Commit | Line | Data |
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252b5132 | 1 | /* IEEE floating point support routines, for GDB, the GNU Debugger. |
59e11e17 | 2 | Copyright 1991, 1994, 1999, 2000, 2003, 2005, 2006, 2010 |
3b6940c0 | 3 | Free Software Foundation, Inc. |
252b5132 RH |
4 | |
5 | This file is part of GDB. | |
6 | ||
7 | This program is free software; you can redistribute it and/or modify | |
8 | it under the terms of the GNU General Public License as published by | |
9 | the Free Software Foundation; either version 2 of the License, or | |
10 | (at your option) any later version. | |
11 | ||
12 | This program is distributed in the hope that it will be useful, | |
13 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
15 | GNU General Public License for more details. | |
16 | ||
17 | You should have received a copy of the GNU General Public License | |
18 | along with this program; if not, write to the Free Software | |
979c05d3 | 19 | Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA. */ |
252b5132 | 20 | |
b52927b7 DD |
21 | /* This is needed to pick up the NAN macro on some systems. */ |
22 | #define _GNU_SOURCE | |
23 | ||
24 | #ifdef HAVE_CONFIG_H | |
25 | #include "config.h" | |
26 | #endif | |
27 | ||
28 | #include <math.h> | |
29 | ||
30 | #ifdef HAVE_STRING_H | |
31 | #include <string.h> | |
32 | #endif | |
33 | ||
e27d251e DD |
34 | /* On some platforms, <float.h> provides DBL_QNAN. */ |
35 | #ifdef STDC_HEADERS | |
36 | #include <float.h> | |
37 | #endif | |
38 | ||
1ea16ec5 | 39 | #include "ansidecl.h" |
b52927b7 | 40 | #include "libiberty.h" |
252b5132 | 41 | #include "floatformat.h" |
b52927b7 DD |
42 | |
43 | #ifndef INFINITY | |
44 | #ifdef HUGE_VAL | |
45 | #define INFINITY HUGE_VAL | |
252b5132 | 46 | #else |
b52927b7 DD |
47 | #define INFINITY (1.0 / 0.0) |
48 | #endif | |
49 | #endif | |
50 | ||
51 | #ifndef NAN | |
e27d251e DD |
52 | #ifdef DBL_QNAN |
53 | #define NAN DBL_QNAN | |
54 | #else | |
b52927b7 | 55 | #define NAN (0.0 / 0.0) |
252b5132 | 56 | #endif |
e27d251e | 57 | #endif |
252b5132 | 58 | |
b14d30e1 | 59 | static int mant_bits_set (const struct floatformat *, const unsigned char *); |
49b1fae4 DD |
60 | static unsigned long get_field (const unsigned char *, |
61 | enum floatformat_byteorders, | |
62 | unsigned int, | |
63 | unsigned int, | |
64 | unsigned int); | |
65 | static int floatformat_always_valid (const struct floatformat *fmt, | |
3b6940c0 | 66 | const void *from); |
5324d185 AC |
67 | |
68 | static int | |
49b1fae4 | 69 | floatformat_always_valid (const struct floatformat *fmt ATTRIBUTE_UNUSED, |
3b6940c0 | 70 | const void *from ATTRIBUTE_UNUSED) |
5324d185 AC |
71 | { |
72 | return 1; | |
73 | } | |
74 | ||
252b5132 RH |
75 | /* The odds that CHAR_BIT will be anything but 8 are low enough that I'm not |
76 | going to bother with trying to muck around with whether it is defined in | |
77 | a system header, what we do if not, etc. */ | |
78 | #define FLOATFORMAT_CHAR_BIT 8 | |
79 | ||
f9e9243a UW |
80 | /* floatformats for IEEE half, single and double, big and little endian. */ |
81 | const struct floatformat floatformat_ieee_half_big = | |
82 | { | |
83 | floatformat_big, 16, 0, 1, 5, 15, 31, 6, 10, | |
84 | floatformat_intbit_no, | |
85 | "floatformat_ieee_half_big", | |
86 | floatformat_always_valid, | |
87 | NULL | |
88 | }; | |
89 | const struct floatformat floatformat_ieee_half_little = | |
90 | { | |
91 | floatformat_little, 16, 0, 1, 5, 15, 31, 6, 10, | |
92 | floatformat_intbit_no, | |
93 | "floatformat_ieee_half_little", | |
94 | floatformat_always_valid, | |
95 | NULL | |
96 | }; | |
252b5132 RH |
97 | const struct floatformat floatformat_ieee_single_big = |
98 | { | |
f03aa80d AC |
99 | floatformat_big, 32, 0, 1, 8, 127, 255, 9, 23, |
100 | floatformat_intbit_no, | |
5324d185 | 101 | "floatformat_ieee_single_big", |
b14d30e1 JM |
102 | floatformat_always_valid, |
103 | NULL | |
252b5132 RH |
104 | }; |
105 | const struct floatformat floatformat_ieee_single_little = | |
106 | { | |
f03aa80d AC |
107 | floatformat_little, 32, 0, 1, 8, 127, 255, 9, 23, |
108 | floatformat_intbit_no, | |
5324d185 | 109 | "floatformat_ieee_single_little", |
b14d30e1 JM |
110 | floatformat_always_valid, |
111 | NULL | |
252b5132 RH |
112 | }; |
113 | const struct floatformat floatformat_ieee_double_big = | |
114 | { | |
f03aa80d AC |
115 | floatformat_big, 64, 0, 1, 11, 1023, 2047, 12, 52, |
116 | floatformat_intbit_no, | |
5324d185 | 117 | "floatformat_ieee_double_big", |
b14d30e1 JM |
118 | floatformat_always_valid, |
119 | NULL | |
252b5132 RH |
120 | }; |
121 | const struct floatformat floatformat_ieee_double_little = | |
122 | { | |
f03aa80d AC |
123 | floatformat_little, 64, 0, 1, 11, 1023, 2047, 12, 52, |
124 | floatformat_intbit_no, | |
5324d185 | 125 | "floatformat_ieee_double_little", |
b14d30e1 JM |
126 | floatformat_always_valid, |
127 | NULL | |
252b5132 RH |
128 | }; |
129 | ||
130 | /* floatformat for IEEE double, little endian byte order, with big endian word | |
131 | ordering, as on the ARM. */ | |
132 | ||
133 | const struct floatformat floatformat_ieee_double_littlebyte_bigword = | |
134 | { | |
f03aa80d AC |
135 | floatformat_littlebyte_bigword, 64, 0, 1, 11, 1023, 2047, 12, 52, |
136 | floatformat_intbit_no, | |
5324d185 | 137 | "floatformat_ieee_double_littlebyte_bigword", |
b14d30e1 JM |
138 | floatformat_always_valid, |
139 | NULL | |
252b5132 RH |
140 | }; |
141 | ||
fb10537e DD |
142 | /* floatformat for VAX. Not quite IEEE, but close enough. */ |
143 | ||
144 | const struct floatformat floatformat_vax_f = | |
145 | { | |
146 | floatformat_vax, 32, 0, 1, 8, 129, 0, 9, 23, | |
147 | floatformat_intbit_no, | |
148 | "floatformat_vax_f", | |
b14d30e1 JM |
149 | floatformat_always_valid, |
150 | NULL | |
fb10537e DD |
151 | }; |
152 | const struct floatformat floatformat_vax_d = | |
153 | { | |
154 | floatformat_vax, 64, 0, 1, 8, 129, 0, 9, 55, | |
155 | floatformat_intbit_no, | |
156 | "floatformat_vax_d", | |
b14d30e1 JM |
157 | floatformat_always_valid, |
158 | NULL | |
fb10537e DD |
159 | }; |
160 | const struct floatformat floatformat_vax_g = | |
161 | { | |
162 | floatformat_vax, 64, 0, 1, 11, 1025, 0, 12, 52, | |
163 | floatformat_intbit_no, | |
164 | "floatformat_vax_g", | |
b14d30e1 JM |
165 | floatformat_always_valid, |
166 | NULL | |
fb10537e DD |
167 | }; |
168 | ||
3b6940c0 DD |
169 | static int floatformat_i387_ext_is_valid (const struct floatformat *fmt, |
170 | const void *from); | |
5324d185 AC |
171 | |
172 | static int | |
3b6940c0 | 173 | floatformat_i387_ext_is_valid (const struct floatformat *fmt, const void *from) |
5324d185 AC |
174 | { |
175 | /* In the i387 double-extended format, if the exponent is all ones, | |
176 | then the integer bit must be set. If the exponent is neither 0 | |
177 | nor ~0, the intbit must also be set. Only if the exponent is | |
178 | zero can it be zero, and then it must be zero. */ | |
179 | unsigned long exponent, int_bit; | |
648c3dc0 | 180 | const unsigned char *ufrom = (const unsigned char *) from; |
3b6940c0 | 181 | |
5324d185 AC |
182 | exponent = get_field (ufrom, fmt->byteorder, fmt->totalsize, |
183 | fmt->exp_start, fmt->exp_len); | |
184 | int_bit = get_field (ufrom, fmt->byteorder, fmt->totalsize, | |
185 | fmt->man_start, 1); | |
3b6940c0 | 186 | |
5324d185 AC |
187 | if ((exponent == 0) != (int_bit == 0)) |
188 | return 0; | |
189 | else | |
190 | return 1; | |
191 | } | |
192 | ||
252b5132 RH |
193 | const struct floatformat floatformat_i387_ext = |
194 | { | |
195 | floatformat_little, 80, 0, 1, 15, 0x3fff, 0x7fff, 16, 64, | |
f03aa80d | 196 | floatformat_intbit_yes, |
5324d185 | 197 | "floatformat_i387_ext", |
b14d30e1 JM |
198 | floatformat_i387_ext_is_valid, |
199 | NULL | |
252b5132 RH |
200 | }; |
201 | const struct floatformat floatformat_m68881_ext = | |
202 | { | |
203 | /* Note that the bits from 16 to 31 are unused. */ | |
f03aa80d AC |
204 | floatformat_big, 96, 0, 1, 15, 0x3fff, 0x7fff, 32, 64, |
205 | floatformat_intbit_yes, | |
5324d185 | 206 | "floatformat_m68881_ext", |
b14d30e1 JM |
207 | floatformat_always_valid, |
208 | NULL | |
252b5132 RH |
209 | }; |
210 | const struct floatformat floatformat_i960_ext = | |
211 | { | |
212 | /* Note that the bits from 0 to 15 are unused. */ | |
213 | floatformat_little, 96, 16, 17, 15, 0x3fff, 0x7fff, 32, 64, | |
f03aa80d | 214 | floatformat_intbit_yes, |
5324d185 | 215 | "floatformat_i960_ext", |
b14d30e1 JM |
216 | floatformat_always_valid, |
217 | NULL | |
252b5132 RH |
218 | }; |
219 | const struct floatformat floatformat_m88110_ext = | |
220 | { | |
eb828599 AC |
221 | floatformat_big, 80, 0, 1, 15, 0x3fff, 0x7fff, 16, 64, |
222 | floatformat_intbit_yes, | |
5324d185 | 223 | "floatformat_m88110_ext", |
b14d30e1 JM |
224 | floatformat_always_valid, |
225 | NULL | |
eb828599 AC |
226 | }; |
227 | const struct floatformat floatformat_m88110_harris_ext = | |
228 | { | |
252b5132 RH |
229 | /* Harris uses raw format 128 bytes long, but the number is just an ieee |
230 | double, and the last 64 bits are wasted. */ | |
231 | floatformat_big,128, 0, 1, 11, 0x3ff, 0x7ff, 12, 52, | |
f03aa80d | 232 | floatformat_intbit_no, |
5324d185 | 233 | "floatformat_m88110_ext_harris", |
b14d30e1 JM |
234 | floatformat_always_valid, |
235 | NULL | |
252b5132 | 236 | }; |
eb828599 AC |
237 | const struct floatformat floatformat_arm_ext_big = |
238 | { | |
239 | /* Bits 1 to 16 are unused. */ | |
240 | floatformat_big, 96, 0, 17, 15, 0x3fff, 0x7fff, 32, 64, | |
241 | floatformat_intbit_yes, | |
5324d185 | 242 | "floatformat_arm_ext_big", |
b14d30e1 JM |
243 | floatformat_always_valid, |
244 | NULL | |
eb828599 AC |
245 | }; |
246 | const struct floatformat floatformat_arm_ext_littlebyte_bigword = | |
247 | { | |
248 | /* Bits 1 to 16 are unused. */ | |
249 | floatformat_littlebyte_bigword, 96, 0, 17, 15, 0x3fff, 0x7fff, 32, 64, | |
250 | floatformat_intbit_yes, | |
5324d185 | 251 | "floatformat_arm_ext_littlebyte_bigword", |
b14d30e1 JM |
252 | floatformat_always_valid, |
253 | NULL | |
eb828599 AC |
254 | }; |
255 | const struct floatformat floatformat_ia64_spill_big = | |
256 | { | |
257 | floatformat_big, 128, 0, 1, 17, 65535, 0x1ffff, 18, 64, | |
258 | floatformat_intbit_yes, | |
5324d185 | 259 | "floatformat_ia64_spill_big", |
b14d30e1 JM |
260 | floatformat_always_valid, |
261 | NULL | |
eb828599 AC |
262 | }; |
263 | const struct floatformat floatformat_ia64_spill_little = | |
264 | { | |
265 | floatformat_little, 128, 0, 1, 17, 65535, 0x1ffff, 18, 64, | |
266 | floatformat_intbit_yes, | |
5324d185 | 267 | "floatformat_ia64_spill_little", |
b14d30e1 JM |
268 | floatformat_always_valid, |
269 | NULL | |
eb828599 AC |
270 | }; |
271 | const struct floatformat floatformat_ia64_quad_big = | |
272 | { | |
273 | floatformat_big, 128, 0, 1, 15, 16383, 0x7fff, 16, 112, | |
274 | floatformat_intbit_no, | |
5324d185 | 275 | "floatformat_ia64_quad_big", |
b14d30e1 JM |
276 | floatformat_always_valid, |
277 | NULL | |
eb828599 AC |
278 | }; |
279 | const struct floatformat floatformat_ia64_quad_little = | |
280 | { | |
281 | floatformat_little, 128, 0, 1, 15, 16383, 0x7fff, 16, 112, | |
282 | floatformat_intbit_no, | |
5324d185 | 283 | "floatformat_ia64_quad_little", |
b14d30e1 JM |
284 | floatformat_always_valid, |
285 | NULL | |
286 | }; | |
287 | ||
288 | static int | |
289 | floatformat_ibm_long_double_is_valid (const struct floatformat *fmt, | |
290 | const void *from) | |
291 | { | |
292 | const unsigned char *ufrom = (const unsigned char *) from; | |
293 | const struct floatformat *hfmt = fmt->split_half; | |
294 | long top_exp, bot_exp; | |
295 | int top_nan = 0; | |
296 | ||
297 | top_exp = get_field (ufrom, hfmt->byteorder, hfmt->totalsize, | |
298 | hfmt->exp_start, hfmt->exp_len); | |
299 | bot_exp = get_field (ufrom + 8, hfmt->byteorder, hfmt->totalsize, | |
300 | hfmt->exp_start, hfmt->exp_len); | |
301 | ||
38e654e2 | 302 | if ((unsigned long) top_exp == hfmt->exp_nan) |
b14d30e1 JM |
303 | top_nan = mant_bits_set (hfmt, ufrom); |
304 | ||
305 | /* A NaN is valid with any low part. */ | |
306 | if (top_nan) | |
307 | return 1; | |
308 | ||
309 | /* An infinity, zero or denormal requires low part 0 (positive or | |
310 | negative). */ | |
38e654e2 | 311 | if ((unsigned long) top_exp == hfmt->exp_nan || top_exp == 0) |
b14d30e1 | 312 | { |
b14d30e1 JM |
313 | if (bot_exp != 0) |
314 | return 0; | |
315 | ||
316 | return !mant_bits_set (hfmt, ufrom + 8); | |
317 | } | |
318 | ||
319 | /* The top part is now a finite normal value. The long double value | |
320 | is the sum of the two parts, and the top part must equal the | |
321 | result of rounding the long double value to nearest double. Thus | |
322 | the bottom part must be <= 0.5ulp of the top part in absolute | |
323 | value, and if it is < 0.5ulp then the long double is definitely | |
324 | valid. */ | |
325 | if (bot_exp < top_exp - 53) | |
326 | return 1; | |
327 | if (bot_exp > top_exp - 53 && bot_exp != 0) | |
328 | return 0; | |
329 | if (bot_exp == 0) | |
330 | { | |
331 | /* The bottom part is 0 or denormal. Determine which, and if | |
332 | denormal the first two set bits. */ | |
333 | int first_bit = -1, second_bit = -1, cur_bit; | |
38e654e2 | 334 | for (cur_bit = 0; (unsigned int) cur_bit < hfmt->man_len; cur_bit++) |
b14d30e1 JM |
335 | if (get_field (ufrom + 8, hfmt->byteorder, hfmt->totalsize, |
336 | hfmt->man_start + cur_bit, 1)) | |
337 | { | |
338 | if (first_bit == -1) | |
339 | first_bit = cur_bit; | |
340 | else | |
341 | { | |
342 | second_bit = cur_bit; | |
343 | break; | |
344 | } | |
345 | } | |
346 | /* Bottom part 0 is OK. */ | |
347 | if (first_bit == -1) | |
348 | return 1; | |
349 | /* The real exponent of the bottom part is -first_bit. */ | |
350 | if (-first_bit < top_exp - 53) | |
351 | return 1; | |
352 | if (-first_bit > top_exp - 53) | |
353 | return 0; | |
354 | /* The bottom part is at least 0.5ulp of the top part. For this | |
355 | to be OK, the bottom part must be exactly 0.5ulp (i.e. no | |
356 | more bits set) and the top part must have last bit 0. */ | |
357 | if (second_bit != -1) | |
358 | return 0; | |
359 | return !get_field (ufrom, hfmt->byteorder, hfmt->totalsize, | |
360 | hfmt->man_start + hfmt->man_len - 1, 1); | |
361 | } | |
362 | else | |
363 | { | |
364 | /* The bottom part is at least 0.5ulp of the top part. For this | |
365 | to be OK, it must be exactly 0.5ulp (i.e. no explicit bits | |
366 | set) and the top part must have last bit 0. */ | |
367 | if (get_field (ufrom, hfmt->byteorder, hfmt->totalsize, | |
368 | hfmt->man_start + hfmt->man_len - 1, 1)) | |
369 | return 0; | |
370 | return !mant_bits_set (hfmt, ufrom + 8); | |
371 | } | |
372 | } | |
373 | ||
374 | const struct floatformat floatformat_ibm_long_double = | |
375 | { | |
376 | floatformat_big, 128, 0, 1, 11, 1023, 2047, 12, 52, | |
377 | floatformat_intbit_no, | |
378 | "floatformat_ibm_long_double", | |
38e654e2 | 379 | floatformat_ibm_long_double_is_valid, |
b14d30e1 | 380 | &floatformat_ieee_double_big |
eb828599 | 381 | }; |
252b5132 | 382 | \f |
9e59254c JB |
383 | |
384 | #ifndef min | |
385 | #define min(a, b) ((a) < (b) ? (a) : (b)) | |
386 | #endif | |
387 | ||
b14d30e1 JM |
388 | /* Return 1 if any bits are explicitly set in the mantissa of UFROM, |
389 | format FMT, 0 otherwise. */ | |
390 | static int | |
391 | mant_bits_set (const struct floatformat *fmt, const unsigned char *ufrom) | |
392 | { | |
393 | unsigned int mant_bits, mant_off; | |
394 | int mant_bits_left; | |
395 | ||
396 | mant_off = fmt->man_start; | |
397 | mant_bits_left = fmt->man_len; | |
398 | while (mant_bits_left > 0) | |
399 | { | |
400 | mant_bits = min (mant_bits_left, 32); | |
401 | ||
402 | if (get_field (ufrom, fmt->byteorder, fmt->totalsize, | |
403 | mant_off, mant_bits) != 0) | |
404 | return 1; | |
405 | ||
406 | mant_off += mant_bits; | |
407 | mant_bits_left -= mant_bits; | |
408 | } | |
409 | return 0; | |
410 | } | |
411 | ||
3f2aacaf | 412 | /* Extract a field which starts at START and is LEN bits long. DATA and |
252b5132 RH |
413 | TOTAL_LEN are the thing we are extracting it from, in byteorder ORDER. */ |
414 | static unsigned long | |
49b1fae4 DD |
415 | get_field (const unsigned char *data, enum floatformat_byteorders order, |
416 | unsigned int total_len, unsigned int start, unsigned int len) | |
252b5132 | 417 | { |
9e59254c | 418 | unsigned long result = 0; |
252b5132 | 419 | unsigned int cur_byte; |
9e59254c JB |
420 | int lo_bit, hi_bit, cur_bitshift = 0; |
421 | int nextbyte = (order == floatformat_little) ? 1 : -1; | |
422 | ||
423 | /* Start is in big-endian bit order! Fix that first. */ | |
424 | start = total_len - (start + len); | |
252b5132 RH |
425 | |
426 | /* Start at the least significant part of the field. */ | |
252b5132 | 427 | if (order == floatformat_little) |
9e59254c | 428 | cur_byte = start / FLOATFORMAT_CHAR_BIT; |
252b5132 | 429 | else |
9e59254c | 430 | cur_byte = (total_len - start - 1) / FLOATFORMAT_CHAR_BIT; |
252b5132 | 431 | |
9e59254c JB |
432 | lo_bit = start % FLOATFORMAT_CHAR_BIT; |
433 | hi_bit = min (lo_bit + len, FLOATFORMAT_CHAR_BIT); | |
434 | ||
435 | do | |
252b5132 | 436 | { |
9e59254c JB |
437 | unsigned int shifted = *(data + cur_byte) >> lo_bit; |
438 | unsigned int bits = hi_bit - lo_bit; | |
439 | unsigned int mask = (1 << bits) - 1; | |
440 | result |= (shifted & mask) << cur_bitshift; | |
441 | len -= bits; | |
442 | cur_bitshift += bits; | |
443 | cur_byte += nextbyte; | |
444 | lo_bit = 0; | |
445 | hi_bit = min (len, FLOATFORMAT_CHAR_BIT); | |
252b5132 | 446 | } |
9e59254c JB |
447 | while (len != 0); |
448 | ||
252b5132 RH |
449 | return result; |
450 | } | |
451 | ||
252b5132 RH |
452 | /* Convert from FMT to a double. |
453 | FROM is the address of the extended float. | |
454 | Store the double in *TO. */ | |
455 | ||
456 | void | |
49b1fae4 | 457 | floatformat_to_double (const struct floatformat *fmt, |
3b6940c0 | 458 | const void *from, double *to) |
252b5132 | 459 | { |
648c3dc0 | 460 | const unsigned char *ufrom = (const unsigned char *) from; |
252b5132 RH |
461 | double dto; |
462 | long exponent; | |
463 | unsigned long mant; | |
464 | unsigned int mant_bits, mant_off; | |
465 | int mant_bits_left; | |
466 | int special_exponent; /* It's a NaN, denorm or zero */ | |
467 | ||
b14d30e1 JM |
468 | /* Split values are not handled specially, since the top half has |
469 | the correctly rounded double value (in the only supported case of | |
470 | split values). */ | |
471 | ||
252b5132 RH |
472 | exponent = get_field (ufrom, fmt->byteorder, fmt->totalsize, |
473 | fmt->exp_start, fmt->exp_len); | |
b52927b7 DD |
474 | |
475 | /* If the exponent indicates a NaN, we don't have information to | |
476 | decide what to do. So we handle it like IEEE, except that we | |
477 | don't try to preserve the type of NaN. FIXME. */ | |
478 | if ((unsigned long) exponent == fmt->exp_nan) | |
479 | { | |
b14d30e1 | 480 | int nan = mant_bits_set (fmt, ufrom); |
b52927b7 | 481 | |
f2942ea4 DD |
482 | /* On certain systems (such as GNU/Linux), the use of the |
483 | INFINITY macro below may generate a warning that can not be | |
484 | silenced due to a bug in GCC (PR preprocessor/11931). The | |
485 | preprocessor fails to recognise the __extension__ keyword in | |
486 | conjunction with the GNU/C99 extension for hexadecimal | |
487 | floating point constants and will issue a warning when | |
488 | compiling with -pedantic. */ | |
b52927b7 DD |
489 | if (nan) |
490 | dto = NAN; | |
491 | else | |
492 | dto = INFINITY; | |
493 | ||
494 | if (get_field (ufrom, fmt->byteorder, fmt->totalsize, fmt->sign_start, 1)) | |
495 | dto = -dto; | |
496 | ||
497 | *to = dto; | |
498 | ||
499 | return; | |
500 | } | |
252b5132 RH |
501 | |
502 | mant_bits_left = fmt->man_len; | |
503 | mant_off = fmt->man_start; | |
504 | dto = 0.0; | |
505 | ||
08372f14 | 506 | special_exponent = exponent == 0 || (unsigned long) exponent == fmt->exp_nan; |
252b5132 RH |
507 | |
508 | /* Don't bias zero's, denorms or NaNs. */ | |
509 | if (!special_exponent) | |
510 | exponent -= fmt->exp_bias; | |
511 | ||
512 | /* Build the result algebraically. Might go infinite, underflow, etc; | |
513 | who cares. */ | |
514 | ||
515 | /* If this format uses a hidden bit, explicitly add it in now. Otherwise, | |
516 | increment the exponent by one to account for the integer bit. */ | |
517 | ||
518 | if (!special_exponent) | |
519 | { | |
520 | if (fmt->intbit == floatformat_intbit_no) | |
521 | dto = ldexp (1.0, exponent); | |
522 | else | |
523 | exponent++; | |
524 | } | |
525 | ||
526 | while (mant_bits_left > 0) | |
527 | { | |
528 | mant_bits = min (mant_bits_left, 32); | |
529 | ||
530 | mant = get_field (ufrom, fmt->byteorder, fmt->totalsize, | |
531 | mant_off, mant_bits); | |
532 | ||
b52927b7 DD |
533 | /* Handle denormalized numbers. FIXME: What should we do for |
534 | non-IEEE formats? */ | |
c77d28ac | 535 | if (special_exponent && exponent == 0 && mant != 0) |
b52927b7 DD |
536 | dto += ldexp ((double)mant, |
537 | (- fmt->exp_bias | |
538 | - mant_bits | |
539 | - (mant_off - fmt->man_start) | |
540 | + 1)); | |
541 | else | |
542 | dto += ldexp ((double)mant, exponent - mant_bits); | |
543 | if (exponent != 0) | |
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 |
555 | static 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. */ |
563 | static void | |
49b1fae4 DD |
564 | put_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 | ||
603 | void | |
49b1fae4 | 604 | floatformat_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 | ||
703 | int | |
3b6940c0 | 704 | floatformat_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 | ||
716 | void | |
49b1fae4 | 717 | ieee_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 | ||
754 | int | |
49b1fae4 | 755 | main (void) |
252b5132 | 756 | { |
b52927b7 | 757 | ieee_test (0.0); |
252b5132 RH |
758 | ieee_test (0.5); |
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); | |
b52927b7 DD |
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); | |
252b5132 RH |
773 | return 0; |
774 | } | |
775 | #endif |