1 /* IEEE floating point support routines, for GDB, the GNU Debugger.
2 Copyright (C) 1991-2023 Free Software Foundation, Inc.
3
4 This file is part of GDB.
5
6 This program is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2 of the License, or
9 (at your option) any later version.
10
11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
15
16 You should have received a copy of the GNU General Public License
17 along with this program; if not, write to the Free Software
18 Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA. */
19
20 /* This is needed to pick up the NAN macro on some systems. */
21 #ifndef _GNU_SOURCE
22 #define _GNU_SOURCE
23 #endif
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
35 /* On some platforms, <float.h> provides DBL_QNAN. */
36 #ifdef STDC_HEADERS
37 #include <float.h>
38 #endif
39
40 #include "ansidecl.h"
41 #include "libiberty.h"
42 #include "floatformat.h"
43
44 #ifndef INFINITY
45 #ifdef HUGE_VAL
46 #define INFINITY HUGE_VAL
47 #else
48 #define INFINITY (1.0 / 0.0)
49 #endif
50 #endif
51
52 #ifndef NAN
53 #ifdef DBL_QNAN
54 #define NAN DBL_QNAN
55 #else
56 #define NAN (0.0 / 0.0)
57 #endif
58 #endif
59
60 static int mant_bits_set (const struct floatformat *, const unsigned char *);
61 static unsigned long get_field (const unsigned char *,
62 enum floatformat_byteorders,
63 unsigned int,
64 unsigned int,
65 unsigned int);
66 static int floatformat_always_valid (const struct floatformat *fmt,
67 const void *from);
68
69 static int
70 floatformat_always_valid (const struct floatformat *fmt ATTRIBUTE_UNUSED,
71 const void *from ATTRIBUTE_UNUSED)
72 {
73 return 1;
74 }
75
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
81 /* floatformats for IEEE half, single, double and quad, big and little endian. */
82 const 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 };
90 const 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 };
98 const struct floatformat floatformat_ieee_single_big =
99 {
100 floatformat_big, 32, 0, 1, 8, 127, 255, 9, 23,
101 floatformat_intbit_no,
102 "floatformat_ieee_single_big",
103 floatformat_always_valid,
104 NULL
105 };
106 const struct floatformat floatformat_ieee_single_little =
107 {
108 floatformat_little, 32, 0, 1, 8, 127, 255, 9, 23,
109 floatformat_intbit_no,
110 "floatformat_ieee_single_little",
111 floatformat_always_valid,
112 NULL
113 };
114 const struct floatformat floatformat_ieee_double_big =
115 {
116 floatformat_big, 64, 0, 1, 11, 1023, 2047, 12, 52,
117 floatformat_intbit_no,
118 "floatformat_ieee_double_big",
119 floatformat_always_valid,
120 NULL
121 };
122 const struct floatformat floatformat_ieee_double_little =
123 {
124 floatformat_little, 64, 0, 1, 11, 1023, 2047, 12, 52,
125 floatformat_intbit_no,
126 "floatformat_ieee_double_little",
127 floatformat_always_valid,
128 NULL
129 };
130 const struct floatformat floatformat_ieee_quad_big =
131 {
132 floatformat_big, 128, 0, 1, 15, 16383, 0x7fff, 16, 112,
133 floatformat_intbit_no,
134 "floatformat_ieee_quad_big",
135 floatformat_always_valid,
136 NULL
137 };
138 const struct floatformat floatformat_ieee_quad_little =
139 {
140 floatformat_little, 128, 0, 1, 15, 16383, 0x7fff, 16, 112,
141 floatformat_intbit_no,
142 "floatformat_ieee_quad_little",
143 floatformat_always_valid,
144 NULL
145 };
146
147 /* floatformat for IEEE double, little endian byte order, with big endian word
148 ordering, as on the ARM. */
149
150 const struct floatformat floatformat_ieee_double_littlebyte_bigword =
151 {
152 floatformat_littlebyte_bigword, 64, 0, 1, 11, 1023, 2047, 12, 52,
153 floatformat_intbit_no,
154 "floatformat_ieee_double_littlebyte_bigword",
155 floatformat_always_valid,
156 NULL
157 };
158
159 /* floatformat for VAX. Not quite IEEE, but close enough. */
160
161 const struct floatformat floatformat_vax_f =
162 {
163 floatformat_vax, 32, 0, 1, 8, 129, 0, 9, 23,
164 floatformat_intbit_no,
165 "floatformat_vax_f",
166 floatformat_always_valid,
167 NULL
168 };
169 const struct floatformat floatformat_vax_d =
170 {
171 floatformat_vax, 64, 0, 1, 8, 129, 0, 9, 55,
172 floatformat_intbit_no,
173 "floatformat_vax_d",
174 floatformat_always_valid,
175 NULL
176 };
177 const struct floatformat floatformat_vax_g =
178 {
179 floatformat_vax, 64, 0, 1, 11, 1025, 0, 12, 52,
180 floatformat_intbit_no,
181 "floatformat_vax_g",
182 floatformat_always_valid,
183 NULL
184 };
185
186 static int floatformat_i387_ext_is_valid (const struct floatformat *fmt,
187 const void *from);
188
189 static int
190 floatformat_i387_ext_is_valid (const struct floatformat *fmt, const void *from)
191 {
192 /* In the i387 double-extended format, if the exponent is all ones,
193 then the integer bit must be set. If the exponent is neither 0
194 nor ~0, the intbit must also be set. Only if the exponent is
195 zero can it be zero, and then it must be zero. */
196 unsigned long exponent, int_bit;
197 const unsigned char *ufrom = (const unsigned char *) from;
198
199 exponent = get_field (ufrom, fmt->byteorder, fmt->totalsize,
200 fmt->exp_start, fmt->exp_len);
201 int_bit = get_field (ufrom, fmt->byteorder, fmt->totalsize,
202 fmt->man_start, 1);
203
204 if ((exponent == 0) != (int_bit == 0))
205 return 0;
206 else
207 return 1;
208 }
209
210 const struct floatformat floatformat_i387_ext =
211 {
212 floatformat_little, 80, 0, 1, 15, 0x3fff, 0x7fff, 16, 64,
213 floatformat_intbit_yes,
214 "floatformat_i387_ext",
215 floatformat_i387_ext_is_valid,
216 NULL
217 };
218 const struct floatformat floatformat_m68881_ext =
219 {
220 /* Note that the bits from 16 to 31 are unused. */
221 floatformat_big, 96, 0, 1, 15, 0x3fff, 0x7fff, 32, 64,
222 floatformat_intbit_yes,
223 "floatformat_m68881_ext",
224 floatformat_always_valid,
225 NULL
226 };
227 const struct floatformat floatformat_i960_ext =
228 {
229 /* Note that the bits from 0 to 15 are unused. */
230 floatformat_little, 96, 16, 17, 15, 0x3fff, 0x7fff, 32, 64,
231 floatformat_intbit_yes,
232 "floatformat_i960_ext",
233 floatformat_always_valid,
234 NULL
235 };
236 const struct floatformat floatformat_m88110_ext =
237 {
238 floatformat_big, 80, 0, 1, 15, 0x3fff, 0x7fff, 16, 64,
239 floatformat_intbit_yes,
240 "floatformat_m88110_ext",
241 floatformat_always_valid,
242 NULL
243 };
244 const struct floatformat floatformat_m88110_harris_ext =
245 {
246 /* Harris uses raw format 128 bytes long, but the number is just an ieee
247 double, and the last 64 bits are wasted. */
248 floatformat_big,128, 0, 1, 11, 0x3ff, 0x7ff, 12, 52,
249 floatformat_intbit_no,
250 "floatformat_m88110_ext_harris",
251 floatformat_always_valid,
252 NULL
253 };
254 const struct floatformat floatformat_arm_ext_big =
255 {
256 /* Bits 1 to 16 are unused. */
257 floatformat_big, 96, 0, 17, 15, 0x3fff, 0x7fff, 32, 64,
258 floatformat_intbit_yes,
259 "floatformat_arm_ext_big",
260 floatformat_always_valid,
261 NULL
262 };
263 const struct floatformat floatformat_arm_ext_littlebyte_bigword =
264 {
265 /* Bits 1 to 16 are unused. */
266 floatformat_littlebyte_bigword, 96, 0, 17, 15, 0x3fff, 0x7fff, 32, 64,
267 floatformat_intbit_yes,
268 "floatformat_arm_ext_littlebyte_bigword",
269 floatformat_always_valid,
270 NULL
271 };
272 const struct floatformat floatformat_ia64_spill_big =
273 {
274 floatformat_big, 128, 0, 1, 17, 65535, 0x1ffff, 18, 64,
275 floatformat_intbit_yes,
276 "floatformat_ia64_spill_big",
277 floatformat_always_valid,
278 NULL
279 };
280 const struct floatformat floatformat_ia64_spill_little =
281 {
282 floatformat_little, 128, 0, 1, 17, 65535, 0x1ffff, 18, 64,
283 floatformat_intbit_yes,
284 "floatformat_ia64_spill_little",
285 floatformat_always_valid,
286 NULL
287 };
288
289 static int
290 floatformat_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
303 if ((unsigned long) top_exp == hfmt->exp_nan)
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). */
312 if ((unsigned long) top_exp == hfmt->exp_nan || top_exp == 0)
313 {
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;
335 for (cur_bit = 0; (unsigned int) cur_bit < hfmt->man_len; cur_bit++)
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
375 const struct floatformat floatformat_ibm_long_double_big =
376 {
377 floatformat_big, 128, 0, 1, 11, 1023, 2047, 12, 52,
378 floatformat_intbit_no,
379 "floatformat_ibm_long_double_big",
380 floatformat_ibm_long_double_is_valid,
381 &floatformat_ieee_double_big
382 };
383
384 const 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 };
392
393 const struct floatformat floatformat_bfloat16_big =
394 {
395 floatformat_big, 16, 0, 1, 8, 127, 255, 9, 7,
396 floatformat_intbit_no,
397 "floatformat_bfloat16_big",
398 floatformat_always_valid,
399 NULL
400 };
401
402 const struct floatformat floatformat_bfloat16_little =
403 {
404 floatformat_little, 16, 0, 1, 8, 127, 255, 9, 7,
405 floatformat_intbit_no,
406 "floatformat_bfloat16_little",
407 floatformat_always_valid,
408 NULL
409 };
410
411 #ifndef min
412 #define min(a, b) ((a) < (b) ? (a) : (b))
413 #endif
414
415 /* Return 1 if any bits are explicitly set in the mantissa of UFROM,
416 format FMT, 0 otherwise. */
417 static int
418 mant_bits_set (const struct floatformat *fmt, const unsigned char *ufrom)
419 {
420 unsigned int mant_bits, mant_off;
421 int mant_bits_left;
422
423 mant_off = fmt->man_start;
424 mant_bits_left = fmt->man_len;
425 while (mant_bits_left > 0)
426 {
427 mant_bits = min (mant_bits_left, 32);
428
429 if (get_field (ufrom, fmt->byteorder, fmt->totalsize,
430 mant_off, mant_bits) != 0)
431 return 1;
432
433 mant_off += mant_bits;
434 mant_bits_left -= mant_bits;
435 }
436 return 0;
437 }
438
439 /* Extract a field which starts at START and is LEN bits long. DATA and
440 TOTAL_LEN are the thing we are extracting it from, in byteorder ORDER. */
441 static unsigned long
442 get_field (const unsigned char *data, enum floatformat_byteorders order,
443 unsigned int total_len, unsigned int start, unsigned int len)
444 {
445 unsigned long result = 0;
446 unsigned int cur_byte;
447 int lo_bit, hi_bit, cur_bitshift = 0;
448 int nextbyte = (order == floatformat_little) ? 1 : -1;
449
450 /* Start is in big-endian bit order! Fix that first. */
451 start = total_len - (start + len);
452
453 /* Start at the least significant part of the field. */
454 if (order == floatformat_little)
455 cur_byte = start / FLOATFORMAT_CHAR_BIT;
456 else
457 cur_byte = (total_len - start - 1) / FLOATFORMAT_CHAR_BIT;
458
459 lo_bit = start % FLOATFORMAT_CHAR_BIT;
460 hi_bit = min (lo_bit + len, FLOATFORMAT_CHAR_BIT);
461
462 do
463 {
464 unsigned int shifted = *(data + cur_byte) >> lo_bit;
465 unsigned int bits = hi_bit - lo_bit;
466 unsigned int mask = (1 << bits) - 1;
467 result |= (shifted & mask) << cur_bitshift;
468 len -= bits;
469 cur_bitshift += bits;
470 cur_byte += nextbyte;
471 lo_bit = 0;
472 hi_bit = min (len, FLOATFORMAT_CHAR_BIT);
473 }
474 while (len != 0);
475
476 return result;
477 }
478
479 /* Convert from FMT to a double.
480 FROM is the address of the extended float.
481 Store the double in *TO. */
482
483 void
484 floatformat_to_double (const struct floatformat *fmt,
485 const void *from, double *to)
486 {
487 const unsigned char *ufrom = (const unsigned char *) from;
488 double dto;
489 long exponent;
490 unsigned long mant;
491 unsigned int mant_bits, mant_off;
492 int mant_bits_left;
493
494 /* Split values are not handled specially, since the top half has
495 the correctly rounded double value (in the only supported case of
496 split values). */
497
498 exponent = get_field (ufrom, fmt->byteorder, fmt->totalsize,
499 fmt->exp_start, fmt->exp_len);
500
501 /* If the exponent indicates a NaN, we don't have information to
502 decide what to do. So we handle it like IEEE, except that we
503 don't try to preserve the type of NaN. FIXME. */
504 if ((unsigned long) exponent == fmt->exp_nan)
505 {
506 int nan = mant_bits_set (fmt, ufrom);
507
508 /* On certain systems (such as GNU/Linux), the use of the
509 INFINITY macro below may generate a warning that cannot be
510 silenced due to a bug in GCC (PR preprocessor/11931). The
511 preprocessor fails to recognise the __extension__ keyword in
512 conjunction with the GNU/C99 extension for hexadecimal
513 floating point constants and will issue a warning when
514 compiling with -pedantic. */
515 if (nan)
516 dto = NAN;
517 else
518 dto = INFINITY;
519
520 if (get_field (ufrom, fmt->byteorder, fmt->totalsize, fmt->sign_start, 1))
521 dto = -dto;
522
523 *to = dto;
524
525 return;
526 }
527
528 mant_bits_left = fmt->man_len;
529 mant_off = fmt->man_start;
530 dto = 0.0;
531
532 /* Build the result algebraically. Might go infinite, underflow, etc;
533 who cares. */
534
535 /* For denorms use minimum exponent. */
536 if (exponent == 0)
537 exponent = 1 - fmt->exp_bias;
538 else
539 {
540 exponent -= fmt->exp_bias;
541
542 /* If this format uses a hidden bit, explicitly add it in now.
543 Otherwise, increment the exponent by one to account for the
544 integer bit. */
545
546 if (fmt->intbit == floatformat_intbit_no)
547 dto = ldexp (1.0, exponent);
548 else
549 exponent++;
550 }
551
552 while (mant_bits_left > 0)
553 {
554 mant_bits = min (mant_bits_left, 32);
555
556 mant = get_field (ufrom, fmt->byteorder, fmt->totalsize,
557 mant_off, mant_bits);
558
559 dto += ldexp ((double) mant, exponent - mant_bits);
560 exponent -= mant_bits;
561 mant_off += mant_bits;
562 mant_bits_left -= mant_bits;
563 }
564
565 /* Negate it if negative. */
566 if (get_field (ufrom, fmt->byteorder, fmt->totalsize, fmt->sign_start, 1))
567 dto = -dto;
568 *to = dto;
569 }
570
571 static void put_field (unsigned char *, enum floatformat_byteorders,
572 unsigned int,
573 unsigned int,
574 unsigned int,
575 unsigned long);
576
577 /* Set a field which starts at START and is LEN bits long. DATA and
578 TOTAL_LEN are the thing we are extracting it from, in byteorder ORDER. */
579 static void
580 put_field (unsigned char *data, enum floatformat_byteorders order,
581 unsigned int total_len, unsigned int start, unsigned int len,
582 unsigned long stuff_to_put)
583 {
584 unsigned int cur_byte;
585 int lo_bit, hi_bit;
586 int nextbyte = (order == floatformat_little) ? 1 : -1;
587
588 /* Start is in big-endian bit order! Fix that first. */
589 start = total_len - (start + len);
590
591 /* Start at the least significant part of the field. */
592 if (order == floatformat_little)
593 cur_byte = start / FLOATFORMAT_CHAR_BIT;
594 else
595 cur_byte = (total_len - start - 1) / FLOATFORMAT_CHAR_BIT;
596
597 lo_bit = start % FLOATFORMAT_CHAR_BIT;
598 hi_bit = min (lo_bit + len, FLOATFORMAT_CHAR_BIT);
599
600 do
601 {
602 unsigned char *byte_ptr = data + cur_byte;
603 unsigned int bits = hi_bit - lo_bit;
604 unsigned int mask = ((1 << bits) - 1) << lo_bit;
605 *byte_ptr = (*byte_ptr & ~mask) | ((stuff_to_put << lo_bit) & mask);
606 stuff_to_put >>= bits;
607 len -= bits;
608 cur_byte += nextbyte;
609 lo_bit = 0;
610 hi_bit = min (len, FLOATFORMAT_CHAR_BIT);
611 }
612 while (len != 0);
613 }
614
615 /* The converse: convert the double *FROM to an extended float
616 and store where TO points. Neither FROM nor TO have any alignment
617 restrictions. */
618
619 void
620 floatformat_from_double (const struct floatformat *fmt,
621 const double *from, void *to)
622 {
623 double dfrom;
624 int exponent;
625 double mant;
626 unsigned int mant_bits, mant_off;
627 int mant_bits_left;
628 unsigned char *uto = (unsigned char *) to;
629
630 dfrom = *from;
631 memset (uto, 0, fmt->totalsize / FLOATFORMAT_CHAR_BIT);
632
633 /* Split values are not handled specially, since a bottom half of
634 zero is correct for any value representable as double (in the
635 only supported case of split values). */
636
637 /* If negative, set the sign bit. */
638 if (dfrom < 0)
639 {
640 put_field (uto, fmt->byteorder, fmt->totalsize, fmt->sign_start, 1, 1);
641 dfrom = -dfrom;
642 }
643
644 if (dfrom == 0)
645 {
646 /* 0.0. */
647 return;
648 }
649
650 if (dfrom != dfrom)
651 {
652 /* NaN. */
653 put_field (uto, fmt->byteorder, fmt->totalsize, fmt->exp_start,
654 fmt->exp_len, fmt->exp_nan);
655 /* Be sure it's not infinity, but NaN value is irrelevant. */
656 put_field (uto, fmt->byteorder, fmt->totalsize, fmt->man_start,
657 32, 1);
658 return;
659 }
660
661 if (dfrom + dfrom == dfrom)
662 {
663 /* This can only happen for an infinite value (or zero, which we
664 already handled above). */
665 put_field (uto, fmt->byteorder, fmt->totalsize, fmt->exp_start,
666 fmt->exp_len, fmt->exp_nan);
667 return;
668 }
669
670 mant = frexp (dfrom, &exponent);
671 if (exponent + fmt->exp_bias - 1 > 0)
672 put_field (uto, fmt->byteorder, fmt->totalsize, fmt->exp_start,
673 fmt->exp_len, exponent + fmt->exp_bias - 1);
674 else
675 {
676 /* Handle a denormalized number. FIXME: What should we do for
677 non-IEEE formats? */
678 put_field (uto, fmt->byteorder, fmt->totalsize, fmt->exp_start,
679 fmt->exp_len, 0);
680 mant = ldexp (mant, exponent + fmt->exp_bias - 1);
681 }
682
683 mant_bits_left = fmt->man_len;
684 mant_off = fmt->man_start;
685 while (mant_bits_left > 0)
686 {
687 unsigned long mant_long;
688 mant_bits = mant_bits_left < 32 ? mant_bits_left : 32;
689
690 mant *= 4294967296.0;
691 mant_long = (unsigned long)mant;
692 mant -= mant_long;
693
694 /* If the integer bit is implicit, and we are not creating a
695 denormalized number, then we need to discard it. */
696 if ((unsigned int) mant_bits_left == fmt->man_len
697 && fmt->intbit == floatformat_intbit_no
698 && exponent + fmt->exp_bias - 1 > 0)
699 {
700 mant_long &= 0x7fffffff;
701 mant_bits -= 1;
702 }
703 else if (mant_bits < 32)
704 {
705 /* The bits we want are in the most significant MANT_BITS bits of
706 mant_long. Move them to the least significant. */
707 mant_long >>= 32 - mant_bits;
708 }
709
710 put_field (uto, fmt->byteorder, fmt->totalsize,
711 mant_off, mant_bits, mant_long);
712 mant_off += mant_bits;
713 mant_bits_left -= mant_bits;
714 }
715 }
716
717 /* Return non-zero iff the data at FROM is a valid number in format FMT. */
718
719 int
720 floatformat_is_valid (const struct floatformat *fmt, const void *from)
721 {
722 return fmt->is_valid (fmt, from);
723 }
724
725
726 #ifdef IEEE_DEBUG
727
728 #include <stdio.h>
729
730 /* This is to be run on a host which uses IEEE floating point. */
731
732 void
733 ieee_test (double n)
734 {
735 double result;
736
737 floatformat_to_double (&floatformat_ieee_double_little, &n, &result);
738 if ((n != result && (! isnan (n) || ! isnan (result)))
739 || (n < 0 && result >= 0)
740 || (n >= 0 && result < 0))
741 printf ("Differ(to): %.20g -> %.20g\n", n, result);
742
743 floatformat_from_double (&floatformat_ieee_double_little, &n, &result);
744 if ((n != result && (! isnan (n) || ! isnan (result)))
745 || (n < 0 && result >= 0)
746 || (n >= 0 && result < 0))
747 printf ("Differ(from): %.20g -> %.20g\n", n, result);
748
749 #if 0
750 {
751 char exten[16];
752
753 floatformat_from_double (&floatformat_m68881_ext, &n, exten);
754 floatformat_to_double (&floatformat_m68881_ext, exten, &result);
755 if (n != result)
756 printf ("Differ(to+from): %.20g -> %.20g\n", n, result);
757 }
758 #endif
759
760 #if IEEE_DEBUG > 1
761 /* This is to be run on a host which uses 68881 format. */
762 {
763 long double ex = *(long double *)exten;
764 if (ex != n)
765 printf ("Differ(from vs. extended): %.20g\n", n);
766 }
767 #endif
768 }
769
770 int
771 main (void)
772 {
773 ieee_test (0.0);
774 ieee_test (0.5);
775 ieee_test (1.1);
776 ieee_test (256.0);
777 ieee_test (0.12345);
778 ieee_test (234235.78907234);
779 ieee_test (-512.0);
780 ieee_test (-0.004321);
781 ieee_test (1.2E-70);
782 ieee_test (1.2E-316);
783 ieee_test (4.9406564584124654E-324);
784 ieee_test (- 4.9406564584124654E-324);
785 ieee_test (- 0.0);
786 ieee_test (- INFINITY);
787 ieee_test (- NAN);
788 ieee_test (INFINITY);
789 ieee_test (NAN);
790 return 0;
791 }
792 #endif