floatformat.c revision 1.1.1.1 1 /* IEEE floating point support routines, for GDB, the GNU Debugger.
2 Copyright 1991, 1994, 1999, 2000, 2003, 2005, 2006, 2010
3 Free Software Foundation, Inc.
4
5 This file is part of GDB.
6
7 This program is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2 of the License, or
10 (at your option) any later version.
11
12 This program is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
16
17 You should have received a copy of the GNU General Public License
18 along with this program; if not, write to the Free Software
19 Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA. */
20
21 /* This is needed to pick up the NAN macro on some systems. */
22 #define _GNU_SOURCE
23
24 #ifdef HAVE_CONFIG_H
25 #include "config.h"
26 #endif
27
28 #include <math.h>
29
30 #ifdef HAVE_STRING_H
31 #include <string.h>
32 #endif
33
34 /* On some platforms, <float.h> provides DBL_QNAN. */
35 #ifdef STDC_HEADERS
36 #include <float.h>
37 #endif
38
39 #include "ansidecl.h"
40 #include "libiberty.h"
41 #include "floatformat.h"
42
43 #ifndef INFINITY
44 #ifdef HUGE_VAL
45 #define INFINITY HUGE_VAL
46 #else
47 #define INFINITY (1.0 / 0.0)
48 #endif
49 #endif
50
51 #ifndef NAN
52 #ifdef DBL_QNAN
53 #define NAN DBL_QNAN
54 #else
55 #define NAN (0.0 / 0.0)
56 #endif
57 #endif
58
59 static int mant_bits_set (const struct floatformat *, const unsigned char *);
60 static unsigned long get_field (const unsigned char *,
61 enum floatformat_byteorders,
62 unsigned int,
63 unsigned int,
64 unsigned int);
65 static int floatformat_always_valid (const struct floatformat *fmt,
66 const void *from);
67
68 static int
69 floatformat_always_valid (const struct floatformat *fmt ATTRIBUTE_UNUSED,
70 const void *from ATTRIBUTE_UNUSED)
71 {
72 return 1;
73 }
74
75 /* The odds that CHAR_BIT will be anything but 8 are low enough that I'm not
76 going to bother with trying to muck around with whether it is defined in
77 a system header, what we do if not, etc. */
78 #define FLOATFORMAT_CHAR_BIT 8
79
80 /* floatformats for IEEE half, single and double, big and little endian. */
81 const struct floatformat floatformat_ieee_half_big =
82 {
83 floatformat_big, 16, 0, 1, 5, 15, 31, 6, 10,
84 floatformat_intbit_no,
85 "floatformat_ieee_half_big",
86 floatformat_always_valid,
87 NULL
88 };
89 const struct floatformat floatformat_ieee_half_little =
90 {
91 floatformat_little, 16, 0, 1, 5, 15, 31, 6, 10,
92 floatformat_intbit_no,
93 "floatformat_ieee_half_little",
94 floatformat_always_valid,
95 NULL
96 };
97 const struct floatformat floatformat_ieee_single_big =
98 {
99 floatformat_big, 32, 0, 1, 8, 127, 255, 9, 23,
100 floatformat_intbit_no,
101 "floatformat_ieee_single_big",
102 floatformat_always_valid,
103 NULL
104 };
105 const struct floatformat floatformat_ieee_single_little =
106 {
107 floatformat_little, 32, 0, 1, 8, 127, 255, 9, 23,
108 floatformat_intbit_no,
109 "floatformat_ieee_single_little",
110 floatformat_always_valid,
111 NULL
112 };
113 const struct floatformat floatformat_ieee_double_big =
114 {
115 floatformat_big, 64, 0, 1, 11, 1023, 2047, 12, 52,
116 floatformat_intbit_no,
117 "floatformat_ieee_double_big",
118 floatformat_always_valid,
119 NULL
120 };
121 const struct floatformat floatformat_ieee_double_little =
122 {
123 floatformat_little, 64, 0, 1, 11, 1023, 2047, 12, 52,
124 floatformat_intbit_no,
125 "floatformat_ieee_double_little",
126 floatformat_always_valid,
127 NULL
128 };
129
130 /* floatformat for IEEE double, little endian byte order, with big endian word
131 ordering, as on the ARM. */
132
133 const struct floatformat floatformat_ieee_double_littlebyte_bigword =
134 {
135 floatformat_littlebyte_bigword, 64, 0, 1, 11, 1023, 2047, 12, 52,
136 floatformat_intbit_no,
137 "floatformat_ieee_double_littlebyte_bigword",
138 floatformat_always_valid,
139 NULL
140 };
141
142 /* floatformat for VAX. Not quite IEEE, but close enough. */
143
144 const struct floatformat floatformat_vax_f =
145 {
146 floatformat_vax, 32, 0, 1, 8, 129, 0, 9, 23,
147 floatformat_intbit_no,
148 "floatformat_vax_f",
149 floatformat_always_valid,
150 NULL
151 };
152 const struct floatformat floatformat_vax_d =
153 {
154 floatformat_vax, 64, 0, 1, 8, 129, 0, 9, 55,
155 floatformat_intbit_no,
156 "floatformat_vax_d",
157 floatformat_always_valid,
158 NULL
159 };
160 const struct floatformat floatformat_vax_g =
161 {
162 floatformat_vax, 64, 0, 1, 11, 1025, 0, 12, 52,
163 floatformat_intbit_no,
164 "floatformat_vax_g",
165 floatformat_always_valid,
166 NULL
167 };
168
169 static int floatformat_i387_ext_is_valid (const struct floatformat *fmt,
170 const void *from);
171
172 static int
173 floatformat_i387_ext_is_valid (const struct floatformat *fmt, const void *from)
174 {
175 /* In the i387 double-extended format, if the exponent is all ones,
176 then the integer bit must be set. If the exponent is neither 0
177 nor ~0, the intbit must also be set. Only if the exponent is
178 zero can it be zero, and then it must be zero. */
179 unsigned long exponent, int_bit;
180 const unsigned char *ufrom = (const unsigned char *) from;
181
182 exponent = get_field (ufrom, fmt->byteorder, fmt->totalsize,
183 fmt->exp_start, fmt->exp_len);
184 int_bit = get_field (ufrom, fmt->byteorder, fmt->totalsize,
185 fmt->man_start, 1);
186
187 if ((exponent == 0) != (int_bit == 0))
188 return 0;
189 else
190 return 1;
191 }
192
193 const struct floatformat floatformat_i387_ext =
194 {
195 floatformat_little, 80, 0, 1, 15, 0x3fff, 0x7fff, 16, 64,
196 floatformat_intbit_yes,
197 "floatformat_i387_ext",
198 floatformat_i387_ext_is_valid,
199 NULL
200 };
201 const struct floatformat floatformat_m68881_ext =
202 {
203 /* Note that the bits from 16 to 31 are unused. */
204 floatformat_big, 96, 0, 1, 15, 0x3fff, 0x7fff, 32, 64,
205 floatformat_intbit_yes,
206 "floatformat_m68881_ext",
207 floatformat_always_valid,
208 NULL
209 };
210 const struct floatformat floatformat_i960_ext =
211 {
212 /* Note that the bits from 0 to 15 are unused. */
213 floatformat_little, 96, 16, 17, 15, 0x3fff, 0x7fff, 32, 64,
214 floatformat_intbit_yes,
215 "floatformat_i960_ext",
216 floatformat_always_valid,
217 NULL
218 };
219 const struct floatformat floatformat_m88110_ext =
220 {
221 floatformat_big, 80, 0, 1, 15, 0x3fff, 0x7fff, 16, 64,
222 floatformat_intbit_yes,
223 "floatformat_m88110_ext",
224 floatformat_always_valid,
225 NULL
226 };
227 const struct floatformat floatformat_m88110_harris_ext =
228 {
229 /* Harris uses raw format 128 bytes long, but the number is just an ieee
230 double, and the last 64 bits are wasted. */
231 floatformat_big,128, 0, 1, 11, 0x3ff, 0x7ff, 12, 52,
232 floatformat_intbit_no,
233 "floatformat_m88110_ext_harris",
234 floatformat_always_valid,
235 NULL
236 };
237 const struct floatformat floatformat_arm_ext_big =
238 {
239 /* Bits 1 to 16 are unused. */
240 floatformat_big, 96, 0, 17, 15, 0x3fff, 0x7fff, 32, 64,
241 floatformat_intbit_yes,
242 "floatformat_arm_ext_big",
243 floatformat_always_valid,
244 NULL
245 };
246 const struct floatformat floatformat_arm_ext_littlebyte_bigword =
247 {
248 /* Bits 1 to 16 are unused. */
249 floatformat_littlebyte_bigword, 96, 0, 17, 15, 0x3fff, 0x7fff, 32, 64,
250 floatformat_intbit_yes,
251 "floatformat_arm_ext_littlebyte_bigword",
252 floatformat_always_valid,
253 NULL
254 };
255 const struct floatformat floatformat_ia64_spill_big =
256 {
257 floatformat_big, 128, 0, 1, 17, 65535, 0x1ffff, 18, 64,
258 floatformat_intbit_yes,
259 "floatformat_ia64_spill_big",
260 floatformat_always_valid,
261 NULL
262 };
263 const struct floatformat floatformat_ia64_spill_little =
264 {
265 floatformat_little, 128, 0, 1, 17, 65535, 0x1ffff, 18, 64,
266 floatformat_intbit_yes,
267 "floatformat_ia64_spill_little",
268 floatformat_always_valid,
269 NULL
270 };
271 const struct floatformat floatformat_ia64_quad_big =
272 {
273 floatformat_big, 128, 0, 1, 15, 16383, 0x7fff, 16, 112,
274 floatformat_intbit_no,
275 "floatformat_ia64_quad_big",
276 floatformat_always_valid,
277 NULL
278 };
279 const struct floatformat floatformat_ia64_quad_little =
280 {
281 floatformat_little, 128, 0, 1, 15, 16383, 0x7fff, 16, 112,
282 floatformat_intbit_no,
283 "floatformat_ia64_quad_little",
284 floatformat_always_valid,
285 NULL
286 };
287
288 static int
289 floatformat_ibm_long_double_is_valid (const struct floatformat *fmt,
290 const void *from)
291 {
292 const unsigned char *ufrom = (const unsigned char *) from;
293 const struct floatformat *hfmt = fmt->split_half;
294 long top_exp, bot_exp;
295 int top_nan = 0;
296
297 top_exp = get_field (ufrom, hfmt->byteorder, hfmt->totalsize,
298 hfmt->exp_start, hfmt->exp_len);
299 bot_exp = get_field (ufrom + 8, hfmt->byteorder, hfmt->totalsize,
300 hfmt->exp_start, hfmt->exp_len);
301
302 if ((unsigned long) top_exp == hfmt->exp_nan)
303 top_nan = mant_bits_set (hfmt, ufrom);
304
305 /* A NaN is valid with any low part. */
306 if (top_nan)
307 return 1;
308
309 /* An infinity, zero or denormal requires low part 0 (positive or
310 negative). */
311 if ((unsigned long) top_exp == hfmt->exp_nan || top_exp == 0)
312 {
313 if (bot_exp != 0)
314 return 0;
315
316 return !mant_bits_set (hfmt, ufrom + 8);
317 }
318
319 /* The top part is now a finite normal value. The long double value
320 is the sum of the two parts, and the top part must equal the
321 result of rounding the long double value to nearest double. Thus
322 the bottom part must be <= 0.5ulp of the top part in absolute
323 value, and if it is < 0.5ulp then the long double is definitely
324 valid. */
325 if (bot_exp < top_exp - 53)
326 return 1;
327 if (bot_exp > top_exp - 53 && bot_exp != 0)
328 return 0;
329 if (bot_exp == 0)
330 {
331 /* The bottom part is 0 or denormal. Determine which, and if
332 denormal the first two set bits. */
333 int first_bit = -1, second_bit = -1, cur_bit;
334 for (cur_bit = 0; (unsigned int) cur_bit < hfmt->man_len; cur_bit++)
335 if (get_field (ufrom + 8, hfmt->byteorder, hfmt->totalsize,
336 hfmt->man_start + cur_bit, 1))
337 {
338 if (first_bit == -1)
339 first_bit = cur_bit;
340 else
341 {
342 second_bit = cur_bit;
343 break;
344 }
345 }
346 /* Bottom part 0 is OK. */
347 if (first_bit == -1)
348 return 1;
349 /* The real exponent of the bottom part is -first_bit. */
350 if (-first_bit < top_exp - 53)
351 return 1;
352 if (-first_bit > top_exp - 53)
353 return 0;
354 /* The bottom part is at least 0.5ulp of the top part. For this
355 to be OK, the bottom part must be exactly 0.5ulp (i.e. no
356 more bits set) and the top part must have last bit 0. */
357 if (second_bit != -1)
358 return 0;
359 return !get_field (ufrom, hfmt->byteorder, hfmt->totalsize,
360 hfmt->man_start + hfmt->man_len - 1, 1);
361 }
362 else
363 {
364 /* The bottom part is at least 0.5ulp of the top part. For this
365 to be OK, it must be exactly 0.5ulp (i.e. no explicit bits
366 set) and the top part must have last bit 0. */
367 if (get_field (ufrom, hfmt->byteorder, hfmt->totalsize,
368 hfmt->man_start + hfmt->man_len - 1, 1))
369 return 0;
370 return !mant_bits_set (hfmt, ufrom + 8);
371 }
372 }
373
374 const struct floatformat floatformat_ibm_long_double =
375 {
376 floatformat_big, 128, 0, 1, 11, 1023, 2047, 12, 52,
377 floatformat_intbit_no,
378 "floatformat_ibm_long_double",
379 floatformat_ibm_long_double_is_valid,
380 &floatformat_ieee_double_big
381 };
382
383
385 #ifndef min
386 #define min(a, b) ((a) < (b) ? (a) : (b))
387 #endif
388
389 /* Return 1 if any bits are explicitly set in the mantissa of UFROM,
390 format FMT, 0 otherwise. */
391 static int
392 mant_bits_set (const struct floatformat *fmt, const unsigned char *ufrom)
393 {
394 unsigned int mant_bits, mant_off;
395 int mant_bits_left;
396
397 mant_off = fmt->man_start;
398 mant_bits_left = fmt->man_len;
399 while (mant_bits_left > 0)
400 {
401 mant_bits = min (mant_bits_left, 32);
402
403 if (get_field (ufrom, fmt->byteorder, fmt->totalsize,
404 mant_off, mant_bits) != 0)
405 return 1;
406
407 mant_off += mant_bits;
408 mant_bits_left -= mant_bits;
409 }
410 return 0;
411 }
412
413 /* Extract a field which starts at START and is LEN bits long. DATA and
414 TOTAL_LEN are the thing we are extracting it from, in byteorder ORDER. */
415 static unsigned long
416 get_field (const unsigned char *data, enum floatformat_byteorders order,
417 unsigned int total_len, unsigned int start, unsigned int len)
418 {
419 unsigned long result = 0;
420 unsigned int cur_byte;
421 int lo_bit, hi_bit, cur_bitshift = 0;
422 int nextbyte = (order == floatformat_little) ? 1 : -1;
423
424 /* Start is in big-endian bit order! Fix that first. */
425 start = total_len - (start + len);
426
427 /* Start at the least significant part of the field. */
428 if (order == floatformat_little)
429 cur_byte = start / FLOATFORMAT_CHAR_BIT;
430 else
431 cur_byte = (total_len - start - 1) / FLOATFORMAT_CHAR_BIT;
432
433 lo_bit = start % FLOATFORMAT_CHAR_BIT;
434 hi_bit = min (lo_bit + len, FLOATFORMAT_CHAR_BIT);
435
436 do
437 {
438 unsigned int shifted = *(data + cur_byte) >> lo_bit;
439 unsigned int bits = hi_bit - lo_bit;
440 unsigned int mask = (1 << bits) - 1;
441 result |= (shifted & mask) << cur_bitshift;
442 len -= bits;
443 cur_bitshift += bits;
444 cur_byte += nextbyte;
445 lo_bit = 0;
446 hi_bit = min (len, FLOATFORMAT_CHAR_BIT);
447 }
448 while (len != 0);
449
450 return result;
451 }
452
453 /* Convert from FMT to a double.
454 FROM is the address of the extended float.
455 Store the double in *TO. */
456
457 void
458 floatformat_to_double (const struct floatformat *fmt,
459 const void *from, double *to)
460 {
461 const unsigned char *ufrom = (const unsigned char *) from;
462 double dto;
463 long exponent;
464 unsigned long mant;
465 unsigned int mant_bits, mant_off;
466 int mant_bits_left;
467 int special_exponent; /* It's a NaN, denorm or zero */
468
469 /* Split values are not handled specially, since the top half has
470 the correctly rounded double value (in the only supported case of
471 split values). */
472
473 exponent = get_field (ufrom, fmt->byteorder, fmt->totalsize,
474 fmt->exp_start, fmt->exp_len);
475
476 /* If the exponent indicates a NaN, we don't have information to
477 decide what to do. So we handle it like IEEE, except that we
478 don't try to preserve the type of NaN. FIXME. */
479 if ((unsigned long) exponent == fmt->exp_nan)
480 {
481 int nan = mant_bits_set (fmt, ufrom);
482
483 /* On certain systems (such as GNU/Linux), the use of the
484 INFINITY macro below may generate a warning that can not be
485 silenced due to a bug in GCC (PR preprocessor/11931). The
486 preprocessor fails to recognise the __extension__ keyword in
487 conjunction with the GNU/C99 extension for hexadecimal
488 floating point constants and will issue a warning when
489 compiling with -pedantic. */
490 if (nan)
491 dto = NAN;
492 else
493 dto = INFINITY;
494
495 if (get_field (ufrom, fmt->byteorder, fmt->totalsize, fmt->sign_start, 1))
496 dto = -dto;
497
498 *to = dto;
499
500 return;
501 }
502
503 mant_bits_left = fmt->man_len;
504 mant_off = fmt->man_start;
505 dto = 0.0;
506
507 special_exponent = exponent == 0 || (unsigned long) exponent == fmt->exp_nan;
508
509 /* Don't bias zero's, denorms or NaNs. */
510 if (!special_exponent)
511 exponent -= fmt->exp_bias;
512
513 /* Build the result algebraically. Might go infinite, underflow, etc;
514 who cares. */
515
516 /* If this format uses a hidden bit, explicitly add it in now. Otherwise,
517 increment the exponent by one to account for the integer bit. */
518
519 if (!special_exponent)
520 {
521 if (fmt->intbit == floatformat_intbit_no)
522 dto = ldexp (1.0, exponent);
523 else
524 exponent++;
525 }
526
527 while (mant_bits_left > 0)
528 {
529 mant_bits = min (mant_bits_left, 32);
530
531 mant = get_field (ufrom, fmt->byteorder, fmt->totalsize,
532 mant_off, mant_bits);
533
534 /* Handle denormalized numbers. FIXME: What should we do for
535 non-IEEE formats? */
536 if (special_exponent && exponent == 0 && mant != 0)
537 dto += ldexp ((double)mant,
538 (- fmt->exp_bias
539 - mant_bits
540 - (mant_off - fmt->man_start)
541 + 1));
542 else
543 dto += ldexp ((double)mant, exponent - mant_bits);
544 if (exponent != 0)
545 exponent -= mant_bits;
546 mant_off += mant_bits;
547 mant_bits_left -= mant_bits;
548 }
549
550 /* Negate it if negative. */
551 if (get_field (ufrom, fmt->byteorder, fmt->totalsize, fmt->sign_start, 1))
552 dto = -dto;
553 *to = dto;
554 }
555
556 static void put_field (unsigned char *, enum floatformat_byteorders,
558 unsigned int,
559 unsigned int,
560 unsigned int,
561 unsigned long);
562
563 /* Set a field which starts at START and is LEN bits long. DATA and
564 TOTAL_LEN are the thing we are extracting it from, in byteorder ORDER. */
565 static void
566 put_field (unsigned char *data, enum floatformat_byteorders order,
567 unsigned int total_len, unsigned int start, unsigned int len,
568 unsigned long stuff_to_put)
569 {
570 unsigned int cur_byte;
571 int lo_bit, hi_bit;
572 int nextbyte = (order == floatformat_little) ? 1 : -1;
573
574 /* Start is in big-endian bit order! Fix that first. */
575 start = total_len - (start + len);
576
577 /* Start at the least significant part of the field. */
578 if (order == floatformat_little)
579 cur_byte = start / FLOATFORMAT_CHAR_BIT;
580 else
581 cur_byte = (total_len - start - 1) / FLOATFORMAT_CHAR_BIT;
582
583 lo_bit = start % FLOATFORMAT_CHAR_BIT;
584 hi_bit = min (lo_bit + len, FLOATFORMAT_CHAR_BIT);
585
586 do
587 {
588 unsigned char *byte_ptr = data + cur_byte;
589 unsigned int bits = hi_bit - lo_bit;
590 unsigned int mask = ((1 << bits) - 1) << lo_bit;
591 *byte_ptr = (*byte_ptr & ~mask) | ((stuff_to_put << lo_bit) & mask);
592 stuff_to_put >>= bits;
593 len -= bits;
594 cur_byte += nextbyte;
595 lo_bit = 0;
596 hi_bit = min (len, FLOATFORMAT_CHAR_BIT);
597 }
598 while (len != 0);
599 }
600
601 /* The converse: convert the double *FROM to an extended float
602 and store where TO points. Neither FROM nor TO have any alignment
603 restrictions. */
604
605 void
606 floatformat_from_double (const struct floatformat *fmt,
607 const double *from, void *to)
608 {
609 double dfrom;
610 int exponent;
611 double mant;
612 unsigned int mant_bits, mant_off;
613 int mant_bits_left;
614 unsigned char *uto = (unsigned char *) to;
615
616 dfrom = *from;
617 memset (uto, 0, fmt->totalsize / FLOATFORMAT_CHAR_BIT);
618
619 /* Split values are not handled specially, since a bottom half of
620 zero is correct for any value representable as double (in the
621 only supported case of split values). */
622
623 /* If negative, set the sign bit. */
624 if (dfrom < 0)
625 {
626 put_field (uto, fmt->byteorder, fmt->totalsize, fmt->sign_start, 1, 1);
627 dfrom = -dfrom;
628 }
629
630 if (dfrom == 0)
631 {
632 /* 0.0. */
633 return;
634 }
635
636 if (dfrom != dfrom)
637 {
638 /* NaN. */
639 put_field (uto, fmt->byteorder, fmt->totalsize, fmt->exp_start,
640 fmt->exp_len, fmt->exp_nan);
641 /* Be sure it's not infinity, but NaN value is irrelevant. */
642 put_field (uto, fmt->byteorder, fmt->totalsize, fmt->man_start,
643 32, 1);
644 return;
645 }
646
647 if (dfrom + dfrom == dfrom)
648 {
649 /* This can only happen for an infinite value (or zero, which we
650 already handled above). */
651 put_field (uto, fmt->byteorder, fmt->totalsize, fmt->exp_start,
652 fmt->exp_len, fmt->exp_nan);
653 return;
654 }
655
656 mant = frexp (dfrom, &exponent);
657 if (exponent + fmt->exp_bias - 1 > 0)
658 put_field (uto, fmt->byteorder, fmt->totalsize, fmt->exp_start,
659 fmt->exp_len, exponent + fmt->exp_bias - 1);
660 else
661 {
662 /* Handle a denormalized number. FIXME: What should we do for
663 non-IEEE formats? */
664 put_field (uto, fmt->byteorder, fmt->totalsize, fmt->exp_start,
665 fmt->exp_len, 0);
666 mant = ldexp (mant, exponent + fmt->exp_bias - 1);
667 }
668
669 mant_bits_left = fmt->man_len;
670 mant_off = fmt->man_start;
671 while (mant_bits_left > 0)
672 {
673 unsigned long mant_long;
674 mant_bits = mant_bits_left < 32 ? mant_bits_left : 32;
675
676 mant *= 4294967296.0;
677 mant_long = (unsigned long)mant;
678 mant -= mant_long;
679
680 /* If the integer bit is implicit, and we are not creating a
681 denormalized number, then we need to discard it. */
682 if ((unsigned int) mant_bits_left == fmt->man_len
683 && fmt->intbit == floatformat_intbit_no
684 && exponent + fmt->exp_bias - 1 > 0)
685 {
686 mant_long &= 0x7fffffff;
687 mant_bits -= 1;
688 }
689 else if (mant_bits < 32)
690 {
691 /* The bits we want are in the most significant MANT_BITS bits of
692 mant_long. Move them to the least significant. */
693 mant_long >>= 32 - mant_bits;
694 }
695
696 put_field (uto, fmt->byteorder, fmt->totalsize,
697 mant_off, mant_bits, mant_long);
698 mant_off += mant_bits;
699 mant_bits_left -= mant_bits;
700 }
701 }
702
703 /* Return non-zero iff the data at FROM is a valid number in format FMT. */
704
705 int
706 floatformat_is_valid (const struct floatformat *fmt, const void *from)
707 {
708 return fmt->is_valid (fmt, from);
709 }
710
711
712 #ifdef IEEE_DEBUG
713
714 #include <stdio.h>
715
716 /* This is to be run on a host which uses IEEE floating point. */
717
718 void
719 ieee_test (double n)
720 {
721 double result;
722
723 floatformat_to_double (&floatformat_ieee_double_little, &n, &result);
724 if ((n != result && (! isnan (n) || ! isnan (result)))
725 || (n < 0 && result >= 0)
726 || (n >= 0 && result < 0))
727 printf ("Differ(to): %.20g -> %.20g\n", n, result);
728
729 floatformat_from_double (&floatformat_ieee_double_little, &n, &result);
730 if ((n != result && (! isnan (n) || ! isnan (result)))
731 || (n < 0 && result >= 0)
732 || (n >= 0 && result < 0))
733 printf ("Differ(from): %.20g -> %.20g\n", n, result);
734
735 #if 0
736 {
737 char exten[16];
738
739 floatformat_from_double (&floatformat_m68881_ext, &n, exten);
740 floatformat_to_double (&floatformat_m68881_ext, exten, &result);
741 if (n != result)
742 printf ("Differ(to+from): %.20g -> %.20g\n", n, result);
743 }
744 #endif
745
746 #if IEEE_DEBUG > 1
747 /* This is to be run on a host which uses 68881 format. */
748 {
749 long double ex = *(long double *)exten;
750 if (ex != n)
751 printf ("Differ(from vs. extended): %.20g\n", n);
752 }
753 #endif
754 }
755
756 int
757 main (void)
758 {
759 ieee_test (0.0);
760 ieee_test (0.5);
761 ieee_test (256.0);
762 ieee_test (0.12345);
763 ieee_test (234235.78907234);
764 ieee_test (-512.0);
765 ieee_test (-0.004321);
766 ieee_test (1.2E-70);
767 ieee_test (1.2E-316);
768 ieee_test (4.9406564584124654E-324);
769 ieee_test (- 4.9406564584124654E-324);
770 ieee_test (- 0.0);
771 ieee_test (- INFINITY);
772 ieee_test (- NAN);
773 ieee_test (INFINITY);
774 ieee_test (NAN);
775 return 0;
776 }
777 #endif
778