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28e9041c 1/* IEEE floating point support routines, for GDB, the GNU Debugger.
fbd26352 2 Copyright (C) 1991-2019 Free Software Foundation, Inc.
28e9041c 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
95b8d1bc 18Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA. */
28e9041c 19
fa152dff 20/* This is needed to pick up the NAN macro on some systems. */
19ecc7c1 21#ifndef _GNU_SOURCE
fa152dff 22#define _GNU_SOURCE
19ecc7c1 23#endif
fa152dff 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
a975d4e0 35/* On some platforms, <float.h> provides DBL_QNAN. */
36#ifdef STDC_HEADERS
37#include <float.h>
38#endif
39
ca3ccdf6 40#include "ansidecl.h"
fa152dff 41#include "libiberty.h"
28e9041c 42#include "floatformat.h"
fa152dff 43
44#ifndef INFINITY
45#ifdef HUGE_VAL
46#define INFINITY HUGE_VAL
28e9041c 47#else
fa152dff 48#define INFINITY (1.0 / 0.0)
49#endif
50#endif
51
52#ifndef NAN
a975d4e0 53#ifdef DBL_QNAN
54#define NAN DBL_QNAN
55#else
fa152dff 56#define NAN (0.0 / 0.0)
28e9041c 57#endif
a975d4e0 58#endif
28e9041c 59
4d403838 60static int mant_bits_set (const struct floatformat *, const unsigned char *);
8858115e 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,
5a929093 67 const void *from);
63cb126c 68
69static int
8858115e 70floatformat_always_valid (const struct floatformat *fmt ATTRIBUTE_UNUSED,
5a929093 71 const void *from ATTRIBUTE_UNUSED)
63cb126c 72{
73 return 1;
74}
75
28e9041c 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
b2d17628 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};
28e9041c 98const struct floatformat floatformat_ieee_single_big =
99{
b5495c1d 100 floatformat_big, 32, 0, 1, 8, 127, 255, 9, 23,
101 floatformat_intbit_no,
63cb126c 102 "floatformat_ieee_single_big",
4d403838 103 floatformat_always_valid,
104 NULL
28e9041c 105};
106const struct floatformat floatformat_ieee_single_little =
107{
b5495c1d 108 floatformat_little, 32, 0, 1, 8, 127, 255, 9, 23,
109 floatformat_intbit_no,
63cb126c 110 "floatformat_ieee_single_little",
4d403838 111 floatformat_always_valid,
112 NULL
28e9041c 113};
114const struct floatformat floatformat_ieee_double_big =
115{
b5495c1d 116 floatformat_big, 64, 0, 1, 11, 1023, 2047, 12, 52,
117 floatformat_intbit_no,
63cb126c 118 "floatformat_ieee_double_big",
4d403838 119 floatformat_always_valid,
120 NULL
28e9041c 121};
122const struct floatformat floatformat_ieee_double_little =
123{
b5495c1d 124 floatformat_little, 64, 0, 1, 11, 1023, 2047, 12, 52,
125 floatformat_intbit_no,
63cb126c 126 "floatformat_ieee_double_little",
4d403838 127 floatformat_always_valid,
128 NULL
28e9041c 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{
b5495c1d 136 floatformat_littlebyte_bigword, 64, 0, 1, 11, 1023, 2047, 12, 52,
137 floatformat_intbit_no,
63cb126c 138 "floatformat_ieee_double_littlebyte_bigword",
4d403838 139 floatformat_always_valid,
140 NULL
28e9041c 141};
142
c38d39c9 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",
4d403838 150 floatformat_always_valid,
151 NULL
c38d39c9 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",
4d403838 158 floatformat_always_valid,
159 NULL
c38d39c9 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",
4d403838 166 floatformat_always_valid,
167 NULL
c38d39c9 168};
169
5a929093 170static int floatformat_i387_ext_is_valid (const struct floatformat *fmt,
171 const void *from);
63cb126c 172
173static int
5a929093 174floatformat_i387_ext_is_valid (const struct floatformat *fmt, const void *from)
63cb126c 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;
0ff8da43 181 const unsigned char *ufrom = (const unsigned char *) from;
5a929093 182
63cb126c 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);
5a929093 187
63cb126c 188 if ((exponent == 0) != (int_bit == 0))
189 return 0;
190 else
191 return 1;
192}
193
28e9041c 194const struct floatformat floatformat_i387_ext =
195{
196 floatformat_little, 80, 0, 1, 15, 0x3fff, 0x7fff, 16, 64,
b5495c1d 197 floatformat_intbit_yes,
63cb126c 198 "floatformat_i387_ext",
4d403838 199 floatformat_i387_ext_is_valid,
200 NULL
28e9041c 201};
202const struct floatformat floatformat_m68881_ext =
203{
204 /* Note that the bits from 16 to 31 are unused. */
b5495c1d 205 floatformat_big, 96, 0, 1, 15, 0x3fff, 0x7fff, 32, 64,
206 floatformat_intbit_yes,
63cb126c 207 "floatformat_m68881_ext",
4d403838 208 floatformat_always_valid,
209 NULL
28e9041c 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,
b5495c1d 215 floatformat_intbit_yes,
63cb126c 216 "floatformat_i960_ext",
4d403838 217 floatformat_always_valid,
218 NULL
28e9041c 219};
220const struct floatformat floatformat_m88110_ext =
221{
95f0a124 222 floatformat_big, 80, 0, 1, 15, 0x3fff, 0x7fff, 16, 64,
223 floatformat_intbit_yes,
63cb126c 224 "floatformat_m88110_ext",
4d403838 225 floatformat_always_valid,
226 NULL
95f0a124 227};
228const struct floatformat floatformat_m88110_harris_ext =
229{
28e9041c 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,
b5495c1d 233 floatformat_intbit_no,
63cb126c 234 "floatformat_m88110_ext_harris",
4d403838 235 floatformat_always_valid,
236 NULL
28e9041c 237};
95f0a124 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,
63cb126c 243 "floatformat_arm_ext_big",
4d403838 244 floatformat_always_valid,
245 NULL
95f0a124 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,
63cb126c 252 "floatformat_arm_ext_littlebyte_bigword",
4d403838 253 floatformat_always_valid,
254 NULL
95f0a124 255};
256const struct floatformat floatformat_ia64_spill_big =
257{
258 floatformat_big, 128, 0, 1, 17, 65535, 0x1ffff, 18, 64,
259 floatformat_intbit_yes,
63cb126c 260 "floatformat_ia64_spill_big",
4d403838 261 floatformat_always_valid,
262 NULL
95f0a124 263};
264const struct floatformat floatformat_ia64_spill_little =
265{
266 floatformat_little, 128, 0, 1, 17, 65535, 0x1ffff, 18, 64,
267 floatformat_intbit_yes,
63cb126c 268 "floatformat_ia64_spill_little",
4d403838 269 floatformat_always_valid,
270 NULL
95f0a124 271};
272const struct floatformat floatformat_ia64_quad_big =
273{
274 floatformat_big, 128, 0, 1, 15, 16383, 0x7fff, 16, 112,
275 floatformat_intbit_no,
63cb126c 276 "floatformat_ia64_quad_big",
4d403838 277 floatformat_always_valid,
278 NULL
95f0a124 279};
280const struct floatformat floatformat_ia64_quad_little =
281{
282 floatformat_little, 128, 0, 1, 15, 16383, 0x7fff, 16, 112,
283 floatformat_intbit_no,
63cb126c 284 "floatformat_ia64_quad_little",
4d403838 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
fc8211b7 303 if ((unsigned long) top_exp == hfmt->exp_nan)
4d403838 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). */
fc8211b7 312 if ((unsigned long) top_exp == hfmt->exp_nan || top_exp == 0)
4d403838 313 {
4d403838 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;
fc8211b7 335 for (cur_bit = 0; (unsigned int) cur_bit < hfmt->man_len; cur_bit++)
4d403838 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
6d69d407 375const struct floatformat floatformat_ibm_long_double_big =
4d403838 376{
377 floatformat_big, 128, 0, 1, 11, 1023, 2047, 12, 52,
378 floatformat_intbit_no,
6d69d407 379 "floatformat_ibm_long_double_big",
fc8211b7 380 floatformat_ibm_long_double_is_valid,
4d403838 381 &floatformat_ieee_double_big
95f0a124 382};
6d69d407 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};
28e9041c 392\f
58163c09 393
394#ifndef min
395#define min(a, b) ((a) < (b) ? (a) : (b))
396#endif
397
4d403838 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
8109b385 422/* Extract a field which starts at START and is LEN bits long. DATA and
28e9041c 423 TOTAL_LEN are the thing we are extracting it from, in byteorder ORDER. */
424static unsigned long
8858115e 425get_field (const unsigned char *data, enum floatformat_byteorders order,
426 unsigned int total_len, unsigned int start, unsigned int len)
28e9041c 427{
58163c09 428 unsigned long result = 0;
28e9041c 429 unsigned int cur_byte;
58163c09 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);
28e9041c 435
436 /* Start at the least significant part of the field. */
28e9041c 437 if (order == floatformat_little)
58163c09 438 cur_byte = start / FLOATFORMAT_CHAR_BIT;
28e9041c 439 else
58163c09 440 cur_byte = (total_len - start - 1) / FLOATFORMAT_CHAR_BIT;
28e9041c 441
58163c09 442 lo_bit = start % FLOATFORMAT_CHAR_BIT;
443 hi_bit = min (lo_bit + len, FLOATFORMAT_CHAR_BIT);
444
445 do
28e9041c 446 {
58163c09 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);
28e9041c 456 }
58163c09 457 while (len != 0);
458
28e9041c 459 return result;
460}
461
28e9041c 462/* Convert from FMT to a double.
463 FROM is the address of the extended float.
464 Store the double in *TO. */
465
466void
8858115e 467floatformat_to_double (const struct floatformat *fmt,
5a929093 468 const void *from, double *to)
28e9041c 469{
0ff8da43 470 const unsigned char *ufrom = (const unsigned char *) from;
28e9041c 471 double dto;
472 long exponent;
473 unsigned long mant;
474 unsigned int mant_bits, mant_off;
475 int mant_bits_left;
28e9041c 476
4d403838 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
28e9041c 481 exponent = get_field (ufrom, fmt->byteorder, fmt->totalsize,
482 fmt->exp_start, fmt->exp_len);
fa152dff 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 {
4d403838 489 int nan = mant_bits_set (fmt, ufrom);
fa152dff 490
88618d58 491 /* On certain systems (such as GNU/Linux), the use of the
130bd651 492 INFINITY macro below may generate a warning that cannot be
88618d58 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. */
fa152dff 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 }
28e9041c 510
511 mant_bits_left = fmt->man_len;
512 mant_off = fmt->man_start;
513 dto = 0.0;
514
28e9041c 515 /* Build the result algebraically. Might go infinite, underflow, etc;
516 who cares. */
517
660ea833 518 /* For denorms use minimum exponent. */
519 if (exponent == 0)
520 exponent = 1 - fmt->exp_bias;
521 else
7c8c70e9 522 {
660ea833 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
7c8c70e9 529 if (fmt->intbit == floatformat_intbit_no)
530 dto = ldexp (1.0, exponent);
531 else
532 exponent++;
533 }
28e9041c 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
660ea833 542 dto += ldexp ((double) mant, exponent - mant_bits);
543 exponent -= mant_bits;
28e9041c 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
8858115e 554static void put_field (unsigned char *, enum floatformat_byteorders,
555 unsigned int,
556 unsigned int,
557 unsigned int,
558 unsigned long);
28e9041c 559
8109b385 560/* Set a field which starts at START and is LEN bits long. DATA and
28e9041c 561 TOTAL_LEN are the thing we are extracting it from, in byteorder ORDER. */
562static void
8858115e 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)
28e9041c 566{
567 unsigned int cur_byte;
58163c09 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);
28e9041c 573
574 /* Start at the least significant part of the field. */
28e9041c 575 if (order == floatformat_little)
58163c09 576 cur_byte = start / FLOATFORMAT_CHAR_BIT;
28e9041c 577 else
58163c09 578 cur_byte = (total_len - start - 1) / FLOATFORMAT_CHAR_BIT;
28e9041c 579
58163c09 580 lo_bit = start % FLOATFORMAT_CHAR_BIT;
581 hi_bit = min (lo_bit + len, FLOATFORMAT_CHAR_BIT);
582
583 do
28e9041c 584 {
58163c09 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);
28e9041c 594 }
58163c09 595 while (len != 0);
28e9041c 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
8858115e 603floatformat_from_double (const struct floatformat *fmt,
5a929093 604 const double *from, void *to)
28e9041c 605{
606 double dfrom;
607 int exponent;
608 double mant;
609 unsigned int mant_bits, mant_off;
610 int mant_bits_left;
0ff8da43 611 unsigned char *uto = (unsigned char *) to;
28e9041c 612
fa152dff 613 dfrom = *from;
28e9041c 614 memset (uto, 0, fmt->totalsize / FLOATFORMAT_CHAR_BIT);
fa152dff 615
4d403838 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
fa152dff 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
28e9041c 627 if (dfrom == 0)
fa152dff 628 {
629 /* 0.0. */
630 return;
631 }
632
28e9041c 633 if (dfrom != dfrom)
634 {
fa152dff 635 /* NaN. */
28e9041c 636 put_field (uto, fmt->byteorder, fmt->totalsize, fmt->exp_start,
637 fmt->exp_len, fmt->exp_nan);
fa152dff 638 /* Be sure it's not infinity, but NaN value is irrelevant. */
28e9041c 639 put_field (uto, fmt->byteorder, fmt->totalsize, fmt->man_start,
640 32, 1);
641 return;
642 }
643
fa152dff 644 if (dfrom + dfrom == dfrom)
28e9041c 645 {
fa152dff 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;
28e9041c 651 }
652
28e9041c 653 mant = frexp (dfrom, &exponent);
fa152dff 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 }
28e9041c 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
fa152dff 677 /* If the integer bit is implicit, and we are not creating a
678 denormalized number, then we need to discard it. */
1f33a375 679 if ((unsigned int) mant_bits_left == fmt->man_len
fa152dff 680 && fmt->intbit == floatformat_intbit_no
681 && exponent + fmt->exp_bias - 1 > 0)
28e9041c 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
8109b385 700/* Return non-zero iff the data at FROM is a valid number in format FMT. */
701
702int
5a929093 703floatformat_is_valid (const struct floatformat *fmt, const void *from)
8109b385 704{
63cb126c 705 return fmt->is_valid (fmt, from);
8109b385 706}
707
28e9041c 708
709#ifdef IEEE_DEBUG
710
fa152dff 711#include <stdio.h>
712
28e9041c 713/* This is to be run on a host which uses IEEE floating point. */
714
715void
8858115e 716ieee_test (double n)
28e9041c 717{
718 double result;
28e9041c 719
5a929093 720 floatformat_to_double (&floatformat_ieee_double_little, &n, &result);
fa152dff 721 if ((n != result && (! isnan (n) || ! isnan (result)))
722 || (n < 0 && result >= 0)
723 || (n >= 0 && result < 0))
28e9041c 724 printf ("Differ(to): %.20g -> %.20g\n", n, result);
fa152dff 725
5a929093 726 floatformat_from_double (&floatformat_ieee_double_little, &n, &result);
fa152dff 727 if ((n != result && (! isnan (n) || ! isnan (result)))
728 || (n < 0 && result >= 0)
729 || (n >= 0 && result < 0))
28e9041c 730 printf ("Differ(from): %.20g -> %.20g\n", n, result);
731
fa152dff 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
28e9041c 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
8858115e 754main (void)
28e9041c 755{
fa152dff 756 ieee_test (0.0);
28e9041c 757 ieee_test (0.5);
660ea833 758 ieee_test (1.1);
28e9041c 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);
fa152dff 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);
28e9041c 773 return 0;
774}
775#endif