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1 | /* fpu.c --- FPU emulator for stand-alone RX simulator. |
2 | ||
dc3cf14f | 3 | Copyright (C) 2008, 2009, 2010 Free Software Foundation, Inc. |
4f8d4a38 DD |
4 | Contributed by Red Hat, Inc. |
5 | ||
6 | This file is part of the GNU simulators. | |
7 | ||
8 | This program is free software; you can redistribute it and/or modify | |
9 | it under the terms of the GNU General Public License as published by | |
10 | the Free Software Foundation; either version 3 of the License, or | |
11 | (at your option) any later version. | |
12 | ||
13 | This program is distributed in the hope that it will be useful, | |
14 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
16 | GNU General Public License for more details. | |
17 | ||
18 | You should have received a copy of the GNU General Public License | |
19 | along with this program. If not, see <http://www.gnu.org/licenses/>. */ | |
20 | ||
21 | #include <stdio.h> | |
22 | #include <stdlib.h> | |
23 | ||
24 | #include "cpu.h" | |
25 | #include "fpu.h" | |
26 | ||
27 | /* FPU encodings are as follows: | |
28 | ||
29 | S EXPONENT MANTISSA | |
30 | 1 12345678 12345678901234567890123 | |
31 | ||
32 | 0 00000000 00000000000000000000000 +0 | |
33 | 1 00000000 00000000000000000000000 -0 | |
34 | ||
35 | X 00000000 00000000000000000000001 Denormals | |
36 | X 00000000 11111111111111111111111 | |
37 | ||
38 | X 00000001 XXXXXXXXXXXXXXXXXXXXXXX Normals | |
39 | X 11111110 XXXXXXXXXXXXXXXXXXXXXXX | |
40 | ||
41 | 0 11111111 00000000000000000000000 +Inf | |
42 | 1 11111111 00000000000000000000000 -Inf | |
43 | ||
44 | X 11111111 0XXXXXXXXXXXXXXXXXXXXXX SNaN (X != 0) | |
45 | X 11111111 1XXXXXXXXXXXXXXXXXXXXXX QNaN (X != 0) | |
46 | ||
47 | */ | |
48 | ||
49 | #define trace 0 | |
50 | #define tprintf if (trace) printf | |
51 | ||
52 | /* Some magic numbers. */ | |
53 | #define PLUS_MAX 0x7f7fffffUL | |
54 | #define MINUS_MAX 0xff7fffffUL | |
55 | #define PLUS_INF 0x7f800000UL | |
56 | #define MINUS_INF 0xff800000UL | |
57 | #define PLUS_ZERO 0x00000000UL | |
58 | #define MINUS_ZERO 0x80000000UL | |
59 | ||
60 | #define FP_RAISE(e) fp_raise(FPSWBITS_C##e) | |
61 | static void | |
62 | fp_raise (int mask) | |
63 | { | |
64 | regs.r_fpsw |= mask; | |
65 | if (mask != FPSWBITS_CE) | |
66 | { | |
67 | if (regs.r_fpsw & (mask << FPSW_CESH)) | |
68 | regs.r_fpsw |= (mask << FPSW_CFSH); | |
69 | if (regs.r_fpsw & FPSWBITS_FMASK) | |
70 | regs.r_fpsw |= FPSWBITS_FSUM; | |
71 | else | |
72 | regs.r_fpsw &= ~FPSWBITS_FSUM; | |
73 | } | |
74 | } | |
75 | ||
76 | /* We classify all numbers as one of these. They correspond to the | |
77 | rows/colums in the exception tables. */ | |
78 | typedef enum { | |
79 | FP_NORMAL, | |
80 | FP_PZERO, | |
81 | FP_NZERO, | |
82 | FP_PINFINITY, | |
83 | FP_NINFINITY, | |
84 | FP_DENORMAL, | |
85 | FP_QNAN, | |
86 | FP_SNAN | |
87 | } FP_Type; | |
88 | ||
89 | #if defined DEBUG0 | |
90 | static const char *fpt_names[] = { | |
91 | "Normal", "+0", "-0", "+Inf", "-Inf", "Denormal", "QNaN", "SNaN" | |
92 | }; | |
93 | #endif | |
94 | ||
95 | #define EXP_BIAS 127 | |
96 | #define EXP_ZERO -127 | |
97 | #define EXP_INF 128 | |
98 | ||
99 | #define MANT_BIAS 0x00080000UL | |
100 | ||
101 | typedef struct { | |
102 | int exp; | |
103 | unsigned int mant; /* 24 bits */ | |
104 | char type; | |
105 | char sign; | |
106 | fp_t orig_value; | |
107 | } FP_Parts; | |
108 | ||
109 | static void | |
110 | fp_explode (fp_t f, FP_Parts *p) | |
111 | { | |
112 | int exp, mant, sign; | |
113 | ||
114 | exp = ((f & 0x7f800000UL) >> 23); | |
115 | mant = f & 0x007fffffUL; | |
116 | sign = f & 0x80000000UL; | |
117 | /*printf("explode: %08x %x %2x %6x\n", f, sign, exp, mant);*/ | |
118 | ||
119 | p->sign = sign ? -1 : 1; | |
120 | p->exp = exp - EXP_BIAS; | |
121 | p->orig_value = f; | |
122 | p->mant = mant | 0x00800000UL; | |
123 | ||
124 | if (p->exp == EXP_ZERO) | |
125 | { | |
126 | if (regs.r_fpsw & FPSWBITS_DN) | |
127 | mant = 0; | |
128 | if (mant) | |
129 | p->type = FP_DENORMAL; | |
130 | else | |
131 | { | |
132 | p->mant = 0; | |
133 | p->type = sign ? FP_NZERO : FP_PZERO; | |
134 | } | |
135 | } | |
136 | else if (p->exp == EXP_INF) | |
137 | { | |
138 | if (mant == 0) | |
139 | p->type = sign ? FP_NINFINITY : FP_PINFINITY; | |
140 | else if (mant & 0x00400000UL) | |
141 | p->type = FP_QNAN; | |
142 | else | |
143 | p->type = FP_SNAN; | |
144 | } | |
145 | else | |
146 | p->type = FP_NORMAL; | |
147 | } | |
148 | ||
149 | static fp_t | |
150 | fp_implode (FP_Parts *p) | |
151 | { | |
152 | int exp, mant; | |
153 | ||
154 | exp = p->exp + EXP_BIAS; | |
155 | mant = p->mant; | |
156 | /*printf("implode: exp %d mant 0x%x\n", exp, mant);*/ | |
157 | if (p->type == FP_NORMAL) | |
158 | { | |
159 | while (mant | |
160 | && exp > 0 | |
161 | && mant < 0x00800000UL) | |
162 | { | |
163 | mant <<= 1; | |
164 | exp --; | |
165 | } | |
166 | while (mant > 0x00ffffffUL) | |
167 | { | |
168 | mant >>= 1; | |
169 | exp ++; | |
170 | } | |
171 | if (exp < 0) | |
172 | { | |
173 | /* underflow */ | |
174 | exp = 0; | |
175 | mant = 0; | |
176 | FP_RAISE (E); | |
177 | } | |
178 | if (exp >= 255) | |
179 | { | |
180 | /* overflow */ | |
181 | exp = 255; | |
182 | mant = 0; | |
183 | FP_RAISE (O); | |
184 | } | |
185 | } | |
186 | mant &= 0x007fffffUL; | |
187 | exp &= 0xff; | |
188 | mant |= exp << 23; | |
189 | if (p->sign < 0) | |
190 | mant |= 0x80000000UL; | |
191 | ||
192 | return mant; | |
193 | } | |
194 | ||
195 | typedef union { | |
196 | unsigned long long ll; | |
197 | double d; | |
198 | } U_d_ll; | |
199 | ||
200 | static int checked_format = 0; | |
201 | ||
202 | /* We assume a double format like this: | |
203 | S[1] E[11] M[52] | |
204 | */ | |
205 | ||
206 | static double | |
207 | fp_to_double (FP_Parts *p) | |
208 | { | |
209 | U_d_ll u; | |
210 | ||
211 | if (!checked_format) | |
212 | { | |
213 | u.d = 1.5; | |
214 | if (u.ll != 0x3ff8000000000000ULL) | |
215 | abort (); | |
216 | u.d = -225; | |
217 | if (u.ll != 0xc06c200000000000ULL) | |
218 | abort (); | |
219 | u.d = 10.1; | |
220 | if (u.ll != 0x4024333333333333ULL) | |
221 | abort (); | |
222 | checked_format = 1; | |
223 | } | |
224 | ||
225 | u.ll = 0; | |
226 | if (p->sign < 0) | |
227 | u.ll |= (1ULL << 63); | |
228 | /* Make sure a zero encoding stays a zero. */ | |
229 | if (p->exp != -EXP_BIAS) | |
230 | u.ll |= ((unsigned long long)p->exp + 1023ULL) << 52; | |
231 | u.ll |= (unsigned long long) (p->mant & 0x007fffffUL) << (52 - 23); | |
232 | return u.d; | |
233 | } | |
234 | ||
235 | static void | |
236 | double_to_fp (double d, FP_Parts *p) | |
237 | { | |
238 | int exp; | |
239 | U_d_ll u; | |
240 | int sign; | |
241 | ||
242 | u.d = d; | |
243 | ||
244 | sign = (u.ll & 0x8000000000000000ULL) ? 1 : 0; | |
245 | exp = u.ll >> 52; | |
246 | exp = (exp & 0x7ff); | |
247 | ||
248 | if (exp == 0) | |
249 | { | |
250 | /* A generated denormal should show up as an underflow, not | |
251 | here. */ | |
252 | if (sign) | |
253 | fp_explode (MINUS_ZERO, p); | |
254 | else | |
255 | fp_explode (PLUS_ZERO, p); | |
256 | return; | |
257 | } | |
258 | ||
259 | exp = exp - 1023; | |
260 | if ((exp + EXP_BIAS) > 254) | |
261 | { | |
262 | FP_RAISE (O); | |
263 | switch (regs.r_fpsw & FPSWBITS_RM) | |
264 | { | |
265 | case FPRM_NEAREST: | |
266 | if (sign) | |
267 | fp_explode (MINUS_INF, p); | |
268 | else | |
269 | fp_explode (PLUS_INF, p); | |
270 | break; | |
271 | case FPRM_ZERO: | |
272 | if (sign) | |
273 | fp_explode (MINUS_MAX, p); | |
274 | else | |
275 | fp_explode (PLUS_MAX, p); | |
276 | break; | |
277 | case FPRM_PINF: | |
278 | if (sign) | |
279 | fp_explode (MINUS_MAX, p); | |
280 | else | |
281 | fp_explode (PLUS_INF, p); | |
282 | break; | |
283 | case FPRM_NINF: | |
284 | if (sign) | |
285 | fp_explode (MINUS_INF, p); | |
286 | else | |
287 | fp_explode (PLUS_MAX, p); | |
288 | break; | |
289 | } | |
290 | return; | |
291 | } | |
292 | if ((exp + EXP_BIAS) < 1) | |
293 | { | |
294 | if (sign) | |
295 | fp_explode (MINUS_ZERO, p); | |
296 | else | |
297 | fp_explode (PLUS_ZERO, p); | |
298 | FP_RAISE (U); | |
299 | } | |
300 | ||
301 | p->sign = sign ? -1 : 1; | |
302 | p->exp = exp; | |
303 | p->mant = u.ll >> (52-23) & 0x007fffffUL; | |
304 | p->mant |= 0x00800000UL; | |
305 | p->type = FP_NORMAL; | |
306 | ||
307 | if (u.ll & 0x1fffffffULL) | |
308 | { | |
309 | switch (regs.r_fpsw & FPSWBITS_RM) | |
310 | { | |
311 | case FPRM_NEAREST: | |
312 | if (u.ll & 0x10000000ULL) | |
313 | p->mant ++; | |
314 | break; | |
315 | case FPRM_ZERO: | |
316 | break; | |
317 | case FPRM_PINF: | |
318 | if (sign == 1) | |
319 | p->mant ++; | |
320 | break; | |
321 | case FPRM_NINF: | |
322 | if (sign == -1) | |
323 | p->mant ++; | |
324 | break; | |
325 | } | |
326 | FP_RAISE (X); | |
327 | } | |
328 | ||
329 | } | |
330 | ||
331 | typedef enum { | |
332 | eNR, /* Use the normal result. */ | |
333 | ePZ, eNZ, /* +- zero */ | |
334 | eSZ, /* signed zero - XOR signs of ops together. */ | |
335 | eRZ, /* +- zero depending on rounding mode. */ | |
336 | ePI, eNI, /* +- Infinity */ | |
337 | eSI, /* signed infinity - XOR signs of ops together. */ | |
338 | eQN, eSN, /* Quiet/Signalling NANs */ | |
339 | eIn, /* Invalid. */ | |
340 | eUn, /* Unimplemented. */ | |
341 | eDZ, /* Divide-by-zero. */ | |
342 | eLT, /* less than */ | |
343 | eGT, /* greater than */ | |
344 | eEQ, /* equal to */ | |
345 | } FP_ExceptionCases; | |
346 | ||
347 | #if defined DEBUG0 | |
348 | static const char *ex_names[] = { | |
349 | "NR", "PZ", "NZ", "SZ", "RZ", "PI", "NI", "SI", "QN", "SN", "IN", "Un", "DZ", "LT", "GT", "EQ" | |
350 | }; | |
351 | #endif | |
352 | ||
353 | /* This checks for all exceptional cases (not all FP exceptions) and | |
354 | returns TRUE if it is providing the result in *c. If it returns | |
355 | FALSE, the caller should do the "normal" operation. */ | |
356 | int | |
357 | check_exceptions (FP_Parts *a, FP_Parts *b, fp_t *c, | |
358 | FP_ExceptionCases ex_tab[5][5], | |
359 | FP_ExceptionCases *case_ret) | |
360 | { | |
361 | FP_ExceptionCases fpec; | |
362 | ||
363 | if (a->type == FP_SNAN | |
364 | || b->type == FP_SNAN) | |
365 | fpec = eIn; | |
366 | else if (a->type == FP_QNAN | |
367 | || b->type == FP_QNAN) | |
368 | fpec = eQN; | |
369 | else if (a->type == FP_DENORMAL | |
370 | || b->type == FP_DENORMAL) | |
371 | fpec = eUn; | |
372 | else | |
373 | fpec = ex_tab[(int)(a->type)][(int)(b->type)]; | |
374 | ||
375 | /*printf("%s %s -> %s\n", fpt_names[(int)(a->type)], fpt_names[(int)(b->type)], ex_names[(int)(fpec)]);*/ | |
376 | ||
377 | if (case_ret) | |
378 | *case_ret = fpec; | |
379 | ||
380 | switch (fpec) | |
381 | { | |
382 | case eNR: /* Use the normal result. */ | |
383 | return 0; | |
384 | ||
385 | case ePZ: /* + zero */ | |
386 | *c = 0x00000000; | |
387 | return 1; | |
388 | ||
389 | case eNZ: /* - zero */ | |
390 | *c = 0x80000000; | |
391 | return 1; | |
392 | ||
393 | case eSZ: /* signed zero */ | |
394 | *c = (a->sign == b->sign) ? PLUS_ZERO : MINUS_ZERO; | |
395 | return 1; | |
396 | ||
397 | case eRZ: /* +- zero depending on rounding mode. */ | |
398 | if ((regs.r_fpsw & FPSWBITS_RM) == FPRM_NINF) | |
399 | *c = 0x80000000; | |
400 | else | |
401 | *c = 0x00000000; | |
402 | return 1; | |
403 | ||
404 | case ePI: /* + Infinity */ | |
405 | *c = 0x7F800000; | |
406 | return 1; | |
407 | ||
408 | case eNI: /* - Infinity */ | |
409 | *c = 0xFF800000; | |
410 | return 1; | |
411 | ||
412 | case eSI: /* sign Infinity */ | |
413 | *c = (a->sign == b->sign) ? PLUS_INF : MINUS_INF; | |
414 | return 1; | |
415 | ||
416 | case eQN: /* Quiet NANs */ | |
417 | if (a->type == FP_QNAN) | |
418 | *c = a->orig_value; | |
419 | else | |
420 | *c = b->orig_value; | |
421 | return 1; | |
422 | ||
423 | case eSN: /* Signalling NANs */ | |
424 | if (a->type == FP_SNAN) | |
425 | *c = a->orig_value; | |
426 | else | |
427 | *c = b->orig_value; | |
428 | FP_RAISE (V); | |
429 | return 1; | |
430 | ||
431 | case eIn: /* Invalid. */ | |
432 | FP_RAISE (V); | |
433 | if (a->type == FP_SNAN) | |
434 | *c = a->orig_value | 0x00400000; | |
435 | else if (a->type == FP_SNAN) | |
436 | *c = b->orig_value | 0x00400000; | |
437 | else | |
438 | *c = 0x7fc00000; | |
439 | return 1; | |
440 | ||
441 | case eUn: /* Unimplemented. */ | |
442 | FP_RAISE (E); | |
443 | return 1; | |
444 | ||
445 | case eDZ: /* Division-by-zero. */ | |
446 | *c = (a->sign == b->sign) ? PLUS_INF : MINUS_INF; | |
447 | FP_RAISE (Z); | |
448 | return 1; | |
449 | ||
450 | default: | |
451 | return 0; | |
452 | } | |
453 | } | |
454 | ||
455 | #define CHECK_EXCEPTIONS(FPPa, FPPb, fpc, ex_tab) \ | |
456 | if (check_exceptions (&FPPa, &FPPb, &fpc, ex_tab, 0)) \ | |
457 | return fpc; | |
458 | ||
459 | /* For each operation, we have two tables of how nonnormal cases are | |
460 | handled. The DN=0 case is first, followed by the DN=1 case, with | |
461 | each table using the following layout: */ | |
462 | ||
463 | static FP_ExceptionCases ex_add_tab[5][5] = { | |
464 | /* N +0 -0 +In -In */ | |
465 | { eNR, eNR, eNR, ePI, eNI }, /* Normal */ | |
466 | { eNR, ePZ, eRZ, ePI, eNI }, /* +0 */ | |
467 | { eNR, eRZ, eNZ, ePI, eNI }, /* -0 */ | |
468 | { ePI, ePI, ePI, ePI, eIn }, /* +Inf */ | |
469 | { eNI, eNI, eNI, eIn, eNI }, /* -Inf */ | |
470 | }; | |
471 | ||
472 | fp_t | |
473 | rxfp_add (fp_t fa, fp_t fb) | |
474 | { | |
475 | FP_Parts a, b, c; | |
476 | fp_t rv; | |
477 | double da, db; | |
478 | ||
479 | fp_explode (fa, &a); | |
480 | fp_explode (fb, &b); | |
481 | CHECK_EXCEPTIONS (a, b, rv, ex_add_tab); | |
482 | ||
483 | da = fp_to_double (&a); | |
484 | db = fp_to_double (&b); | |
485 | tprintf("%g + %g = %g\n", da, db, da+db); | |
486 | ||
487 | double_to_fp (da+db, &c); | |
488 | rv = fp_implode (&c); | |
489 | return rv; | |
490 | } | |
491 | ||
492 | static FP_ExceptionCases ex_sub_tab[5][5] = { | |
493 | /* N +0 -0 +In -In */ | |
494 | { eNR, eNR, eNR, eNI, ePI }, /* Normal */ | |
495 | { eNR, eRZ, ePZ, eNI, ePI }, /* +0 */ | |
496 | { eNR, eNZ, eRZ, eNI, ePI }, /* -0 */ | |
497 | { ePI, ePI, ePI, eIn, ePI }, /* +Inf */ | |
498 | { eNI, eNI, eNI, eNI, eIn }, /* -Inf */ | |
499 | }; | |
500 | ||
501 | fp_t | |
502 | rxfp_sub (fp_t fa, fp_t fb) | |
503 | { | |
504 | FP_Parts a, b, c; | |
505 | fp_t rv; | |
506 | double da, db; | |
507 | ||
508 | fp_explode (fa, &a); | |
509 | fp_explode (fb, &b); | |
510 | CHECK_EXCEPTIONS (a, b, rv, ex_sub_tab); | |
511 | ||
512 | da = fp_to_double (&a); | |
513 | db = fp_to_double (&b); | |
514 | tprintf("%g - %g = %g\n", da, db, da-db); | |
515 | ||
516 | double_to_fp (da-db, &c); | |
517 | rv = fp_implode (&c); | |
518 | ||
519 | return rv; | |
520 | } | |
521 | ||
522 | static FP_ExceptionCases ex_mul_tab[5][5] = { | |
523 | /* N +0 -0 +In -In */ | |
524 | { eNR, eNR, eNR, eSI, eSI }, /* Normal */ | |
525 | { eNR, ePZ, eNZ, eIn, eIn }, /* +0 */ | |
526 | { eNR, eNZ, ePZ, eIn, eIn }, /* -0 */ | |
527 | { eSI, eIn, eIn, ePI, eNI }, /* +Inf */ | |
528 | { eSI, eIn, eIn, eNI, ePI }, /* -Inf */ | |
529 | }; | |
530 | ||
531 | fp_t | |
532 | rxfp_mul (fp_t fa, fp_t fb) | |
533 | { | |
534 | FP_Parts a, b, c; | |
535 | fp_t rv; | |
536 | double da, db; | |
537 | ||
538 | fp_explode (fa, &a); | |
539 | fp_explode (fb, &b); | |
540 | CHECK_EXCEPTIONS (a, b, rv, ex_mul_tab); | |
541 | ||
542 | da = fp_to_double (&a); | |
543 | db = fp_to_double (&b); | |
544 | tprintf("%g x %g = %g\n", da, db, da*db); | |
545 | ||
546 | double_to_fp (da*db, &c); | |
547 | rv = fp_implode (&c); | |
548 | ||
549 | return rv; | |
550 | } | |
551 | ||
552 | static FP_ExceptionCases ex_div_tab[5][5] = { | |
553 | /* N +0 -0 +In -In */ | |
554 | { eNR, eDZ, eDZ, eSZ, eSZ }, /* Normal */ | |
555 | { eSZ, eIn, eIn, ePZ, eNZ }, /* +0 */ | |
556 | { eSZ, eIn, eIn, eNZ, ePZ }, /* -0 */ | |
557 | { eSI, ePI, eNI, eIn, eIn }, /* +Inf */ | |
558 | { eSI, eNI, ePI, eIn, eIn }, /* -Inf */ | |
559 | }; | |
560 | ||
561 | fp_t | |
562 | rxfp_div (fp_t fa, fp_t fb) | |
563 | { | |
564 | FP_Parts a, b, c; | |
565 | fp_t rv; | |
566 | double da, db; | |
567 | ||
568 | fp_explode (fa, &a); | |
569 | fp_explode (fb, &b); | |
570 | CHECK_EXCEPTIONS (a, b, rv, ex_div_tab); | |
571 | ||
572 | da = fp_to_double (&a); | |
573 | db = fp_to_double (&b); | |
574 | tprintf("%g / %g = %g\n", da, db, da/db); | |
575 | ||
576 | double_to_fp (da/db, &c); | |
577 | rv = fp_implode (&c); | |
578 | ||
579 | return rv; | |
580 | } | |
581 | ||
582 | static FP_ExceptionCases ex_cmp_tab[5][5] = { | |
583 | /* N +0 -0 +In -In */ | |
584 | { eNR, eNR, eNR, eLT, eGT }, /* Normal */ | |
585 | { eNR, eEQ, eEQ, eLT, eGT }, /* +0 */ | |
586 | { eNR, eEQ, eEQ, eLT, eGT }, /* -0 */ | |
587 | { eGT, eGT, eGT, eEQ, eGT }, /* +Inf */ | |
588 | { eLT, eLT, eLT, eLT, eEQ }, /* -Inf */ | |
589 | }; | |
590 | ||
591 | void | |
592 | rxfp_cmp (fp_t fa, fp_t fb) | |
593 | { | |
594 | FP_Parts a, b; | |
595 | fp_t c; | |
596 | FP_ExceptionCases reason; | |
597 | int flags = 0; | |
598 | double da, db; | |
599 | ||
600 | fp_explode (fa, &a); | |
601 | fp_explode (fb, &b); | |
602 | ||
603 | if (check_exceptions (&a, &b, &c, ex_cmp_tab, &reason)) | |
604 | { | |
605 | if (reason == eQN) | |
606 | { | |
607 | /* Special case - incomparable. */ | |
608 | set_flags (FLAGBIT_Z | FLAGBIT_S | FLAGBIT_O, FLAGBIT_O); | |
609 | return; | |
610 | } | |
611 | return; | |
612 | } | |
613 | ||
614 | switch (reason) | |
615 | { | |
616 | case eEQ: | |
617 | flags = FLAGBIT_Z; | |
618 | break; | |
619 | case eLT: | |
620 | flags = FLAGBIT_S; | |
621 | break; | |
622 | case eGT: | |
623 | flags = 0; | |
624 | break; | |
625 | case eNR: | |
626 | da = fp_to_double (&a); | |
627 | db = fp_to_double (&b); | |
628 | tprintf("fcmp: %g cmp %g\n", da, db); | |
629 | if (da < db) | |
630 | flags = FLAGBIT_S; | |
631 | else if (da == db) | |
632 | flags = FLAGBIT_Z; | |
633 | else | |
634 | flags = 0; | |
635 | break; | |
636 | default: | |
637 | abort(); | |
638 | } | |
639 | ||
640 | set_flags (FLAGBIT_Z | FLAGBIT_S | FLAGBIT_O, flags); | |
641 | } | |
642 | ||
643 | long | |
644 | rxfp_ftoi (fp_t fa, int round_mode) | |
645 | { | |
646 | FP_Parts a; | |
647 | fp_t rv; | |
648 | int sign; | |
649 | int whole_bits, frac_bits; | |
650 | ||
651 | fp_explode (fa, &a); | |
652 | sign = fa & 0x80000000UL; | |
653 | ||
654 | switch (a.type) | |
655 | { | |
656 | case FP_NORMAL: | |
657 | break; | |
658 | case FP_PZERO: | |
659 | case FP_NZERO: | |
660 | return 0; | |
661 | case FP_PINFINITY: | |
662 | FP_RAISE (V); | |
663 | return 0x7fffffffL; | |
664 | case FP_NINFINITY: | |
665 | FP_RAISE (V); | |
666 | return 0x80000000L; | |
667 | case FP_DENORMAL: | |
668 | FP_RAISE (E); | |
669 | return 0; | |
670 | case FP_QNAN: | |
671 | case FP_SNAN: | |
672 | FP_RAISE (V); | |
673 | return sign ? 0x80000000U : 0x7fffffff; | |
674 | } | |
675 | ||
676 | if (a.exp >= 31) | |
677 | { | |
678 | FP_RAISE (V); | |
679 | return sign ? 0x80000000U : 0x7fffffff; | |
680 | } | |
681 | ||
682 | a.exp -= 23; | |
683 | ||
684 | if (a.exp <= -25) | |
685 | { | |
686 | /* Less than 0.49999 */ | |
687 | frac_bits = a.mant; | |
688 | whole_bits = 0; | |
689 | } | |
690 | else if (a.exp < 0) | |
691 | { | |
692 | frac_bits = a.mant << (32 + a.exp); | |
693 | whole_bits = a.mant >> (-a.exp); | |
694 | } | |
695 | else | |
696 | { | |
697 | frac_bits = 0; | |
698 | whole_bits = a.mant << a.exp; | |
699 | } | |
700 | ||
701 | if (frac_bits) | |
702 | { | |
703 | switch (round_mode & 3) | |
704 | { | |
705 | case FPRM_NEAREST: | |
706 | if (frac_bits & 0x80000000UL) | |
707 | whole_bits ++; | |
708 | break; | |
709 | case FPRM_ZERO: | |
710 | break; | |
711 | case FPRM_PINF: | |
712 | if (!sign) | |
713 | whole_bits ++; | |
714 | break; | |
715 | case FPRM_NINF: | |
716 | if (sign) | |
717 | whole_bits ++; | |
718 | break; | |
719 | } | |
720 | } | |
721 | ||
722 | rv = sign ? -whole_bits : whole_bits; | |
723 | ||
724 | return rv; | |
725 | } | |
726 | ||
727 | fp_t | |
728 | rxfp_itof (long fa, int round_mode) | |
729 | { | |
730 | fp_t rv; | |
731 | int sign = 0; | |
732 | unsigned int frac_bits; | |
733 | volatile unsigned int whole_bits; | |
734 | FP_Parts a; | |
735 | ||
736 | if (fa == 0) | |
737 | return PLUS_ZERO; | |
738 | ||
739 | if (fa < 0) | |
740 | { | |
741 | fa = -fa; | |
742 | sign = 1; | |
743 | a.sign = -1; | |
744 | } | |
745 | else | |
746 | a.sign = 1; | |
747 | ||
748 | whole_bits = fa; | |
749 | a.exp = 31; | |
750 | ||
751 | while (! (whole_bits & 0x80000000UL)) | |
752 | { | |
753 | a.exp --; | |
754 | whole_bits <<= 1; | |
755 | } | |
756 | frac_bits = whole_bits & 0xff; | |
757 | whole_bits = whole_bits >> 8; | |
758 | ||
759 | if (frac_bits) | |
760 | { | |
761 | /* We must round */ | |
762 | switch (round_mode & 3) | |
763 | { | |
764 | case FPRM_NEAREST: | |
765 | if (frac_bits & 0x80) | |
766 | whole_bits ++; | |
767 | break; | |
768 | case FPRM_ZERO: | |
769 | break; | |
770 | case FPRM_PINF: | |
771 | if (!sign) | |
772 | whole_bits ++; | |
773 | break; | |
774 | case FPRM_NINF: | |
775 | if (sign) | |
776 | whole_bits ++; | |
777 | break; | |
778 | } | |
779 | } | |
780 | ||
781 | a.mant = whole_bits; | |
782 | if (whole_bits & 0xff000000UL) | |
783 | { | |
784 | a.mant >>= 1; | |
785 | a.exp ++; | |
786 | } | |
787 | ||
788 | rv = fp_implode (&a); | |
789 | return rv; | |
790 | } | |
791 |