libiberty: Add -Wshadow=local to warning flags (if supported).
[deliverable/binutils-gdb.git] / libiberty / floatformat.c
CommitLineData
252b5132 1/* IEEE floating point support routines, for GDB, the GNU Debugger.
f91ca6bc 2 Copyright 1991, 1994, 1999, 2000, 2003, 2005, 2006, 2010, 2012, 2015
3b6940c0 3 Free Software Foundation, Inc.
252b5132
RH
4
5This file is part of GDB.
6
7This program is free software; you can redistribute it and/or modify
8it under the terms of the GNU General Public License as published by
9the Free Software Foundation; either version 2 of the License, or
10(at your option) any later version.
11
12This program is distributed in the hope that it will be useful,
13but WITHOUT ANY WARRANTY; without even the implied warranty of
14MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15GNU General Public License for more details.
16
17You should have received a copy of the GNU General Public License
18along with this program; if not, write to the Free Software
979c05d3 19Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA. */
252b5132 20
b52927b7 21/* This is needed to pick up the NAN macro on some systems. */
f91ca6bc 22#ifndef _GNU_SOURCE
b52927b7 23#define _GNU_SOURCE
f91ca6bc 24#endif
b52927b7
DD
25
26#ifdef HAVE_CONFIG_H
27#include "config.h"
28#endif
29
30#include <math.h>
31
32#ifdef HAVE_STRING_H
33#include <string.h>
34#endif
35
e27d251e
DD
36/* On some platforms, <float.h> provides DBL_QNAN. */
37#ifdef STDC_HEADERS
38#include <float.h>
39#endif
40
1ea16ec5 41#include "ansidecl.h"
b52927b7 42#include "libiberty.h"
252b5132 43#include "floatformat.h"
b52927b7
DD
44
45#ifndef INFINITY
46#ifdef HUGE_VAL
47#define INFINITY HUGE_VAL
252b5132 48#else
b52927b7
DD
49#define INFINITY (1.0 / 0.0)
50#endif
51#endif
52
53#ifndef NAN
e27d251e
DD
54#ifdef DBL_QNAN
55#define NAN DBL_QNAN
56#else
b52927b7 57#define NAN (0.0 / 0.0)
252b5132 58#endif
e27d251e 59#endif
252b5132 60
b14d30e1 61static int mant_bits_set (const struct floatformat *, const unsigned char *);
49b1fae4
DD
62static unsigned long get_field (const unsigned char *,
63 enum floatformat_byteorders,
64 unsigned int,
65 unsigned int,
66 unsigned int);
67static int floatformat_always_valid (const struct floatformat *fmt,
3b6940c0 68 const void *from);
5324d185
AC
69
70static int
49b1fae4 71floatformat_always_valid (const struct floatformat *fmt ATTRIBUTE_UNUSED,
3b6940c0 72 const void *from ATTRIBUTE_UNUSED)
5324d185
AC
73{
74 return 1;
75}
76
252b5132
RH
77/* The odds that CHAR_BIT will be anything but 8 are low enough that I'm not
78 going to bother with trying to muck around with whether it is defined in
79 a system header, what we do if not, etc. */
80#define FLOATFORMAT_CHAR_BIT 8
81
f9e9243a
UW
82/* floatformats for IEEE half, single and double, big and little endian. */
83const struct floatformat floatformat_ieee_half_big =
84{
85 floatformat_big, 16, 0, 1, 5, 15, 31, 6, 10,
86 floatformat_intbit_no,
87 "floatformat_ieee_half_big",
88 floatformat_always_valid,
89 NULL
90};
91const struct floatformat floatformat_ieee_half_little =
92{
93 floatformat_little, 16, 0, 1, 5, 15, 31, 6, 10,
94 floatformat_intbit_no,
95 "floatformat_ieee_half_little",
96 floatformat_always_valid,
97 NULL
98};
252b5132
RH
99const struct floatformat floatformat_ieee_single_big =
100{
f03aa80d
AC
101 floatformat_big, 32, 0, 1, 8, 127, 255, 9, 23,
102 floatformat_intbit_no,
5324d185 103 "floatformat_ieee_single_big",
b14d30e1
JM
104 floatformat_always_valid,
105 NULL
252b5132
RH
106};
107const struct floatformat floatformat_ieee_single_little =
108{
f03aa80d
AC
109 floatformat_little, 32, 0, 1, 8, 127, 255, 9, 23,
110 floatformat_intbit_no,
5324d185 111 "floatformat_ieee_single_little",
b14d30e1
JM
112 floatformat_always_valid,
113 NULL
252b5132
RH
114};
115const struct floatformat floatformat_ieee_double_big =
116{
f03aa80d
AC
117 floatformat_big, 64, 0, 1, 11, 1023, 2047, 12, 52,
118 floatformat_intbit_no,
5324d185 119 "floatformat_ieee_double_big",
b14d30e1
JM
120 floatformat_always_valid,
121 NULL
252b5132
RH
122};
123const struct floatformat floatformat_ieee_double_little =
124{
f03aa80d
AC
125 floatformat_little, 64, 0, 1, 11, 1023, 2047, 12, 52,
126 floatformat_intbit_no,
5324d185 127 "floatformat_ieee_double_little",
b14d30e1
JM
128 floatformat_always_valid,
129 NULL
252b5132
RH
130};
131
132/* floatformat for IEEE double, little endian byte order, with big endian word
133 ordering, as on the ARM. */
134
135const struct floatformat floatformat_ieee_double_littlebyte_bigword =
136{
f03aa80d
AC
137 floatformat_littlebyte_bigword, 64, 0, 1, 11, 1023, 2047, 12, 52,
138 floatformat_intbit_no,
5324d185 139 "floatformat_ieee_double_littlebyte_bigword",
b14d30e1
JM
140 floatformat_always_valid,
141 NULL
252b5132
RH
142};
143
fb10537e
DD
144/* floatformat for VAX. Not quite IEEE, but close enough. */
145
146const struct floatformat floatformat_vax_f =
147{
148 floatformat_vax, 32, 0, 1, 8, 129, 0, 9, 23,
149 floatformat_intbit_no,
150 "floatformat_vax_f",
b14d30e1
JM
151 floatformat_always_valid,
152 NULL
fb10537e
DD
153};
154const struct floatformat floatformat_vax_d =
155{
156 floatformat_vax, 64, 0, 1, 8, 129, 0, 9, 55,
157 floatformat_intbit_no,
158 "floatformat_vax_d",
b14d30e1
JM
159 floatformat_always_valid,
160 NULL
fb10537e
DD
161};
162const struct floatformat floatformat_vax_g =
163{
164 floatformat_vax, 64, 0, 1, 11, 1025, 0, 12, 52,
165 floatformat_intbit_no,
166 "floatformat_vax_g",
b14d30e1
JM
167 floatformat_always_valid,
168 NULL
fb10537e
DD
169};
170
3b6940c0
DD
171static int floatformat_i387_ext_is_valid (const struct floatformat *fmt,
172 const void *from);
5324d185
AC
173
174static int
3b6940c0 175floatformat_i387_ext_is_valid (const struct floatformat *fmt, const void *from)
5324d185
AC
176{
177 /* In the i387 double-extended format, if the exponent is all ones,
178 then the integer bit must be set. If the exponent is neither 0
179 nor ~0, the intbit must also be set. Only if the exponent is
180 zero can it be zero, and then it must be zero. */
181 unsigned long exponent, int_bit;
648c3dc0 182 const unsigned char *ufrom = (const unsigned char *) from;
3b6940c0 183
5324d185
AC
184 exponent = get_field (ufrom, fmt->byteorder, fmt->totalsize,
185 fmt->exp_start, fmt->exp_len);
186 int_bit = get_field (ufrom, fmt->byteorder, fmt->totalsize,
187 fmt->man_start, 1);
3b6940c0 188
5324d185
AC
189 if ((exponent == 0) != (int_bit == 0))
190 return 0;
191 else
192 return 1;
193}
194
252b5132
RH
195const struct floatformat floatformat_i387_ext =
196{
197 floatformat_little, 80, 0, 1, 15, 0x3fff, 0x7fff, 16, 64,
f03aa80d 198 floatformat_intbit_yes,
5324d185 199 "floatformat_i387_ext",
b14d30e1
JM
200 floatformat_i387_ext_is_valid,
201 NULL
252b5132
RH
202};
203const struct floatformat floatformat_m68881_ext =
204{
205 /* Note that the bits from 16 to 31 are unused. */
f03aa80d
AC
206 floatformat_big, 96, 0, 1, 15, 0x3fff, 0x7fff, 32, 64,
207 floatformat_intbit_yes,
5324d185 208 "floatformat_m68881_ext",
b14d30e1
JM
209 floatformat_always_valid,
210 NULL
252b5132
RH
211};
212const struct floatformat floatformat_i960_ext =
213{
214 /* Note that the bits from 0 to 15 are unused. */
215 floatformat_little, 96, 16, 17, 15, 0x3fff, 0x7fff, 32, 64,
f03aa80d 216 floatformat_intbit_yes,
5324d185 217 "floatformat_i960_ext",
b14d30e1
JM
218 floatformat_always_valid,
219 NULL
252b5132
RH
220};
221const struct floatformat floatformat_m88110_ext =
222{
eb828599
AC
223 floatformat_big, 80, 0, 1, 15, 0x3fff, 0x7fff, 16, 64,
224 floatformat_intbit_yes,
5324d185 225 "floatformat_m88110_ext",
b14d30e1
JM
226 floatformat_always_valid,
227 NULL
eb828599
AC
228};
229const struct floatformat floatformat_m88110_harris_ext =
230{
252b5132
RH
231 /* Harris uses raw format 128 bytes long, but the number is just an ieee
232 double, and the last 64 bits are wasted. */
233 floatformat_big,128, 0, 1, 11, 0x3ff, 0x7ff, 12, 52,
f03aa80d 234 floatformat_intbit_no,
5324d185 235 "floatformat_m88110_ext_harris",
b14d30e1
JM
236 floatformat_always_valid,
237 NULL
252b5132 238};
eb828599
AC
239const struct floatformat floatformat_arm_ext_big =
240{
241 /* Bits 1 to 16 are unused. */
242 floatformat_big, 96, 0, 17, 15, 0x3fff, 0x7fff, 32, 64,
243 floatformat_intbit_yes,
5324d185 244 "floatformat_arm_ext_big",
b14d30e1
JM
245 floatformat_always_valid,
246 NULL
eb828599
AC
247};
248const struct floatformat floatformat_arm_ext_littlebyte_bigword =
249{
250 /* Bits 1 to 16 are unused. */
251 floatformat_littlebyte_bigword, 96, 0, 17, 15, 0x3fff, 0x7fff, 32, 64,
252 floatformat_intbit_yes,
5324d185 253 "floatformat_arm_ext_littlebyte_bigword",
b14d30e1
JM
254 floatformat_always_valid,
255 NULL
eb828599
AC
256};
257const struct floatformat floatformat_ia64_spill_big =
258{
259 floatformat_big, 128, 0, 1, 17, 65535, 0x1ffff, 18, 64,
260 floatformat_intbit_yes,
5324d185 261 "floatformat_ia64_spill_big",
b14d30e1
JM
262 floatformat_always_valid,
263 NULL
eb828599
AC
264};
265const struct floatformat floatformat_ia64_spill_little =
266{
267 floatformat_little, 128, 0, 1, 17, 65535, 0x1ffff, 18, 64,
268 floatformat_intbit_yes,
5324d185 269 "floatformat_ia64_spill_little",
b14d30e1
JM
270 floatformat_always_valid,
271 NULL
eb828599
AC
272};
273const struct floatformat floatformat_ia64_quad_big =
274{
275 floatformat_big, 128, 0, 1, 15, 16383, 0x7fff, 16, 112,
276 floatformat_intbit_no,
5324d185 277 "floatformat_ia64_quad_big",
b14d30e1
JM
278 floatformat_always_valid,
279 NULL
eb828599
AC
280};
281const struct floatformat floatformat_ia64_quad_little =
282{
283 floatformat_little, 128, 0, 1, 15, 16383, 0x7fff, 16, 112,
284 floatformat_intbit_no,
5324d185 285 "floatformat_ia64_quad_little",
b14d30e1
JM
286 floatformat_always_valid,
287 NULL
288};
289
290static int
291floatformat_ibm_long_double_is_valid (const struct floatformat *fmt,
292 const void *from)
293{
294 const unsigned char *ufrom = (const unsigned char *) from;
295 const struct floatformat *hfmt = fmt->split_half;
296 long top_exp, bot_exp;
297 int top_nan = 0;
298
299 top_exp = get_field (ufrom, hfmt->byteorder, hfmt->totalsize,
300 hfmt->exp_start, hfmt->exp_len);
301 bot_exp = get_field (ufrom + 8, hfmt->byteorder, hfmt->totalsize,
302 hfmt->exp_start, hfmt->exp_len);
303
38e654e2 304 if ((unsigned long) top_exp == hfmt->exp_nan)
b14d30e1
JM
305 top_nan = mant_bits_set (hfmt, ufrom);
306
307 /* A NaN is valid with any low part. */
308 if (top_nan)
309 return 1;
310
311 /* An infinity, zero or denormal requires low part 0 (positive or
312 negative). */
38e654e2 313 if ((unsigned long) top_exp == hfmt->exp_nan || top_exp == 0)
b14d30e1 314 {
b14d30e1
JM
315 if (bot_exp != 0)
316 return 0;
317
318 return !mant_bits_set (hfmt, ufrom + 8);
319 }
320
321 /* The top part is now a finite normal value. The long double value
322 is the sum of the two parts, and the top part must equal the
323 result of rounding the long double value to nearest double. Thus
324 the bottom part must be <= 0.5ulp of the top part in absolute
325 value, and if it is < 0.5ulp then the long double is definitely
326 valid. */
327 if (bot_exp < top_exp - 53)
328 return 1;
329 if (bot_exp > top_exp - 53 && bot_exp != 0)
330 return 0;
331 if (bot_exp == 0)
332 {
333 /* The bottom part is 0 or denormal. Determine which, and if
334 denormal the first two set bits. */
335 int first_bit = -1, second_bit = -1, cur_bit;
38e654e2 336 for (cur_bit = 0; (unsigned int) cur_bit < hfmt->man_len; cur_bit++)
b14d30e1
JM
337 if (get_field (ufrom + 8, hfmt->byteorder, hfmt->totalsize,
338 hfmt->man_start + cur_bit, 1))
339 {
340 if (first_bit == -1)
341 first_bit = cur_bit;
342 else
343 {
344 second_bit = cur_bit;
345 break;
346 }
347 }
348 /* Bottom part 0 is OK. */
349 if (first_bit == -1)
350 return 1;
351 /* The real exponent of the bottom part is -first_bit. */
352 if (-first_bit < top_exp - 53)
353 return 1;
354 if (-first_bit > top_exp - 53)
355 return 0;
356 /* The bottom part is at least 0.5ulp of the top part. For this
357 to be OK, the bottom part must be exactly 0.5ulp (i.e. no
358 more bits set) and the top part must have last bit 0. */
359 if (second_bit != -1)
360 return 0;
361 return !get_field (ufrom, hfmt->byteorder, hfmt->totalsize,
362 hfmt->man_start + hfmt->man_len - 1, 1);
363 }
364 else
365 {
366 /* The bottom part is at least 0.5ulp of the top part. For this
367 to be OK, it must be exactly 0.5ulp (i.e. no explicit bits
368 set) and the top part must have last bit 0. */
369 if (get_field (ufrom, hfmt->byteorder, hfmt->totalsize,
370 hfmt->man_start + hfmt->man_len - 1, 1))
371 return 0;
372 return !mant_bits_set (hfmt, ufrom + 8);
373 }
374}
375
21290977 376const struct floatformat floatformat_ibm_long_double_big =
b14d30e1
JM
377{
378 floatformat_big, 128, 0, 1, 11, 1023, 2047, 12, 52,
379 floatformat_intbit_no,
21290977 380 "floatformat_ibm_long_double_big",
38e654e2 381 floatformat_ibm_long_double_is_valid,
b14d30e1 382 &floatformat_ieee_double_big
eb828599 383};
21290977
DD
384
385const struct floatformat floatformat_ibm_long_double_little =
386{
387 floatformat_little, 128, 0, 1, 11, 1023, 2047, 12, 52,
388 floatformat_intbit_no,
389 "floatformat_ibm_long_double_little",
390 floatformat_ibm_long_double_is_valid,
391 &floatformat_ieee_double_little
392};
252b5132 393\f
9e59254c
JB
394
395#ifndef min
396#define min(a, b) ((a) < (b) ? (a) : (b))
397#endif
398
b14d30e1
JM
399/* Return 1 if any bits are explicitly set in the mantissa of UFROM,
400 format FMT, 0 otherwise. */
401static int
402mant_bits_set (const struct floatformat *fmt, const unsigned char *ufrom)
403{
404 unsigned int mant_bits, mant_off;
405 int mant_bits_left;
406
407 mant_off = fmt->man_start;
408 mant_bits_left = fmt->man_len;
409 while (mant_bits_left > 0)
410 {
411 mant_bits = min (mant_bits_left, 32);
412
413 if (get_field (ufrom, fmt->byteorder, fmt->totalsize,
414 mant_off, mant_bits) != 0)
415 return 1;
416
417 mant_off += mant_bits;
418 mant_bits_left -= mant_bits;
419 }
420 return 0;
421}
422
3f2aacaf 423/* Extract a field which starts at START and is LEN bits long. DATA and
252b5132
RH
424 TOTAL_LEN are the thing we are extracting it from, in byteorder ORDER. */
425static unsigned long
49b1fae4
DD
426get_field (const unsigned char *data, enum floatformat_byteorders order,
427 unsigned int total_len, unsigned int start, unsigned int len)
252b5132 428{
9e59254c 429 unsigned long result = 0;
252b5132 430 unsigned int cur_byte;
9e59254c
JB
431 int lo_bit, hi_bit, cur_bitshift = 0;
432 int nextbyte = (order == floatformat_little) ? 1 : -1;
433
434 /* Start is in big-endian bit order! Fix that first. */
435 start = total_len - (start + len);
252b5132
RH
436
437 /* Start at the least significant part of the field. */
252b5132 438 if (order == floatformat_little)
9e59254c 439 cur_byte = start / FLOATFORMAT_CHAR_BIT;
252b5132 440 else
9e59254c 441 cur_byte = (total_len - start - 1) / FLOATFORMAT_CHAR_BIT;
252b5132 442
9e59254c
JB
443 lo_bit = start % FLOATFORMAT_CHAR_BIT;
444 hi_bit = min (lo_bit + len, FLOATFORMAT_CHAR_BIT);
445
446 do
252b5132 447 {
9e59254c
JB
448 unsigned int shifted = *(data + cur_byte) >> lo_bit;
449 unsigned int bits = hi_bit - lo_bit;
450 unsigned int mask = (1 << bits) - 1;
451 result |= (shifted & mask) << cur_bitshift;
452 len -= bits;
453 cur_bitshift += bits;
454 cur_byte += nextbyte;
455 lo_bit = 0;
456 hi_bit = min (len, FLOATFORMAT_CHAR_BIT);
252b5132 457 }
9e59254c
JB
458 while (len != 0);
459
252b5132
RH
460 return result;
461}
462
252b5132
RH
463/* Convert from FMT to a double.
464 FROM is the address of the extended float.
465 Store the double in *TO. */
466
467void
49b1fae4 468floatformat_to_double (const struct floatformat *fmt,
3b6940c0 469 const void *from, double *to)
252b5132 470{
648c3dc0 471 const unsigned char *ufrom = (const unsigned char *) from;
252b5132
RH
472 double dto;
473 long exponent;
474 unsigned long mant;
475 unsigned int mant_bits, mant_off;
476 int mant_bits_left;
252b5132 477
b14d30e1
JM
478 /* Split values are not handled specially, since the top half has
479 the correctly rounded double value (in the only supported case of
480 split values). */
481
252b5132
RH
482 exponent = get_field (ufrom, fmt->byteorder, fmt->totalsize,
483 fmt->exp_start, fmt->exp_len);
b52927b7
DD
484
485 /* If the exponent indicates a NaN, we don't have information to
486 decide what to do. So we handle it like IEEE, except that we
487 don't try to preserve the type of NaN. FIXME. */
488 if ((unsigned long) exponent == fmt->exp_nan)
489 {
b14d30e1 490 int nan = mant_bits_set (fmt, ufrom);
b52927b7 491
f2942ea4
DD
492 /* On certain systems (such as GNU/Linux), the use of the
493 INFINITY macro below may generate a warning that can not be
494 silenced due to a bug in GCC (PR preprocessor/11931). The
495 preprocessor fails to recognise the __extension__ keyword in
496 conjunction with the GNU/C99 extension for hexadecimal
497 floating point constants and will issue a warning when
498 compiling with -pedantic. */
b52927b7
DD
499 if (nan)
500 dto = NAN;
501 else
502 dto = INFINITY;
503
504 if (get_field (ufrom, fmt->byteorder, fmt->totalsize, fmt->sign_start, 1))
505 dto = -dto;
506
507 *to = dto;
508
509 return;
510 }
252b5132
RH
511
512 mant_bits_left = fmt->man_len;
513 mant_off = fmt->man_start;
514 dto = 0.0;
515
252b5132
RH
516 /* Build the result algebraically. Might go infinite, underflow, etc;
517 who cares. */
518
e372c21c
AS
519 /* For denorms use minimum exponent. */
520 if (exponent == 0)
521 exponent = 1 - fmt->exp_bias;
522 else
252b5132 523 {
e372c21c
AS
524 exponent -= fmt->exp_bias;
525
526 /* If this format uses a hidden bit, explicitly add it in now.
527 Otherwise, increment the exponent by one to account for the
528 integer bit. */
529
252b5132
RH
530 if (fmt->intbit == floatformat_intbit_no)
531 dto = ldexp (1.0, exponent);
532 else
533 exponent++;
534 }
535
536 while (mant_bits_left > 0)
537 {
538 mant_bits = min (mant_bits_left, 32);
539
540 mant = get_field (ufrom, fmt->byteorder, fmt->totalsize,
541 mant_off, mant_bits);
542
e372c21c
AS
543 dto += ldexp ((double) mant, exponent - mant_bits);
544 exponent -= mant_bits;
252b5132
RH
545 mant_off += mant_bits;
546 mant_bits_left -= mant_bits;
547 }
548
549 /* Negate it if negative. */
550 if (get_field (ufrom, fmt->byteorder, fmt->totalsize, fmt->sign_start, 1))
551 dto = -dto;
552 *to = dto;
553}
554\f
49b1fae4
DD
555static void put_field (unsigned char *, enum floatformat_byteorders,
556 unsigned int,
557 unsigned int,
558 unsigned int,
559 unsigned long);
252b5132 560
3f2aacaf 561/* Set a field which starts at START and is LEN bits long. DATA and
252b5132
RH
562 TOTAL_LEN are the thing we are extracting it from, in byteorder ORDER. */
563static void
49b1fae4
DD
564put_field (unsigned char *data, enum floatformat_byteorders order,
565 unsigned int total_len, unsigned int start, unsigned int len,
566 unsigned long stuff_to_put)
252b5132
RH
567{
568 unsigned int cur_byte;
9e59254c
JB
569 int lo_bit, hi_bit;
570 int nextbyte = (order == floatformat_little) ? 1 : -1;
571
572 /* Start is in big-endian bit order! Fix that first. */
573 start = total_len - (start + len);
252b5132
RH
574
575 /* Start at the least significant part of the field. */
252b5132 576 if (order == floatformat_little)
9e59254c 577 cur_byte = start / FLOATFORMAT_CHAR_BIT;
252b5132 578 else
9e59254c 579 cur_byte = (total_len - start - 1) / FLOATFORMAT_CHAR_BIT;
252b5132 580
9e59254c
JB
581 lo_bit = start % FLOATFORMAT_CHAR_BIT;
582 hi_bit = min (lo_bit + len, FLOATFORMAT_CHAR_BIT);
583
584 do
252b5132 585 {
9e59254c
JB
586 unsigned char *byte_ptr = data + cur_byte;
587 unsigned int bits = hi_bit - lo_bit;
588 unsigned int mask = ((1 << bits) - 1) << lo_bit;
589 *byte_ptr = (*byte_ptr & ~mask) | ((stuff_to_put << lo_bit) & mask);
590 stuff_to_put >>= bits;
591 len -= bits;
592 cur_byte += nextbyte;
593 lo_bit = 0;
594 hi_bit = min (len, FLOATFORMAT_CHAR_BIT);
252b5132 595 }
9e59254c 596 while (len != 0);
252b5132
RH
597}
598
599/* The converse: convert the double *FROM to an extended float
600 and store where TO points. Neither FROM nor TO have any alignment
601 restrictions. */
602
603void
49b1fae4 604floatformat_from_double (const struct floatformat *fmt,
3b6940c0 605 const double *from, void *to)
252b5132
RH
606{
607 double dfrom;
608 int exponent;
609 double mant;
610 unsigned int mant_bits, mant_off;
611 int mant_bits_left;
648c3dc0 612 unsigned char *uto = (unsigned char *) to;
252b5132 613
b52927b7 614 dfrom = *from;
252b5132 615 memset (uto, 0, fmt->totalsize / FLOATFORMAT_CHAR_BIT);
b52927b7 616
b14d30e1
JM
617 /* Split values are not handled specially, since a bottom half of
618 zero is correct for any value representable as double (in the
619 only supported case of split values). */
620
b52927b7
DD
621 /* If negative, set the sign bit. */
622 if (dfrom < 0)
623 {
624 put_field (uto, fmt->byteorder, fmt->totalsize, fmt->sign_start, 1, 1);
625 dfrom = -dfrom;
626 }
627
252b5132 628 if (dfrom == 0)
b52927b7
DD
629 {
630 /* 0.0. */
631 return;
632 }
633
252b5132
RH
634 if (dfrom != dfrom)
635 {
b52927b7 636 /* NaN. */
252b5132
RH
637 put_field (uto, fmt->byteorder, fmt->totalsize, fmt->exp_start,
638 fmt->exp_len, fmt->exp_nan);
b52927b7 639 /* Be sure it's not infinity, but NaN value is irrelevant. */
252b5132
RH
640 put_field (uto, fmt->byteorder, fmt->totalsize, fmt->man_start,
641 32, 1);
642 return;
643 }
644
b52927b7 645 if (dfrom + dfrom == dfrom)
252b5132 646 {
b52927b7
DD
647 /* This can only happen for an infinite value (or zero, which we
648 already handled above). */
649 put_field (uto, fmt->byteorder, fmt->totalsize, fmt->exp_start,
650 fmt->exp_len, fmt->exp_nan);
651 return;
252b5132
RH
652 }
653
252b5132 654 mant = frexp (dfrom, &exponent);
b52927b7
DD
655 if (exponent + fmt->exp_bias - 1 > 0)
656 put_field (uto, fmt->byteorder, fmt->totalsize, fmt->exp_start,
657 fmt->exp_len, exponent + fmt->exp_bias - 1);
658 else
659 {
660 /* Handle a denormalized number. FIXME: What should we do for
661 non-IEEE formats? */
662 put_field (uto, fmt->byteorder, fmt->totalsize, fmt->exp_start,
663 fmt->exp_len, 0);
664 mant = ldexp (mant, exponent + fmt->exp_bias - 1);
665 }
252b5132
RH
666
667 mant_bits_left = fmt->man_len;
668 mant_off = fmt->man_start;
669 while (mant_bits_left > 0)
670 {
671 unsigned long mant_long;
672 mant_bits = mant_bits_left < 32 ? mant_bits_left : 32;
673
674 mant *= 4294967296.0;
675 mant_long = (unsigned long)mant;
676 mant -= mant_long;
677
b52927b7
DD
678 /* If the integer bit is implicit, and we are not creating a
679 denormalized number, then we need to discard it. */
08372f14 680 if ((unsigned int) mant_bits_left == fmt->man_len
b52927b7
DD
681 && fmt->intbit == floatformat_intbit_no
682 && exponent + fmt->exp_bias - 1 > 0)
252b5132
RH
683 {
684 mant_long &= 0x7fffffff;
685 mant_bits -= 1;
686 }
687 else if (mant_bits < 32)
688 {
689 /* The bits we want are in the most significant MANT_BITS bits of
690 mant_long. Move them to the least significant. */
691 mant_long >>= 32 - mant_bits;
692 }
693
694 put_field (uto, fmt->byteorder, fmt->totalsize,
695 mant_off, mant_bits, mant_long);
696 mant_off += mant_bits;
697 mant_bits_left -= mant_bits;
698 }
699}
700
3f2aacaf
DJ
701/* Return non-zero iff the data at FROM is a valid number in format FMT. */
702
703int
3b6940c0 704floatformat_is_valid (const struct floatformat *fmt, const void *from)
3f2aacaf 705{
5324d185 706 return fmt->is_valid (fmt, from);
3f2aacaf
DJ
707}
708
252b5132
RH
709
710#ifdef IEEE_DEBUG
711
b52927b7
DD
712#include <stdio.h>
713
252b5132
RH
714/* This is to be run on a host which uses IEEE floating point. */
715
716void
49b1fae4 717ieee_test (double n)
252b5132
RH
718{
719 double result;
252b5132 720
3b6940c0 721 floatformat_to_double (&floatformat_ieee_double_little, &n, &result);
b52927b7
DD
722 if ((n != result && (! isnan (n) || ! isnan (result)))
723 || (n < 0 && result >= 0)
724 || (n >= 0 && result < 0))
252b5132 725 printf ("Differ(to): %.20g -> %.20g\n", n, result);
b52927b7 726
3b6940c0 727 floatformat_from_double (&floatformat_ieee_double_little, &n, &result);
b52927b7
DD
728 if ((n != result && (! isnan (n) || ! isnan (result)))
729 || (n < 0 && result >= 0)
730 || (n >= 0 && result < 0))
252b5132
RH
731 printf ("Differ(from): %.20g -> %.20g\n", n, result);
732
b52927b7
DD
733#if 0
734 {
735 char exten[16];
736
737 floatformat_from_double (&floatformat_m68881_ext, &n, exten);
738 floatformat_to_double (&floatformat_m68881_ext, exten, &result);
739 if (n != result)
740 printf ("Differ(to+from): %.20g -> %.20g\n", n, result);
741 }
742#endif
252b5132
RH
743
744#if IEEE_DEBUG > 1
745 /* This is to be run on a host which uses 68881 format. */
746 {
747 long double ex = *(long double *)exten;
748 if (ex != n)
749 printf ("Differ(from vs. extended): %.20g\n", n);
750 }
751#endif
752}
753
754int
49b1fae4 755main (void)
252b5132 756{
b52927b7 757 ieee_test (0.0);
252b5132 758 ieee_test (0.5);
e372c21c 759 ieee_test (1.1);
252b5132
RH
760 ieee_test (256.0);
761 ieee_test (0.12345);
762 ieee_test (234235.78907234);
763 ieee_test (-512.0);
764 ieee_test (-0.004321);
b52927b7
DD
765 ieee_test (1.2E-70);
766 ieee_test (1.2E-316);
767 ieee_test (4.9406564584124654E-324);
768 ieee_test (- 4.9406564584124654E-324);
769 ieee_test (- 0.0);
770 ieee_test (- INFINITY);
771 ieee_test (- NAN);
772 ieee_test (INFINITY);
773 ieee_test (NAN);
252b5132
RH
774 return 0;
775}
776#endif
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