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1da177e4 LT |
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/fmpyfadd.c $Revision: 1.1 $ | |
26 | * | |
27 | * Purpose: | |
28 | * Double Floating-point Multiply Fused Add | |
29 | * Double Floating-point Multiply Negate Fused Add | |
30 | * Single Floating-point Multiply Fused Add | |
31 | * Single Floating-point Multiply Negate Fused Add | |
32 | * | |
33 | * External Interfaces: | |
34 | * dbl_fmpyfadd(src1ptr,src2ptr,src3ptr,status,dstptr) | |
35 | * dbl_fmpynfadd(src1ptr,src2ptr,src3ptr,status,dstptr) | |
36 | * sgl_fmpyfadd(src1ptr,src2ptr,src3ptr,status,dstptr) | |
37 | * sgl_fmpynfadd(src1ptr,src2ptr,src3ptr,status,dstptr) | |
38 | * | |
39 | * Internal Interfaces: | |
40 | * | |
41 | * Theory: | |
42 | * <<please update with a overview of the operation of this file>> | |
43 | * | |
44 | * END_DESC | |
45 | */ | |
46 | ||
47 | ||
48 | #include "float.h" | |
49 | #include "sgl_float.h" | |
50 | #include "dbl_float.h" | |
51 | ||
52 | ||
53 | /* | |
54 | * Double Floating-point Multiply Fused Add | |
55 | */ | |
56 | ||
57 | int | |
58 | dbl_fmpyfadd( | |
59 | dbl_floating_point *src1ptr, | |
60 | dbl_floating_point *src2ptr, | |
61 | dbl_floating_point *src3ptr, | |
62 | unsigned int *status, | |
63 | dbl_floating_point *dstptr) | |
64 | { | |
65 | unsigned int opnd1p1, opnd1p2, opnd2p1, opnd2p2, opnd3p1, opnd3p2; | |
66 | register unsigned int tmpresp1, tmpresp2, tmpresp3, tmpresp4; | |
67 | unsigned int rightp1, rightp2, rightp3, rightp4; | |
68 | unsigned int resultp1, resultp2 = 0, resultp3 = 0, resultp4 = 0; | |
69 | register int mpy_exponent, add_exponent, count; | |
70 | boolean inexact = FALSE, is_tiny = FALSE; | |
71 | ||
72 | unsigned int signlessleft1, signlessright1, save; | |
73 | register int result_exponent, diff_exponent; | |
74 | int sign_save, jumpsize; | |
75 | ||
76 | Dbl_copyfromptr(src1ptr,opnd1p1,opnd1p2); | |
77 | Dbl_copyfromptr(src2ptr,opnd2p1,opnd2p2); | |
78 | Dbl_copyfromptr(src3ptr,opnd3p1,opnd3p2); | |
79 | ||
80 | /* | |
81 | * set sign bit of result of multiply | |
82 | */ | |
83 | if (Dbl_sign(opnd1p1) ^ Dbl_sign(opnd2p1)) | |
84 | Dbl_setnegativezerop1(resultp1); | |
85 | else Dbl_setzerop1(resultp1); | |
86 | ||
87 | /* | |
88 | * Generate multiply exponent | |
89 | */ | |
90 | mpy_exponent = Dbl_exponent(opnd1p1) + Dbl_exponent(opnd2p1) - DBL_BIAS; | |
91 | ||
92 | /* | |
93 | * check first operand for NaN's or infinity | |
94 | */ | |
95 | if (Dbl_isinfinity_exponent(opnd1p1)) { | |
96 | if (Dbl_iszero_mantissa(opnd1p1,opnd1p2)) { | |
97 | if (Dbl_isnotnan(opnd2p1,opnd2p2) && | |
98 | Dbl_isnotnan(opnd3p1,opnd3p2)) { | |
99 | if (Dbl_iszero_exponentmantissa(opnd2p1,opnd2p2)) { | |
100 | /* | |
101 | * invalid since operands are infinity | |
102 | * and zero | |
103 | */ | |
104 | if (Is_invalidtrap_enabled()) | |
105 | return(OPC_2E_INVALIDEXCEPTION); | |
106 | Set_invalidflag(); | |
107 | Dbl_makequietnan(resultp1,resultp2); | |
108 | Dbl_copytoptr(resultp1,resultp2,dstptr); | |
109 | return(NOEXCEPTION); | |
110 | } | |
111 | /* | |
112 | * Check third operand for infinity with a | |
113 | * sign opposite of the multiply result | |
114 | */ | |
115 | if (Dbl_isinfinity(opnd3p1,opnd3p2) && | |
116 | (Dbl_sign(resultp1) ^ Dbl_sign(opnd3p1))) { | |
117 | /* | |
118 | * invalid since attempting a magnitude | |
119 | * subtraction of infinities | |
120 | */ | |
121 | if (Is_invalidtrap_enabled()) | |
122 | return(OPC_2E_INVALIDEXCEPTION); | |
123 | Set_invalidflag(); | |
124 | Dbl_makequietnan(resultp1,resultp2); | |
125 | Dbl_copytoptr(resultp1,resultp2,dstptr); | |
126 | return(NOEXCEPTION); | |
127 | } | |
128 | ||
129 | /* | |
130 | * return infinity | |
131 | */ | |
132 | Dbl_setinfinity_exponentmantissa(resultp1,resultp2); | |
133 | Dbl_copytoptr(resultp1,resultp2,dstptr); | |
134 | return(NOEXCEPTION); | |
135 | } | |
136 | } | |
137 | else { | |
138 | /* | |
139 | * is NaN; signaling or quiet? | |
140 | */ | |
141 | if (Dbl_isone_signaling(opnd1p1)) { | |
142 | /* trap if INVALIDTRAP enabled */ | |
143 | if (Is_invalidtrap_enabled()) | |
144 | return(OPC_2E_INVALIDEXCEPTION); | |
145 | /* make NaN quiet */ | |
146 | Set_invalidflag(); | |
147 | Dbl_set_quiet(opnd1p1); | |
148 | } | |
149 | /* | |
150 | * is second operand a signaling NaN? | |
151 | */ | |
152 | else if (Dbl_is_signalingnan(opnd2p1)) { | |
153 | /* trap if INVALIDTRAP enabled */ | |
154 | if (Is_invalidtrap_enabled()) | |
155 | return(OPC_2E_INVALIDEXCEPTION); | |
156 | /* make NaN quiet */ | |
157 | Set_invalidflag(); | |
158 | Dbl_set_quiet(opnd2p1); | |
159 | Dbl_copytoptr(opnd2p1,opnd2p2,dstptr); | |
160 | return(NOEXCEPTION); | |
161 | } | |
162 | /* | |
163 | * is third operand a signaling NaN? | |
164 | */ | |
165 | else if (Dbl_is_signalingnan(opnd3p1)) { | |
166 | /* trap if INVALIDTRAP enabled */ | |
167 | if (Is_invalidtrap_enabled()) | |
168 | return(OPC_2E_INVALIDEXCEPTION); | |
169 | /* make NaN quiet */ | |
170 | Set_invalidflag(); | |
171 | Dbl_set_quiet(opnd3p1); | |
172 | Dbl_copytoptr(opnd3p1,opnd3p2,dstptr); | |
173 | return(NOEXCEPTION); | |
174 | } | |
175 | /* | |
176 | * return quiet NaN | |
177 | */ | |
178 | Dbl_copytoptr(opnd1p1,opnd1p2,dstptr); | |
179 | return(NOEXCEPTION); | |
180 | } | |
181 | } | |
182 | ||
183 | /* | |
184 | * check second operand for NaN's or infinity | |
185 | */ | |
186 | if (Dbl_isinfinity_exponent(opnd2p1)) { | |
187 | if (Dbl_iszero_mantissa(opnd2p1,opnd2p2)) { | |
188 | if (Dbl_isnotnan(opnd3p1,opnd3p2)) { | |
189 | if (Dbl_iszero_exponentmantissa(opnd1p1,opnd1p2)) { | |
190 | /* | |
191 | * invalid since multiply operands are | |
192 | * zero & infinity | |
193 | */ | |
194 | if (Is_invalidtrap_enabled()) | |
195 | return(OPC_2E_INVALIDEXCEPTION); | |
196 | Set_invalidflag(); | |
197 | Dbl_makequietnan(opnd2p1,opnd2p2); | |
198 | Dbl_copytoptr(opnd2p1,opnd2p2,dstptr); | |
199 | return(NOEXCEPTION); | |
200 | } | |
201 | ||
202 | /* | |
203 | * Check third operand for infinity with a | |
204 | * sign opposite of the multiply result | |
205 | */ | |
206 | if (Dbl_isinfinity(opnd3p1,opnd3p2) && | |
207 | (Dbl_sign(resultp1) ^ Dbl_sign(opnd3p1))) { | |
208 | /* | |
209 | * invalid since attempting a magnitude | |
210 | * subtraction of infinities | |
211 | */ | |
212 | if (Is_invalidtrap_enabled()) | |
213 | return(OPC_2E_INVALIDEXCEPTION); | |
214 | Set_invalidflag(); | |
215 | Dbl_makequietnan(resultp1,resultp2); | |
216 | Dbl_copytoptr(resultp1,resultp2,dstptr); | |
217 | return(NOEXCEPTION); | |
218 | } | |
219 | ||
220 | /* | |
221 | * return infinity | |
222 | */ | |
223 | Dbl_setinfinity_exponentmantissa(resultp1,resultp2); | |
224 | Dbl_copytoptr(resultp1,resultp2,dstptr); | |
225 | return(NOEXCEPTION); | |
226 | } | |
227 | } | |
228 | else { | |
229 | /* | |
230 | * is NaN; signaling or quiet? | |
231 | */ | |
232 | if (Dbl_isone_signaling(opnd2p1)) { | |
233 | /* trap if INVALIDTRAP enabled */ | |
234 | if (Is_invalidtrap_enabled()) | |
235 | return(OPC_2E_INVALIDEXCEPTION); | |
236 | /* make NaN quiet */ | |
237 | Set_invalidflag(); | |
238 | Dbl_set_quiet(opnd2p1); | |
239 | } | |
240 | /* | |
241 | * is third operand a signaling NaN? | |
242 | */ | |
243 | else if (Dbl_is_signalingnan(opnd3p1)) { | |
244 | /* trap if INVALIDTRAP enabled */ | |
245 | if (Is_invalidtrap_enabled()) | |
246 | return(OPC_2E_INVALIDEXCEPTION); | |
247 | /* make NaN quiet */ | |
248 | Set_invalidflag(); | |
249 | Dbl_set_quiet(opnd3p1); | |
250 | Dbl_copytoptr(opnd3p1,opnd3p2,dstptr); | |
251 | return(NOEXCEPTION); | |
252 | } | |
253 | /* | |
254 | * return quiet NaN | |
255 | */ | |
256 | Dbl_copytoptr(opnd2p1,opnd2p2,dstptr); | |
257 | return(NOEXCEPTION); | |
258 | } | |
259 | } | |
260 | ||
261 | /* | |
262 | * check third operand for NaN's or infinity | |
263 | */ | |
264 | if (Dbl_isinfinity_exponent(opnd3p1)) { | |
265 | if (Dbl_iszero_mantissa(opnd3p1,opnd3p2)) { | |
266 | /* return infinity */ | |
267 | Dbl_copytoptr(opnd3p1,opnd3p2,dstptr); | |
268 | return(NOEXCEPTION); | |
269 | } else { | |
270 | /* | |
271 | * is NaN; signaling or quiet? | |
272 | */ | |
273 | if (Dbl_isone_signaling(opnd3p1)) { | |
274 | /* trap if INVALIDTRAP enabled */ | |
275 | if (Is_invalidtrap_enabled()) | |
276 | return(OPC_2E_INVALIDEXCEPTION); | |
277 | /* make NaN quiet */ | |
278 | Set_invalidflag(); | |
279 | Dbl_set_quiet(opnd3p1); | |
280 | } | |
281 | /* | |
282 | * return quiet NaN | |
283 | */ | |
284 | Dbl_copytoptr(opnd3p1,opnd3p2,dstptr); | |
285 | return(NOEXCEPTION); | |
286 | } | |
287 | } | |
288 | ||
289 | /* | |
290 | * Generate multiply mantissa | |
291 | */ | |
292 | if (Dbl_isnotzero_exponent(opnd1p1)) { | |
293 | /* set hidden bit */ | |
294 | Dbl_clear_signexponent_set_hidden(opnd1p1); | |
295 | } | |
296 | else { | |
297 | /* check for zero */ | |
298 | if (Dbl_iszero_mantissa(opnd1p1,opnd1p2)) { | |
299 | /* | |
300 | * Perform the add opnd3 with zero here. | |
301 | */ | |
302 | if (Dbl_iszero_exponentmantissa(opnd3p1,opnd3p2)) { | |
303 | if (Is_rounding_mode(ROUNDMINUS)) { | |
304 | Dbl_or_signs(opnd3p1,resultp1); | |
305 | } else { | |
306 | Dbl_and_signs(opnd3p1,resultp1); | |
307 | } | |
308 | } | |
309 | /* | |
310 | * Now let's check for trapped underflow case. | |
311 | */ | |
312 | else if (Dbl_iszero_exponent(opnd3p1) && | |
313 | Is_underflowtrap_enabled()) { | |
314 | /* need to normalize results mantissa */ | |
315 | sign_save = Dbl_signextendedsign(opnd3p1); | |
316 | result_exponent = 0; | |
317 | Dbl_leftshiftby1(opnd3p1,opnd3p2); | |
318 | Dbl_normalize(opnd3p1,opnd3p2,result_exponent); | |
319 | Dbl_set_sign(opnd3p1,/*using*/sign_save); | |
320 | Dbl_setwrapped_exponent(opnd3p1,result_exponent, | |
321 | unfl); | |
322 | Dbl_copytoptr(opnd3p1,opnd3p2,dstptr); | |
323 | /* inexact = FALSE */ | |
324 | return(OPC_2E_UNDERFLOWEXCEPTION); | |
325 | } | |
326 | Dbl_copytoptr(opnd3p1,opnd3p2,dstptr); | |
327 | return(NOEXCEPTION); | |
328 | } | |
329 | /* is denormalized, adjust exponent */ | |
330 | Dbl_clear_signexponent(opnd1p1); | |
331 | Dbl_leftshiftby1(opnd1p1,opnd1p2); | |
332 | Dbl_normalize(opnd1p1,opnd1p2,mpy_exponent); | |
333 | } | |
334 | /* opnd2 needs to have hidden bit set with msb in hidden bit */ | |
335 | if (Dbl_isnotzero_exponent(opnd2p1)) { | |
336 | Dbl_clear_signexponent_set_hidden(opnd2p1); | |
337 | } | |
338 | else { | |
339 | /* check for zero */ | |
340 | if (Dbl_iszero_mantissa(opnd2p1,opnd2p2)) { | |
341 | /* | |
342 | * Perform the add opnd3 with zero here. | |
343 | */ | |
344 | if (Dbl_iszero_exponentmantissa(opnd3p1,opnd3p2)) { | |
345 | if (Is_rounding_mode(ROUNDMINUS)) { | |
346 | Dbl_or_signs(opnd3p1,resultp1); | |
347 | } else { | |
348 | Dbl_and_signs(opnd3p1,resultp1); | |
349 | } | |
350 | } | |
351 | /* | |
352 | * Now let's check for trapped underflow case. | |
353 | */ | |
354 | else if (Dbl_iszero_exponent(opnd3p1) && | |
355 | Is_underflowtrap_enabled()) { | |
356 | /* need to normalize results mantissa */ | |
357 | sign_save = Dbl_signextendedsign(opnd3p1); | |
358 | result_exponent = 0; | |
359 | Dbl_leftshiftby1(opnd3p1,opnd3p2); | |
360 | Dbl_normalize(opnd3p1,opnd3p2,result_exponent); | |
361 | Dbl_set_sign(opnd3p1,/*using*/sign_save); | |
362 | Dbl_setwrapped_exponent(opnd3p1,result_exponent, | |
363 | unfl); | |
364 | Dbl_copytoptr(opnd3p1,opnd3p2,dstptr); | |
365 | /* inexact = FALSE */ | |
366 | return(OPC_2E_UNDERFLOWEXCEPTION); | |
367 | } | |
368 | Dbl_copytoptr(opnd3p1,opnd3p2,dstptr); | |
369 | return(NOEXCEPTION); | |
370 | } | |
371 | /* is denormalized; want to normalize */ | |
372 | Dbl_clear_signexponent(opnd2p1); | |
373 | Dbl_leftshiftby1(opnd2p1,opnd2p2); | |
374 | Dbl_normalize(opnd2p1,opnd2p2,mpy_exponent); | |
375 | } | |
376 | ||
377 | /* Multiply the first two source mantissas together */ | |
378 | ||
379 | /* | |
380 | * The intermediate result will be kept in tmpres, | |
381 | * which needs enough room for 106 bits of mantissa, | |
382 | * so lets call it a Double extended. | |
383 | */ | |
384 | Dblext_setzero(tmpresp1,tmpresp2,tmpresp3,tmpresp4); | |
385 | ||
386 | /* | |
387 | * Four bits at a time are inspected in each loop, and a | |
388 | * simple shift and add multiply algorithm is used. | |
389 | */ | |
390 | for (count = DBL_P-1; count >= 0; count -= 4) { | |
391 | Dblext_rightshiftby4(tmpresp1,tmpresp2,tmpresp3,tmpresp4); | |
392 | if (Dbit28p2(opnd1p2)) { | |
393 | /* Fourword_add should be an ADD followed by 3 ADDC's */ | |
394 | Fourword_add(tmpresp1, tmpresp2, tmpresp3, tmpresp4, | |
395 | opnd2p1<<3 | opnd2p2>>29, opnd2p2<<3, 0, 0); | |
396 | } | |
397 | if (Dbit29p2(opnd1p2)) { | |
398 | Fourword_add(tmpresp1, tmpresp2, tmpresp3, tmpresp4, | |
399 | opnd2p1<<2 | opnd2p2>>30, opnd2p2<<2, 0, 0); | |
400 | } | |
401 | if (Dbit30p2(opnd1p2)) { | |
402 | Fourword_add(tmpresp1, tmpresp2, tmpresp3, tmpresp4, | |
403 | opnd2p1<<1 | opnd2p2>>31, opnd2p2<<1, 0, 0); | |
404 | } | |
405 | if (Dbit31p2(opnd1p2)) { | |
406 | Fourword_add(tmpresp1, tmpresp2, tmpresp3, tmpresp4, | |
407 | opnd2p1, opnd2p2, 0, 0); | |
408 | } | |
409 | Dbl_rightshiftby4(opnd1p1,opnd1p2); | |
410 | } | |
411 | if (Is_dexthiddenoverflow(tmpresp1)) { | |
412 | /* result mantissa >= 2 (mantissa overflow) */ | |
413 | mpy_exponent++; | |
414 | Dblext_rightshiftby1(tmpresp1,tmpresp2,tmpresp3,tmpresp4); | |
415 | } | |
416 | ||
417 | /* | |
418 | * Restore the sign of the mpy result which was saved in resultp1. | |
419 | * The exponent will continue to be kept in mpy_exponent. | |
420 | */ | |
421 | Dblext_set_sign(tmpresp1,Dbl_sign(resultp1)); | |
422 | ||
423 | /* | |
424 | * No rounding is required, since the result of the multiply | |
425 | * is exact in the extended format. | |
426 | */ | |
427 | ||
428 | /* | |
429 | * Now we are ready to perform the add portion of the operation. | |
430 | * | |
431 | * The exponents need to be kept as integers for now, since the | |
432 | * multiply result might not fit into the exponent field. We | |
433 | * can't overflow or underflow because of this yet, since the | |
434 | * add could bring the final result back into range. | |
435 | */ | |
436 | add_exponent = Dbl_exponent(opnd3p1); | |
437 | ||
438 | /* | |
439 | * Check for denormalized or zero add operand. | |
440 | */ | |
441 | if (add_exponent == 0) { | |
442 | /* check for zero */ | |
443 | if (Dbl_iszero_mantissa(opnd3p1,opnd3p2)) { | |
444 | /* right is zero */ | |
445 | /* Left can't be zero and must be result. | |
446 | * | |
447 | * The final result is now in tmpres and mpy_exponent, | |
448 | * and needs to be rounded and squeezed back into | |
449 | * double precision format from double extended. | |
450 | */ | |
451 | result_exponent = mpy_exponent; | |
452 | Dblext_copy(tmpresp1,tmpresp2,tmpresp3,tmpresp4, | |
453 | resultp1,resultp2,resultp3,resultp4); | |
454 | sign_save = Dbl_signextendedsign(resultp1);/*save sign*/ | |
455 | goto round; | |
456 | } | |
457 | ||
458 | /* | |
459 | * Neither are zeroes. | |
460 | * Adjust exponent and normalize add operand. | |
461 | */ | |
462 | sign_save = Dbl_signextendedsign(opnd3p1); /* save sign */ | |
463 | Dbl_clear_signexponent(opnd3p1); | |
464 | Dbl_leftshiftby1(opnd3p1,opnd3p2); | |
465 | Dbl_normalize(opnd3p1,opnd3p2,add_exponent); | |
466 | Dbl_set_sign(opnd3p1,sign_save); /* restore sign */ | |
467 | } else { | |
468 | Dbl_clear_exponent_set_hidden(opnd3p1); | |
469 | } | |
470 | /* | |
471 | * Copy opnd3 to the double extended variable called right. | |
472 | */ | |
473 | Dbl_copyto_dblext(opnd3p1,opnd3p2,rightp1,rightp2,rightp3,rightp4); | |
474 | ||
475 | /* | |
476 | * A zero "save" helps discover equal operands (for later), | |
477 | * and is used in swapping operands (if needed). | |
478 | */ | |
479 | Dblext_xortointp1(tmpresp1,rightp1,/*to*/save); | |
480 | ||
481 | /* | |
482 | * Compare magnitude of operands. | |
483 | */ | |
484 | Dblext_copytoint_exponentmantissap1(tmpresp1,signlessleft1); | |
485 | Dblext_copytoint_exponentmantissap1(rightp1,signlessright1); | |
486 | if (mpy_exponent < add_exponent || mpy_exponent == add_exponent && | |
487 | Dblext_ismagnitudeless(tmpresp2,rightp2,signlessleft1,signlessright1)){ | |
488 | /* | |
489 | * Set the left operand to the larger one by XOR swap. | |
490 | * First finish the first word "save". | |
491 | */ | |
492 | Dblext_xorfromintp1(save,rightp1,/*to*/rightp1); | |
493 | Dblext_xorfromintp1(save,tmpresp1,/*to*/tmpresp1); | |
494 | Dblext_swap_lower(tmpresp2,tmpresp3,tmpresp4, | |
495 | rightp2,rightp3,rightp4); | |
496 | /* also setup exponents used in rest of routine */ | |
497 | diff_exponent = add_exponent - mpy_exponent; | |
498 | result_exponent = add_exponent; | |
499 | } else { | |
500 | /* also setup exponents used in rest of routine */ | |
501 | diff_exponent = mpy_exponent - add_exponent; | |
502 | result_exponent = mpy_exponent; | |
503 | } | |
504 | /* Invariant: left is not smaller than right. */ | |
505 | ||
506 | /* | |
507 | * Special case alignment of operands that would force alignment | |
508 | * beyond the extent of the extension. A further optimization | |
509 | * could special case this but only reduces the path length for | |
510 | * this infrequent case. | |
511 | */ | |
512 | if (diff_exponent > DBLEXT_THRESHOLD) { | |
513 | diff_exponent = DBLEXT_THRESHOLD; | |
514 | } | |
515 | ||
516 | /* Align right operand by shifting it to the right */ | |
517 | Dblext_clear_sign(rightp1); | |
518 | Dblext_right_align(rightp1,rightp2,rightp3,rightp4, | |
519 | /*shifted by*/diff_exponent); | |
520 | ||
521 | /* Treat sum and difference of the operands separately. */ | |
522 | if ((int)save < 0) { | |
523 | /* | |
524 | * Difference of the two operands. Overflow can occur if the | |
525 | * multiply overflowed. A borrow can occur out of the hidden | |
526 | * bit and force a post normalization phase. | |
527 | */ | |
528 | Dblext_subtract(tmpresp1,tmpresp2,tmpresp3,tmpresp4, | |
529 | rightp1,rightp2,rightp3,rightp4, | |
530 | resultp1,resultp2,resultp3,resultp4); | |
531 | sign_save = Dbl_signextendedsign(resultp1); | |
532 | if (Dbl_iszero_hidden(resultp1)) { | |
533 | /* Handle normalization */ | |
25985edc | 534 | /* A straightforward algorithm would now shift the |
1da177e4 LT |
535 | * result and extension left until the hidden bit |
536 | * becomes one. Not all of the extension bits need | |
537 | * participate in the shift. Only the two most | |
538 | * significant bits (round and guard) are needed. | |
539 | * If only a single shift is needed then the guard | |
540 | * bit becomes a significant low order bit and the | |
541 | * extension must participate in the rounding. | |
542 | * If more than a single shift is needed, then all | |
543 | * bits to the right of the guard bit are zeros, | |
544 | * and the guard bit may or may not be zero. */ | |
545 | Dblext_leftshiftby1(resultp1,resultp2,resultp3, | |
546 | resultp4); | |
547 | ||
548 | /* Need to check for a zero result. The sign and | |
549 | * exponent fields have already been zeroed. The more | |
550 | * efficient test of the full object can be used. | |
551 | */ | |
552 | if(Dblext_iszero(resultp1,resultp2,resultp3,resultp4)){ | |
553 | /* Must have been "x-x" or "x+(-x)". */ | |
554 | if (Is_rounding_mode(ROUNDMINUS)) | |
555 | Dbl_setone_sign(resultp1); | |
556 | Dbl_copytoptr(resultp1,resultp2,dstptr); | |
557 | return(NOEXCEPTION); | |
558 | } | |
559 | result_exponent--; | |
560 | ||
561 | /* Look to see if normalization is finished. */ | |
562 | if (Dbl_isone_hidden(resultp1)) { | |
563 | /* No further normalization is needed */ | |
564 | goto round; | |
565 | } | |
566 | ||
567 | /* Discover first one bit to determine shift amount. | |
568 | * Use a modified binary search. We have already | |
569 | * shifted the result one position right and still | |
570 | * not found a one so the remainder of the extension | |
571 | * must be zero and simplifies rounding. */ | |
572 | /* Scan bytes */ | |
573 | while (Dbl_iszero_hiddenhigh7mantissa(resultp1)) { | |
574 | Dblext_leftshiftby8(resultp1,resultp2,resultp3,resultp4); | |
575 | result_exponent -= 8; | |
576 | } | |
577 | /* Now narrow it down to the nibble */ | |
578 | if (Dbl_iszero_hiddenhigh3mantissa(resultp1)) { | |
579 | /* The lower nibble contains the | |
580 | * normalizing one */ | |
581 | Dblext_leftshiftby4(resultp1,resultp2,resultp3,resultp4); | |
582 | result_exponent -= 4; | |
583 | } | |
584 | /* Select case where first bit is set (already | |
585 | * normalized) otherwise select the proper shift. */ | |
586 | jumpsize = Dbl_hiddenhigh3mantissa(resultp1); | |
587 | if (jumpsize <= 7) switch(jumpsize) { | |
588 | case 1: | |
589 | Dblext_leftshiftby3(resultp1,resultp2,resultp3, | |
590 | resultp4); | |
591 | result_exponent -= 3; | |
592 | break; | |
593 | case 2: | |
594 | case 3: | |
595 | Dblext_leftshiftby2(resultp1,resultp2,resultp3, | |
596 | resultp4); | |
597 | result_exponent -= 2; | |
598 | break; | |
599 | case 4: | |
600 | case 5: | |
601 | case 6: | |
602 | case 7: | |
603 | Dblext_leftshiftby1(resultp1,resultp2,resultp3, | |
604 | resultp4); | |
605 | result_exponent -= 1; | |
606 | break; | |
607 | } | |
608 | } /* end if (hidden...)... */ | |
609 | /* Fall through and round */ | |
610 | } /* end if (save < 0)... */ | |
611 | else { | |
612 | /* Add magnitudes */ | |
613 | Dblext_addition(tmpresp1,tmpresp2,tmpresp3,tmpresp4, | |
614 | rightp1,rightp2,rightp3,rightp4, | |
615 | /*to*/resultp1,resultp2,resultp3,resultp4); | |
616 | sign_save = Dbl_signextendedsign(resultp1); | |
617 | if (Dbl_isone_hiddenoverflow(resultp1)) { | |
618 | /* Prenormalization required. */ | |
619 | Dblext_arithrightshiftby1(resultp1,resultp2,resultp3, | |
620 | resultp4); | |
621 | result_exponent++; | |
622 | } /* end if hiddenoverflow... */ | |
623 | } /* end else ...add magnitudes... */ | |
624 | ||
625 | /* Round the result. If the extension and lower two words are | |
626 | * all zeros, then the result is exact. Otherwise round in the | |
627 | * correct direction. Underflow is possible. If a postnormalization | |
628 | * is necessary, then the mantissa is all zeros so no shift is needed. | |
629 | */ | |
630 | round: | |
631 | if (result_exponent <= 0 && !Is_underflowtrap_enabled()) { | |
632 | Dblext_denormalize(resultp1,resultp2,resultp3,resultp4, | |
633 | result_exponent,is_tiny); | |
634 | } | |
635 | Dbl_set_sign(resultp1,/*using*/sign_save); | |
636 | if (Dblext_isnotzero_mantissap3(resultp3) || | |
637 | Dblext_isnotzero_mantissap4(resultp4)) { | |
638 | inexact = TRUE; | |
639 | switch(Rounding_mode()) { | |
640 | case ROUNDNEAREST: /* The default. */ | |
641 | if (Dblext_isone_highp3(resultp3)) { | |
642 | /* at least 1/2 ulp */ | |
643 | if (Dblext_isnotzero_low31p3(resultp3) || | |
644 | Dblext_isnotzero_mantissap4(resultp4) || | |
645 | Dblext_isone_lowp2(resultp2)) { | |
646 | /* either exactly half way and odd or | |
647 | * more than 1/2ulp */ | |
648 | Dbl_increment(resultp1,resultp2); | |
649 | } | |
650 | } | |
651 | break; | |
652 | ||
653 | case ROUNDPLUS: | |
654 | if (Dbl_iszero_sign(resultp1)) { | |
655 | /* Round up positive results */ | |
656 | Dbl_increment(resultp1,resultp2); | |
657 | } | |
658 | break; | |
659 | ||
660 | case ROUNDMINUS: | |
661 | if (Dbl_isone_sign(resultp1)) { | |
662 | /* Round down negative results */ | |
663 | Dbl_increment(resultp1,resultp2); | |
664 | } | |
665 | ||
666 | case ROUNDZERO:; | |
667 | /* truncate is simple */ | |
668 | } /* end switch... */ | |
669 | if (Dbl_isone_hiddenoverflow(resultp1)) result_exponent++; | |
670 | } | |
671 | if (result_exponent >= DBL_INFINITY_EXPONENT) { | |
672 | /* trap if OVERFLOWTRAP enabled */ | |
673 | if (Is_overflowtrap_enabled()) { | |
674 | /* | |
675 | * Adjust bias of result | |
676 | */ | |
677 | Dbl_setwrapped_exponent(resultp1,result_exponent,ovfl); | |
678 | Dbl_copytoptr(resultp1,resultp2,dstptr); | |
679 | if (inexact) | |
680 | if (Is_inexacttrap_enabled()) | |
681 | return (OPC_2E_OVERFLOWEXCEPTION | | |
682 | OPC_2E_INEXACTEXCEPTION); | |
683 | else Set_inexactflag(); | |
684 | return (OPC_2E_OVERFLOWEXCEPTION); | |
685 | } | |
686 | inexact = TRUE; | |
687 | Set_overflowflag(); | |
688 | /* set result to infinity or largest number */ | |
689 | Dbl_setoverflow(resultp1,resultp2); | |
690 | ||
691 | } else if (result_exponent <= 0) { /* underflow case */ | |
692 | if (Is_underflowtrap_enabled()) { | |
693 | /* | |
694 | * Adjust bias of result | |
695 | */ | |
696 | Dbl_setwrapped_exponent(resultp1,result_exponent,unfl); | |
697 | Dbl_copytoptr(resultp1,resultp2,dstptr); | |
698 | if (inexact) | |
699 | if (Is_inexacttrap_enabled()) | |
700 | return (OPC_2E_UNDERFLOWEXCEPTION | | |
701 | OPC_2E_INEXACTEXCEPTION); | |
702 | else Set_inexactflag(); | |
703 | return(OPC_2E_UNDERFLOWEXCEPTION); | |
704 | } | |
705 | else if (inexact && is_tiny) Set_underflowflag(); | |
706 | } | |
707 | else Dbl_set_exponent(resultp1,result_exponent); | |
708 | Dbl_copytoptr(resultp1,resultp2,dstptr); | |
709 | if (inexact) | |
710 | if (Is_inexacttrap_enabled()) return(OPC_2E_INEXACTEXCEPTION); | |
711 | else Set_inexactflag(); | |
712 | return(NOEXCEPTION); | |
713 | } | |
714 | ||
715 | /* | |
716 | * Double Floating-point Multiply Negate Fused Add | |
717 | */ | |
718 | ||
719 | dbl_fmpynfadd(src1ptr,src2ptr,src3ptr,status,dstptr) | |
720 | ||
721 | dbl_floating_point *src1ptr, *src2ptr, *src3ptr, *dstptr; | |
722 | unsigned int *status; | |
723 | { | |
724 | unsigned int opnd1p1, opnd1p2, opnd2p1, opnd2p2, opnd3p1, opnd3p2; | |
725 | register unsigned int tmpresp1, tmpresp2, tmpresp3, tmpresp4; | |
726 | unsigned int rightp1, rightp2, rightp3, rightp4; | |
727 | unsigned int resultp1, resultp2 = 0, resultp3 = 0, resultp4 = 0; | |
728 | register int mpy_exponent, add_exponent, count; | |
729 | boolean inexact = FALSE, is_tiny = FALSE; | |
730 | ||
731 | unsigned int signlessleft1, signlessright1, save; | |
732 | register int result_exponent, diff_exponent; | |
733 | int sign_save, jumpsize; | |
734 | ||
735 | Dbl_copyfromptr(src1ptr,opnd1p1,opnd1p2); | |
736 | Dbl_copyfromptr(src2ptr,opnd2p1,opnd2p2); | |
737 | Dbl_copyfromptr(src3ptr,opnd3p1,opnd3p2); | |
738 | ||
739 | /* | |
740 | * set sign bit of result of multiply | |
741 | */ | |
742 | if (Dbl_sign(opnd1p1) ^ Dbl_sign(opnd2p1)) | |
743 | Dbl_setzerop1(resultp1); | |
744 | else | |
745 | Dbl_setnegativezerop1(resultp1); | |
746 | ||
747 | /* | |
748 | * Generate multiply exponent | |
749 | */ | |
750 | mpy_exponent = Dbl_exponent(opnd1p1) + Dbl_exponent(opnd2p1) - DBL_BIAS; | |
751 | ||
752 | /* | |
753 | * check first operand for NaN's or infinity | |
754 | */ | |
755 | if (Dbl_isinfinity_exponent(opnd1p1)) { | |
756 | if (Dbl_iszero_mantissa(opnd1p1,opnd1p2)) { | |
757 | if (Dbl_isnotnan(opnd2p1,opnd2p2) && | |
758 | Dbl_isnotnan(opnd3p1,opnd3p2)) { | |
759 | if (Dbl_iszero_exponentmantissa(opnd2p1,opnd2p2)) { | |
760 | /* | |
761 | * invalid since operands are infinity | |
762 | * and zero | |
763 | */ | |
764 | if (Is_invalidtrap_enabled()) | |
765 | return(OPC_2E_INVALIDEXCEPTION); | |
766 | Set_invalidflag(); | |
767 | Dbl_makequietnan(resultp1,resultp2); | |
768 | Dbl_copytoptr(resultp1,resultp2,dstptr); | |
769 | return(NOEXCEPTION); | |
770 | } | |
771 | /* | |
772 | * Check third operand for infinity with a | |
773 | * sign opposite of the multiply result | |
774 | */ | |
775 | if (Dbl_isinfinity(opnd3p1,opnd3p2) && | |
776 | (Dbl_sign(resultp1) ^ Dbl_sign(opnd3p1))) { | |
777 | /* | |
778 | * invalid since attempting a magnitude | |
779 | * subtraction of infinities | |
780 | */ | |
781 | if (Is_invalidtrap_enabled()) | |
782 | return(OPC_2E_INVALIDEXCEPTION); | |
783 | Set_invalidflag(); | |
784 | Dbl_makequietnan(resultp1,resultp2); | |
785 | Dbl_copytoptr(resultp1,resultp2,dstptr); | |
786 | return(NOEXCEPTION); | |
787 | } | |
788 | ||
789 | /* | |
790 | * return infinity | |
791 | */ | |
792 | Dbl_setinfinity_exponentmantissa(resultp1,resultp2); | |
793 | Dbl_copytoptr(resultp1,resultp2,dstptr); | |
794 | return(NOEXCEPTION); | |
795 | } | |
796 | } | |
797 | else { | |
798 | /* | |
799 | * is NaN; signaling or quiet? | |
800 | */ | |
801 | if (Dbl_isone_signaling(opnd1p1)) { | |
802 | /* trap if INVALIDTRAP enabled */ | |
803 | if (Is_invalidtrap_enabled()) | |
804 | return(OPC_2E_INVALIDEXCEPTION); | |
805 | /* make NaN quiet */ | |
806 | Set_invalidflag(); | |
807 | Dbl_set_quiet(opnd1p1); | |
808 | } | |
809 | /* | |
810 | * is second operand a signaling NaN? | |
811 | */ | |
812 | else if (Dbl_is_signalingnan(opnd2p1)) { | |
813 | /* trap if INVALIDTRAP enabled */ | |
814 | if (Is_invalidtrap_enabled()) | |
815 | return(OPC_2E_INVALIDEXCEPTION); | |
816 | /* make NaN quiet */ | |
817 | Set_invalidflag(); | |
818 | Dbl_set_quiet(opnd2p1); | |
819 | Dbl_copytoptr(opnd2p1,opnd2p2,dstptr); | |
820 | return(NOEXCEPTION); | |
821 | } | |
822 | /* | |
823 | * is third operand a signaling NaN? | |
824 | */ | |
825 | else if (Dbl_is_signalingnan(opnd3p1)) { | |
826 | /* trap if INVALIDTRAP enabled */ | |
827 | if (Is_invalidtrap_enabled()) | |
828 | return(OPC_2E_INVALIDEXCEPTION); | |
829 | /* make NaN quiet */ | |
830 | Set_invalidflag(); | |
831 | Dbl_set_quiet(opnd3p1); | |
832 | Dbl_copytoptr(opnd3p1,opnd3p2,dstptr); | |
833 | return(NOEXCEPTION); | |
834 | } | |
835 | /* | |
836 | * return quiet NaN | |
837 | */ | |
838 | Dbl_copytoptr(opnd1p1,opnd1p2,dstptr); | |
839 | return(NOEXCEPTION); | |
840 | } | |
841 | } | |
842 | ||
843 | /* | |
844 | * check second operand for NaN's or infinity | |
845 | */ | |
846 | if (Dbl_isinfinity_exponent(opnd2p1)) { | |
847 | if (Dbl_iszero_mantissa(opnd2p1,opnd2p2)) { | |
848 | if (Dbl_isnotnan(opnd3p1,opnd3p2)) { | |
849 | if (Dbl_iszero_exponentmantissa(opnd1p1,opnd1p2)) { | |
850 | /* | |
851 | * invalid since multiply operands are | |
852 | * zero & infinity | |
853 | */ | |
854 | if (Is_invalidtrap_enabled()) | |
855 | return(OPC_2E_INVALIDEXCEPTION); | |
856 | Set_invalidflag(); | |
857 | Dbl_makequietnan(opnd2p1,opnd2p2); | |
858 | Dbl_copytoptr(opnd2p1,opnd2p2,dstptr); | |
859 | return(NOEXCEPTION); | |
860 | } | |
861 | ||
862 | /* | |
863 | * Check third operand for infinity with a | |
864 | * sign opposite of the multiply result | |
865 | */ | |
866 | if (Dbl_isinfinity(opnd3p1,opnd3p2) && | |
867 | (Dbl_sign(resultp1) ^ Dbl_sign(opnd3p1))) { | |
868 | /* | |
869 | * invalid since attempting a magnitude | |
870 | * subtraction of infinities | |
871 | */ | |
872 | if (Is_invalidtrap_enabled()) | |
873 | return(OPC_2E_INVALIDEXCEPTION); | |
874 | Set_invalidflag(); | |
875 | Dbl_makequietnan(resultp1,resultp2); | |
876 | Dbl_copytoptr(resultp1,resultp2,dstptr); | |
877 | return(NOEXCEPTION); | |
878 | } | |
879 | ||
880 | /* | |
881 | * return infinity | |
882 | */ | |
883 | Dbl_setinfinity_exponentmantissa(resultp1,resultp2); | |
884 | Dbl_copytoptr(resultp1,resultp2,dstptr); | |
885 | return(NOEXCEPTION); | |
886 | } | |
887 | } | |
888 | else { | |
889 | /* | |
890 | * is NaN; signaling or quiet? | |
891 | */ | |
892 | if (Dbl_isone_signaling(opnd2p1)) { | |
893 | /* trap if INVALIDTRAP enabled */ | |
894 | if (Is_invalidtrap_enabled()) | |
895 | return(OPC_2E_INVALIDEXCEPTION); | |
896 | /* make NaN quiet */ | |
897 | Set_invalidflag(); | |
898 | Dbl_set_quiet(opnd2p1); | |
899 | } | |
900 | /* | |
901 | * is third operand a signaling NaN? | |
902 | */ | |
903 | else if (Dbl_is_signalingnan(opnd3p1)) { | |
904 | /* trap if INVALIDTRAP enabled */ | |
905 | if (Is_invalidtrap_enabled()) | |
906 | return(OPC_2E_INVALIDEXCEPTION); | |
907 | /* make NaN quiet */ | |
908 | Set_invalidflag(); | |
909 | Dbl_set_quiet(opnd3p1); | |
910 | Dbl_copytoptr(opnd3p1,opnd3p2,dstptr); | |
911 | return(NOEXCEPTION); | |
912 | } | |
913 | /* | |
914 | * return quiet NaN | |
915 | */ | |
916 | Dbl_copytoptr(opnd2p1,opnd2p2,dstptr); | |
917 | return(NOEXCEPTION); | |
918 | } | |
919 | } | |
920 | ||
921 | /* | |
922 | * check third operand for NaN's or infinity | |
923 | */ | |
924 | if (Dbl_isinfinity_exponent(opnd3p1)) { | |
925 | if (Dbl_iszero_mantissa(opnd3p1,opnd3p2)) { | |
926 | /* return infinity */ | |
927 | Dbl_copytoptr(opnd3p1,opnd3p2,dstptr); | |
928 | return(NOEXCEPTION); | |
929 | } else { | |
930 | /* | |
931 | * is NaN; signaling or quiet? | |
932 | */ | |
933 | if (Dbl_isone_signaling(opnd3p1)) { | |
934 | /* trap if INVALIDTRAP enabled */ | |
935 | if (Is_invalidtrap_enabled()) | |
936 | return(OPC_2E_INVALIDEXCEPTION); | |
937 | /* make NaN quiet */ | |
938 | Set_invalidflag(); | |
939 | Dbl_set_quiet(opnd3p1); | |
940 | } | |
941 | /* | |
942 | * return quiet NaN | |
943 | */ | |
944 | Dbl_copytoptr(opnd3p1,opnd3p2,dstptr); | |
945 | return(NOEXCEPTION); | |
946 | } | |
947 | } | |
948 | ||
949 | /* | |
950 | * Generate multiply mantissa | |
951 | */ | |
952 | if (Dbl_isnotzero_exponent(opnd1p1)) { | |
953 | /* set hidden bit */ | |
954 | Dbl_clear_signexponent_set_hidden(opnd1p1); | |
955 | } | |
956 | else { | |
957 | /* check for zero */ | |
958 | if (Dbl_iszero_mantissa(opnd1p1,opnd1p2)) { | |
959 | /* | |
960 | * Perform the add opnd3 with zero here. | |
961 | */ | |
962 | if (Dbl_iszero_exponentmantissa(opnd3p1,opnd3p2)) { | |
963 | if (Is_rounding_mode(ROUNDMINUS)) { | |
964 | Dbl_or_signs(opnd3p1,resultp1); | |
965 | } else { | |
966 | Dbl_and_signs(opnd3p1,resultp1); | |
967 | } | |
968 | } | |
969 | /* | |
970 | * Now let's check for trapped underflow case. | |
971 | */ | |
972 | else if (Dbl_iszero_exponent(opnd3p1) && | |
973 | Is_underflowtrap_enabled()) { | |
974 | /* need to normalize results mantissa */ | |
975 | sign_save = Dbl_signextendedsign(opnd3p1); | |
976 | result_exponent = 0; | |
977 | Dbl_leftshiftby1(opnd3p1,opnd3p2); | |
978 | Dbl_normalize(opnd3p1,opnd3p2,result_exponent); | |
979 | Dbl_set_sign(opnd3p1,/*using*/sign_save); | |
980 | Dbl_setwrapped_exponent(opnd3p1,result_exponent, | |
981 | unfl); | |
982 | Dbl_copytoptr(opnd3p1,opnd3p2,dstptr); | |
983 | /* inexact = FALSE */ | |
984 | return(OPC_2E_UNDERFLOWEXCEPTION); | |
985 | } | |
986 | Dbl_copytoptr(opnd3p1,opnd3p2,dstptr); | |
987 | return(NOEXCEPTION); | |
988 | } | |
989 | /* is denormalized, adjust exponent */ | |
990 | Dbl_clear_signexponent(opnd1p1); | |
991 | Dbl_leftshiftby1(opnd1p1,opnd1p2); | |
992 | Dbl_normalize(opnd1p1,opnd1p2,mpy_exponent); | |
993 | } | |
994 | /* opnd2 needs to have hidden bit set with msb in hidden bit */ | |
995 | if (Dbl_isnotzero_exponent(opnd2p1)) { | |
996 | Dbl_clear_signexponent_set_hidden(opnd2p1); | |
997 | } | |
998 | else { | |
999 | /* check for zero */ | |
1000 | if (Dbl_iszero_mantissa(opnd2p1,opnd2p2)) { | |
1001 | /* | |
1002 | * Perform the add opnd3 with zero here. | |
1003 | */ | |
1004 | if (Dbl_iszero_exponentmantissa(opnd3p1,opnd3p2)) { | |
1005 | if (Is_rounding_mode(ROUNDMINUS)) { | |
1006 | Dbl_or_signs(opnd3p1,resultp1); | |
1007 | } else { | |
1008 | Dbl_and_signs(opnd3p1,resultp1); | |
1009 | } | |
1010 | } | |
1011 | /* | |
1012 | * Now let's check for trapped underflow case. | |
1013 | */ | |
1014 | else if (Dbl_iszero_exponent(opnd3p1) && | |
1015 | Is_underflowtrap_enabled()) { | |
1016 | /* need to normalize results mantissa */ | |
1017 | sign_save = Dbl_signextendedsign(opnd3p1); | |
1018 | result_exponent = 0; | |
1019 | Dbl_leftshiftby1(opnd3p1,opnd3p2); | |
1020 | Dbl_normalize(opnd3p1,opnd3p2,result_exponent); | |
1021 | Dbl_set_sign(opnd3p1,/*using*/sign_save); | |
1022 | Dbl_setwrapped_exponent(opnd3p1,result_exponent, | |
1023 | unfl); | |
1024 | Dbl_copytoptr(opnd3p1,opnd3p2,dstptr); | |
1025 | /* inexact = FALSE */ | |
1026 | return(OPC_2E_UNDERFLOWEXCEPTION); | |
1027 | } | |
1028 | Dbl_copytoptr(opnd3p1,opnd3p2,dstptr); | |
1029 | return(NOEXCEPTION); | |
1030 | } | |
1031 | /* is denormalized; want to normalize */ | |
1032 | Dbl_clear_signexponent(opnd2p1); | |
1033 | Dbl_leftshiftby1(opnd2p1,opnd2p2); | |
1034 | Dbl_normalize(opnd2p1,opnd2p2,mpy_exponent); | |
1035 | } | |
1036 | ||
1037 | /* Multiply the first two source mantissas together */ | |
1038 | ||
1039 | /* | |
1040 | * The intermediate result will be kept in tmpres, | |
1041 | * which needs enough room for 106 bits of mantissa, | |
1042 | * so lets call it a Double extended. | |
1043 | */ | |
1044 | Dblext_setzero(tmpresp1,tmpresp2,tmpresp3,tmpresp4); | |
1045 | ||
1046 | /* | |
1047 | * Four bits at a time are inspected in each loop, and a | |
1048 | * simple shift and add multiply algorithm is used. | |
1049 | */ | |
1050 | for (count = DBL_P-1; count >= 0; count -= 4) { | |
1051 | Dblext_rightshiftby4(tmpresp1,tmpresp2,tmpresp3,tmpresp4); | |
1052 | if (Dbit28p2(opnd1p2)) { | |
1053 | /* Fourword_add should be an ADD followed by 3 ADDC's */ | |
1054 | Fourword_add(tmpresp1, tmpresp2, tmpresp3, tmpresp4, | |
1055 | opnd2p1<<3 | opnd2p2>>29, opnd2p2<<3, 0, 0); | |
1056 | } | |
1057 | if (Dbit29p2(opnd1p2)) { | |
1058 | Fourword_add(tmpresp1, tmpresp2, tmpresp3, tmpresp4, | |
1059 | opnd2p1<<2 | opnd2p2>>30, opnd2p2<<2, 0, 0); | |
1060 | } | |
1061 | if (Dbit30p2(opnd1p2)) { | |
1062 | Fourword_add(tmpresp1, tmpresp2, tmpresp3, tmpresp4, | |
1063 | opnd2p1<<1 | opnd2p2>>31, opnd2p2<<1, 0, 0); | |
1064 | } | |
1065 | if (Dbit31p2(opnd1p2)) { | |
1066 | Fourword_add(tmpresp1, tmpresp2, tmpresp3, tmpresp4, | |
1067 | opnd2p1, opnd2p2, 0, 0); | |
1068 | } | |
1069 | Dbl_rightshiftby4(opnd1p1,opnd1p2); | |
1070 | } | |
1071 | if (Is_dexthiddenoverflow(tmpresp1)) { | |
1072 | /* result mantissa >= 2 (mantissa overflow) */ | |
1073 | mpy_exponent++; | |
1074 | Dblext_rightshiftby1(tmpresp1,tmpresp2,tmpresp3,tmpresp4); | |
1075 | } | |
1076 | ||
1077 | /* | |
1078 | * Restore the sign of the mpy result which was saved in resultp1. | |
1079 | * The exponent will continue to be kept in mpy_exponent. | |
1080 | */ | |
1081 | Dblext_set_sign(tmpresp1,Dbl_sign(resultp1)); | |
1082 | ||
1083 | /* | |
1084 | * No rounding is required, since the result of the multiply | |
1085 | * is exact in the extended format. | |
1086 | */ | |
1087 | ||
1088 | /* | |
1089 | * Now we are ready to perform the add portion of the operation. | |
1090 | * | |
1091 | * The exponents need to be kept as integers for now, since the | |
1092 | * multiply result might not fit into the exponent field. We | |
1093 | * can't overflow or underflow because of this yet, since the | |
1094 | * add could bring the final result back into range. | |
1095 | */ | |
1096 | add_exponent = Dbl_exponent(opnd3p1); | |
1097 | ||
1098 | /* | |
1099 | * Check for denormalized or zero add operand. | |
1100 | */ | |
1101 | if (add_exponent == 0) { | |
1102 | /* check for zero */ | |
1103 | if (Dbl_iszero_mantissa(opnd3p1,opnd3p2)) { | |
1104 | /* right is zero */ | |
1105 | /* Left can't be zero and must be result. | |
1106 | * | |
1107 | * The final result is now in tmpres and mpy_exponent, | |
1108 | * and needs to be rounded and squeezed back into | |
1109 | * double precision format from double extended. | |
1110 | */ | |
1111 | result_exponent = mpy_exponent; | |
1112 | Dblext_copy(tmpresp1,tmpresp2,tmpresp3,tmpresp4, | |
1113 | resultp1,resultp2,resultp3,resultp4); | |
1114 | sign_save = Dbl_signextendedsign(resultp1);/*save sign*/ | |
1115 | goto round; | |
1116 | } | |
1117 | ||
1118 | /* | |
1119 | * Neither are zeroes. | |
1120 | * Adjust exponent and normalize add operand. | |
1121 | */ | |
1122 | sign_save = Dbl_signextendedsign(opnd3p1); /* save sign */ | |
1123 | Dbl_clear_signexponent(opnd3p1); | |
1124 | Dbl_leftshiftby1(opnd3p1,opnd3p2); | |
1125 | Dbl_normalize(opnd3p1,opnd3p2,add_exponent); | |
1126 | Dbl_set_sign(opnd3p1,sign_save); /* restore sign */ | |
1127 | } else { | |
1128 | Dbl_clear_exponent_set_hidden(opnd3p1); | |
1129 | } | |
1130 | /* | |
1131 | * Copy opnd3 to the double extended variable called right. | |
1132 | */ | |
1133 | Dbl_copyto_dblext(opnd3p1,opnd3p2,rightp1,rightp2,rightp3,rightp4); | |
1134 | ||
1135 | /* | |
1136 | * A zero "save" helps discover equal operands (for later), | |
1137 | * and is used in swapping operands (if needed). | |
1138 | */ | |
1139 | Dblext_xortointp1(tmpresp1,rightp1,/*to*/save); | |
1140 | ||
1141 | /* | |
1142 | * Compare magnitude of operands. | |
1143 | */ | |
1144 | Dblext_copytoint_exponentmantissap1(tmpresp1,signlessleft1); | |
1145 | Dblext_copytoint_exponentmantissap1(rightp1,signlessright1); | |
1146 | if (mpy_exponent < add_exponent || mpy_exponent == add_exponent && | |
1147 | Dblext_ismagnitudeless(tmpresp2,rightp2,signlessleft1,signlessright1)){ | |
1148 | /* | |
1149 | * Set the left operand to the larger one by XOR swap. | |
1150 | * First finish the first word "save". | |
1151 | */ | |
1152 | Dblext_xorfromintp1(save,rightp1,/*to*/rightp1); | |
1153 | Dblext_xorfromintp1(save,tmpresp1,/*to*/tmpresp1); | |
1154 | Dblext_swap_lower(tmpresp2,tmpresp3,tmpresp4, | |
1155 | rightp2,rightp3,rightp4); | |
1156 | /* also setup exponents used in rest of routine */ | |
1157 | diff_exponent = add_exponent - mpy_exponent; | |
1158 | result_exponent = add_exponent; | |
1159 | } else { | |
1160 | /* also setup exponents used in rest of routine */ | |
1161 | diff_exponent = mpy_exponent - add_exponent; | |
1162 | result_exponent = mpy_exponent; | |
1163 | } | |
1164 | /* Invariant: left is not smaller than right. */ | |
1165 | ||
1166 | /* | |
1167 | * Special case alignment of operands that would force alignment | |
1168 | * beyond the extent of the extension. A further optimization | |
1169 | * could special case this but only reduces the path length for | |
1170 | * this infrequent case. | |
1171 | */ | |
1172 | if (diff_exponent > DBLEXT_THRESHOLD) { | |
1173 | diff_exponent = DBLEXT_THRESHOLD; | |
1174 | } | |
1175 | ||
1176 | /* Align right operand by shifting it to the right */ | |
1177 | Dblext_clear_sign(rightp1); | |
1178 | Dblext_right_align(rightp1,rightp2,rightp3,rightp4, | |
1179 | /*shifted by*/diff_exponent); | |
1180 | ||
1181 | /* Treat sum and difference of the operands separately. */ | |
1182 | if ((int)save < 0) { | |
1183 | /* | |
1184 | * Difference of the two operands. Overflow can occur if the | |
1185 | * multiply overflowed. A borrow can occur out of the hidden | |
1186 | * bit and force a post normalization phase. | |
1187 | */ | |
1188 | Dblext_subtract(tmpresp1,tmpresp2,tmpresp3,tmpresp4, | |
1189 | rightp1,rightp2,rightp3,rightp4, | |
1190 | resultp1,resultp2,resultp3,resultp4); | |
1191 | sign_save = Dbl_signextendedsign(resultp1); | |
1192 | if (Dbl_iszero_hidden(resultp1)) { | |
1193 | /* Handle normalization */ | |
25985edc | 1194 | /* A straightforward algorithm would now shift the |
1da177e4 LT |
1195 | * result and extension left until the hidden bit |
1196 | * becomes one. Not all of the extension bits need | |
1197 | * participate in the shift. Only the two most | |
1198 | * significant bits (round and guard) are needed. | |
1199 | * If only a single shift is needed then the guard | |
1200 | * bit becomes a significant low order bit and the | |
1201 | * extension must participate in the rounding. | |
1202 | * If more than a single shift is needed, then all | |
1203 | * bits to the right of the guard bit are zeros, | |
1204 | * and the guard bit may or may not be zero. */ | |
1205 | Dblext_leftshiftby1(resultp1,resultp2,resultp3, | |
1206 | resultp4); | |
1207 | ||
1208 | /* Need to check for a zero result. The sign and | |
1209 | * exponent fields have already been zeroed. The more | |
1210 | * efficient test of the full object can be used. | |
1211 | */ | |
1212 | if (Dblext_iszero(resultp1,resultp2,resultp3,resultp4)) { | |
1213 | /* Must have been "x-x" or "x+(-x)". */ | |
1214 | if (Is_rounding_mode(ROUNDMINUS)) | |
1215 | Dbl_setone_sign(resultp1); | |
1216 | Dbl_copytoptr(resultp1,resultp2,dstptr); | |
1217 | return(NOEXCEPTION); | |
1218 | } | |
1219 | result_exponent--; | |
1220 | ||
1221 | /* Look to see if normalization is finished. */ | |
1222 | if (Dbl_isone_hidden(resultp1)) { | |
1223 | /* No further normalization is needed */ | |
1224 | goto round; | |
1225 | } | |
1226 | ||
1227 | /* Discover first one bit to determine shift amount. | |
1228 | * Use a modified binary search. We have already | |
1229 | * shifted the result one position right and still | |
1230 | * not found a one so the remainder of the extension | |
1231 | * must be zero and simplifies rounding. */ | |
1232 | /* Scan bytes */ | |
1233 | while (Dbl_iszero_hiddenhigh7mantissa(resultp1)) { | |
1234 | Dblext_leftshiftby8(resultp1,resultp2,resultp3,resultp4); | |
1235 | result_exponent -= 8; | |
1236 | } | |
1237 | /* Now narrow it down to the nibble */ | |
1238 | if (Dbl_iszero_hiddenhigh3mantissa(resultp1)) { | |
1239 | /* The lower nibble contains the | |
1240 | * normalizing one */ | |
1241 | Dblext_leftshiftby4(resultp1,resultp2,resultp3,resultp4); | |
1242 | result_exponent -= 4; | |
1243 | } | |
1244 | /* Select case where first bit is set (already | |
1245 | * normalized) otherwise select the proper shift. */ | |
1246 | jumpsize = Dbl_hiddenhigh3mantissa(resultp1); | |
1247 | if (jumpsize <= 7) switch(jumpsize) { | |
1248 | case 1: | |
1249 | Dblext_leftshiftby3(resultp1,resultp2,resultp3, | |
1250 | resultp4); | |
1251 | result_exponent -= 3; | |
1252 | break; | |
1253 | case 2: | |
1254 | case 3: | |
1255 | Dblext_leftshiftby2(resultp1,resultp2,resultp3, | |
1256 | resultp4); | |
1257 | result_exponent -= 2; | |
1258 | break; | |
1259 | case 4: | |
1260 | case 5: | |
1261 | case 6: | |
1262 | case 7: | |
1263 | Dblext_leftshiftby1(resultp1,resultp2,resultp3, | |
1264 | resultp4); | |
1265 | result_exponent -= 1; | |
1266 | break; | |
1267 | } | |
1268 | } /* end if (hidden...)... */ | |
1269 | /* Fall through and round */ | |
1270 | } /* end if (save < 0)... */ | |
1271 | else { | |
1272 | /* Add magnitudes */ | |
1273 | Dblext_addition(tmpresp1,tmpresp2,tmpresp3,tmpresp4, | |
1274 | rightp1,rightp2,rightp3,rightp4, | |
1275 | /*to*/resultp1,resultp2,resultp3,resultp4); | |
1276 | sign_save = Dbl_signextendedsign(resultp1); | |
1277 | if (Dbl_isone_hiddenoverflow(resultp1)) { | |
1278 | /* Prenormalization required. */ | |
1279 | Dblext_arithrightshiftby1(resultp1,resultp2,resultp3, | |
1280 | resultp4); | |
1281 | result_exponent++; | |
1282 | } /* end if hiddenoverflow... */ | |
1283 | } /* end else ...add magnitudes... */ | |
1284 | ||
1285 | /* Round the result. If the extension and lower two words are | |
1286 | * all zeros, then the result is exact. Otherwise round in the | |
1287 | * correct direction. Underflow is possible. If a postnormalization | |
1288 | * is necessary, then the mantissa is all zeros so no shift is needed. | |
1289 | */ | |
1290 | round: | |
1291 | if (result_exponent <= 0 && !Is_underflowtrap_enabled()) { | |
1292 | Dblext_denormalize(resultp1,resultp2,resultp3,resultp4, | |
1293 | result_exponent,is_tiny); | |
1294 | } | |
1295 | Dbl_set_sign(resultp1,/*using*/sign_save); | |
1296 | if (Dblext_isnotzero_mantissap3(resultp3) || | |
1297 | Dblext_isnotzero_mantissap4(resultp4)) { | |
1298 | inexact = TRUE; | |
1299 | switch(Rounding_mode()) { | |
1300 | case ROUNDNEAREST: /* The default. */ | |
1301 | if (Dblext_isone_highp3(resultp3)) { | |
1302 | /* at least 1/2 ulp */ | |
1303 | if (Dblext_isnotzero_low31p3(resultp3) || | |
1304 | Dblext_isnotzero_mantissap4(resultp4) || | |
1305 | Dblext_isone_lowp2(resultp2)) { | |
1306 | /* either exactly half way and odd or | |
1307 | * more than 1/2ulp */ | |
1308 | Dbl_increment(resultp1,resultp2); | |
1309 | } | |
1310 | } | |
1311 | break; | |
1312 | ||
1313 | case ROUNDPLUS: | |
1314 | if (Dbl_iszero_sign(resultp1)) { | |
1315 | /* Round up positive results */ | |
1316 | Dbl_increment(resultp1,resultp2); | |
1317 | } | |
1318 | break; | |
1319 | ||
1320 | case ROUNDMINUS: | |
1321 | if (Dbl_isone_sign(resultp1)) { | |
1322 | /* Round down negative results */ | |
1323 | Dbl_increment(resultp1,resultp2); | |
1324 | } | |
1325 | ||
1326 | case ROUNDZERO:; | |
1327 | /* truncate is simple */ | |
1328 | } /* end switch... */ | |
1329 | if (Dbl_isone_hiddenoverflow(resultp1)) result_exponent++; | |
1330 | } | |
1331 | if (result_exponent >= DBL_INFINITY_EXPONENT) { | |
1332 | /* Overflow */ | |
1333 | if (Is_overflowtrap_enabled()) { | |
1334 | /* | |
1335 | * Adjust bias of result | |
1336 | */ | |
1337 | Dbl_setwrapped_exponent(resultp1,result_exponent,ovfl); | |
1338 | Dbl_copytoptr(resultp1,resultp2,dstptr); | |
1339 | if (inexact) | |
1340 | if (Is_inexacttrap_enabled()) | |
1341 | return (OPC_2E_OVERFLOWEXCEPTION | | |
1342 | OPC_2E_INEXACTEXCEPTION); | |
1343 | else Set_inexactflag(); | |
1344 | return (OPC_2E_OVERFLOWEXCEPTION); | |
1345 | } | |
1346 | inexact = TRUE; | |
1347 | Set_overflowflag(); | |
1348 | Dbl_setoverflow(resultp1,resultp2); | |
1349 | } else if (result_exponent <= 0) { /* underflow case */ | |
1350 | if (Is_underflowtrap_enabled()) { | |
1351 | /* | |
1352 | * Adjust bias of result | |
1353 | */ | |
1354 | Dbl_setwrapped_exponent(resultp1,result_exponent,unfl); | |
1355 | Dbl_copytoptr(resultp1,resultp2,dstptr); | |
1356 | if (inexact) | |
1357 | if (Is_inexacttrap_enabled()) | |
1358 | return (OPC_2E_UNDERFLOWEXCEPTION | | |
1359 | OPC_2E_INEXACTEXCEPTION); | |
1360 | else Set_inexactflag(); | |
1361 | return(OPC_2E_UNDERFLOWEXCEPTION); | |
1362 | } | |
1363 | else if (inexact && is_tiny) Set_underflowflag(); | |
1364 | } | |
1365 | else Dbl_set_exponent(resultp1,result_exponent); | |
1366 | Dbl_copytoptr(resultp1,resultp2,dstptr); | |
1367 | if (inexact) | |
1368 | if (Is_inexacttrap_enabled()) return(OPC_2E_INEXACTEXCEPTION); | |
1369 | else Set_inexactflag(); | |
1370 | return(NOEXCEPTION); | |
1371 | } | |
1372 | ||
1373 | /* | |
1374 | * Single Floating-point Multiply Fused Add | |
1375 | */ | |
1376 | ||
1377 | sgl_fmpyfadd(src1ptr,src2ptr,src3ptr,status,dstptr) | |
1378 | ||
1379 | sgl_floating_point *src1ptr, *src2ptr, *src3ptr, *dstptr; | |
1380 | unsigned int *status; | |
1381 | { | |
1382 | unsigned int opnd1, opnd2, opnd3; | |
1383 | register unsigned int tmpresp1, tmpresp2; | |
1384 | unsigned int rightp1, rightp2; | |
1385 | unsigned int resultp1, resultp2 = 0; | |
1386 | register int mpy_exponent, add_exponent, count; | |
1387 | boolean inexact = FALSE, is_tiny = FALSE; | |
1388 | ||
1389 | unsigned int signlessleft1, signlessright1, save; | |
1390 | register int result_exponent, diff_exponent; | |
1391 | int sign_save, jumpsize; | |
1392 | ||
1393 | Sgl_copyfromptr(src1ptr,opnd1); | |
1394 | Sgl_copyfromptr(src2ptr,opnd2); | |
1395 | Sgl_copyfromptr(src3ptr,opnd3); | |
1396 | ||
1397 | /* | |
1398 | * set sign bit of result of multiply | |
1399 | */ | |
1400 | if (Sgl_sign(opnd1) ^ Sgl_sign(opnd2)) | |
1401 | Sgl_setnegativezero(resultp1); | |
1402 | else Sgl_setzero(resultp1); | |
1403 | ||
1404 | /* | |
1405 | * Generate multiply exponent | |
1406 | */ | |
1407 | mpy_exponent = Sgl_exponent(opnd1) + Sgl_exponent(opnd2) - SGL_BIAS; | |
1408 | ||
1409 | /* | |
1410 | * check first operand for NaN's or infinity | |
1411 | */ | |
1412 | if (Sgl_isinfinity_exponent(opnd1)) { | |
1413 | if (Sgl_iszero_mantissa(opnd1)) { | |
1414 | if (Sgl_isnotnan(opnd2) && Sgl_isnotnan(opnd3)) { | |
1415 | if (Sgl_iszero_exponentmantissa(opnd2)) { | |
1416 | /* | |
1417 | * invalid since operands are infinity | |
1418 | * and zero | |
1419 | */ | |
1420 | if (Is_invalidtrap_enabled()) | |
1421 | return(OPC_2E_INVALIDEXCEPTION); | |
1422 | Set_invalidflag(); | |
1423 | Sgl_makequietnan(resultp1); | |
1424 | Sgl_copytoptr(resultp1,dstptr); | |
1425 | return(NOEXCEPTION); | |
1426 | } | |
1427 | /* | |
1428 | * Check third operand for infinity with a | |
1429 | * sign opposite of the multiply result | |
1430 | */ | |
1431 | if (Sgl_isinfinity(opnd3) && | |
1432 | (Sgl_sign(resultp1) ^ Sgl_sign(opnd3))) { | |
1433 | /* | |
1434 | * invalid since attempting a magnitude | |
1435 | * subtraction of infinities | |
1436 | */ | |
1437 | if (Is_invalidtrap_enabled()) | |
1438 | return(OPC_2E_INVALIDEXCEPTION); | |
1439 | Set_invalidflag(); | |
1440 | Sgl_makequietnan(resultp1); | |
1441 | Sgl_copytoptr(resultp1,dstptr); | |
1442 | return(NOEXCEPTION); | |
1443 | } | |
1444 | ||
1445 | /* | |
1446 | * return infinity | |
1447 | */ | |
1448 | Sgl_setinfinity_exponentmantissa(resultp1); | |
1449 | Sgl_copytoptr(resultp1,dstptr); | |
1450 | return(NOEXCEPTION); | |
1451 | } | |
1452 | } | |
1453 | else { | |
1454 | /* | |
1455 | * is NaN; signaling or quiet? | |
1456 | */ | |
1457 | if (Sgl_isone_signaling(opnd1)) { | |
1458 | /* trap if INVALIDTRAP enabled */ | |
1459 | if (Is_invalidtrap_enabled()) | |
1460 | return(OPC_2E_INVALIDEXCEPTION); | |
1461 | /* make NaN quiet */ | |
1462 | Set_invalidflag(); | |
1463 | Sgl_set_quiet(opnd1); | |
1464 | } | |
1465 | /* | |
1466 | * is second operand a signaling NaN? | |
1467 | */ | |
1468 | else if (Sgl_is_signalingnan(opnd2)) { | |
1469 | /* trap if INVALIDTRAP enabled */ | |
1470 | if (Is_invalidtrap_enabled()) | |
1471 | return(OPC_2E_INVALIDEXCEPTION); | |
1472 | /* make NaN quiet */ | |
1473 | Set_invalidflag(); | |
1474 | Sgl_set_quiet(opnd2); | |
1475 | Sgl_copytoptr(opnd2,dstptr); | |
1476 | return(NOEXCEPTION); | |
1477 | } | |
1478 | /* | |
1479 | * is third operand a signaling NaN? | |
1480 | */ | |
1481 | else if (Sgl_is_signalingnan(opnd3)) { | |
1482 | /* trap if INVALIDTRAP enabled */ | |
1483 | if (Is_invalidtrap_enabled()) | |
1484 | return(OPC_2E_INVALIDEXCEPTION); | |
1485 | /* make NaN quiet */ | |
1486 | Set_invalidflag(); | |
1487 | Sgl_set_quiet(opnd3); | |
1488 | Sgl_copytoptr(opnd3,dstptr); | |
1489 | return(NOEXCEPTION); | |
1490 | } | |
1491 | /* | |
1492 | * return quiet NaN | |
1493 | */ | |
1494 | Sgl_copytoptr(opnd1,dstptr); | |
1495 | return(NOEXCEPTION); | |
1496 | } | |
1497 | } | |
1498 | ||
1499 | /* | |
1500 | * check second operand for NaN's or infinity | |
1501 | */ | |
1502 | if (Sgl_isinfinity_exponent(opnd2)) { | |
1503 | if (Sgl_iszero_mantissa(opnd2)) { | |
1504 | if (Sgl_isnotnan(opnd3)) { | |
1505 | if (Sgl_iszero_exponentmantissa(opnd1)) { | |
1506 | /* | |
1507 | * invalid since multiply operands are | |
1508 | * zero & infinity | |
1509 | */ | |
1510 | if (Is_invalidtrap_enabled()) | |
1511 | return(OPC_2E_INVALIDEXCEPTION); | |
1512 | Set_invalidflag(); | |
1513 | Sgl_makequietnan(opnd2); | |
1514 | Sgl_copytoptr(opnd2,dstptr); | |
1515 | return(NOEXCEPTION); | |
1516 | } | |
1517 | ||
1518 | /* | |
1519 | * Check third operand for infinity with a | |
1520 | * sign opposite of the multiply result | |
1521 | */ | |
1522 | if (Sgl_isinfinity(opnd3) && | |
1523 | (Sgl_sign(resultp1) ^ Sgl_sign(opnd3))) { | |
1524 | /* | |
1525 | * invalid since attempting a magnitude | |
1526 | * subtraction of infinities | |
1527 | */ | |
1528 | if (Is_invalidtrap_enabled()) | |
1529 | return(OPC_2E_INVALIDEXCEPTION); | |
1530 | Set_invalidflag(); | |
1531 | Sgl_makequietnan(resultp1); | |
1532 | Sgl_copytoptr(resultp1,dstptr); | |
1533 | return(NOEXCEPTION); | |
1534 | } | |
1535 | ||
1536 | /* | |
1537 | * return infinity | |
1538 | */ | |
1539 | Sgl_setinfinity_exponentmantissa(resultp1); | |
1540 | Sgl_copytoptr(resultp1,dstptr); | |
1541 | return(NOEXCEPTION); | |
1542 | } | |
1543 | } | |
1544 | else { | |
1545 | /* | |
1546 | * is NaN; signaling or quiet? | |
1547 | */ | |
1548 | if (Sgl_isone_signaling(opnd2)) { | |
1549 | /* trap if INVALIDTRAP enabled */ | |
1550 | if (Is_invalidtrap_enabled()) | |
1551 | return(OPC_2E_INVALIDEXCEPTION); | |
1552 | /* make NaN quiet */ | |
1553 | Set_invalidflag(); | |
1554 | Sgl_set_quiet(opnd2); | |
1555 | } | |
1556 | /* | |
1557 | * is third operand a signaling NaN? | |
1558 | */ | |
1559 | else if (Sgl_is_signalingnan(opnd3)) { | |
1560 | /* trap if INVALIDTRAP enabled */ | |
1561 | if (Is_invalidtrap_enabled()) | |
1562 | return(OPC_2E_INVALIDEXCEPTION); | |
1563 | /* make NaN quiet */ | |
1564 | Set_invalidflag(); | |
1565 | Sgl_set_quiet(opnd3); | |
1566 | Sgl_copytoptr(opnd3,dstptr); | |
1567 | return(NOEXCEPTION); | |
1568 | } | |
1569 | /* | |
1570 | * return quiet NaN | |
1571 | */ | |
1572 | Sgl_copytoptr(opnd2,dstptr); | |
1573 | return(NOEXCEPTION); | |
1574 | } | |
1575 | } | |
1576 | ||
1577 | /* | |
1578 | * check third operand for NaN's or infinity | |
1579 | */ | |
1580 | if (Sgl_isinfinity_exponent(opnd3)) { | |
1581 | if (Sgl_iszero_mantissa(opnd3)) { | |
1582 | /* return infinity */ | |
1583 | Sgl_copytoptr(opnd3,dstptr); | |
1584 | return(NOEXCEPTION); | |
1585 | } else { | |
1586 | /* | |
1587 | * is NaN; signaling or quiet? | |
1588 | */ | |
1589 | if (Sgl_isone_signaling(opnd3)) { | |
1590 | /* trap if INVALIDTRAP enabled */ | |
1591 | if (Is_invalidtrap_enabled()) | |
1592 | return(OPC_2E_INVALIDEXCEPTION); | |
1593 | /* make NaN quiet */ | |
1594 | Set_invalidflag(); | |
1595 | Sgl_set_quiet(opnd3); | |
1596 | } | |
1597 | /* | |
1598 | * return quiet NaN | |
1599 | */ | |
1600 | Sgl_copytoptr(opnd3,dstptr); | |
1601 | return(NOEXCEPTION); | |
1602 | } | |
1603 | } | |
1604 | ||
1605 | /* | |
1606 | * Generate multiply mantissa | |
1607 | */ | |
1608 | if (Sgl_isnotzero_exponent(opnd1)) { | |
1609 | /* set hidden bit */ | |
1610 | Sgl_clear_signexponent_set_hidden(opnd1); | |
1611 | } | |
1612 | else { | |
1613 | /* check for zero */ | |
1614 | if (Sgl_iszero_mantissa(opnd1)) { | |
1615 | /* | |
1616 | * Perform the add opnd3 with zero here. | |
1617 | */ | |
1618 | if (Sgl_iszero_exponentmantissa(opnd3)) { | |
1619 | if (Is_rounding_mode(ROUNDMINUS)) { | |
1620 | Sgl_or_signs(opnd3,resultp1); | |
1621 | } else { | |
1622 | Sgl_and_signs(opnd3,resultp1); | |
1623 | } | |
1624 | } | |
1625 | /* | |
1626 | * Now let's check for trapped underflow case. | |
1627 | */ | |
1628 | else if (Sgl_iszero_exponent(opnd3) && | |
1629 | Is_underflowtrap_enabled()) { | |
1630 | /* need to normalize results mantissa */ | |
1631 | sign_save = Sgl_signextendedsign(opnd3); | |
1632 | result_exponent = 0; | |
1633 | Sgl_leftshiftby1(opnd3); | |
1634 | Sgl_normalize(opnd3,result_exponent); | |
1635 | Sgl_set_sign(opnd3,/*using*/sign_save); | |
1636 | Sgl_setwrapped_exponent(opnd3,result_exponent, | |
1637 | unfl); | |
1638 | Sgl_copytoptr(opnd3,dstptr); | |
1639 | /* inexact = FALSE */ | |
1640 | return(OPC_2E_UNDERFLOWEXCEPTION); | |
1641 | } | |
1642 | Sgl_copytoptr(opnd3,dstptr); | |
1643 | return(NOEXCEPTION); | |
1644 | } | |
1645 | /* is denormalized, adjust exponent */ | |
1646 | Sgl_clear_signexponent(opnd1); | |
1647 | Sgl_leftshiftby1(opnd1); | |
1648 | Sgl_normalize(opnd1,mpy_exponent); | |
1649 | } | |
1650 | /* opnd2 needs to have hidden bit set with msb in hidden bit */ | |
1651 | if (Sgl_isnotzero_exponent(opnd2)) { | |
1652 | Sgl_clear_signexponent_set_hidden(opnd2); | |
1653 | } | |
1654 | else { | |
1655 | /* check for zero */ | |
1656 | if (Sgl_iszero_mantissa(opnd2)) { | |
1657 | /* | |
1658 | * Perform the add opnd3 with zero here. | |
1659 | */ | |
1660 | if (Sgl_iszero_exponentmantissa(opnd3)) { | |
1661 | if (Is_rounding_mode(ROUNDMINUS)) { | |
1662 | Sgl_or_signs(opnd3,resultp1); | |
1663 | } else { | |
1664 | Sgl_and_signs(opnd3,resultp1); | |
1665 | } | |
1666 | } | |
1667 | /* | |
1668 | * Now let's check for trapped underflow case. | |
1669 | */ | |
1670 | else if (Sgl_iszero_exponent(opnd3) && | |
1671 | Is_underflowtrap_enabled()) { | |
1672 | /* need to normalize results mantissa */ | |
1673 | sign_save = Sgl_signextendedsign(opnd3); | |
1674 | result_exponent = 0; | |
1675 | Sgl_leftshiftby1(opnd3); | |
1676 | Sgl_normalize(opnd3,result_exponent); | |
1677 | Sgl_set_sign(opnd3,/*using*/sign_save); | |
1678 | Sgl_setwrapped_exponent(opnd3,result_exponent, | |
1679 | unfl); | |
1680 | Sgl_copytoptr(opnd3,dstptr); | |
1681 | /* inexact = FALSE */ | |
1682 | return(OPC_2E_UNDERFLOWEXCEPTION); | |
1683 | } | |
1684 | Sgl_copytoptr(opnd3,dstptr); | |
1685 | return(NOEXCEPTION); | |
1686 | } | |
1687 | /* is denormalized; want to normalize */ | |
1688 | Sgl_clear_signexponent(opnd2); | |
1689 | Sgl_leftshiftby1(opnd2); | |
1690 | Sgl_normalize(opnd2,mpy_exponent); | |
1691 | } | |
1692 | ||
1693 | /* Multiply the first two source mantissas together */ | |
1694 | ||
1695 | /* | |
1696 | * The intermediate result will be kept in tmpres, | |
1697 | * which needs enough room for 106 bits of mantissa, | |
1698 | * so lets call it a Double extended. | |
1699 | */ | |
1700 | Sglext_setzero(tmpresp1,tmpresp2); | |
1701 | ||
1702 | /* | |
1703 | * Four bits at a time are inspected in each loop, and a | |
1704 | * simple shift and add multiply algorithm is used. | |
1705 | */ | |
1706 | for (count = SGL_P-1; count >= 0; count -= 4) { | |
1707 | Sglext_rightshiftby4(tmpresp1,tmpresp2); | |
1708 | if (Sbit28(opnd1)) { | |
1709 | /* Twoword_add should be an ADD followed by 2 ADDC's */ | |
1710 | Twoword_add(tmpresp1, tmpresp2, opnd2<<3, 0); | |
1711 | } | |
1712 | if (Sbit29(opnd1)) { | |
1713 | Twoword_add(tmpresp1, tmpresp2, opnd2<<2, 0); | |
1714 | } | |
1715 | if (Sbit30(opnd1)) { | |
1716 | Twoword_add(tmpresp1, tmpresp2, opnd2<<1, 0); | |
1717 | } | |
1718 | if (Sbit31(opnd1)) { | |
1719 | Twoword_add(tmpresp1, tmpresp2, opnd2, 0); | |
1720 | } | |
1721 | Sgl_rightshiftby4(opnd1); | |
1722 | } | |
1723 | if (Is_sexthiddenoverflow(tmpresp1)) { | |
1724 | /* result mantissa >= 2 (mantissa overflow) */ | |
1725 | mpy_exponent++; | |
1726 | Sglext_rightshiftby4(tmpresp1,tmpresp2); | |
1727 | } else { | |
1728 | Sglext_rightshiftby3(tmpresp1,tmpresp2); | |
1729 | } | |
1730 | ||
1731 | /* | |
1732 | * Restore the sign of the mpy result which was saved in resultp1. | |
1733 | * The exponent will continue to be kept in mpy_exponent. | |
1734 | */ | |
1735 | Sglext_set_sign(tmpresp1,Sgl_sign(resultp1)); | |
1736 | ||
1737 | /* | |
1738 | * No rounding is required, since the result of the multiply | |
1739 | * is exact in the extended format. | |
1740 | */ | |
1741 | ||
1742 | /* | |
1743 | * Now we are ready to perform the add portion of the operation. | |
1744 | * | |
1745 | * The exponents need to be kept as integers for now, since the | |
1746 | * multiply result might not fit into the exponent field. We | |
1747 | * can't overflow or underflow because of this yet, since the | |
1748 | * add could bring the final result back into range. | |
1749 | */ | |
1750 | add_exponent = Sgl_exponent(opnd3); | |
1751 | ||
1752 | /* | |
1753 | * Check for denormalized or zero add operand. | |
1754 | */ | |
1755 | if (add_exponent == 0) { | |
1756 | /* check for zero */ | |
1757 | if (Sgl_iszero_mantissa(opnd3)) { | |
1758 | /* right is zero */ | |
1759 | /* Left can't be zero and must be result. | |
1760 | * | |
1761 | * The final result is now in tmpres and mpy_exponent, | |
1762 | * and needs to be rounded and squeezed back into | |
1763 | * double precision format from double extended. | |
1764 | */ | |
1765 | result_exponent = mpy_exponent; | |
1766 | Sglext_copy(tmpresp1,tmpresp2,resultp1,resultp2); | |
1767 | sign_save = Sgl_signextendedsign(resultp1);/*save sign*/ | |
1768 | goto round; | |
1769 | } | |
1770 | ||
1771 | /* | |
1772 | * Neither are zeroes. | |
1773 | * Adjust exponent and normalize add operand. | |
1774 | */ | |
1775 | sign_save = Sgl_signextendedsign(opnd3); /* save sign */ | |
1776 | Sgl_clear_signexponent(opnd3); | |
1777 | Sgl_leftshiftby1(opnd3); | |
1778 | Sgl_normalize(opnd3,add_exponent); | |
1779 | Sgl_set_sign(opnd3,sign_save); /* restore sign */ | |
1780 | } else { | |
1781 | Sgl_clear_exponent_set_hidden(opnd3); | |
1782 | } | |
1783 | /* | |
1784 | * Copy opnd3 to the double extended variable called right. | |
1785 | */ | |
1786 | Sgl_copyto_sglext(opnd3,rightp1,rightp2); | |
1787 | ||
1788 | /* | |
1789 | * A zero "save" helps discover equal operands (for later), | |
1790 | * and is used in swapping operands (if needed). | |
1791 | */ | |
1792 | Sglext_xortointp1(tmpresp1,rightp1,/*to*/save); | |
1793 | ||
1794 | /* | |
1795 | * Compare magnitude of operands. | |
1796 | */ | |
1797 | Sglext_copytoint_exponentmantissa(tmpresp1,signlessleft1); | |
1798 | Sglext_copytoint_exponentmantissa(rightp1,signlessright1); | |
1799 | if (mpy_exponent < add_exponent || mpy_exponent == add_exponent && | |
1800 | Sglext_ismagnitudeless(signlessleft1,signlessright1)) { | |
1801 | /* | |
1802 | * Set the left operand to the larger one by XOR swap. | |
1803 | * First finish the first word "save". | |
1804 | */ | |
1805 | Sglext_xorfromintp1(save,rightp1,/*to*/rightp1); | |
1806 | Sglext_xorfromintp1(save,tmpresp1,/*to*/tmpresp1); | |
1807 | Sglext_swap_lower(tmpresp2,rightp2); | |
1808 | /* also setup exponents used in rest of routine */ | |
1809 | diff_exponent = add_exponent - mpy_exponent; | |
1810 | result_exponent = add_exponent; | |
1811 | } else { | |
1812 | /* also setup exponents used in rest of routine */ | |
1813 | diff_exponent = mpy_exponent - add_exponent; | |
1814 | result_exponent = mpy_exponent; | |
1815 | } | |
1816 | /* Invariant: left is not smaller than right. */ | |
1817 | ||
1818 | /* | |
1819 | * Special case alignment of operands that would force alignment | |
1820 | * beyond the extent of the extension. A further optimization | |
1821 | * could special case this but only reduces the path length for | |
1822 | * this infrequent case. | |
1823 | */ | |
1824 | if (diff_exponent > SGLEXT_THRESHOLD) { | |
1825 | diff_exponent = SGLEXT_THRESHOLD; | |
1826 | } | |
1827 | ||
1828 | /* Align right operand by shifting it to the right */ | |
1829 | Sglext_clear_sign(rightp1); | |
1830 | Sglext_right_align(rightp1,rightp2,/*shifted by*/diff_exponent); | |
1831 | ||
1832 | /* Treat sum and difference of the operands separately. */ | |
1833 | if ((int)save < 0) { | |
1834 | /* | |
1835 | * Difference of the two operands. Overflow can occur if the | |
1836 | * multiply overflowed. A borrow can occur out of the hidden | |
1837 | * bit and force a post normalization phase. | |
1838 | */ | |
1839 | Sglext_subtract(tmpresp1,tmpresp2, rightp1,rightp2, | |
1840 | resultp1,resultp2); | |
1841 | sign_save = Sgl_signextendedsign(resultp1); | |
1842 | if (Sgl_iszero_hidden(resultp1)) { | |
1843 | /* Handle normalization */ | |
25985edc | 1844 | /* A straightforward algorithm would now shift the |
1da177e4 LT |
1845 | * result and extension left until the hidden bit |
1846 | * becomes one. Not all of the extension bits need | |
1847 | * participate in the shift. Only the two most | |
1848 | * significant bits (round and guard) are needed. | |
1849 | * If only a single shift is needed then the guard | |
1850 | * bit becomes a significant low order bit and the | |
1851 | * extension must participate in the rounding. | |
1852 | * If more than a single shift is needed, then all | |
1853 | * bits to the right of the guard bit are zeros, | |
1854 | * and the guard bit may or may not be zero. */ | |
1855 | Sglext_leftshiftby1(resultp1,resultp2); | |
1856 | ||
1857 | /* Need to check for a zero result. The sign and | |
1858 | * exponent fields have already been zeroed. The more | |
1859 | * efficient test of the full object can be used. | |
1860 | */ | |
1861 | if (Sglext_iszero(resultp1,resultp2)) { | |
1862 | /* Must have been "x-x" or "x+(-x)". */ | |
1863 | if (Is_rounding_mode(ROUNDMINUS)) | |
1864 | Sgl_setone_sign(resultp1); | |
1865 | Sgl_copytoptr(resultp1,dstptr); | |
1866 | return(NOEXCEPTION); | |
1867 | } | |
1868 | result_exponent--; | |
1869 | ||
1870 | /* Look to see if normalization is finished. */ | |
1871 | if (Sgl_isone_hidden(resultp1)) { | |
1872 | /* No further normalization is needed */ | |
1873 | goto round; | |
1874 | } | |
1875 | ||
1876 | /* Discover first one bit to determine shift amount. | |
1877 | * Use a modified binary search. We have already | |
1878 | * shifted the result one position right and still | |
1879 | * not found a one so the remainder of the extension | |
1880 | * must be zero and simplifies rounding. */ | |
1881 | /* Scan bytes */ | |
1882 | while (Sgl_iszero_hiddenhigh7mantissa(resultp1)) { | |
1883 | Sglext_leftshiftby8(resultp1,resultp2); | |
1884 | result_exponent -= 8; | |
1885 | } | |
1886 | /* Now narrow it down to the nibble */ | |
1887 | if (Sgl_iszero_hiddenhigh3mantissa(resultp1)) { | |
1888 | /* The lower nibble contains the | |
1889 | * normalizing one */ | |
1890 | Sglext_leftshiftby4(resultp1,resultp2); | |
1891 | result_exponent -= 4; | |
1892 | } | |
1893 | /* Select case where first bit is set (already | |
1894 | * normalized) otherwise select the proper shift. */ | |
1895 | jumpsize = Sgl_hiddenhigh3mantissa(resultp1); | |
1896 | if (jumpsize <= 7) switch(jumpsize) { | |
1897 | case 1: | |
1898 | Sglext_leftshiftby3(resultp1,resultp2); | |
1899 | result_exponent -= 3; | |
1900 | break; | |
1901 | case 2: | |
1902 | case 3: | |
1903 | Sglext_leftshiftby2(resultp1,resultp2); | |
1904 | result_exponent -= 2; | |
1905 | break; | |
1906 | case 4: | |
1907 | case 5: | |
1908 | case 6: | |
1909 | case 7: | |
1910 | Sglext_leftshiftby1(resultp1,resultp2); | |
1911 | result_exponent -= 1; | |
1912 | break; | |
1913 | } | |
1914 | } /* end if (hidden...)... */ | |
1915 | /* Fall through and round */ | |
1916 | } /* end if (save < 0)... */ | |
1917 | else { | |
1918 | /* Add magnitudes */ | |
1919 | Sglext_addition(tmpresp1,tmpresp2, | |
1920 | rightp1,rightp2, /*to*/resultp1,resultp2); | |
1921 | sign_save = Sgl_signextendedsign(resultp1); | |
1922 | if (Sgl_isone_hiddenoverflow(resultp1)) { | |
1923 | /* Prenormalization required. */ | |
1924 | Sglext_arithrightshiftby1(resultp1,resultp2); | |
1925 | result_exponent++; | |
1926 | } /* end if hiddenoverflow... */ | |
1927 | } /* end else ...add magnitudes... */ | |
1928 | ||
1929 | /* Round the result. If the extension and lower two words are | |
1930 | * all zeros, then the result is exact. Otherwise round in the | |
1931 | * correct direction. Underflow is possible. If a postnormalization | |
1932 | * is necessary, then the mantissa is all zeros so no shift is needed. | |
1933 | */ | |
1934 | round: | |
1935 | if (result_exponent <= 0 && !Is_underflowtrap_enabled()) { | |
1936 | Sglext_denormalize(resultp1,resultp2,result_exponent,is_tiny); | |
1937 | } | |
1938 | Sgl_set_sign(resultp1,/*using*/sign_save); | |
1939 | if (Sglext_isnotzero_mantissap2(resultp2)) { | |
1940 | inexact = TRUE; | |
1941 | switch(Rounding_mode()) { | |
1942 | case ROUNDNEAREST: /* The default. */ | |
1943 | if (Sglext_isone_highp2(resultp2)) { | |
1944 | /* at least 1/2 ulp */ | |
1945 | if (Sglext_isnotzero_low31p2(resultp2) || | |
1946 | Sglext_isone_lowp1(resultp1)) { | |
1947 | /* either exactly half way and odd or | |
1948 | * more than 1/2ulp */ | |
1949 | Sgl_increment(resultp1); | |
1950 | } | |
1951 | } | |
1952 | break; | |
1953 | ||
1954 | case ROUNDPLUS: | |
1955 | if (Sgl_iszero_sign(resultp1)) { | |
1956 | /* Round up positive results */ | |
1957 | Sgl_increment(resultp1); | |
1958 | } | |
1959 | break; | |
1960 | ||
1961 | case ROUNDMINUS: | |
1962 | if (Sgl_isone_sign(resultp1)) { | |
1963 | /* Round down negative results */ | |
1964 | Sgl_increment(resultp1); | |
1965 | } | |
1966 | ||
1967 | case ROUNDZERO:; | |
1968 | /* truncate is simple */ | |
1969 | } /* end switch... */ | |
1970 | if (Sgl_isone_hiddenoverflow(resultp1)) result_exponent++; | |
1971 | } | |
1972 | if (result_exponent >= SGL_INFINITY_EXPONENT) { | |
1973 | /* Overflow */ | |
1974 | if (Is_overflowtrap_enabled()) { | |
1975 | /* | |
1976 | * Adjust bias of result | |
1977 | */ | |
1978 | Sgl_setwrapped_exponent(resultp1,result_exponent,ovfl); | |
1979 | Sgl_copytoptr(resultp1,dstptr); | |
1980 | if (inexact) | |
1981 | if (Is_inexacttrap_enabled()) | |
1982 | return (OPC_2E_OVERFLOWEXCEPTION | | |
1983 | OPC_2E_INEXACTEXCEPTION); | |
1984 | else Set_inexactflag(); | |
1985 | return (OPC_2E_OVERFLOWEXCEPTION); | |
1986 | } | |
1987 | inexact = TRUE; | |
1988 | Set_overflowflag(); | |
1989 | Sgl_setoverflow(resultp1); | |
1990 | } else if (result_exponent <= 0) { /* underflow case */ | |
1991 | if (Is_underflowtrap_enabled()) { | |
1992 | /* | |
1993 | * Adjust bias of result | |
1994 | */ | |
1995 | Sgl_setwrapped_exponent(resultp1,result_exponent,unfl); | |
1996 | Sgl_copytoptr(resultp1,dstptr); | |
1997 | if (inexact) | |
1998 | if (Is_inexacttrap_enabled()) | |
1999 | return (OPC_2E_UNDERFLOWEXCEPTION | | |
2000 | OPC_2E_INEXACTEXCEPTION); | |
2001 | else Set_inexactflag(); | |
2002 | return(OPC_2E_UNDERFLOWEXCEPTION); | |
2003 | } | |
2004 | else if (inexact && is_tiny) Set_underflowflag(); | |
2005 | } | |
2006 | else Sgl_set_exponent(resultp1,result_exponent); | |
2007 | Sgl_copytoptr(resultp1,dstptr); | |
2008 | if (inexact) | |
2009 | if (Is_inexacttrap_enabled()) return(OPC_2E_INEXACTEXCEPTION); | |
2010 | else Set_inexactflag(); | |
2011 | return(NOEXCEPTION); | |
2012 | } | |
2013 | ||
2014 | /* | |
2015 | * Single Floating-point Multiply Negate Fused Add | |
2016 | */ | |
2017 | ||
2018 | sgl_fmpynfadd(src1ptr,src2ptr,src3ptr,status,dstptr) | |
2019 | ||
2020 | sgl_floating_point *src1ptr, *src2ptr, *src3ptr, *dstptr; | |
2021 | unsigned int *status; | |
2022 | { | |
2023 | unsigned int opnd1, opnd2, opnd3; | |
2024 | register unsigned int tmpresp1, tmpresp2; | |
2025 | unsigned int rightp1, rightp2; | |
2026 | unsigned int resultp1, resultp2 = 0; | |
2027 | register int mpy_exponent, add_exponent, count; | |
2028 | boolean inexact = FALSE, is_tiny = FALSE; | |
2029 | ||
2030 | unsigned int signlessleft1, signlessright1, save; | |
2031 | register int result_exponent, diff_exponent; | |
2032 | int sign_save, jumpsize; | |
2033 | ||
2034 | Sgl_copyfromptr(src1ptr,opnd1); | |
2035 | Sgl_copyfromptr(src2ptr,opnd2); | |
2036 | Sgl_copyfromptr(src3ptr,opnd3); | |
2037 | ||
2038 | /* | |
2039 | * set sign bit of result of multiply | |
2040 | */ | |
2041 | if (Sgl_sign(opnd1) ^ Sgl_sign(opnd2)) | |
2042 | Sgl_setzero(resultp1); | |
2043 | else | |
2044 | Sgl_setnegativezero(resultp1); | |
2045 | ||
2046 | /* | |
2047 | * Generate multiply exponent | |
2048 | */ | |
2049 | mpy_exponent = Sgl_exponent(opnd1) + Sgl_exponent(opnd2) - SGL_BIAS; | |
2050 | ||
2051 | /* | |
2052 | * check first operand for NaN's or infinity | |
2053 | */ | |
2054 | if (Sgl_isinfinity_exponent(opnd1)) { | |
2055 | if (Sgl_iszero_mantissa(opnd1)) { | |
2056 | if (Sgl_isnotnan(opnd2) && Sgl_isnotnan(opnd3)) { | |
2057 | if (Sgl_iszero_exponentmantissa(opnd2)) { | |
2058 | /* | |
2059 | * invalid since operands are infinity | |
2060 | * and zero | |
2061 | */ | |
2062 | if (Is_invalidtrap_enabled()) | |
2063 | return(OPC_2E_INVALIDEXCEPTION); | |
2064 | Set_invalidflag(); | |
2065 | Sgl_makequietnan(resultp1); | |
2066 | Sgl_copytoptr(resultp1,dstptr); | |
2067 | return(NOEXCEPTION); | |
2068 | } | |
2069 | /* | |
2070 | * Check third operand for infinity with a | |
2071 | * sign opposite of the multiply result | |
2072 | */ | |
2073 | if (Sgl_isinfinity(opnd3) && | |
2074 | (Sgl_sign(resultp1) ^ Sgl_sign(opnd3))) { | |
2075 | /* | |
2076 | * invalid since attempting a magnitude | |
2077 | * subtraction of infinities | |
2078 | */ | |
2079 | if (Is_invalidtrap_enabled()) | |
2080 | return(OPC_2E_INVALIDEXCEPTION); | |
2081 | Set_invalidflag(); | |
2082 | Sgl_makequietnan(resultp1); | |
2083 | Sgl_copytoptr(resultp1,dstptr); | |
2084 | return(NOEXCEPTION); | |
2085 | } | |
2086 | ||
2087 | /* | |
2088 | * return infinity | |
2089 | */ | |
2090 | Sgl_setinfinity_exponentmantissa(resultp1); | |
2091 | Sgl_copytoptr(resultp1,dstptr); | |
2092 | return(NOEXCEPTION); | |
2093 | } | |
2094 | } | |
2095 | else { | |
2096 | /* | |
2097 | * is NaN; signaling or quiet? | |
2098 | */ | |
2099 | if (Sgl_isone_signaling(opnd1)) { | |
2100 | /* trap if INVALIDTRAP enabled */ | |
2101 | if (Is_invalidtrap_enabled()) | |
2102 | return(OPC_2E_INVALIDEXCEPTION); | |
2103 | /* make NaN quiet */ | |
2104 | Set_invalidflag(); | |
2105 | Sgl_set_quiet(opnd1); | |
2106 | } | |
2107 | /* | |
2108 | * is second operand a signaling NaN? | |
2109 | */ | |
2110 | else if (Sgl_is_signalingnan(opnd2)) { | |
2111 | /* trap if INVALIDTRAP enabled */ | |
2112 | if (Is_invalidtrap_enabled()) | |
2113 | return(OPC_2E_INVALIDEXCEPTION); | |
2114 | /* make NaN quiet */ | |
2115 | Set_invalidflag(); | |
2116 | Sgl_set_quiet(opnd2); | |
2117 | Sgl_copytoptr(opnd2,dstptr); | |
2118 | return(NOEXCEPTION); | |
2119 | } | |
2120 | /* | |
2121 | * is third operand a signaling NaN? | |
2122 | */ | |
2123 | else if (Sgl_is_signalingnan(opnd3)) { | |
2124 | /* trap if INVALIDTRAP enabled */ | |
2125 | if (Is_invalidtrap_enabled()) | |
2126 | return(OPC_2E_INVALIDEXCEPTION); | |
2127 | /* make NaN quiet */ | |
2128 | Set_invalidflag(); | |
2129 | Sgl_set_quiet(opnd3); | |
2130 | Sgl_copytoptr(opnd3,dstptr); | |
2131 | return(NOEXCEPTION); | |
2132 | } | |
2133 | /* | |
2134 | * return quiet NaN | |
2135 | */ | |
2136 | Sgl_copytoptr(opnd1,dstptr); | |
2137 | return(NOEXCEPTION); | |
2138 | } | |
2139 | } | |
2140 | ||
2141 | /* | |
2142 | * check second operand for NaN's or infinity | |
2143 | */ | |
2144 | if (Sgl_isinfinity_exponent(opnd2)) { | |
2145 | if (Sgl_iszero_mantissa(opnd2)) { | |
2146 | if (Sgl_isnotnan(opnd3)) { | |
2147 | if (Sgl_iszero_exponentmantissa(opnd1)) { | |
2148 | /* | |
2149 | * invalid since multiply operands are | |
2150 | * zero & infinity | |
2151 | */ | |
2152 | if (Is_invalidtrap_enabled()) | |
2153 | return(OPC_2E_INVALIDEXCEPTION); | |
2154 | Set_invalidflag(); | |
2155 | Sgl_makequietnan(opnd2); | |
2156 | Sgl_copytoptr(opnd2,dstptr); | |
2157 | return(NOEXCEPTION); | |
2158 | } | |
2159 | ||
2160 | /* | |
2161 | * Check third operand for infinity with a | |
2162 | * sign opposite of the multiply result | |
2163 | */ | |
2164 | if (Sgl_isinfinity(opnd3) && | |
2165 | (Sgl_sign(resultp1) ^ Sgl_sign(opnd3))) { | |
2166 | /* | |
2167 | * invalid since attempting a magnitude | |
2168 | * subtraction of infinities | |
2169 | */ | |
2170 | if (Is_invalidtrap_enabled()) | |
2171 | return(OPC_2E_INVALIDEXCEPTION); | |
2172 | Set_invalidflag(); | |
2173 | Sgl_makequietnan(resultp1); | |
2174 | Sgl_copytoptr(resultp1,dstptr); | |
2175 | return(NOEXCEPTION); | |
2176 | } | |
2177 | ||
2178 | /* | |
2179 | * return infinity | |
2180 | */ | |
2181 | Sgl_setinfinity_exponentmantissa(resultp1); | |
2182 | Sgl_copytoptr(resultp1,dstptr); | |
2183 | return(NOEXCEPTION); | |
2184 | } | |
2185 | } | |
2186 | else { | |
2187 | /* | |
2188 | * is NaN; signaling or quiet? | |
2189 | */ | |
2190 | if (Sgl_isone_signaling(opnd2)) { | |
2191 | /* trap if INVALIDTRAP enabled */ | |
2192 | if (Is_invalidtrap_enabled()) | |
2193 | return(OPC_2E_INVALIDEXCEPTION); | |
2194 | /* make NaN quiet */ | |
2195 | Set_invalidflag(); | |
2196 | Sgl_set_quiet(opnd2); | |
2197 | } | |
2198 | /* | |
2199 | * is third operand a signaling NaN? | |
2200 | */ | |
2201 | else if (Sgl_is_signalingnan(opnd3)) { | |
2202 | /* trap if INVALIDTRAP enabled */ | |
2203 | if (Is_invalidtrap_enabled()) | |
2204 | return(OPC_2E_INVALIDEXCEPTION); | |
2205 | /* make NaN quiet */ | |
2206 | Set_invalidflag(); | |
2207 | Sgl_set_quiet(opnd3); | |
2208 | Sgl_copytoptr(opnd3,dstptr); | |
2209 | return(NOEXCEPTION); | |
2210 | } | |
2211 | /* | |
2212 | * return quiet NaN | |
2213 | */ | |
2214 | Sgl_copytoptr(opnd2,dstptr); | |
2215 | return(NOEXCEPTION); | |
2216 | } | |
2217 | } | |
2218 | ||
2219 | /* | |
2220 | * check third operand for NaN's or infinity | |
2221 | */ | |
2222 | if (Sgl_isinfinity_exponent(opnd3)) { | |
2223 | if (Sgl_iszero_mantissa(opnd3)) { | |
2224 | /* return infinity */ | |
2225 | Sgl_copytoptr(opnd3,dstptr); | |
2226 | return(NOEXCEPTION); | |
2227 | } else { | |
2228 | /* | |
2229 | * is NaN; signaling or quiet? | |
2230 | */ | |
2231 | if (Sgl_isone_signaling(opnd3)) { | |
2232 | /* trap if INVALIDTRAP enabled */ | |
2233 | if (Is_invalidtrap_enabled()) | |
2234 | return(OPC_2E_INVALIDEXCEPTION); | |
2235 | /* make NaN quiet */ | |
2236 | Set_invalidflag(); | |
2237 | Sgl_set_quiet(opnd3); | |
2238 | } | |
2239 | /* | |
2240 | * return quiet NaN | |
2241 | */ | |
2242 | Sgl_copytoptr(opnd3,dstptr); | |
2243 | return(NOEXCEPTION); | |
2244 | } | |
2245 | } | |
2246 | ||
2247 | /* | |
2248 | * Generate multiply mantissa | |
2249 | */ | |
2250 | if (Sgl_isnotzero_exponent(opnd1)) { | |
2251 | /* set hidden bit */ | |
2252 | Sgl_clear_signexponent_set_hidden(opnd1); | |
2253 | } | |
2254 | else { | |
2255 | /* check for zero */ | |
2256 | if (Sgl_iszero_mantissa(opnd1)) { | |
2257 | /* | |
2258 | * Perform the add opnd3 with zero here. | |
2259 | */ | |
2260 | if (Sgl_iszero_exponentmantissa(opnd3)) { | |
2261 | if (Is_rounding_mode(ROUNDMINUS)) { | |
2262 | Sgl_or_signs(opnd3,resultp1); | |
2263 | } else { | |
2264 | Sgl_and_signs(opnd3,resultp1); | |
2265 | } | |
2266 | } | |
2267 | /* | |
2268 | * Now let's check for trapped underflow case. | |
2269 | */ | |
2270 | else if (Sgl_iszero_exponent(opnd3) && | |
2271 | Is_underflowtrap_enabled()) { | |
2272 | /* need to normalize results mantissa */ | |
2273 | sign_save = Sgl_signextendedsign(opnd3); | |
2274 | result_exponent = 0; | |
2275 | Sgl_leftshiftby1(opnd3); | |
2276 | Sgl_normalize(opnd3,result_exponent); | |
2277 | Sgl_set_sign(opnd3,/*using*/sign_save); | |
2278 | Sgl_setwrapped_exponent(opnd3,result_exponent, | |
2279 | unfl); | |
2280 | Sgl_copytoptr(opnd3,dstptr); | |
2281 | /* inexact = FALSE */ | |
2282 | return(OPC_2E_UNDERFLOWEXCEPTION); | |
2283 | } | |
2284 | Sgl_copytoptr(opnd3,dstptr); | |
2285 | return(NOEXCEPTION); | |
2286 | } | |
2287 | /* is denormalized, adjust exponent */ | |
2288 | Sgl_clear_signexponent(opnd1); | |
2289 | Sgl_leftshiftby1(opnd1); | |
2290 | Sgl_normalize(opnd1,mpy_exponent); | |
2291 | } | |
2292 | /* opnd2 needs to have hidden bit set with msb in hidden bit */ | |
2293 | if (Sgl_isnotzero_exponent(opnd2)) { | |
2294 | Sgl_clear_signexponent_set_hidden(opnd2); | |
2295 | } | |
2296 | else { | |
2297 | /* check for zero */ | |
2298 | if (Sgl_iszero_mantissa(opnd2)) { | |
2299 | /* | |
2300 | * Perform the add opnd3 with zero here. | |
2301 | */ | |
2302 | if (Sgl_iszero_exponentmantissa(opnd3)) { | |
2303 | if (Is_rounding_mode(ROUNDMINUS)) { | |
2304 | Sgl_or_signs(opnd3,resultp1); | |
2305 | } else { | |
2306 | Sgl_and_signs(opnd3,resultp1); | |
2307 | } | |
2308 | } | |
2309 | /* | |
2310 | * Now let's check for trapped underflow case. | |
2311 | */ | |
2312 | else if (Sgl_iszero_exponent(opnd3) && | |
2313 | Is_underflowtrap_enabled()) { | |
2314 | /* need to normalize results mantissa */ | |
2315 | sign_save = Sgl_signextendedsign(opnd3); | |
2316 | result_exponent = 0; | |
2317 | Sgl_leftshiftby1(opnd3); | |
2318 | Sgl_normalize(opnd3,result_exponent); | |
2319 | Sgl_set_sign(opnd3,/*using*/sign_save); | |
2320 | Sgl_setwrapped_exponent(opnd3,result_exponent, | |
2321 | unfl); | |
2322 | Sgl_copytoptr(opnd3,dstptr); | |
2323 | /* inexact = FALSE */ | |
2324 | return(OPC_2E_UNDERFLOWEXCEPTION); | |
2325 | } | |
2326 | Sgl_copytoptr(opnd3,dstptr); | |
2327 | return(NOEXCEPTION); | |
2328 | } | |
2329 | /* is denormalized; want to normalize */ | |
2330 | Sgl_clear_signexponent(opnd2); | |
2331 | Sgl_leftshiftby1(opnd2); | |
2332 | Sgl_normalize(opnd2,mpy_exponent); | |
2333 | } | |
2334 | ||
2335 | /* Multiply the first two source mantissas together */ | |
2336 | ||
2337 | /* | |
2338 | * The intermediate result will be kept in tmpres, | |
2339 | * which needs enough room for 106 bits of mantissa, | |
2340 | * so lets call it a Double extended. | |
2341 | */ | |
2342 | Sglext_setzero(tmpresp1,tmpresp2); | |
2343 | ||
2344 | /* | |
2345 | * Four bits at a time are inspected in each loop, and a | |
2346 | * simple shift and add multiply algorithm is used. | |
2347 | */ | |
2348 | for (count = SGL_P-1; count >= 0; count -= 4) { | |
2349 | Sglext_rightshiftby4(tmpresp1,tmpresp2); | |
2350 | if (Sbit28(opnd1)) { | |
2351 | /* Twoword_add should be an ADD followed by 2 ADDC's */ | |
2352 | Twoword_add(tmpresp1, tmpresp2, opnd2<<3, 0); | |
2353 | } | |
2354 | if (Sbit29(opnd1)) { | |
2355 | Twoword_add(tmpresp1, tmpresp2, opnd2<<2, 0); | |
2356 | } | |
2357 | if (Sbit30(opnd1)) { | |
2358 | Twoword_add(tmpresp1, tmpresp2, opnd2<<1, 0); | |
2359 | } | |
2360 | if (Sbit31(opnd1)) { | |
2361 | Twoword_add(tmpresp1, tmpresp2, opnd2, 0); | |
2362 | } | |
2363 | Sgl_rightshiftby4(opnd1); | |
2364 | } | |
2365 | if (Is_sexthiddenoverflow(tmpresp1)) { | |
2366 | /* result mantissa >= 2 (mantissa overflow) */ | |
2367 | mpy_exponent++; | |
2368 | Sglext_rightshiftby4(tmpresp1,tmpresp2); | |
2369 | } else { | |
2370 | Sglext_rightshiftby3(tmpresp1,tmpresp2); | |
2371 | } | |
2372 | ||
2373 | /* | |
2374 | * Restore the sign of the mpy result which was saved in resultp1. | |
2375 | * The exponent will continue to be kept in mpy_exponent. | |
2376 | */ | |
2377 | Sglext_set_sign(tmpresp1,Sgl_sign(resultp1)); | |
2378 | ||
2379 | /* | |
2380 | * No rounding is required, since the result of the multiply | |
2381 | * is exact in the extended format. | |
2382 | */ | |
2383 | ||
2384 | /* | |
2385 | * Now we are ready to perform the add portion of the operation. | |
2386 | * | |
2387 | * The exponents need to be kept as integers for now, since the | |
2388 | * multiply result might not fit into the exponent field. We | |
2389 | * can't overflow or underflow because of this yet, since the | |
2390 | * add could bring the final result back into range. | |
2391 | */ | |
2392 | add_exponent = Sgl_exponent(opnd3); | |
2393 | ||
2394 | /* | |
2395 | * Check for denormalized or zero add operand. | |
2396 | */ | |
2397 | if (add_exponent == 0) { | |
2398 | /* check for zero */ | |
2399 | if (Sgl_iszero_mantissa(opnd3)) { | |
2400 | /* right is zero */ | |
2401 | /* Left can't be zero and must be result. | |
2402 | * | |
2403 | * The final result is now in tmpres and mpy_exponent, | |
2404 | * and needs to be rounded and squeezed back into | |
2405 | * double precision format from double extended. | |
2406 | */ | |
2407 | result_exponent = mpy_exponent; | |
2408 | Sglext_copy(tmpresp1,tmpresp2,resultp1,resultp2); | |
2409 | sign_save = Sgl_signextendedsign(resultp1);/*save sign*/ | |
2410 | goto round; | |
2411 | } | |
2412 | ||
2413 | /* | |
2414 | * Neither are zeroes. | |
2415 | * Adjust exponent and normalize add operand. | |
2416 | */ | |
2417 | sign_save = Sgl_signextendedsign(opnd3); /* save sign */ | |
2418 | Sgl_clear_signexponent(opnd3); | |
2419 | Sgl_leftshiftby1(opnd3); | |
2420 | Sgl_normalize(opnd3,add_exponent); | |
2421 | Sgl_set_sign(opnd3,sign_save); /* restore sign */ | |
2422 | } else { | |
2423 | Sgl_clear_exponent_set_hidden(opnd3); | |
2424 | } | |
2425 | /* | |
2426 | * Copy opnd3 to the double extended variable called right. | |
2427 | */ | |
2428 | Sgl_copyto_sglext(opnd3,rightp1,rightp2); | |
2429 | ||
2430 | /* | |
2431 | * A zero "save" helps discover equal operands (for later), | |
2432 | * and is used in swapping operands (if needed). | |
2433 | */ | |
2434 | Sglext_xortointp1(tmpresp1,rightp1,/*to*/save); | |
2435 | ||
2436 | /* | |
2437 | * Compare magnitude of operands. | |
2438 | */ | |
2439 | Sglext_copytoint_exponentmantissa(tmpresp1,signlessleft1); | |
2440 | Sglext_copytoint_exponentmantissa(rightp1,signlessright1); | |
2441 | if (mpy_exponent < add_exponent || mpy_exponent == add_exponent && | |
2442 | Sglext_ismagnitudeless(signlessleft1,signlessright1)) { | |
2443 | /* | |
2444 | * Set the left operand to the larger one by XOR swap. | |
2445 | * First finish the first word "save". | |
2446 | */ | |
2447 | Sglext_xorfromintp1(save,rightp1,/*to*/rightp1); | |
2448 | Sglext_xorfromintp1(save,tmpresp1,/*to*/tmpresp1); | |
2449 | Sglext_swap_lower(tmpresp2,rightp2); | |
2450 | /* also setup exponents used in rest of routine */ | |
2451 | diff_exponent = add_exponent - mpy_exponent; | |
2452 | result_exponent = add_exponent; | |
2453 | } else { | |
2454 | /* also setup exponents used in rest of routine */ | |
2455 | diff_exponent = mpy_exponent - add_exponent; | |
2456 | result_exponent = mpy_exponent; | |
2457 | } | |
2458 | /* Invariant: left is not smaller than right. */ | |
2459 | ||
2460 | /* | |
2461 | * Special case alignment of operands that would force alignment | |
2462 | * beyond the extent of the extension. A further optimization | |
2463 | * could special case this but only reduces the path length for | |
2464 | * this infrequent case. | |
2465 | */ | |
2466 | if (diff_exponent > SGLEXT_THRESHOLD) { | |
2467 | diff_exponent = SGLEXT_THRESHOLD; | |
2468 | } | |
2469 | ||
2470 | /* Align right operand by shifting it to the right */ | |
2471 | Sglext_clear_sign(rightp1); | |
2472 | Sglext_right_align(rightp1,rightp2,/*shifted by*/diff_exponent); | |
2473 | ||
2474 | /* Treat sum and difference of the operands separately. */ | |
2475 | if ((int)save < 0) { | |
2476 | /* | |
2477 | * Difference of the two operands. Overflow can occur if the | |
2478 | * multiply overflowed. A borrow can occur out of the hidden | |
2479 | * bit and force a post normalization phase. | |
2480 | */ | |
2481 | Sglext_subtract(tmpresp1,tmpresp2, rightp1,rightp2, | |
2482 | resultp1,resultp2); | |
2483 | sign_save = Sgl_signextendedsign(resultp1); | |
2484 | if (Sgl_iszero_hidden(resultp1)) { | |
2485 | /* Handle normalization */ | |
25985edc | 2486 | /* A straightforward algorithm would now shift the |
1da177e4 LT |
2487 | * result and extension left until the hidden bit |
2488 | * becomes one. Not all of the extension bits need | |
2489 | * participate in the shift. Only the two most | |
2490 | * significant bits (round and guard) are needed. | |
2491 | * If only a single shift is needed then the guard | |
2492 | * bit becomes a significant low order bit and the | |
2493 | * extension must participate in the rounding. | |
2494 | * If more than a single shift is needed, then all | |
2495 | * bits to the right of the guard bit are zeros, | |
2496 | * and the guard bit may or may not be zero. */ | |
2497 | Sglext_leftshiftby1(resultp1,resultp2); | |
2498 | ||
2499 | /* Need to check for a zero result. The sign and | |
2500 | * exponent fields have already been zeroed. The more | |
2501 | * efficient test of the full object can be used. | |
2502 | */ | |
2503 | if (Sglext_iszero(resultp1,resultp2)) { | |
2504 | /* Must have been "x-x" or "x+(-x)". */ | |
2505 | if (Is_rounding_mode(ROUNDMINUS)) | |
2506 | Sgl_setone_sign(resultp1); | |
2507 | Sgl_copytoptr(resultp1,dstptr); | |
2508 | return(NOEXCEPTION); | |
2509 | } | |
2510 | result_exponent--; | |
2511 | ||
2512 | /* Look to see if normalization is finished. */ | |
2513 | if (Sgl_isone_hidden(resultp1)) { | |
2514 | /* No further normalization is needed */ | |
2515 | goto round; | |
2516 | } | |
2517 | ||
2518 | /* Discover first one bit to determine shift amount. | |
2519 | * Use a modified binary search. We have already | |
2520 | * shifted the result one position right and still | |
2521 | * not found a one so the remainder of the extension | |
2522 | * must be zero and simplifies rounding. */ | |
2523 | /* Scan bytes */ | |
2524 | while (Sgl_iszero_hiddenhigh7mantissa(resultp1)) { | |
2525 | Sglext_leftshiftby8(resultp1,resultp2); | |
2526 | result_exponent -= 8; | |
2527 | } | |
2528 | /* Now narrow it down to the nibble */ | |
2529 | if (Sgl_iszero_hiddenhigh3mantissa(resultp1)) { | |
2530 | /* The lower nibble contains the | |
2531 | * normalizing one */ | |
2532 | Sglext_leftshiftby4(resultp1,resultp2); | |
2533 | result_exponent -= 4; | |
2534 | } | |
2535 | /* Select case where first bit is set (already | |
2536 | * normalized) otherwise select the proper shift. */ | |
2537 | jumpsize = Sgl_hiddenhigh3mantissa(resultp1); | |
2538 | if (jumpsize <= 7) switch(jumpsize) { | |
2539 | case 1: | |
2540 | Sglext_leftshiftby3(resultp1,resultp2); | |
2541 | result_exponent -= 3; | |
2542 | break; | |
2543 | case 2: | |
2544 | case 3: | |
2545 | Sglext_leftshiftby2(resultp1,resultp2); | |
2546 | result_exponent -= 2; | |
2547 | break; | |
2548 | case 4: | |
2549 | case 5: | |
2550 | case 6: | |
2551 | case 7: | |
2552 | Sglext_leftshiftby1(resultp1,resultp2); | |
2553 | result_exponent -= 1; | |
2554 | break; | |
2555 | } | |
2556 | } /* end if (hidden...)... */ | |
2557 | /* Fall through and round */ | |
2558 | } /* end if (save < 0)... */ | |
2559 | else { | |
2560 | /* Add magnitudes */ | |
2561 | Sglext_addition(tmpresp1,tmpresp2, | |
2562 | rightp1,rightp2, /*to*/resultp1,resultp2); | |
2563 | sign_save = Sgl_signextendedsign(resultp1); | |
2564 | if (Sgl_isone_hiddenoverflow(resultp1)) { | |
2565 | /* Prenormalization required. */ | |
2566 | Sglext_arithrightshiftby1(resultp1,resultp2); | |
2567 | result_exponent++; | |
2568 | } /* end if hiddenoverflow... */ | |
2569 | } /* end else ...add magnitudes... */ | |
2570 | ||
2571 | /* Round the result. If the extension and lower two words are | |
2572 | * all zeros, then the result is exact. Otherwise round in the | |
2573 | * correct direction. Underflow is possible. If a postnormalization | |
2574 | * is necessary, then the mantissa is all zeros so no shift is needed. | |
2575 | */ | |
2576 | round: | |
2577 | if (result_exponent <= 0 && !Is_underflowtrap_enabled()) { | |
2578 | Sglext_denormalize(resultp1,resultp2,result_exponent,is_tiny); | |
2579 | } | |
2580 | Sgl_set_sign(resultp1,/*using*/sign_save); | |
2581 | if (Sglext_isnotzero_mantissap2(resultp2)) { | |
2582 | inexact = TRUE; | |
2583 | switch(Rounding_mode()) { | |
2584 | case ROUNDNEAREST: /* The default. */ | |
2585 | if (Sglext_isone_highp2(resultp2)) { | |
2586 | /* at least 1/2 ulp */ | |
2587 | if (Sglext_isnotzero_low31p2(resultp2) || | |
2588 | Sglext_isone_lowp1(resultp1)) { | |
2589 | /* either exactly half way and odd or | |
2590 | * more than 1/2ulp */ | |
2591 | Sgl_increment(resultp1); | |
2592 | } | |
2593 | } | |
2594 | break; | |
2595 | ||
2596 | case ROUNDPLUS: | |
2597 | if (Sgl_iszero_sign(resultp1)) { | |
2598 | /* Round up positive results */ | |
2599 | Sgl_increment(resultp1); | |
2600 | } | |
2601 | break; | |
2602 | ||
2603 | case ROUNDMINUS: | |
2604 | if (Sgl_isone_sign(resultp1)) { | |
2605 | /* Round down negative results */ | |
2606 | Sgl_increment(resultp1); | |
2607 | } | |
2608 | ||
2609 | case ROUNDZERO:; | |
2610 | /* truncate is simple */ | |
2611 | } /* end switch... */ | |
2612 | if (Sgl_isone_hiddenoverflow(resultp1)) result_exponent++; | |
2613 | } | |
2614 | if (result_exponent >= SGL_INFINITY_EXPONENT) { | |
2615 | /* Overflow */ | |
2616 | if (Is_overflowtrap_enabled()) { | |
2617 | /* | |
2618 | * Adjust bias of result | |
2619 | */ | |
2620 | Sgl_setwrapped_exponent(resultp1,result_exponent,ovfl); | |
2621 | Sgl_copytoptr(resultp1,dstptr); | |
2622 | if (inexact) | |
2623 | if (Is_inexacttrap_enabled()) | |
2624 | return (OPC_2E_OVERFLOWEXCEPTION | | |
2625 | OPC_2E_INEXACTEXCEPTION); | |
2626 | else Set_inexactflag(); | |
2627 | return (OPC_2E_OVERFLOWEXCEPTION); | |
2628 | } | |
2629 | inexact = TRUE; | |
2630 | Set_overflowflag(); | |
2631 | Sgl_setoverflow(resultp1); | |
2632 | } else if (result_exponent <= 0) { /* underflow case */ | |
2633 | if (Is_underflowtrap_enabled()) { | |
2634 | /* | |
2635 | * Adjust bias of result | |
2636 | */ | |
2637 | Sgl_setwrapped_exponent(resultp1,result_exponent,unfl); | |
2638 | Sgl_copytoptr(resultp1,dstptr); | |
2639 | if (inexact) | |
2640 | if (Is_inexacttrap_enabled()) | |
2641 | return (OPC_2E_UNDERFLOWEXCEPTION | | |
2642 | OPC_2E_INEXACTEXCEPTION); | |
2643 | else Set_inexactflag(); | |
2644 | return(OPC_2E_UNDERFLOWEXCEPTION); | |
2645 | } | |
2646 | else if (inexact && is_tiny) Set_underflowflag(); | |
2647 | } | |
2648 | else Sgl_set_exponent(resultp1,result_exponent); | |
2649 | Sgl_copytoptr(resultp1,dstptr); | |
2650 | if (inexact) | |
2651 | if (Is_inexacttrap_enabled()) return(OPC_2E_INEXACTEXCEPTION); | |
2652 | else Set_inexactflag(); | |
2653 | return(NOEXCEPTION); | |
2654 | } | |
2655 |