diff options
author | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 18:20:36 -0400 |
---|---|---|
committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 18:20:36 -0400 |
commit | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch) | |
tree | 0bba044c4ce775e45a88a51686b5d9f90697ea9d /arch/parisc/math-emu/sfadd.c |
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
Diffstat (limited to 'arch/parisc/math-emu/sfadd.c')
-rw-r--r-- | arch/parisc/math-emu/sfadd.c | 518 |
1 files changed, 518 insertions, 0 deletions
diff --git a/arch/parisc/math-emu/sfadd.c b/arch/parisc/math-emu/sfadd.c new file mode 100644 index 000000000000..008d721b5d22 --- /dev/null +++ b/arch/parisc/math-emu/sfadd.c | |||
@@ -0,0 +1,518 @@ | |||
1 | /* | ||
2 | * Linux/PA-RISC Project (http://www.parisc-linux.org/) | ||
3 | * | ||
4 | * Floating-point emulation code | ||
5 | * Copyright (C) 2001 Hewlett-Packard (Paul Bame) <bame@debian.org> | ||
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, or (at your option) | ||
10 | * 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 | ||
19 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | ||
20 | */ | ||
21 | /* | ||
22 | * BEGIN_DESC | ||
23 | * | ||
24 | * File: | ||
25 | * @(#) pa/spmath/sfadd.c $Revision: 1.1 $ | ||
26 | * | ||
27 | * Purpose: | ||
28 | * Single_add: add two single precision values. | ||
29 | * | ||
30 | * External Interfaces: | ||
31 | * sgl_fadd(leftptr, rightptr, dstptr, status) | ||
32 | * | ||
33 | * Internal Interfaces: | ||
34 | * | ||
35 | * Theory: | ||
36 | * <<please update with a overview of the operation of this file>> | ||
37 | * | ||
38 | * END_DESC | ||
39 | */ | ||
40 | |||
41 | |||
42 | #include "float.h" | ||
43 | #include "sgl_float.h" | ||
44 | |||
45 | /* | ||
46 | * Single_add: add two single precision values. | ||
47 | */ | ||
48 | int | ||
49 | sgl_fadd( | ||
50 | sgl_floating_point *leftptr, | ||
51 | sgl_floating_point *rightptr, | ||
52 | sgl_floating_point *dstptr, | ||
53 | unsigned int *status) | ||
54 | { | ||
55 | register unsigned int left, right, result, extent; | ||
56 | register unsigned int signless_upper_left, signless_upper_right, save; | ||
57 | |||
58 | |||
59 | register int result_exponent, right_exponent, diff_exponent; | ||
60 | register int sign_save, jumpsize; | ||
61 | register boolean inexact = FALSE; | ||
62 | register boolean underflowtrap; | ||
63 | |||
64 | /* Create local copies of the numbers */ | ||
65 | left = *leftptr; | ||
66 | right = *rightptr; | ||
67 | |||
68 | /* A zero "save" helps discover equal operands (for later), * | ||
69 | * and is used in swapping operands (if needed). */ | ||
70 | Sgl_xortointp1(left,right,/*to*/save); | ||
71 | |||
72 | /* | ||
73 | * check first operand for NaN's or infinity | ||
74 | */ | ||
75 | if ((result_exponent = Sgl_exponent(left)) == SGL_INFINITY_EXPONENT) | ||
76 | { | ||
77 | if (Sgl_iszero_mantissa(left)) | ||
78 | { | ||
79 | if (Sgl_isnotnan(right)) | ||
80 | { | ||
81 | if (Sgl_isinfinity(right) && save!=0) | ||
82 | { | ||
83 | /* | ||
84 | * invalid since operands are opposite signed infinity's | ||
85 | */ | ||
86 | if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION); | ||
87 | Set_invalidflag(); | ||
88 | Sgl_makequietnan(result); | ||
89 | *dstptr = result; | ||
90 | return(NOEXCEPTION); | ||
91 | } | ||
92 | /* | ||
93 | * return infinity | ||
94 | */ | ||
95 | *dstptr = left; | ||
96 | return(NOEXCEPTION); | ||
97 | } | ||
98 | } | ||
99 | else | ||
100 | { | ||
101 | /* | ||
102 | * is NaN; signaling or quiet? | ||
103 | */ | ||
104 | if (Sgl_isone_signaling(left)) | ||
105 | { | ||
106 | /* trap if INVALIDTRAP enabled */ | ||
107 | if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION); | ||
108 | /* make NaN quiet */ | ||
109 | Set_invalidflag(); | ||
110 | Sgl_set_quiet(left); | ||
111 | } | ||
112 | /* | ||
113 | * is second operand a signaling NaN? | ||
114 | */ | ||
115 | else if (Sgl_is_signalingnan(right)) | ||
116 | { | ||
117 | /* trap if INVALIDTRAP enabled */ | ||
118 | if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION); | ||
119 | /* make NaN quiet */ | ||
120 | Set_invalidflag(); | ||
121 | Sgl_set_quiet(right); | ||
122 | *dstptr = right; | ||
123 | return(NOEXCEPTION); | ||
124 | } | ||
125 | /* | ||
126 | * return quiet NaN | ||
127 | */ | ||
128 | *dstptr = left; | ||
129 | return(NOEXCEPTION); | ||
130 | } | ||
131 | } /* End left NaN or Infinity processing */ | ||
132 | /* | ||
133 | * check second operand for NaN's or infinity | ||
134 | */ | ||
135 | if (Sgl_isinfinity_exponent(right)) | ||
136 | { | ||
137 | if (Sgl_iszero_mantissa(right)) | ||
138 | { | ||
139 | /* return infinity */ | ||
140 | *dstptr = right; | ||
141 | return(NOEXCEPTION); | ||
142 | } | ||
143 | /* | ||
144 | * is NaN; signaling or quiet? | ||
145 | */ | ||
146 | if (Sgl_isone_signaling(right)) | ||
147 | { | ||
148 | /* trap if INVALIDTRAP enabled */ | ||
149 | if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION); | ||
150 | /* make NaN quiet */ | ||
151 | Set_invalidflag(); | ||
152 | Sgl_set_quiet(right); | ||
153 | } | ||
154 | /* | ||
155 | * return quiet NaN | ||
156 | */ | ||
157 | *dstptr = right; | ||
158 | return(NOEXCEPTION); | ||
159 | } /* End right NaN or Infinity processing */ | ||
160 | |||
161 | /* Invariant: Must be dealing with finite numbers */ | ||
162 | |||
163 | /* Compare operands by removing the sign */ | ||
164 | Sgl_copytoint_exponentmantissa(left,signless_upper_left); | ||
165 | Sgl_copytoint_exponentmantissa(right,signless_upper_right); | ||
166 | |||
167 | /* sign difference selects add or sub operation. */ | ||
168 | if(Sgl_ismagnitudeless(signless_upper_left,signless_upper_right)) | ||
169 | { | ||
170 | /* Set the left operand to the larger one by XOR swap * | ||
171 | * First finish the first word using "save" */ | ||
172 | Sgl_xorfromintp1(save,right,/*to*/right); | ||
173 | Sgl_xorfromintp1(save,left,/*to*/left); | ||
174 | result_exponent = Sgl_exponent(left); | ||
175 | } | ||
176 | /* Invariant: left is not smaller than right. */ | ||
177 | |||
178 | if((right_exponent = Sgl_exponent(right)) == 0) | ||
179 | { | ||
180 | /* Denormalized operands. First look for zeroes */ | ||
181 | if(Sgl_iszero_mantissa(right)) | ||
182 | { | ||
183 | /* right is zero */ | ||
184 | if(Sgl_iszero_exponentmantissa(left)) | ||
185 | { | ||
186 | /* Both operands are zeros */ | ||
187 | if(Is_rounding_mode(ROUNDMINUS)) | ||
188 | { | ||
189 | Sgl_or_signs(left,/*with*/right); | ||
190 | } | ||
191 | else | ||
192 | { | ||
193 | Sgl_and_signs(left,/*with*/right); | ||
194 | } | ||
195 | } | ||
196 | else | ||
197 | { | ||
198 | /* Left is not a zero and must be the result. Trapped | ||
199 | * underflows are signaled if left is denormalized. Result | ||
200 | * is always exact. */ | ||
201 | if( (result_exponent == 0) && Is_underflowtrap_enabled() ) | ||
202 | { | ||
203 | /* need to normalize results mantissa */ | ||
204 | sign_save = Sgl_signextendedsign(left); | ||
205 | Sgl_leftshiftby1(left); | ||
206 | Sgl_normalize(left,result_exponent); | ||
207 | Sgl_set_sign(left,/*using*/sign_save); | ||
208 | Sgl_setwrapped_exponent(left,result_exponent,unfl); | ||
209 | *dstptr = left; | ||
210 | return(UNDERFLOWEXCEPTION); | ||
211 | } | ||
212 | } | ||
213 | *dstptr = left; | ||
214 | return(NOEXCEPTION); | ||
215 | } | ||
216 | |||
217 | /* Neither are zeroes */ | ||
218 | Sgl_clear_sign(right); /* Exponent is already cleared */ | ||
219 | if(result_exponent == 0 ) | ||
220 | { | ||
221 | /* Both operands are denormalized. The result must be exact | ||
222 | * and is simply calculated. A sum could become normalized and a | ||
223 | * difference could cancel to a true zero. */ | ||
224 | if( (/*signed*/int) save < 0 ) | ||
225 | { | ||
226 | Sgl_subtract(left,/*minus*/right,/*into*/result); | ||
227 | if(Sgl_iszero_mantissa(result)) | ||
228 | { | ||
229 | if(Is_rounding_mode(ROUNDMINUS)) | ||
230 | { | ||
231 | Sgl_setone_sign(result); | ||
232 | } | ||
233 | else | ||
234 | { | ||
235 | Sgl_setzero_sign(result); | ||
236 | } | ||
237 | *dstptr = result; | ||
238 | return(NOEXCEPTION); | ||
239 | } | ||
240 | } | ||
241 | else | ||
242 | { | ||
243 | Sgl_addition(left,right,/*into*/result); | ||
244 | if(Sgl_isone_hidden(result)) | ||
245 | { | ||
246 | *dstptr = result; | ||
247 | return(NOEXCEPTION); | ||
248 | } | ||
249 | } | ||
250 | if(Is_underflowtrap_enabled()) | ||
251 | { | ||
252 | /* need to normalize result */ | ||
253 | sign_save = Sgl_signextendedsign(result); | ||
254 | Sgl_leftshiftby1(result); | ||
255 | Sgl_normalize(result,result_exponent); | ||
256 | Sgl_set_sign(result,/*using*/sign_save); | ||
257 | Sgl_setwrapped_exponent(result,result_exponent,unfl); | ||
258 | *dstptr = result; | ||
259 | return(UNDERFLOWEXCEPTION); | ||
260 | } | ||
261 | *dstptr = result; | ||
262 | return(NOEXCEPTION); | ||
263 | } | ||
264 | right_exponent = 1; /* Set exponent to reflect different bias | ||
265 | * with denomalized numbers. */ | ||
266 | } | ||
267 | else | ||
268 | { | ||
269 | Sgl_clear_signexponent_set_hidden(right); | ||
270 | } | ||
271 | Sgl_clear_exponent_set_hidden(left); | ||
272 | diff_exponent = result_exponent - right_exponent; | ||
273 | |||
274 | /* | ||
275 | * Special case alignment of operands that would force alignment | ||
276 | * beyond the extent of the extension. A further optimization | ||
277 | * could special case this but only reduces the path length for this | ||
278 | * infrequent case. | ||
279 | */ | ||
280 | if(diff_exponent > SGL_THRESHOLD) | ||
281 | { | ||
282 | diff_exponent = SGL_THRESHOLD; | ||
283 | } | ||
284 | |||
285 | /* Align right operand by shifting to right */ | ||
286 | Sgl_right_align(/*operand*/right,/*shifted by*/diff_exponent, | ||
287 | /*and lower to*/extent); | ||
288 | |||
289 | /* Treat sum and difference of the operands separately. */ | ||
290 | if( (/*signed*/int) save < 0 ) | ||
291 | { | ||
292 | /* | ||
293 | * Difference of the two operands. Their can be no overflow. A | ||
294 | * borrow can occur out of the hidden bit and force a post | ||
295 | * normalization phase. | ||
296 | */ | ||
297 | Sgl_subtract_withextension(left,/*minus*/right,/*with*/extent,/*into*/result); | ||
298 | if(Sgl_iszero_hidden(result)) | ||
299 | { | ||
300 | /* Handle normalization */ | ||
301 | /* A straight foward algorithm would now shift the result | ||
302 | * and extension left until the hidden bit becomes one. Not | ||
303 | * all of the extension bits need participate in the shift. | ||
304 | * Only the two most significant bits (round and guard) are | ||
305 | * needed. If only a single shift is needed then the guard | ||
306 | * bit becomes a significant low order bit and the extension | ||
307 | * must participate in the rounding. If more than a single | ||
308 | * shift is needed, then all bits to the right of the guard | ||
309 | * bit are zeros, and the guard bit may or may not be zero. */ | ||
310 | sign_save = Sgl_signextendedsign(result); | ||
311 | Sgl_leftshiftby1_withextent(result,extent,result); | ||
312 | |||
313 | /* Need to check for a zero result. The sign and exponent | ||
314 | * fields have already been zeroed. The more efficient test | ||
315 | * of the full object can be used. | ||
316 | */ | ||
317 | if(Sgl_iszero(result)) | ||
318 | /* Must have been "x-x" or "x+(-x)". */ | ||
319 | { | ||
320 | if(Is_rounding_mode(ROUNDMINUS)) Sgl_setone_sign(result); | ||
321 | *dstptr = result; | ||
322 | return(NOEXCEPTION); | ||
323 | } | ||
324 | result_exponent--; | ||
325 | /* Look to see if normalization is finished. */ | ||
326 | if(Sgl_isone_hidden(result)) | ||
327 | { | ||
328 | if(result_exponent==0) | ||
329 | { | ||
330 | /* Denormalized, exponent should be zero. Left operand * | ||
331 | * was normalized, so extent (guard, round) was zero */ | ||
332 | goto underflow; | ||
333 | } | ||
334 | else | ||
335 | { | ||
336 | /* No further normalization is needed. */ | ||
337 | Sgl_set_sign(result,/*using*/sign_save); | ||
338 | Ext_leftshiftby1(extent); | ||
339 | goto round; | ||
340 | } | ||
341 | } | ||
342 | |||
343 | /* Check for denormalized, exponent should be zero. Left * | ||
344 | * operand was normalized, so extent (guard, round) was zero */ | ||
345 | if(!(underflowtrap = Is_underflowtrap_enabled()) && | ||
346 | result_exponent==0) goto underflow; | ||
347 | |||
348 | /* Shift extension to complete one bit of normalization and | ||
349 | * update exponent. */ | ||
350 | Ext_leftshiftby1(extent); | ||
351 | |||
352 | /* Discover first one bit to determine shift amount. Use a | ||
353 | * modified binary search. We have already shifted the result | ||
354 | * one position right and still not found a one so the remainder | ||
355 | * of the extension must be zero and simplifies rounding. */ | ||
356 | /* Scan bytes */ | ||
357 | while(Sgl_iszero_hiddenhigh7mantissa(result)) | ||
358 | { | ||
359 | Sgl_leftshiftby8(result); | ||
360 | if((result_exponent -= 8) <= 0 && !underflowtrap) | ||
361 | goto underflow; | ||
362 | } | ||
363 | /* Now narrow it down to the nibble */ | ||
364 | if(Sgl_iszero_hiddenhigh3mantissa(result)) | ||
365 | { | ||
366 | /* The lower nibble contains the normalizing one */ | ||
367 | Sgl_leftshiftby4(result); | ||
368 | if((result_exponent -= 4) <= 0 && !underflowtrap) | ||
369 | goto underflow; | ||
370 | } | ||
371 | /* Select case were first bit is set (already normalized) | ||
372 | * otherwise select the proper shift. */ | ||
373 | if((jumpsize = Sgl_hiddenhigh3mantissa(result)) > 7) | ||
374 | { | ||
375 | /* Already normalized */ | ||
376 | if(result_exponent <= 0) goto underflow; | ||
377 | Sgl_set_sign(result,/*using*/sign_save); | ||
378 | Sgl_set_exponent(result,/*using*/result_exponent); | ||
379 | *dstptr = result; | ||
380 | return(NOEXCEPTION); | ||
381 | } | ||
382 | Sgl_sethigh4bits(result,/*using*/sign_save); | ||
383 | switch(jumpsize) | ||
384 | { | ||
385 | case 1: | ||
386 | { | ||
387 | Sgl_leftshiftby3(result); | ||
388 | result_exponent -= 3; | ||
389 | break; | ||
390 | } | ||
391 | case 2: | ||
392 | case 3: | ||
393 | { | ||
394 | Sgl_leftshiftby2(result); | ||
395 | result_exponent -= 2; | ||
396 | break; | ||
397 | } | ||
398 | case 4: | ||
399 | case 5: | ||
400 | case 6: | ||
401 | case 7: | ||
402 | { | ||
403 | Sgl_leftshiftby1(result); | ||
404 | result_exponent -= 1; | ||
405 | break; | ||
406 | } | ||
407 | } | ||
408 | if(result_exponent > 0) | ||
409 | { | ||
410 | Sgl_set_exponent(result,/*using*/result_exponent); | ||
411 | *dstptr = result; | ||
412 | return(NOEXCEPTION); /* Sign bit is already set */ | ||
413 | } | ||
414 | /* Fixup potential underflows */ | ||
415 | underflow: | ||
416 | if(Is_underflowtrap_enabled()) | ||
417 | { | ||
418 | Sgl_set_sign(result,sign_save); | ||
419 | Sgl_setwrapped_exponent(result,result_exponent,unfl); | ||
420 | *dstptr = result; | ||
421 | /* inexact = FALSE; */ | ||
422 | return(UNDERFLOWEXCEPTION); | ||
423 | } | ||
424 | /* | ||
425 | * Since we cannot get an inexact denormalized result, | ||
426 | * we can now return. | ||
427 | */ | ||
428 | Sgl_right_align(result,/*by*/(1-result_exponent),extent); | ||
429 | Sgl_clear_signexponent(result); | ||
430 | Sgl_set_sign(result,sign_save); | ||
431 | *dstptr = result; | ||
432 | return(NOEXCEPTION); | ||
433 | } /* end if(hidden...)... */ | ||
434 | /* Fall through and round */ | ||
435 | } /* end if(save < 0)... */ | ||
436 | else | ||
437 | { | ||
438 | /* Add magnitudes */ | ||
439 | Sgl_addition(left,right,/*to*/result); | ||
440 | if(Sgl_isone_hiddenoverflow(result)) | ||
441 | { | ||
442 | /* Prenormalization required. */ | ||
443 | Sgl_rightshiftby1_withextent(result,extent,extent); | ||
444 | Sgl_arithrightshiftby1(result); | ||
445 | result_exponent++; | ||
446 | } /* end if hiddenoverflow... */ | ||
447 | } /* end else ...add magnitudes... */ | ||
448 | |||
449 | /* Round the result. If the extension is all zeros,then the result is | ||
450 | * exact. Otherwise round in the correct direction. No underflow is | ||
451 | * possible. If a postnormalization is necessary, then the mantissa is | ||
452 | * all zeros so no shift is needed. */ | ||
453 | round: | ||
454 | if(Ext_isnotzero(extent)) | ||
455 | { | ||
456 | inexact = TRUE; | ||
457 | switch(Rounding_mode()) | ||
458 | { | ||
459 | case ROUNDNEAREST: /* The default. */ | ||
460 | if(Ext_isone_sign(extent)) | ||
461 | { | ||
462 | /* at least 1/2 ulp */ | ||
463 | if(Ext_isnotzero_lower(extent) || | ||
464 | Sgl_isone_lowmantissa(result)) | ||
465 | { | ||
466 | /* either exactly half way and odd or more than 1/2ulp */ | ||
467 | Sgl_increment(result); | ||
468 | } | ||
469 | } | ||
470 | break; | ||
471 | |||
472 | case ROUNDPLUS: | ||
473 | if(Sgl_iszero_sign(result)) | ||
474 | { | ||
475 | /* Round up positive results */ | ||
476 | Sgl_increment(result); | ||
477 | } | ||
478 | break; | ||
479 | |||
480 | case ROUNDMINUS: | ||
481 | if(Sgl_isone_sign(result)) | ||
482 | { | ||
483 | /* Round down negative results */ | ||
484 | Sgl_increment(result); | ||
485 | } | ||
486 | |||
487 | case ROUNDZERO:; | ||
488 | /* truncate is simple */ | ||
489 | } /* end switch... */ | ||
490 | if(Sgl_isone_hiddenoverflow(result)) result_exponent++; | ||
491 | } | ||
492 | if(result_exponent == SGL_INFINITY_EXPONENT) | ||
493 | { | ||
494 | /* Overflow */ | ||
495 | if(Is_overflowtrap_enabled()) | ||
496 | { | ||
497 | Sgl_setwrapped_exponent(result,result_exponent,ovfl); | ||
498 | *dstptr = result; | ||
499 | if (inexact) | ||
500 | if (Is_inexacttrap_enabled()) | ||
501 | return(OVERFLOWEXCEPTION | INEXACTEXCEPTION); | ||
502 | else Set_inexactflag(); | ||
503 | return(OVERFLOWEXCEPTION); | ||
504 | } | ||
505 | else | ||
506 | { | ||
507 | Set_overflowflag(); | ||
508 | inexact = TRUE; | ||
509 | Sgl_setoverflow(result); | ||
510 | } | ||
511 | } | ||
512 | else Sgl_set_exponent(result,result_exponent); | ||
513 | *dstptr = result; | ||
514 | if(inexact) | ||
515 | if(Is_inexacttrap_enabled()) return(INEXACTEXCEPTION); | ||
516 | else Set_inexactflag(); | ||
517 | return(NOEXCEPTION); | ||
518 | } | ||