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