Mercurial > hg > CbC > CbC_gcc
annotate libiberty/floatformat.c @ 120:f93fa5091070
fix conv1.c
author | mir3636 |
---|---|
date | Thu, 08 Mar 2018 14:53:42 +0900 |
parents | 04ced10e8804 |
children | 84e7813d76e9 |
rev | line source |
---|---|
0 | 1 /* IEEE floating point support routines, for GDB, the GNU Debugger. |
111 | 2 Copyright (C) 1991-2017 Free Software Foundation, Inc. |
0 | 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. */ | |
111 | 21 #ifndef _GNU_SOURCE |
0 | 22 #define _GNU_SOURCE |
111 | 23 #endif |
0 | 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 | |
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 | |
67
f6334be47118
update gcc from gcc-4.6-20100522 to gcc-4.6-20110318
nobuyasu <dimolto@cr.ie.u-ryukyu.ac.jp>
parents:
0
diff
changeset
|
81 /* floatformats for IEEE half, single and double, big and little endian. */ |
f6334be47118
update gcc from gcc-4.6-20100522 to gcc-4.6-20110318
nobuyasu <dimolto@cr.ie.u-ryukyu.ac.jp>
parents:
0
diff
changeset
|
82 const struct floatformat floatformat_ieee_half_big = |
f6334be47118
update gcc from gcc-4.6-20100522 to gcc-4.6-20110318
nobuyasu <dimolto@cr.ie.u-ryukyu.ac.jp>
parents:
0
diff
changeset
|
83 { |
f6334be47118
update gcc from gcc-4.6-20100522 to gcc-4.6-20110318
nobuyasu <dimolto@cr.ie.u-ryukyu.ac.jp>
parents:
0
diff
changeset
|
84 floatformat_big, 16, 0, 1, 5, 15, 31, 6, 10, |
f6334be47118
update gcc from gcc-4.6-20100522 to gcc-4.6-20110318
nobuyasu <dimolto@cr.ie.u-ryukyu.ac.jp>
parents:
0
diff
changeset
|
85 floatformat_intbit_no, |
f6334be47118
update gcc from gcc-4.6-20100522 to gcc-4.6-20110318
nobuyasu <dimolto@cr.ie.u-ryukyu.ac.jp>
parents:
0
diff
changeset
|
86 "floatformat_ieee_half_big", |
f6334be47118
update gcc from gcc-4.6-20100522 to gcc-4.6-20110318
nobuyasu <dimolto@cr.ie.u-ryukyu.ac.jp>
parents:
0
diff
changeset
|
87 floatformat_always_valid, |
f6334be47118
update gcc from gcc-4.6-20100522 to gcc-4.6-20110318
nobuyasu <dimolto@cr.ie.u-ryukyu.ac.jp>
parents:
0
diff
changeset
|
88 NULL |
f6334be47118
update gcc from gcc-4.6-20100522 to gcc-4.6-20110318
nobuyasu <dimolto@cr.ie.u-ryukyu.ac.jp>
parents:
0
diff
changeset
|
89 }; |
f6334be47118
update gcc from gcc-4.6-20100522 to gcc-4.6-20110318
nobuyasu <dimolto@cr.ie.u-ryukyu.ac.jp>
parents:
0
diff
changeset
|
90 const struct floatformat floatformat_ieee_half_little = |
f6334be47118
update gcc from gcc-4.6-20100522 to gcc-4.6-20110318
nobuyasu <dimolto@cr.ie.u-ryukyu.ac.jp>
parents:
0
diff
changeset
|
91 { |
f6334be47118
update gcc from gcc-4.6-20100522 to gcc-4.6-20110318
nobuyasu <dimolto@cr.ie.u-ryukyu.ac.jp>
parents:
0
diff
changeset
|
92 floatformat_little, 16, 0, 1, 5, 15, 31, 6, 10, |
f6334be47118
update gcc from gcc-4.6-20100522 to gcc-4.6-20110318
nobuyasu <dimolto@cr.ie.u-ryukyu.ac.jp>
parents:
0
diff
changeset
|
93 floatformat_intbit_no, |
f6334be47118
update gcc from gcc-4.6-20100522 to gcc-4.6-20110318
nobuyasu <dimolto@cr.ie.u-ryukyu.ac.jp>
parents:
0
diff
changeset
|
94 "floatformat_ieee_half_little", |
f6334be47118
update gcc from gcc-4.6-20100522 to gcc-4.6-20110318
nobuyasu <dimolto@cr.ie.u-ryukyu.ac.jp>
parents:
0
diff
changeset
|
95 floatformat_always_valid, |
f6334be47118
update gcc from gcc-4.6-20100522 to gcc-4.6-20110318
nobuyasu <dimolto@cr.ie.u-ryukyu.ac.jp>
parents:
0
diff
changeset
|
96 NULL |
f6334be47118
update gcc from gcc-4.6-20100522 to gcc-4.6-20110318
nobuyasu <dimolto@cr.ie.u-ryukyu.ac.jp>
parents:
0
diff
changeset
|
97 }; |
0 | 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 | |
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 | |
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 | |
111 | 375 const struct floatformat floatformat_ibm_long_double_big = |
0 | 376 { |
377 floatformat_big, 128, 0, 1, 11, 1023, 2047, 12, 52, | |
378 floatformat_intbit_no, | |
111 | 379 "floatformat_ibm_long_double_big", |
0 | 380 floatformat_ibm_long_double_is_valid, |
381 &floatformat_ieee_double_big | |
382 }; | |
111 | 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 }; | |
0 | 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 | |
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 | |
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 | |
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 can not 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 | |
111 | 518 /* For denorms use minimum exponent. */ |
519 if (exponent == 0) | |
520 exponent = 1 - fmt->exp_bias; | |
521 else | |
522 { | |
523 exponent -= fmt->exp_bias; | |
0 | 524 |
111 | 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 | |
0 | 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 | |
111 | 542 dto += ldexp ((double) mant, exponent - mant_bits); |
543 exponent -= mant_bits; | |
0 | 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 | |
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 | |
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 | |
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 | |
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 | |
754 main (void) | |
755 { | |
756 ieee_test (0.0); | |
757 ieee_test (0.5); | |
111 | 758 ieee_test (1.1); |
0 | 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 |