /* This can only happen for an infinite value (or zero, which we
647 already handled above). */
648 put_field (uto, fmt->byteorder, fmt->totalsize, fmt->exp_start,
649 fmt->exp_len, fmt->exp_nan);
650 return;
252b5132
RH
651 }
652
252b5132 653 mant = frexp (dfrom, &exponent);
b52927b7
DD
654 if (exponent + fmt->exp_bias - 1 > 0)
655 put_field (uto, fmt->byteorder, fmt->totalsize, fmt->exp_start,
656 fmt->exp_len, exponent + fmt->exp_bias - 1);
657 else
658 {
659 /* Handle a denormalized number. FIXME: What should we do for
660 non-IEEE formats? */
661 put_field (uto, fmt->byteorder, fmt->totalsize, fmt->exp_start,
662 fmt->exp_len, 0);
663 mant = ldexp (mant, exponent + fmt->exp_bias - 1);
664 }
252b5132
RH
665
666 mant_bits_left = fmt->man_len;
667 mant_off = fmt->man_start;
668 while (mant_bits_left > 0)
669 {
670 unsigned long mant_long;
671 mant_bits = mant_bits_left < 32 ? mant_bits_left : 32;
672
673 mant *= 4294967296.0;
674 mant_long = (unsigned long)mant;
675 mant -= mant_long;
676
b52927b7
DD
677 /* If the integer bit is implicit, and we are not creating a
678 denormalized number, then we need to discard it. */
08372f14 679 if ((unsigned int) mant_bits_left == fmt->man_len
b52927b7
DD
680 && fmt->intbit == floatformat_intbit_no
681 && exponent + fmt->exp_bias - 1 > 0)
252b5132
RH
682 {
683 mant_long &= 0x7fffffff;
684 mant_bits -= 1;
685 }
686 else if (mant_bits < 32)
687 {
688 /* The bits we want are in the most significant MANT_BITS bits of
689 mant_long. Move them to the least significant. */
690 mant_long >>= 32 - mant_bits;
691 }
692
693 put_field (uto, fmt->byteorder, fmt->totalsize,
694 mant_off, mant_bits, mant_long);
695 mant_off += mant_bits;
696 mant_bits_left -= mant_bits;
697 }
698}
699
3f2aacaf
DJ
700/* Return non-zero iff the data at FROM is a valid number in format FMT. */
701
702int
3b6940c0 703floatformat_is_valid (const struct floatformat *fmt, const void *from)
3f2aacaf 704{
5324d185 705 return fmt->is_valid (fmt, from);
3f2aacaf
DJ
706}
707
252b5132
RH
708
709#ifdef IEEE_DEBUG
710
b52927b7
DD
711#include <stdio.h>
712
252b5132
RH
713/* This is to be run on a host which uses IEEE floating point. */
714
715void
49b1fae4 716ieee_test (double n)
252b5132
RH
717{
718 double result;
252b5132 719
3b6940c0 720 floatformat_to_double (&floatformat_ieee_double_little, &n, &result);
b52927b7
DD
721 if ((n != result && (! isnan (n) || ! isnan (result)))
722 || (n < 0 && result >= 0)
723 || (n >= 0 && result < 0))
252b5132 724 printf ("Differ(to): %.20g -> %.20g\n", n, result);
b52927b7 725
3b6940c0 726 floatformat_from_double (&floatformat_ieee_double_little, &n, &result);
b52927b7
DD
727 if ((n != result && (! isnan (n) || ! isnan (result)))
728 || (n < 0 && result >= 0)
729 || (n >= 0 && result < 0))
252b5132
RH
730 printf ("Differ(from): %.20g -> %.20g\n", n, result);
731
b52927b7
DD
732#if 0
733 {
734 char exten[16];
735
736 floatformat_from_double (&floatformat_m68881_ext, &n, exten);
737 floatformat_to_double (&floatformat_m68881_ext, exten, &result);
738 if (n != result)
739 printf ("Differ(to+from): %.20g -> %.20g\n", n, result);
740 }
741#endif
252b5132
RH
742
743#if IEEE_DEBUG > 1
744 /* This is to be run on a host which uses 68881 format. */
745 {
746 long double ex = *(long double *)exten;
747 if (ex != n)
748 printf ("Differ(from vs. extended): %.20g\n", n);
749 }
750#endif
751}
752
753int
49b1fae4 754main (void)
252b5132 755{
b52927b7 756 ieee_test (0.0);
252b5132 757 ieee_test (0.5);
e372c21c 758 ieee_test (1.1);
252b5132
RH
759 ieee_test (256.0);
760 ieee_test (0.12345);
761 ieee_test (234235.78907234);
762 ieee_test (-512.0);
763 ieee_test (-0.004321);
b52927b7
DD
764 ieee_test (1.2E-70);
765 ieee_test (1.2E-316);
766 ieee_test (4.9406564584124654E-324);
767 ieee_test (- 4.9406564584124654E-324);
768 ieee_test (- 0.0);
769 ieee_test (- INFINITY);
770 ieee_test (- NAN);
771 ieee_test (INFINITY);
772 ieee_test (NAN);
252b5132
RH
773 return 0;
774}
775#endif
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