Commit | Line | Data |
---|---|---|
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/dfdiv.c $Revision: 1.1 $ | |
26 | * | |
27 | * Purpose: | |
28 | * Double Precision Floating-point Divide | |
29 | * | |
30 | * External Interfaces: | |
31 | * dbl_fdiv(srcptr1,srcptr2,dstptr,status) | |
32 | * | |
33 | * Internal Interfaces: | |
34 | * | |
35 | * Theory: | |
36 | * <<please update with a overview of the operation of this file>> | |
37 | * | |
38 | * END_DESC | |
39 | */ | |
40 | ||
41 | ||
42 | #include "float.h" | |
43 | #include "dbl_float.h" | |
44 | ||
45 | /* | |
46 | * Double Precision Floating-point Divide | |
47 | */ | |
48 | ||
49 | int | |
50 | dbl_fdiv (dbl_floating_point * srcptr1, dbl_floating_point * srcptr2, | |
51 | dbl_floating_point * dstptr, unsigned int *status) | |
52 | { | |
53 | register unsigned int opnd1p1, opnd1p2, opnd2p1, opnd2p2; | |
54 | register unsigned int opnd3p1, opnd3p2, resultp1, resultp2; | |
55 | register int dest_exponent, count; | |
56 | register boolean inexact = FALSE, guardbit = FALSE, stickybit = FALSE; | |
57 | boolean is_tiny; | |
58 | ||
59 | Dbl_copyfromptr(srcptr1,opnd1p1,opnd1p2); | |
60 | Dbl_copyfromptr(srcptr2,opnd2p1,opnd2p2); | |
61 | /* | |
62 | * set sign bit of result | |
63 | */ | |
64 | if (Dbl_sign(opnd1p1) ^ Dbl_sign(opnd2p1)) | |
65 | Dbl_setnegativezerop1(resultp1); | |
66 | else Dbl_setzerop1(resultp1); | |
67 | /* | |
68 | * check first operand for NaN's or infinity | |
69 | */ | |
70 | if (Dbl_isinfinity_exponent(opnd1p1)) { | |
71 | if (Dbl_iszero_mantissa(opnd1p1,opnd1p2)) { | |
72 | if (Dbl_isnotnan(opnd2p1,opnd2p2)) { | |
73 | if (Dbl_isinfinity(opnd2p1,opnd2p2)) { | |
74 | /* | |
75 | * invalid since both operands | |
76 | * are infinity | |
77 | */ | |
78 | if (Is_invalidtrap_enabled()) | |
79 | return(INVALIDEXCEPTION); | |
80 | Set_invalidflag(); | |
81 | Dbl_makequietnan(resultp1,resultp2); | |
82 | Dbl_copytoptr(resultp1,resultp2,dstptr); | |
83 | return(NOEXCEPTION); | |
84 | } | |
85 | /* | |
86 | * return infinity | |
87 | */ | |
88 | Dbl_setinfinity_exponentmantissa(resultp1,resultp2); | |
89 | Dbl_copytoptr(resultp1,resultp2,dstptr); | |
90 | return(NOEXCEPTION); | |
91 | } | |
92 | } | |
93 | else { | |
94 | /* | |
95 | * is NaN; signaling or quiet? | |
96 | */ | |
97 | if (Dbl_isone_signaling(opnd1p1)) { | |
98 | /* trap if INVALIDTRAP enabled */ | |
99 | if (Is_invalidtrap_enabled()) | |
100 | return(INVALIDEXCEPTION); | |
101 | /* make NaN quiet */ | |
102 | Set_invalidflag(); | |
103 | Dbl_set_quiet(opnd1p1); | |
104 | } | |
105 | /* | |
106 | * is second operand a signaling NaN? | |
107 | */ | |
108 | else if (Dbl_is_signalingnan(opnd2p1)) { | |
109 | /* trap if INVALIDTRAP enabled */ | |
110 | if (Is_invalidtrap_enabled()) | |
111 | return(INVALIDEXCEPTION); | |
112 | /* make NaN quiet */ | |
113 | Set_invalidflag(); | |
114 | Dbl_set_quiet(opnd2p1); | |
115 | Dbl_copytoptr(opnd2p1,opnd2p2,dstptr); | |
116 | return(NOEXCEPTION); | |
117 | } | |
118 | /* | |
119 | * return quiet NaN | |
120 | */ | |
121 | Dbl_copytoptr(opnd1p1,opnd1p2,dstptr); | |
122 | return(NOEXCEPTION); | |
123 | } | |
124 | } | |
125 | /* | |
126 | * check second operand for NaN's or infinity | |
127 | */ | |
128 | if (Dbl_isinfinity_exponent(opnd2p1)) { | |
129 | if (Dbl_iszero_mantissa(opnd2p1,opnd2p2)) { | |
130 | /* | |
131 | * return zero | |
132 | */ | |
133 | Dbl_setzero_exponentmantissa(resultp1,resultp2); | |
134 | Dbl_copytoptr(resultp1,resultp2,dstptr); | |
135 | return(NOEXCEPTION); | |
136 | } | |
137 | /* | |
138 | * is NaN; signaling or quiet? | |
139 | */ | |
140 | if (Dbl_isone_signaling(opnd2p1)) { | |
141 | /* trap if INVALIDTRAP enabled */ | |
142 | if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION); | |
143 | /* make NaN quiet */ | |
144 | Set_invalidflag(); | |
145 | Dbl_set_quiet(opnd2p1); | |
146 | } | |
147 | /* | |
148 | * return quiet NaN | |
149 | */ | |
150 | Dbl_copytoptr(opnd2p1,opnd2p2,dstptr); | |
151 | return(NOEXCEPTION); | |
152 | } | |
153 | /* | |
154 | * check for division by zero | |
155 | */ | |
156 | if (Dbl_iszero_exponentmantissa(opnd2p1,opnd2p2)) { | |
157 | if (Dbl_iszero_exponentmantissa(opnd1p1,opnd1p2)) { | |
158 | /* invalid since both operands are zero */ | |
159 | if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION); | |
160 | Set_invalidflag(); | |
161 | Dbl_makequietnan(resultp1,resultp2); | |
162 | Dbl_copytoptr(resultp1,resultp2,dstptr); | |
163 | return(NOEXCEPTION); | |
164 | } | |
165 | if (Is_divisionbyzerotrap_enabled()) | |
166 | return(DIVISIONBYZEROEXCEPTION); | |
167 | Set_divisionbyzeroflag(); | |
168 | Dbl_setinfinity_exponentmantissa(resultp1,resultp2); | |
169 | Dbl_copytoptr(resultp1,resultp2,dstptr); | |
170 | return(NOEXCEPTION); | |
171 | } | |
172 | /* | |
173 | * Generate exponent | |
174 | */ | |
175 | dest_exponent = Dbl_exponent(opnd1p1) - Dbl_exponent(opnd2p1) + DBL_BIAS; | |
176 | ||
177 | /* | |
178 | * Generate mantissa | |
179 | */ | |
180 | if (Dbl_isnotzero_exponent(opnd1p1)) { | |
181 | /* set hidden bit */ | |
182 | Dbl_clear_signexponent_set_hidden(opnd1p1); | |
183 | } | |
184 | else { | |
185 | /* check for zero */ | |
186 | if (Dbl_iszero_mantissa(opnd1p1,opnd1p2)) { | |
187 | Dbl_setzero_exponentmantissa(resultp1,resultp2); | |
188 | Dbl_copytoptr(resultp1,resultp2,dstptr); | |
189 | return(NOEXCEPTION); | |
190 | } | |
191 | /* is denormalized, want to normalize */ | |
192 | Dbl_clear_signexponent(opnd1p1); | |
193 | Dbl_leftshiftby1(opnd1p1,opnd1p2); | |
194 | Dbl_normalize(opnd1p1,opnd1p2,dest_exponent); | |
195 | } | |
196 | /* opnd2 needs to have hidden bit set with msb in hidden bit */ | |
197 | if (Dbl_isnotzero_exponent(opnd2p1)) { | |
198 | Dbl_clear_signexponent_set_hidden(opnd2p1); | |
199 | } | |
200 | else { | |
201 | /* is denormalized; want to normalize */ | |
202 | Dbl_clear_signexponent(opnd2p1); | |
203 | Dbl_leftshiftby1(opnd2p1,opnd2p2); | |
204 | while (Dbl_iszero_hiddenhigh7mantissa(opnd2p1)) { | |
205 | dest_exponent+=8; | |
206 | Dbl_leftshiftby8(opnd2p1,opnd2p2); | |
207 | } | |
208 | if (Dbl_iszero_hiddenhigh3mantissa(opnd2p1)) { | |
209 | dest_exponent+=4; | |
210 | Dbl_leftshiftby4(opnd2p1,opnd2p2); | |
211 | } | |
212 | while (Dbl_iszero_hidden(opnd2p1)) { | |
213 | dest_exponent++; | |
214 | Dbl_leftshiftby1(opnd2p1,opnd2p2); | |
215 | } | |
216 | } | |
217 | ||
218 | /* Divide the source mantissas */ | |
219 | ||
220 | /* | |
221 | * A non-restoring divide algorithm is used. | |
222 | */ | |
223 | Twoword_subtract(opnd1p1,opnd1p2,opnd2p1,opnd2p2); | |
224 | Dbl_setzero(opnd3p1,opnd3p2); | |
225 | for (count=1; count <= DBL_P && (opnd1p1 || opnd1p2); count++) { | |
226 | Dbl_leftshiftby1(opnd1p1,opnd1p2); | |
227 | Dbl_leftshiftby1(opnd3p1,opnd3p2); | |
228 | if (Dbl_iszero_sign(opnd1p1)) { | |
229 | Dbl_setone_lowmantissap2(opnd3p2); | |
230 | Twoword_subtract(opnd1p1,opnd1p2,opnd2p1,opnd2p2); | |
231 | } | |
232 | else { | |
233 | Twoword_add(opnd1p1, opnd1p2, opnd2p1, opnd2p2); | |
234 | } | |
235 | } | |
236 | if (count <= DBL_P) { | |
237 | Dbl_leftshiftby1(opnd3p1,opnd3p2); | |
238 | Dbl_setone_lowmantissap2(opnd3p2); | |
239 | Dbl_leftshift(opnd3p1,opnd3p2,(DBL_P-count)); | |
240 | if (Dbl_iszero_hidden(opnd3p1)) { | |
241 | Dbl_leftshiftby1(opnd3p1,opnd3p2); | |
242 | dest_exponent--; | |
243 | } | |
244 | } | |
245 | else { | |
246 | if (Dbl_iszero_hidden(opnd3p1)) { | |
247 | /* need to get one more bit of result */ | |
248 | Dbl_leftshiftby1(opnd1p1,opnd1p2); | |
249 | Dbl_leftshiftby1(opnd3p1,opnd3p2); | |
250 | if (Dbl_iszero_sign(opnd1p1)) { | |
251 | Dbl_setone_lowmantissap2(opnd3p2); | |
252 | Twoword_subtract(opnd1p1,opnd1p2,opnd2p1,opnd2p2); | |
253 | } | |
254 | else { | |
255 | Twoword_add(opnd1p1,opnd1p2,opnd2p1,opnd2p2); | |
256 | } | |
257 | dest_exponent--; | |
258 | } | |
259 | if (Dbl_iszero_sign(opnd1p1)) guardbit = TRUE; | |
260 | stickybit = Dbl_allp1(opnd1p1) || Dbl_allp2(opnd1p2); | |
261 | } | |
262 | inexact = guardbit | stickybit; | |
263 | ||
264 | /* | |
265 | * round result | |
266 | */ | |
267 | if (inexact && (dest_exponent > 0 || Is_underflowtrap_enabled())) { | |
268 | Dbl_clear_signexponent(opnd3p1); | |
269 | switch (Rounding_mode()) { | |
270 | case ROUNDPLUS: | |
271 | if (Dbl_iszero_sign(resultp1)) | |
272 | Dbl_increment(opnd3p1,opnd3p2); | |
273 | break; | |
274 | case ROUNDMINUS: | |
275 | if (Dbl_isone_sign(resultp1)) | |
276 | Dbl_increment(opnd3p1,opnd3p2); | |
277 | break; | |
278 | case ROUNDNEAREST: | |
279 | if (guardbit && (stickybit || | |
280 | Dbl_isone_lowmantissap2(opnd3p2))) { | |
281 | Dbl_increment(opnd3p1,opnd3p2); | |
282 | } | |
283 | } | |
284 | if (Dbl_isone_hidden(opnd3p1)) dest_exponent++; | |
285 | } | |
286 | Dbl_set_mantissa(resultp1,resultp2,opnd3p1,opnd3p2); | |
287 | ||
288 | /* | |
289 | * Test for overflow | |
290 | */ | |
291 | if (dest_exponent >= DBL_INFINITY_EXPONENT) { | |
292 | /* trap if OVERFLOWTRAP enabled */ | |
293 | if (Is_overflowtrap_enabled()) { | |
294 | /* | |
295 | * Adjust bias of result | |
296 | */ | |
297 | Dbl_setwrapped_exponent(resultp1,dest_exponent,ovfl); | |
298 | Dbl_copytoptr(resultp1,resultp2,dstptr); | |
299 | if (inexact) | |
300 | if (Is_inexacttrap_enabled()) | |
301 | return(OVERFLOWEXCEPTION | INEXACTEXCEPTION); | |
302 | else Set_inexactflag(); | |
303 | return(OVERFLOWEXCEPTION); | |
304 | } | |
305 | Set_overflowflag(); | |
306 | /* set result to infinity or largest number */ | |
307 | Dbl_setoverflow(resultp1,resultp2); | |
308 | inexact = TRUE; | |
309 | } | |
310 | /* | |
311 | * Test for underflow | |
312 | */ | |
313 | else if (dest_exponent <= 0) { | |
314 | /* trap if UNDERFLOWTRAP enabled */ | |
315 | if (Is_underflowtrap_enabled()) { | |
316 | /* | |
317 | * Adjust bias of result | |
318 | */ | |
319 | Dbl_setwrapped_exponent(resultp1,dest_exponent,unfl); | |
320 | Dbl_copytoptr(resultp1,resultp2,dstptr); | |
321 | if (inexact) | |
322 | if (Is_inexacttrap_enabled()) | |
323 | return(UNDERFLOWEXCEPTION | INEXACTEXCEPTION); | |
324 | else Set_inexactflag(); | |
325 | return(UNDERFLOWEXCEPTION); | |
326 | } | |
327 | ||
328 | /* Determine if should set underflow flag */ | |
329 | is_tiny = TRUE; | |
330 | if (dest_exponent == 0 && inexact) { | |
331 | switch (Rounding_mode()) { | |
332 | case ROUNDPLUS: | |
333 | if (Dbl_iszero_sign(resultp1)) { | |
334 | Dbl_increment(opnd3p1,opnd3p2); | |
335 | if (Dbl_isone_hiddenoverflow(opnd3p1)) | |
336 | is_tiny = FALSE; | |
337 | Dbl_decrement(opnd3p1,opnd3p2); | |
338 | } | |
339 | break; | |
340 | case ROUNDMINUS: | |
341 | if (Dbl_isone_sign(resultp1)) { | |
342 | Dbl_increment(opnd3p1,opnd3p2); | |
343 | if (Dbl_isone_hiddenoverflow(opnd3p1)) | |
344 | is_tiny = FALSE; | |
345 | Dbl_decrement(opnd3p1,opnd3p2); | |
346 | } | |
347 | break; | |
348 | case ROUNDNEAREST: | |
349 | if (guardbit && (stickybit || | |
350 | Dbl_isone_lowmantissap2(opnd3p2))) { | |
351 | Dbl_increment(opnd3p1,opnd3p2); | |
352 | if (Dbl_isone_hiddenoverflow(opnd3p1)) | |
353 | is_tiny = FALSE; | |
354 | Dbl_decrement(opnd3p1,opnd3p2); | |
355 | } | |
356 | break; | |
357 | } | |
358 | } | |
359 | ||
360 | /* | |
361 | * denormalize result or set to signed zero | |
362 | */ | |
363 | stickybit = inexact; | |
364 | Dbl_denormalize(opnd3p1,opnd3p2,dest_exponent,guardbit, | |
365 | stickybit,inexact); | |
366 | ||
367 | /* return rounded number */ | |
368 | if (inexact) { | |
369 | switch (Rounding_mode()) { | |
370 | case ROUNDPLUS: | |
371 | if (Dbl_iszero_sign(resultp1)) { | |
372 | Dbl_increment(opnd3p1,opnd3p2); | |
373 | } | |
374 | break; | |
375 | case ROUNDMINUS: | |
376 | if (Dbl_isone_sign(resultp1)) { | |
377 | Dbl_increment(opnd3p1,opnd3p2); | |
378 | } | |
379 | break; | |
380 | case ROUNDNEAREST: | |
381 | if (guardbit && (stickybit || | |
382 | Dbl_isone_lowmantissap2(opnd3p2))) { | |
383 | Dbl_increment(opnd3p1,opnd3p2); | |
384 | } | |
385 | break; | |
386 | } | |
387 | if (is_tiny) Set_underflowflag(); | |
388 | } | |
389 | Dbl_set_exponentmantissa(resultp1,resultp2,opnd3p1,opnd3p2); | |
390 | } | |
391 | else Dbl_set_exponent(resultp1,dest_exponent); | |
392 | Dbl_copytoptr(resultp1,resultp2,dstptr); | |
393 | ||
394 | /* check for inexact */ | |
395 | if (inexact) { | |
396 | if (Is_inexacttrap_enabled()) return(INEXACTEXCEPTION); | |
397 | else Set_inexactflag(); | |
398 | } | |
399 | return(NOEXCEPTION); | |
400 | } |