1 /* IEEE floating point support routines, for GDB, the GNU Debugger.
2 Copyright (C) 1991-2019 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
floatformat_always_valid(const struct floatformat * fmt ATTRIBUTE_UNUSED,const void * from ATTRIBUTE_UNUSED)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 and double, 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
131 /* floatformat for IEEE double, little endian byte order, with big endian word
132 ordering, as on the ARM. */
133
134 const struct floatformat floatformat_ieee_double_littlebyte_bigword =
135 {
136 floatformat_littlebyte_bigword, 64, 0, 1, 11, 1023, 2047, 12, 52,
137 floatformat_intbit_no,
138 "floatformat_ieee_double_littlebyte_bigword",
139 floatformat_always_valid,
140 NULL
141 };
142
143 /* floatformat for VAX. Not quite IEEE, but close enough. */
144
145 const 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",
150 floatformat_always_valid,
151 NULL
152 };
153 const 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",
158 floatformat_always_valid,
159 NULL
160 };
161 const 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",
166 floatformat_always_valid,
167 NULL
168 };
169
170 static int floatformat_i387_ext_is_valid (const struct floatformat *fmt,
171 const void *from);
172
173 static int
floatformat_i387_ext_is_valid(const struct floatformat * fmt,const void * from)174 floatformat_i387_ext_is_valid (const struct floatformat *fmt, const void *from)
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;
181 const unsigned char *ufrom = (const unsigned char *) from;
182
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);
187
188 if ((exponent == 0) != (int_bit == 0))
189 return 0;
190 else
191 return 1;
192 }
193
194 const struct floatformat floatformat_i387_ext =
195 {
196 floatformat_little, 80, 0, 1, 15, 0x3fff, 0x7fff, 16, 64,
197 floatformat_intbit_yes,
198 "floatformat_i387_ext",
199 floatformat_i387_ext_is_valid,
200 NULL
201 };
202 const struct floatformat floatformat_m68881_ext =
203 {
204 /* Note that the bits from 16 to 31 are unused. */
205 floatformat_big, 96, 0, 1, 15, 0x3fff, 0x7fff, 32, 64,
206 floatformat_intbit_yes,
207 "floatformat_m68881_ext",
208 floatformat_always_valid,
209 NULL
210 };
211 const 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,
215 floatformat_intbit_yes,
216 "floatformat_i960_ext",
217 floatformat_always_valid,
218 NULL
219 };
220 const struct floatformat floatformat_m88110_ext =
221 {
222 floatformat_big, 80, 0, 1, 15, 0x3fff, 0x7fff, 16, 64,
223 floatformat_intbit_yes,
224 "floatformat_m88110_ext",
225 floatformat_always_valid,
226 NULL
227 };
228 const struct floatformat floatformat_m88110_harris_ext =
229 {
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,
233 floatformat_intbit_no,
234 "floatformat_m88110_ext_harris",
235 floatformat_always_valid,
236 NULL
237 };
238 const 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,
243 "floatformat_arm_ext_big",
244 floatformat_always_valid,
245 NULL
246 };
247 const 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,
252 "floatformat_arm_ext_littlebyte_bigword",
253 floatformat_always_valid,
254 NULL
255 };
256 const struct floatformat floatformat_ia64_spill_big =
257 {
258 floatformat_big, 128, 0, 1, 17, 65535, 0x1ffff, 18, 64,
259 floatformat_intbit_yes,
260 "floatformat_ia64_spill_big",
261 floatformat_always_valid,
262 NULL
263 };
264 const struct floatformat floatformat_ia64_spill_little =
265 {
266 floatformat_little, 128, 0, 1, 17, 65535, 0x1ffff, 18, 64,
267 floatformat_intbit_yes,
268 "floatformat_ia64_spill_little",
269 floatformat_always_valid,
270 NULL
271 };
272 const struct floatformat floatformat_ia64_quad_big =
273 {
274 floatformat_big, 128, 0, 1, 15, 16383, 0x7fff, 16, 112,
275 floatformat_intbit_no,
276 "floatformat_ia64_quad_big",
277 floatformat_always_valid,
278 NULL
279 };
280 const struct floatformat floatformat_ia64_quad_little =
281 {
282 floatformat_little, 128, 0, 1, 15, 16383, 0x7fff, 16, 112,
283 floatformat_intbit_no,
284 "floatformat_ia64_quad_little",
285 floatformat_always_valid,
286 NULL
287 };
288
289 static int
floatformat_ibm_long_double_is_valid(const struct floatformat * fmt,const void * from)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
394 #ifndef min
395 #define min(a, b) ((a) < (b) ? (a) : (b))
396 #endif
397
398 /* Return 1 if any bits are explicitly set in the mantissa of UFROM,
399 format FMT, 0 otherwise. */
400 static int
mant_bits_set(const struct floatformat * fmt,const unsigned char * ufrom)401 mant_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
422 /* Extract a field which starts at START and is LEN bits long. DATA and
423 TOTAL_LEN are the thing we are extracting it from, in byteorder ORDER. */
424 static unsigned long
get_field(const unsigned char * data,enum floatformat_byteorders order,unsigned int total_len,unsigned int start,unsigned int len)425 get_field (const unsigned char *data, enum floatformat_byteorders order,
426 unsigned int total_len, unsigned int start, unsigned int len)
427 {
428 unsigned long result = 0;
429 unsigned int cur_byte;
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);
435
436 /* Start at the least significant part of the field. */
437 if (order == floatformat_little)
438 cur_byte = start / FLOATFORMAT_CHAR_BIT;
439 else
440 cur_byte = (total_len - start - 1) / FLOATFORMAT_CHAR_BIT;
441
442 lo_bit = start % FLOATFORMAT_CHAR_BIT;
443 hi_bit = min (lo_bit + len, FLOATFORMAT_CHAR_BIT);
444
445 do
446 {
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);
456 }
457 while (len != 0);
458
459 return result;
460 }
461
462 /* Convert from FMT to a double.
463 FROM is the address of the extended float.
464 Store the double in *TO. */
465
466 void
floatformat_to_double(const struct floatformat * fmt,const void * from,double * to)467 floatformat_to_double (const struct floatformat *fmt,
468 const void *from, double *to)
469 {
470 const unsigned char *ufrom = (const unsigned char *) from;
471 double dto;
472 long exponent;
473 unsigned long mant;
474 unsigned int mant_bits, mant_off;
475 int mant_bits_left;
476
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
481 exponent = get_field (ufrom, fmt->byteorder, fmt->totalsize,
482 fmt->exp_start, fmt->exp_len);
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 {
489 int nan = mant_bits_set (fmt, ufrom);
490
491 /* On certain systems (such as GNU/Linux), the use of the
492 INFINITY macro below may generate a warning that cannot be
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. */
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 }
510
511 mant_bits_left = fmt->man_len;
512 mant_off = fmt->man_start;
513 dto = 0.0;
514
515 /* Build the result algebraically. Might go infinite, underflow, etc;
516 who cares. */
517
518 /* For denorms use minimum exponent. */
519 if (exponent == 0)
520 exponent = 1 - fmt->exp_bias;
521 else
522 {
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
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
542 dto += ldexp ((double) mant, exponent - mant_bits);
543 exponent -= mant_bits;
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
554 static void put_field (unsigned char *, enum floatformat_byteorders,
555 unsigned int,
556 unsigned int,
557 unsigned int,
558 unsigned long);
559
560 /* Set a field which starts at START and is LEN bits long. DATA and
561 TOTAL_LEN are the thing we are extracting it from, in byteorder ORDER. */
562 static void
put_field(unsigned char * data,enum floatformat_byteorders order,unsigned int total_len,unsigned int start,unsigned int len,unsigned long stuff_to_put)563 put_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)
566 {
567 unsigned int cur_byte;
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);
573
574 /* Start at the least significant part of the field. */
575 if (order == floatformat_little)
576 cur_byte = start / FLOATFORMAT_CHAR_BIT;
577 else
578 cur_byte = (total_len - start - 1) / FLOATFORMAT_CHAR_BIT;
579
580 lo_bit = start % FLOATFORMAT_CHAR_BIT;
581 hi_bit = min (lo_bit + len, FLOATFORMAT_CHAR_BIT);
582
583 do
584 {
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);
594 }
595 while (len != 0);
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
602 void
floatformat_from_double(const struct floatformat * fmt,const double * from,void * to)603 floatformat_from_double (const struct floatformat *fmt,
604 const double *from, void *to)
605 {
606 double dfrom;
607 int exponent;
608 double mant;
609 unsigned int mant_bits, mant_off;
610 int mant_bits_left;
611 unsigned char *uto = (unsigned char *) to;
612
613 dfrom = *from;
614 memset (uto, 0, fmt->totalsize / FLOATFORMAT_CHAR_BIT);
615
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
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
627 if (dfrom == 0)
628 {
629 /* 0.0. */
630 return;
631 }
632
633 if (dfrom != dfrom)
634 {
635 /* NaN. */
636 put_field (uto, fmt->byteorder, fmt->totalsize, fmt->exp_start,
637 fmt->exp_len, fmt->exp_nan);
638 /* Be sure it's not infinity, but NaN value is irrelevant. */
639 put_field (uto, fmt->byteorder, fmt->totalsize, fmt->man_start,
640 32, 1);
641 return;
642 }
643
644 if (dfrom + dfrom == dfrom)
645 {
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;
651 }
652
653 mant = frexp (dfrom, &exponent);
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 }
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
677 /* If the integer bit is implicit, and we are not creating a
678 denormalized number, then we need to discard it. */
679 if ((unsigned int) mant_bits_left == fmt->man_len
680 && fmt->intbit == floatformat_intbit_no
681 && exponent + fmt->exp_bias - 1 > 0)
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
700 /* Return non-zero iff the data at FROM is a valid number in format FMT. */
701
702 int
floatformat_is_valid(const struct floatformat * fmt,const void * from)703 floatformat_is_valid (const struct floatformat *fmt, const void *from)
704 {
705 return fmt->is_valid (fmt, from);
706 }
707
708
709 #ifdef IEEE_DEBUG
710
711 #include <stdio.h>
712
713 /* This is to be run on a host which uses IEEE floating point. */
714
715 void
ieee_test(double n)716 ieee_test (double n)
717 {
718 double result;
719
720 floatformat_to_double (&floatformat_ieee_double_little, &n, &result);
721 if ((n != result && (! isnan (n) || ! isnan (result)))
722 || (n < 0 && result >= 0)
723 || (n >= 0 && result < 0))
724 printf ("Differ(to): %.20g -> %.20g\n", n, result);
725
726 floatformat_from_double (&floatformat_ieee_double_little, &n, &result);
727 if ((n != result && (! isnan (n) || ! isnan (result)))
728 || (n < 0 && result >= 0)
729 || (n >= 0 && result < 0))
730 printf ("Differ(from): %.20g -> %.20g\n", n, result);
731
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
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
753 int
main(void)754 main (void)
755 {
756 ieee_test (0.0);
757 ieee_test (0.5);
758 ieee_test (1.1);
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);
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);
773 return 0;
774 }
775 #endif
776