Merge branch 'master' into upstream
[linux-2.6] / arch / parisc / math-emu / fcnvff.c
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 }