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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/dfmpy.c $Revision: 1.1 $ | |
26 | * | |
27 | * Purpose: | |
28 | * Double Precision Floating-point Multiply | |
29 | * | |
30 | * External Interfaces: | |
31 | * dbl_fmpy(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 Multiply | |
47 | */ | |
48 | ||
49 | int | |
50 | dbl_fmpy( | |
51 | dbl_floating_point *srcptr1, | |
52 | dbl_floating_point *srcptr2, | |
53 | dbl_floating_point *dstptr, | |
54 | unsigned int *status) | |
55 | { | |
56 | register unsigned int opnd1p1, opnd1p2, opnd2p1, opnd2p2; | |
57 | register unsigned int opnd3p1, opnd3p2, resultp1, resultp2; | |
58 | register int dest_exponent, count; | |
59 | register boolean inexact = FALSE, guardbit = FALSE, stickybit = FALSE; | |
60 | boolean is_tiny; | |
61 | ||
62 | Dbl_copyfromptr(srcptr1,opnd1p1,opnd1p2); | |
63 | Dbl_copyfromptr(srcptr2,opnd2p1,opnd2p2); | |
64 | ||
65 | /* | |
66 | * set sign bit of result | |
67 | */ | |
68 | if (Dbl_sign(opnd1p1) ^ Dbl_sign(opnd2p1)) | |
69 | Dbl_setnegativezerop1(resultp1); | |
70 | else Dbl_setzerop1(resultp1); | |
71 | /* | |
72 | * check first operand for NaN's or infinity | |
73 | */ | |
74 | if (Dbl_isinfinity_exponent(opnd1p1)) { | |
75 | if (Dbl_iszero_mantissa(opnd1p1,opnd1p2)) { | |
76 | if (Dbl_isnotnan(opnd2p1,opnd2p2)) { | |
77 | if (Dbl_iszero_exponentmantissa(opnd2p1,opnd2p2)) { | |
78 | /* | |
79 | * invalid since operands are infinity | |
80 | * and zero | |
81 | */ | |
82 | if (Is_invalidtrap_enabled()) | |
83 | return(INVALIDEXCEPTION); | |
84 | Set_invalidflag(); | |
85 | Dbl_makequietnan(resultp1,resultp2); | |
86 | Dbl_copytoptr(resultp1,resultp2,dstptr); | |
87 | return(NOEXCEPTION); | |
88 | } | |
89 | /* | |
90 | * return infinity | |
91 | */ | |
92 | Dbl_setinfinity_exponentmantissa(resultp1,resultp2); | |
93 | Dbl_copytoptr(resultp1,resultp2,dstptr); | |
94 | return(NOEXCEPTION); | |
95 | } | |
96 | } | |
97 | else { | |
98 | /* | |
99 | * is NaN; signaling or quiet? | |
100 | */ | |
101 | if (Dbl_isone_signaling(opnd1p1)) { | |
102 | /* trap if INVALIDTRAP enabled */ | |
103 | if (Is_invalidtrap_enabled()) | |
104 | return(INVALIDEXCEPTION); | |
105 | /* make NaN quiet */ | |
106 | Set_invalidflag(); | |
107 | Dbl_set_quiet(opnd1p1); | |
108 | } | |
109 | /* | |
110 | * is second operand a signaling NaN? | |
111 | */ | |
112 | else if (Dbl_is_signalingnan(opnd2p1)) { | |
113 | /* trap if INVALIDTRAP enabled */ | |
114 | if (Is_invalidtrap_enabled()) | |
115 | return(INVALIDEXCEPTION); | |
116 | /* make NaN quiet */ | |
117 | Set_invalidflag(); | |
118 | Dbl_set_quiet(opnd2p1); | |
119 | Dbl_copytoptr(opnd2p1,opnd2p2,dstptr); | |
120 | return(NOEXCEPTION); | |
121 | } | |
122 | /* | |
123 | * return quiet NaN | |
124 | */ | |
125 | Dbl_copytoptr(opnd1p1,opnd1p2,dstptr); | |
126 | return(NOEXCEPTION); | |
127 | } | |
128 | } | |
129 | /* | |
130 | * check second operand for NaN's or infinity | |
131 | */ | |
132 | if (Dbl_isinfinity_exponent(opnd2p1)) { | |
133 | if (Dbl_iszero_mantissa(opnd2p1,opnd2p2)) { | |
134 | if (Dbl_iszero_exponentmantissa(opnd1p1,opnd1p2)) { | |
135 | /* invalid since operands are zero & infinity */ | |
136 | if (Is_invalidtrap_enabled()) | |
137 | return(INVALIDEXCEPTION); | |
138 | Set_invalidflag(); | |
139 | Dbl_makequietnan(opnd2p1,opnd2p2); | |
140 | Dbl_copytoptr(opnd2p1,opnd2p2,dstptr); | |
141 | return(NOEXCEPTION); | |
142 | } | |
143 | /* | |
144 | * return infinity | |
145 | */ | |
146 | Dbl_setinfinity_exponentmantissa(resultp1,resultp2); | |
147 | Dbl_copytoptr(resultp1,resultp2,dstptr); | |
148 | return(NOEXCEPTION); | |
149 | } | |
150 | /* | |
151 | * is NaN; signaling or quiet? | |
152 | */ | |
153 | if (Dbl_isone_signaling(opnd2p1)) { | |
154 | /* trap if INVALIDTRAP enabled */ | |
155 | if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION); | |
156 | /* make NaN quiet */ | |
157 | Set_invalidflag(); | |
158 | Dbl_set_quiet(opnd2p1); | |
159 | } | |
160 | /* | |
161 | * return quiet NaN | |
162 | */ | |
163 | Dbl_copytoptr(opnd2p1,opnd2p2,dstptr); | |
164 | return(NOEXCEPTION); | |
165 | } | |
166 | /* | |
167 | * Generate exponent | |
168 | */ | |
169 | dest_exponent = Dbl_exponent(opnd1p1) + Dbl_exponent(opnd2p1) -DBL_BIAS; | |
170 | ||
171 | /* | |
172 | * Generate mantissa | |
173 | */ | |
174 | if (Dbl_isnotzero_exponent(opnd1p1)) { | |
175 | /* set hidden bit */ | |
176 | Dbl_clear_signexponent_set_hidden(opnd1p1); | |
177 | } | |
178 | else { | |
179 | /* check for zero */ | |
180 | if (Dbl_iszero_mantissa(opnd1p1,opnd1p2)) { | |
181 | Dbl_setzero_exponentmantissa(resultp1,resultp2); | |
182 | Dbl_copytoptr(resultp1,resultp2,dstptr); | |
183 | return(NOEXCEPTION); | |
184 | } | |
185 | /* is denormalized, adjust exponent */ | |
186 | Dbl_clear_signexponent(opnd1p1); | |
187 | Dbl_leftshiftby1(opnd1p1,opnd1p2); | |
188 | Dbl_normalize(opnd1p1,opnd1p2,dest_exponent); | |
189 | } | |
190 | /* opnd2 needs to have hidden bit set with msb in hidden bit */ | |
191 | if (Dbl_isnotzero_exponent(opnd2p1)) { | |
192 | Dbl_clear_signexponent_set_hidden(opnd2p1); | |
193 | } | |
194 | else { | |
195 | /* check for zero */ | |
196 | if (Dbl_iszero_mantissa(opnd2p1,opnd2p2)) { | |
197 | Dbl_setzero_exponentmantissa(resultp1,resultp2); | |
198 | Dbl_copytoptr(resultp1,resultp2,dstptr); | |
199 | return(NOEXCEPTION); | |
200 | } | |
201 | /* is denormalized; want to normalize */ | |
202 | Dbl_clear_signexponent(opnd2p1); | |
203 | Dbl_leftshiftby1(opnd2p1,opnd2p2); | |
204 | Dbl_normalize(opnd2p1,opnd2p2,dest_exponent); | |
205 | } | |
206 | ||
207 | /* Multiply two source mantissas together */ | |
208 | ||
209 | /* make room for guard bits */ | |
210 | Dbl_leftshiftby7(opnd2p1,opnd2p2); | |
211 | Dbl_setzero(opnd3p1,opnd3p2); | |
212 | /* | |
213 | * Four bits at a time are inspected in each loop, and a | |
214 | * simple shift and add multiply algorithm is used. | |
215 | */ | |
216 | for (count=1;count<=DBL_P;count+=4) { | |
217 | stickybit |= Dlow4p2(opnd3p2); | |
218 | Dbl_rightshiftby4(opnd3p1,opnd3p2); | |
219 | if (Dbit28p2(opnd1p2)) { | |
220 | /* Twoword_add should be an ADDC followed by an ADD. */ | |
221 | Twoword_add(opnd3p1, opnd3p2, opnd2p1<<3 | opnd2p2>>29, | |
222 | opnd2p2<<3); | |
223 | } | |
224 | if (Dbit29p2(opnd1p2)) { | |
225 | Twoword_add(opnd3p1, opnd3p2, opnd2p1<<2 | opnd2p2>>30, | |
226 | opnd2p2<<2); | |
227 | } | |
228 | if (Dbit30p2(opnd1p2)) { | |
229 | Twoword_add(opnd3p1, opnd3p2, opnd2p1<<1 | opnd2p2>>31, | |
230 | opnd2p2<<1); | |
231 | } | |
232 | if (Dbit31p2(opnd1p2)) { | |
233 | Twoword_add(opnd3p1, opnd3p2, opnd2p1, opnd2p2); | |
234 | } | |
235 | Dbl_rightshiftby4(opnd1p1,opnd1p2); | |
236 | } | |
237 | if (Dbit3p1(opnd3p1)==0) { | |
238 | Dbl_leftshiftby1(opnd3p1,opnd3p2); | |
239 | } | |
240 | else { | |
241 | /* result mantissa >= 2. */ | |
242 | dest_exponent++; | |
243 | } | |
244 | /* check for denormalized result */ | |
245 | while (Dbit3p1(opnd3p1)==0) { | |
246 | Dbl_leftshiftby1(opnd3p1,opnd3p2); | |
247 | dest_exponent--; | |
248 | } | |
249 | /* | |
250 | * check for guard, sticky and inexact bits | |
251 | */ | |
252 | stickybit |= Dallp2(opnd3p2) << 25; | |
253 | guardbit = (Dallp2(opnd3p2) << 24) >> 31; | |
254 | inexact = guardbit | stickybit; | |
255 | ||
256 | /* align result mantissa */ | |
257 | Dbl_rightshiftby8(opnd3p1,opnd3p2); | |
258 | ||
259 | /* | |
260 | * round result | |
261 | */ | |
262 | if (inexact && (dest_exponent>0 || Is_underflowtrap_enabled())) { | |
263 | Dbl_clear_signexponent(opnd3p1); | |
264 | switch (Rounding_mode()) { | |
265 | case ROUNDPLUS: | |
266 | if (Dbl_iszero_sign(resultp1)) | |
267 | Dbl_increment(opnd3p1,opnd3p2); | |
268 | break; | |
269 | case ROUNDMINUS: | |
270 | if (Dbl_isone_sign(resultp1)) | |
271 | Dbl_increment(opnd3p1,opnd3p2); | |
272 | break; | |
273 | case ROUNDNEAREST: | |
274 | if (guardbit) { | |
275 | if (stickybit || Dbl_isone_lowmantissap2(opnd3p2)) | |
276 | Dbl_increment(opnd3p1,opnd3p2); | |
277 | } | |
278 | } | |
279 | if (Dbl_isone_hidden(opnd3p1)) dest_exponent++; | |
280 | } | |
281 | Dbl_set_mantissa(resultp1,resultp2,opnd3p1,opnd3p2); | |
282 | ||
283 | /* | |
284 | * Test for overflow | |
285 | */ | |
286 | if (dest_exponent >= DBL_INFINITY_EXPONENT) { | |
287 | /* trap if OVERFLOWTRAP enabled */ | |
288 | if (Is_overflowtrap_enabled()) { | |
289 | /* | |
290 | * Adjust bias of result | |
291 | */ | |
292 | Dbl_setwrapped_exponent(resultp1,dest_exponent,ovfl); | |
293 | Dbl_copytoptr(resultp1,resultp2,dstptr); | |
294 | if (inexact) | |
295 | if (Is_inexacttrap_enabled()) | |
296 | return (OVERFLOWEXCEPTION | INEXACTEXCEPTION); | |
297 | else Set_inexactflag(); | |
298 | return (OVERFLOWEXCEPTION); | |
299 | } | |
300 | inexact = TRUE; | |
301 | Set_overflowflag(); | |
302 | /* set result to infinity or largest number */ | |
303 | Dbl_setoverflow(resultp1,resultp2); | |
304 | } | |
305 | /* | |
306 | * Test for underflow | |
307 | */ | |
308 | else if (dest_exponent <= 0) { | |
309 | /* trap if UNDERFLOWTRAP enabled */ | |
310 | if (Is_underflowtrap_enabled()) { | |
311 | /* | |
312 | * Adjust bias of result | |
313 | */ | |
314 | Dbl_setwrapped_exponent(resultp1,dest_exponent,unfl); | |
315 | Dbl_copytoptr(resultp1,resultp2,dstptr); | |
316 | if (inexact) | |
317 | if (Is_inexacttrap_enabled()) | |
318 | return (UNDERFLOWEXCEPTION | INEXACTEXCEPTION); | |
319 | else Set_inexactflag(); | |
320 | return (UNDERFLOWEXCEPTION); | |
321 | } | |
322 | ||
323 | /* Determine if should set underflow flag */ | |
324 | is_tiny = TRUE; | |
325 | if (dest_exponent == 0 && inexact) { | |
326 | switch (Rounding_mode()) { | |
327 | case ROUNDPLUS: | |
328 | if (Dbl_iszero_sign(resultp1)) { | |
329 | Dbl_increment(opnd3p1,opnd3p2); | |
330 | if (Dbl_isone_hiddenoverflow(opnd3p1)) | |
331 | is_tiny = FALSE; | |
332 | Dbl_decrement(opnd3p1,opnd3p2); | |
333 | } | |
334 | break; | |
335 | case ROUNDMINUS: | |
336 | if (Dbl_isone_sign(resultp1)) { | |
337 | Dbl_increment(opnd3p1,opnd3p2); | |
338 | if (Dbl_isone_hiddenoverflow(opnd3p1)) | |
339 | is_tiny = FALSE; | |
340 | Dbl_decrement(opnd3p1,opnd3p2); | |
341 | } | |
342 | break; | |
343 | case ROUNDNEAREST: | |
344 | if (guardbit && (stickybit || | |
345 | Dbl_isone_lowmantissap2(opnd3p2))) { | |
346 | Dbl_increment(opnd3p1,opnd3p2); | |
347 | if (Dbl_isone_hiddenoverflow(opnd3p1)) | |
348 | is_tiny = FALSE; | |
349 | Dbl_decrement(opnd3p1,opnd3p2); | |
350 | } | |
351 | break; | |
352 | } | |
353 | } | |
354 | ||
355 | /* | |
356 | * denormalize result or set to signed zero | |
357 | */ | |
358 | stickybit = inexact; | |
359 | Dbl_denormalize(opnd3p1,opnd3p2,dest_exponent,guardbit, | |
360 | stickybit,inexact); | |
361 | ||
362 | /* return zero or smallest number */ | |
363 | if (inexact) { | |
364 | switch (Rounding_mode()) { | |
365 | case ROUNDPLUS: | |
366 | if (Dbl_iszero_sign(resultp1)) { | |
367 | Dbl_increment(opnd3p1,opnd3p2); | |
368 | } | |
369 | break; | |
370 | case ROUNDMINUS: | |
371 | if (Dbl_isone_sign(resultp1)) { | |
372 | Dbl_increment(opnd3p1,opnd3p2); | |
373 | } | |
374 | break; | |
375 | case ROUNDNEAREST: | |
376 | if (guardbit && (stickybit || | |
377 | Dbl_isone_lowmantissap2(opnd3p2))) { | |
378 | Dbl_increment(opnd3p1,opnd3p2); | |
379 | } | |
380 | break; | |
381 | } | |
382 | if (is_tiny) Set_underflowflag(); | |
383 | } | |
384 | Dbl_set_exponentmantissa(resultp1,resultp2,opnd3p1,opnd3p2); | |
385 | } | |
386 | else Dbl_set_exponent(resultp1,dest_exponent); | |
387 | /* check for inexact */ | |
388 | Dbl_copytoptr(resultp1,resultp2,dstptr); | |
389 | if (inexact) { | |
390 | if (Is_inexacttrap_enabled()) return(INEXACTEXCEPTION); | |
391 | else Set_inexactflag(); | |
392 | } | |
393 | return(NOEXCEPTION); | |
394 | } |