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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/fcnvff.c $Revision: 1.1 $ | |
26 | * | |
27 | * Purpose: | |
28 | * Single Floating-point to Double Floating-point | |
29 | * Double Floating-point to Single Floating-point | |
30 | * | |
31 | * External Interfaces: | |
32 | * dbl_to_sgl_fcnvff(srcptr,nullptr,dstptr,status) | |
33 | * sgl_to_dbl_fcnvff(srcptr,nullptr,dstptr,status) | |
34 | * | |
35 | * Internal Interfaces: | |
36 | * | |
37 | * Theory: | |
38 | * <<please update with a overview of the operation of this file>> | |
39 | * | |
40 | * END_DESC | |
41 | */ | |
42 | ||
43 | ||
44 | #include "float.h" | |
45 | #include "sgl_float.h" | |
46 | #include "dbl_float.h" | |
47 | #include "cnv_float.h" | |
48 | ||
49 | /* | |
50 | * Single Floating-point to Double Floating-point | |
51 | */ | |
52 | /*ARGSUSED*/ | |
53 | int | |
54 | sgl_to_dbl_fcnvff( | |
55 | sgl_floating_point *srcptr, | |
56 | unsigned int *nullptr, | |
57 | dbl_floating_point *dstptr, | |
58 | unsigned int *status) | |
59 | { | |
60 | register unsigned int src, resultp1, resultp2; | |
61 | register int src_exponent; | |
62 | ||
63 | src = *srcptr; | |
64 | src_exponent = Sgl_exponent(src); | |
65 | Dbl_allp1(resultp1) = Sgl_all(src); /* set sign of result */ | |
66 | /* | |
67 | * Test for NaN or infinity | |
68 | */ | |
69 | if (src_exponent == SGL_INFINITY_EXPONENT) { | |
70 | /* | |
71 | * determine if NaN or infinity | |
72 | */ | |
73 | if (Sgl_iszero_mantissa(src)) { | |
74 | /* | |
75 | * is infinity; want to return double infinity | |
76 | */ | |
77 | Dbl_setinfinity_exponentmantissa(resultp1,resultp2); | |
78 | Dbl_copytoptr(resultp1,resultp2,dstptr); | |
79 | return(NOEXCEPTION); | |
80 | } | |
81 | else { | |
82 | /* | |
83 | * is NaN; signaling or quiet? | |
84 | */ | |
85 | if (Sgl_isone_signaling(src)) { | |
86 | /* trap if INVALIDTRAP enabled */ | |
87 | if (Is_invalidtrap_enabled()) | |
88 | return(INVALIDEXCEPTION); | |
89 | /* make NaN quiet */ | |
90 | else { | |
91 | Set_invalidflag(); | |
92 | Sgl_set_quiet(src); | |
93 | } | |
94 | } | |
95 | /* | |
96 | * NaN is quiet, return as double NaN | |
97 | */ | |
98 | Dbl_setinfinity_exponent(resultp1); | |
99 | Sgl_to_dbl_mantissa(src,resultp1,resultp2); | |
100 | Dbl_copytoptr(resultp1,resultp2,dstptr); | |
101 | return(NOEXCEPTION); | |
102 | } | |
103 | } | |
104 | /* | |
105 | * Test for zero or denormalized | |
106 | */ | |
107 | if (src_exponent == 0) { | |
108 | /* | |
109 | * determine if zero or denormalized | |
110 | */ | |
111 | if (Sgl_isnotzero_mantissa(src)) { | |
112 | /* | |
113 | * is denormalized; want to normalize | |
114 | */ | |
115 | Sgl_clear_signexponent(src); | |
116 | Sgl_leftshiftby1(src); | |
117 | Sgl_normalize(src,src_exponent); | |
118 | Sgl_to_dbl_exponent(src_exponent,resultp1); | |
119 | Sgl_to_dbl_mantissa(src,resultp1,resultp2); | |
120 | } | |
121 | else { | |
122 | Dbl_setzero_exponentmantissa(resultp1,resultp2); | |
123 | } | |
124 | Dbl_copytoptr(resultp1,resultp2,dstptr); | |
125 | return(NOEXCEPTION); | |
126 | } | |
127 | /* | |
128 | * No special cases, just complete the conversion | |
129 | */ | |
130 | Sgl_to_dbl_exponent(src_exponent, resultp1); | |
131 | Sgl_to_dbl_mantissa(Sgl_mantissa(src), resultp1,resultp2); | |
132 | Dbl_copytoptr(resultp1,resultp2,dstptr); | |
133 | return(NOEXCEPTION); | |
134 | } | |
135 | ||
136 | /* | |
137 | * Double Floating-point to Single Floating-point | |
138 | */ | |
139 | /*ARGSUSED*/ | |
140 | int | |
141 | dbl_to_sgl_fcnvff( | |
142 | dbl_floating_point *srcptr, | |
143 | unsigned int *nullptr, | |
144 | sgl_floating_point *dstptr, | |
145 | unsigned int *status) | |
146 | { | |
147 | register unsigned int srcp1, srcp2, result; | |
148 | register int src_exponent, dest_exponent, dest_mantissa; | |
149 | register boolean inexact = FALSE, guardbit = FALSE, stickybit = FALSE; | |
150 | register boolean lsb_odd = FALSE; | |
151 | boolean is_tiny; | |
152 | ||
153 | Dbl_copyfromptr(srcptr,srcp1,srcp2); | |
154 | src_exponent = Dbl_exponent(srcp1); | |
155 | Sgl_all(result) = Dbl_allp1(srcp1); /* set sign of result */ | |
156 | /* | |
157 | * Test for NaN or infinity | |
158 | */ | |
159 | if (src_exponent == DBL_INFINITY_EXPONENT) { | |
160 | /* | |
161 | * determine if NaN or infinity | |
162 | */ | |
163 | if (Dbl_iszero_mantissa(srcp1,srcp2)) { | |
164 | /* | |
165 | * is infinity; want to return single infinity | |
166 | */ | |
167 | Sgl_setinfinity_exponentmantissa(result); | |
168 | *dstptr = result; | |
169 | return(NOEXCEPTION); | |
170 | } | |
171 | /* | |
172 | * is NaN; signaling or quiet? | |
173 | */ | |
174 | if (Dbl_isone_signaling(srcp1)) { | |
175 | /* trap if INVALIDTRAP enabled */ | |
176 | if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION); | |
177 | else { | |
178 | Set_invalidflag(); | |
179 | /* make NaN quiet */ | |
180 | Dbl_set_quiet(srcp1); | |
181 | } | |
182 | } | |
183 | /* | |
184 | * NaN is quiet, return as single NaN | |
185 | */ | |
186 | Sgl_setinfinity_exponent(result); | |
187 | Sgl_set_mantissa(result,Dallp1(srcp1)<<3 | Dallp2(srcp2)>>29); | |
188 | if (Sgl_iszero_mantissa(result)) Sgl_set_quiet(result); | |
189 | *dstptr = result; | |
190 | return(NOEXCEPTION); | |
191 | } | |
192 | /* | |
193 | * Generate result | |
194 | */ | |
195 | Dbl_to_sgl_exponent(src_exponent,dest_exponent); | |
196 | if (dest_exponent > 0) { | |
197 | Dbl_to_sgl_mantissa(srcp1,srcp2,dest_mantissa,inexact,guardbit, | |
198 | stickybit,lsb_odd); | |
199 | } | |
200 | else { | |
201 | if (Dbl_iszero_exponentmantissa(srcp1,srcp2)){ | |
202 | Sgl_setzero_exponentmantissa(result); | |
203 | *dstptr = result; | |
204 | return(NOEXCEPTION); | |
205 | } | |
206 | if (Is_underflowtrap_enabled()) { | |
207 | Dbl_to_sgl_mantissa(srcp1,srcp2,dest_mantissa,inexact, | |
208 | guardbit,stickybit,lsb_odd); | |
209 | } | |
210 | else { | |
211 | /* compute result, determine inexact info, | |
212 | * and set Underflowflag if appropriate | |
213 | */ | |
214 | Dbl_to_sgl_denormalized(srcp1,srcp2,dest_exponent, | |
215 | dest_mantissa,inexact,guardbit,stickybit,lsb_odd, | |
216 | is_tiny); | |
217 | } | |
218 | } | |
219 | /* | |
220 | * Now round result if not exact | |
221 | */ | |
222 | if (inexact) { | |
223 | switch (Rounding_mode()) { | |
224 | case ROUNDPLUS: | |
225 | if (Sgl_iszero_sign(result)) dest_mantissa++; | |
226 | break; | |
227 | case ROUNDMINUS: | |
228 | if (Sgl_isone_sign(result)) dest_mantissa++; | |
229 | break; | |
230 | case ROUNDNEAREST: | |
231 | if (guardbit) { | |
232 | if (stickybit || lsb_odd) dest_mantissa++; | |
233 | } | |
234 | } | |
235 | } | |
236 | Sgl_set_exponentmantissa(result,dest_mantissa); | |
237 | ||
238 | /* | |
239 | * check for mantissa overflow after rounding | |
240 | */ | |
241 | if ((dest_exponent>0 || Is_underflowtrap_enabled()) && | |
242 | Sgl_isone_hidden(result)) dest_exponent++; | |
243 | ||
244 | /* | |
245 | * Test for overflow | |
246 | */ | |
247 | if (dest_exponent >= SGL_INFINITY_EXPONENT) { | |
248 | /* trap if OVERFLOWTRAP enabled */ | |
249 | if (Is_overflowtrap_enabled()) { | |
250 | /* | |
251 | * Check for gross overflow | |
252 | */ | |
253 | if (dest_exponent >= SGL_INFINITY_EXPONENT+SGL_WRAP) | |
254 | return(UNIMPLEMENTEDEXCEPTION); | |
255 | ||
256 | /* | |
257 | * Adjust bias of result | |
258 | */ | |
259 | Sgl_setwrapped_exponent(result,dest_exponent,ovfl); | |
260 | *dstptr = result; | |
261 | if (inexact) | |
262 | if (Is_inexacttrap_enabled()) | |
263 | return(OVERFLOWEXCEPTION|INEXACTEXCEPTION); | |
264 | else Set_inexactflag(); | |
265 | return(OVERFLOWEXCEPTION); | |
266 | } | |
267 | Set_overflowflag(); | |
268 | inexact = TRUE; | |
269 | /* set result to infinity or largest number */ | |
270 | Sgl_setoverflow(result); | |
271 | } | |
272 | /* | |
273 | * Test for underflow | |
274 | */ | |
275 | else if (dest_exponent <= 0) { | |
276 | /* trap if UNDERFLOWTRAP enabled */ | |
277 | if (Is_underflowtrap_enabled()) { | |
278 | /* | |
279 | * Check for gross underflow | |
280 | */ | |
281 | if (dest_exponent <= -(SGL_WRAP)) | |
282 | return(UNIMPLEMENTEDEXCEPTION); | |
283 | /* | |
284 | * Adjust bias of result | |
285 | */ | |
286 | Sgl_setwrapped_exponent(result,dest_exponent,unfl); | |
287 | *dstptr = result; | |
288 | if (inexact) | |
289 | if (Is_inexacttrap_enabled()) | |
290 | return(UNDERFLOWEXCEPTION|INEXACTEXCEPTION); | |
291 | else Set_inexactflag(); | |
292 | return(UNDERFLOWEXCEPTION); | |
293 | } | |
294 | /* | |
295 | * result is denormalized or signed zero | |
296 | */ | |
297 | if (inexact && is_tiny) Set_underflowflag(); | |
298 | ||
299 | } | |
300 | else Sgl_set_exponent(result,dest_exponent); | |
301 | *dstptr = result; | |
302 | /* | |
303 | * Trap if inexact trap is enabled | |
304 | */ | |
305 | if (inexact) | |
306 | if (Is_inexacttrap_enabled()) return(INEXACTEXCEPTION); | |
307 | else Set_inexactflag(); | |
308 | return(NOEXCEPTION); | |
309 | } |