sfadd.c revision 1.1.2.2 1 1.1.2.2 jdolecek /* $NetBSD: sfadd.c,v 1.1.2.2 2002/06/23 17:37:15 jdolecek Exp $ */
2 1.1.2.2 jdolecek
3 1.1.2.2 jdolecek /* $OpenBSD: sfadd.c,v 1.4 2001/03/29 03:58:19 mickey Exp $ */
4 1.1.2.2 jdolecek
5 1.1.2.2 jdolecek /*
6 1.1.2.2 jdolecek * Copyright 1996 1995 by Open Software Foundation, Inc.
7 1.1.2.2 jdolecek * All Rights Reserved
8 1.1.2.2 jdolecek *
9 1.1.2.2 jdolecek * Permission to use, copy, modify, and distribute this software and
10 1.1.2.2 jdolecek * its documentation for any purpose and without fee is hereby granted,
11 1.1.2.2 jdolecek * provided that the above copyright notice appears in all copies and
12 1.1.2.2 jdolecek * that both the copyright notice and this permission notice appear in
13 1.1.2.2 jdolecek * supporting documentation.
14 1.1.2.2 jdolecek *
15 1.1.2.2 jdolecek * OSF DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE
16 1.1.2.2 jdolecek * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
17 1.1.2.2 jdolecek * FOR A PARTICULAR PURPOSE.
18 1.1.2.2 jdolecek *
19 1.1.2.2 jdolecek * IN NO EVENT SHALL OSF BE LIABLE FOR ANY SPECIAL, INDIRECT, OR
20 1.1.2.2 jdolecek * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
21 1.1.2.2 jdolecek * LOSS OF USE, DATA OR PROFITS, WHETHER IN ACTION OF CONTRACT,
22 1.1.2.2 jdolecek * NEGLIGENCE, OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
23 1.1.2.2 jdolecek * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
24 1.1.2.2 jdolecek *
25 1.1.2.2 jdolecek */
26 1.1.2.2 jdolecek /*
27 1.1.2.2 jdolecek * pmk1.1
28 1.1.2.2 jdolecek */
29 1.1.2.2 jdolecek /*
30 1.1.2.2 jdolecek * (c) Copyright 1986 HEWLETT-PACKARD COMPANY
31 1.1.2.2 jdolecek *
32 1.1.2.2 jdolecek * To anyone who acknowledges that this file is provided "AS IS"
33 1.1.2.2 jdolecek * without any express or implied warranty:
34 1.1.2.2 jdolecek * permission to use, copy, modify, and distribute this file
35 1.1.2.2 jdolecek * for any purpose is hereby granted without fee, provided that
36 1.1.2.2 jdolecek * the above copyright notice and this notice appears in all
37 1.1.2.2 jdolecek * copies, and that the name of Hewlett-Packard Company not be
38 1.1.2.2 jdolecek * used in advertising or publicity pertaining to distribution
39 1.1.2.2 jdolecek * of the software without specific, written prior permission.
40 1.1.2.2 jdolecek * Hewlett-Packard Company makes no representations about the
41 1.1.2.2 jdolecek * suitability of this software for any purpose.
42 1.1.2.2 jdolecek */
43 1.1.2.2 jdolecek
44 1.1.2.2 jdolecek #include "../spmath/float.h"
45 1.1.2.2 jdolecek #include "../spmath/sgl_float.h"
46 1.1.2.2 jdolecek
47 1.1.2.2 jdolecek /*
48 1.1.2.2 jdolecek * Single_add: add two single precision values.
49 1.1.2.2 jdolecek */
50 1.1.2.2 jdolecek int
51 1.1.2.2 jdolecek sgl_fadd(leftptr, rightptr, dstptr, status)
52 1.1.2.2 jdolecek sgl_floating_point *leftptr, *rightptr, *dstptr;
53 1.1.2.2 jdolecek unsigned int *status;
54 1.1.2.2 jdolecek {
55 1.1.2.2 jdolecek register unsigned int left, right, result, extent;
56 1.1.2.2 jdolecek register unsigned int signless_upper_left, signless_upper_right, save;
57 1.1.2.2 jdolecek
58 1.1.2.2 jdolecek
59 1.1.2.2 jdolecek register int result_exponent, right_exponent, diff_exponent;
60 1.1.2.2 jdolecek register int sign_save, jumpsize;
61 1.1.2.2 jdolecek register int inexact = FALSE;
62 1.1.2.2 jdolecek register int underflowtrap;
63 1.1.2.2 jdolecek
64 1.1.2.2 jdolecek /* Create local copies of the numbers */
65 1.1.2.2 jdolecek left = *leftptr;
66 1.1.2.2 jdolecek right = *rightptr;
67 1.1.2.2 jdolecek
68 1.1.2.2 jdolecek /* A zero "save" helps discover equal operands (for later), *
69 1.1.2.2 jdolecek * and is used in swapping operands (if needed). */
70 1.1.2.2 jdolecek Sgl_xortointp1(left,right,/*to*/save);
71 1.1.2.2 jdolecek
72 1.1.2.2 jdolecek /*
73 1.1.2.2 jdolecek * check first operand for NaN's or infinity
74 1.1.2.2 jdolecek */
75 1.1.2.2 jdolecek if ((result_exponent = Sgl_exponent(left)) == SGL_INFINITY_EXPONENT)
76 1.1.2.2 jdolecek {
77 1.1.2.2 jdolecek if (Sgl_iszero_mantissa(left))
78 1.1.2.2 jdolecek {
79 1.1.2.2 jdolecek if (Sgl_isnotnan(right))
80 1.1.2.2 jdolecek {
81 1.1.2.2 jdolecek if (Sgl_isinfinity(right) && save!=0)
82 1.1.2.2 jdolecek {
83 1.1.2.2 jdolecek /*
84 1.1.2.2 jdolecek * invalid since operands are opposite signed infinity's
85 1.1.2.2 jdolecek */
86 1.1.2.2 jdolecek if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION);
87 1.1.2.2 jdolecek Set_invalidflag();
88 1.1.2.2 jdolecek Sgl_makequietnan(result);
89 1.1.2.2 jdolecek *dstptr = result;
90 1.1.2.2 jdolecek return(NOEXCEPTION);
91 1.1.2.2 jdolecek }
92 1.1.2.2 jdolecek /*
93 1.1.2.2 jdolecek * return infinity
94 1.1.2.2 jdolecek */
95 1.1.2.2 jdolecek *dstptr = left;
96 1.1.2.2 jdolecek return(NOEXCEPTION);
97 1.1.2.2 jdolecek }
98 1.1.2.2 jdolecek }
99 1.1.2.2 jdolecek else
100 1.1.2.2 jdolecek {
101 1.1.2.2 jdolecek /*
102 1.1.2.2 jdolecek * is NaN; signaling or quiet?
103 1.1.2.2 jdolecek */
104 1.1.2.2 jdolecek if (Sgl_isone_signaling(left))
105 1.1.2.2 jdolecek {
106 1.1.2.2 jdolecek /* trap if INVALIDTRAP enabled */
107 1.1.2.2 jdolecek if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION);
108 1.1.2.2 jdolecek /* make NaN quiet */
109 1.1.2.2 jdolecek Set_invalidflag();
110 1.1.2.2 jdolecek Sgl_set_quiet(left);
111 1.1.2.2 jdolecek }
112 1.1.2.2 jdolecek /*
113 1.1.2.2 jdolecek * is second operand a signaling NaN?
114 1.1.2.2 jdolecek */
115 1.1.2.2 jdolecek else if (Sgl_is_signalingnan(right))
116 1.1.2.2 jdolecek {
117 1.1.2.2 jdolecek /* trap if INVALIDTRAP enabled */
118 1.1.2.2 jdolecek if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION);
119 1.1.2.2 jdolecek /* make NaN quiet */
120 1.1.2.2 jdolecek Set_invalidflag();
121 1.1.2.2 jdolecek Sgl_set_quiet(right);
122 1.1.2.2 jdolecek *dstptr = right;
123 1.1.2.2 jdolecek return(NOEXCEPTION);
124 1.1.2.2 jdolecek }
125 1.1.2.2 jdolecek /*
126 1.1.2.2 jdolecek * return quiet NaN
127 1.1.2.2 jdolecek */
128 1.1.2.2 jdolecek *dstptr = left;
129 1.1.2.2 jdolecek return(NOEXCEPTION);
130 1.1.2.2 jdolecek }
131 1.1.2.2 jdolecek } /* End left NaN or Infinity processing */
132 1.1.2.2 jdolecek /*
133 1.1.2.2 jdolecek * check second operand for NaN's or infinity
134 1.1.2.2 jdolecek */
135 1.1.2.2 jdolecek if (Sgl_isinfinity_exponent(right))
136 1.1.2.2 jdolecek {
137 1.1.2.2 jdolecek if (Sgl_iszero_mantissa(right))
138 1.1.2.2 jdolecek {
139 1.1.2.2 jdolecek /* return infinity */
140 1.1.2.2 jdolecek *dstptr = right;
141 1.1.2.2 jdolecek return(NOEXCEPTION);
142 1.1.2.2 jdolecek }
143 1.1.2.2 jdolecek /*
144 1.1.2.2 jdolecek * is NaN; signaling or quiet?
145 1.1.2.2 jdolecek */
146 1.1.2.2 jdolecek if (Sgl_isone_signaling(right))
147 1.1.2.2 jdolecek {
148 1.1.2.2 jdolecek /* trap if INVALIDTRAP enabled */
149 1.1.2.2 jdolecek if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION);
150 1.1.2.2 jdolecek /* make NaN quiet */
151 1.1.2.2 jdolecek Set_invalidflag();
152 1.1.2.2 jdolecek Sgl_set_quiet(right);
153 1.1.2.2 jdolecek }
154 1.1.2.2 jdolecek /*
155 1.1.2.2 jdolecek * return quiet NaN
156 1.1.2.2 jdolecek */
157 1.1.2.2 jdolecek *dstptr = right;
158 1.1.2.2 jdolecek return(NOEXCEPTION);
159 1.1.2.2 jdolecek } /* End right NaN or Infinity processing */
160 1.1.2.2 jdolecek
161 1.1.2.2 jdolecek /* Invariant: Must be dealing with finite numbers */
162 1.1.2.2 jdolecek
163 1.1.2.2 jdolecek /* Compare operands by removing the sign */
164 1.1.2.2 jdolecek Sgl_copytoint_exponentmantissa(left,signless_upper_left);
165 1.1.2.2 jdolecek Sgl_copytoint_exponentmantissa(right,signless_upper_right);
166 1.1.2.2 jdolecek
167 1.1.2.2 jdolecek /* sign difference selects add or sub operation. */
168 1.1.2.2 jdolecek if(Sgl_ismagnitudeless(signless_upper_left,signless_upper_right))
169 1.1.2.2 jdolecek {
170 1.1.2.2 jdolecek /* Set the left operand to the larger one by XOR swap *
171 1.1.2.2 jdolecek * First finish the first word using "save" */
172 1.1.2.2 jdolecek Sgl_xorfromintp1(save,right,/*to*/right);
173 1.1.2.2 jdolecek Sgl_xorfromintp1(save,left,/*to*/left);
174 1.1.2.2 jdolecek result_exponent = Sgl_exponent(left);
175 1.1.2.2 jdolecek }
176 1.1.2.2 jdolecek /* Invariant: left is not smaller than right. */
177 1.1.2.2 jdolecek
178 1.1.2.2 jdolecek if((right_exponent = Sgl_exponent(right)) == 0)
179 1.1.2.2 jdolecek {
180 1.1.2.2 jdolecek /* Denormalized operands. First look for zeroes */
181 1.1.2.2 jdolecek if(Sgl_iszero_mantissa(right))
182 1.1.2.2 jdolecek {
183 1.1.2.2 jdolecek /* right is zero */
184 1.1.2.2 jdolecek if(Sgl_iszero_exponentmantissa(left))
185 1.1.2.2 jdolecek {
186 1.1.2.2 jdolecek /* Both operands are zeros */
187 1.1.2.2 jdolecek if(Is_rounding_mode(ROUNDMINUS))
188 1.1.2.2 jdolecek {
189 1.1.2.2 jdolecek Sgl_or_signs(left,/*with*/right);
190 1.1.2.2 jdolecek }
191 1.1.2.2 jdolecek else
192 1.1.2.2 jdolecek {
193 1.1.2.2 jdolecek Sgl_and_signs(left,/*with*/right);
194 1.1.2.2 jdolecek }
195 1.1.2.2 jdolecek }
196 1.1.2.2 jdolecek else
197 1.1.2.2 jdolecek {
198 1.1.2.2 jdolecek /* Left is not a zero and must be the result. Trapped
199 1.1.2.2 jdolecek * underflows are signaled if left is denormalized. Result
200 1.1.2.2 jdolecek * is always exact. */
201 1.1.2.2 jdolecek if( (result_exponent == 0) && Is_underflowtrap_enabled() )
202 1.1.2.2 jdolecek {
203 1.1.2.2 jdolecek /* need to normalize results mantissa */
204 1.1.2.2 jdolecek sign_save = Sgl_signextendedsign(left);
205 1.1.2.2 jdolecek Sgl_leftshiftby1(left);
206 1.1.2.2 jdolecek Sgl_normalize(left,result_exponent);
207 1.1.2.2 jdolecek Sgl_set_sign(left,/*using*/sign_save);
208 1.1.2.2 jdolecek Sgl_setwrapped_exponent(left,result_exponent,unfl);
209 1.1.2.2 jdolecek *dstptr = left;
210 1.1.2.2 jdolecek return(UNDERFLOWEXCEPTION);
211 1.1.2.2 jdolecek }
212 1.1.2.2 jdolecek }
213 1.1.2.2 jdolecek *dstptr = left;
214 1.1.2.2 jdolecek return(NOEXCEPTION);
215 1.1.2.2 jdolecek }
216 1.1.2.2 jdolecek
217 1.1.2.2 jdolecek /* Neither are zeroes */
218 1.1.2.2 jdolecek Sgl_clear_sign(right); /* Exponent is already cleared */
219 1.1.2.2 jdolecek if(result_exponent == 0 )
220 1.1.2.2 jdolecek {
221 1.1.2.2 jdolecek /* Both operands are denormalized. The result must be exact
222 1.1.2.2 jdolecek * and is simply calculated. A sum could become normalized and a
223 1.1.2.2 jdolecek * difference could cancel to a true zero. */
224 1.1.2.2 jdolecek if( (/*signed*/int) save < 0 )
225 1.1.2.2 jdolecek {
226 1.1.2.2 jdolecek Sgl_subtract(left,/*minus*/right,/*into*/result);
227 1.1.2.2 jdolecek if(Sgl_iszero_mantissa(result))
228 1.1.2.2 jdolecek {
229 1.1.2.2 jdolecek if(Is_rounding_mode(ROUNDMINUS))
230 1.1.2.2 jdolecek {
231 1.1.2.2 jdolecek Sgl_setone_sign(result);
232 1.1.2.2 jdolecek }
233 1.1.2.2 jdolecek else
234 1.1.2.2 jdolecek {
235 1.1.2.2 jdolecek Sgl_setzero_sign(result);
236 1.1.2.2 jdolecek }
237 1.1.2.2 jdolecek *dstptr = result;
238 1.1.2.2 jdolecek return(NOEXCEPTION);
239 1.1.2.2 jdolecek }
240 1.1.2.2 jdolecek }
241 1.1.2.2 jdolecek else
242 1.1.2.2 jdolecek {
243 1.1.2.2 jdolecek Sgl_addition(left,right,/*into*/result);
244 1.1.2.2 jdolecek if(Sgl_isone_hidden(result))
245 1.1.2.2 jdolecek {
246 1.1.2.2 jdolecek *dstptr = result;
247 1.1.2.2 jdolecek return(NOEXCEPTION);
248 1.1.2.2 jdolecek }
249 1.1.2.2 jdolecek }
250 1.1.2.2 jdolecek if(Is_underflowtrap_enabled())
251 1.1.2.2 jdolecek {
252 1.1.2.2 jdolecek /* need to normalize result */
253 1.1.2.2 jdolecek sign_save = Sgl_signextendedsign(result);
254 1.1.2.2 jdolecek Sgl_leftshiftby1(result);
255 1.1.2.2 jdolecek Sgl_normalize(result,result_exponent);
256 1.1.2.2 jdolecek Sgl_set_sign(result,/*using*/sign_save);
257 1.1.2.2 jdolecek Sgl_setwrapped_exponent(result,result_exponent,unfl);
258 1.1.2.2 jdolecek *dstptr = result;
259 1.1.2.2 jdolecek return(UNDERFLOWEXCEPTION);
260 1.1.2.2 jdolecek }
261 1.1.2.2 jdolecek *dstptr = result;
262 1.1.2.2 jdolecek return(NOEXCEPTION);
263 1.1.2.2 jdolecek }
264 1.1.2.2 jdolecek right_exponent = 1; /* Set exponent to reflect different bias
265 1.1.2.2 jdolecek * with denomalized numbers. */
266 1.1.2.2 jdolecek }
267 1.1.2.2 jdolecek else
268 1.1.2.2 jdolecek {
269 1.1.2.2 jdolecek Sgl_clear_signexponent_set_hidden(right);
270 1.1.2.2 jdolecek }
271 1.1.2.2 jdolecek Sgl_clear_exponent_set_hidden(left);
272 1.1.2.2 jdolecek diff_exponent = result_exponent - right_exponent;
273 1.1.2.2 jdolecek
274 1.1.2.2 jdolecek /*
275 1.1.2.2 jdolecek * Special case alignment of operands that would force alignment
276 1.1.2.2 jdolecek * beyond the extent of the extension. A further optimization
277 1.1.2.2 jdolecek * could special case this but only reduces the path length for this
278 1.1.2.2 jdolecek * infrequent case.
279 1.1.2.2 jdolecek */
280 1.1.2.2 jdolecek if(diff_exponent > SGL_THRESHOLD)
281 1.1.2.2 jdolecek {
282 1.1.2.2 jdolecek diff_exponent = SGL_THRESHOLD;
283 1.1.2.2 jdolecek }
284 1.1.2.2 jdolecek
285 1.1.2.2 jdolecek /* Align right operand by shifting to right */
286 1.1.2.2 jdolecek Sgl_right_align(/*operand*/right,/*shifted by*/diff_exponent,
287 1.1.2.2 jdolecek /*and lower to*/extent);
288 1.1.2.2 jdolecek
289 1.1.2.2 jdolecek /* Treat sum and difference of the operands separately. */
290 1.1.2.2 jdolecek if( (/*signed*/int) save < 0 )
291 1.1.2.2 jdolecek {
292 1.1.2.2 jdolecek /*
293 1.1.2.2 jdolecek * Difference of the two operands. Their can be no overflow. A
294 1.1.2.2 jdolecek * borrow can occur out of the hidden bit and force a post
295 1.1.2.2 jdolecek * normalization phase.
296 1.1.2.2 jdolecek */
297 1.1.2.2 jdolecek Sgl_subtract_withextension(left,/*minus*/right,/*with*/extent,/*into*/result);
298 1.1.2.2 jdolecek if(Sgl_iszero_hidden(result))
299 1.1.2.2 jdolecek {
300 1.1.2.2 jdolecek /* Handle normalization */
301 1.1.2.2 jdolecek /* A straight foward algorithm would now shift the result
302 1.1.2.2 jdolecek * and extension left until the hidden bit becomes one. Not
303 1.1.2.2 jdolecek * all of the extension bits need participate in the shift.
304 1.1.2.2 jdolecek * Only the two most significant bits (round and guard) are
305 1.1.2.2 jdolecek * needed. If only a single shift is needed then the guard
306 1.1.2.2 jdolecek * bit becomes a significant low order bit and the extension
307 1.1.2.2 jdolecek * must participate in the rounding. If more than a single
308 1.1.2.2 jdolecek * shift is needed, then all bits to the right of the guard
309 1.1.2.2 jdolecek * bit are zeros, and the guard bit may or may not be zero. */
310 1.1.2.2 jdolecek sign_save = Sgl_signextendedsign(result);
311 1.1.2.2 jdolecek Sgl_leftshiftby1_withextent(result,extent,result);
312 1.1.2.2 jdolecek
313 1.1.2.2 jdolecek /* Need to check for a zero result. The sign and exponent
314 1.1.2.2 jdolecek * fields have already been zeroed. The more efficient test
315 1.1.2.2 jdolecek * of the full object can be used.
316 1.1.2.2 jdolecek */
317 1.1.2.2 jdolecek if(Sgl_iszero(result))
318 1.1.2.2 jdolecek /* Must have been "x-x" or "x+(-x)". */
319 1.1.2.2 jdolecek {
320 1.1.2.2 jdolecek if(Is_rounding_mode(ROUNDMINUS)) Sgl_setone_sign(result);
321 1.1.2.2 jdolecek *dstptr = result;
322 1.1.2.2 jdolecek return(NOEXCEPTION);
323 1.1.2.2 jdolecek }
324 1.1.2.2 jdolecek result_exponent--;
325 1.1.2.2 jdolecek /* Look to see if normalization is finished. */
326 1.1.2.2 jdolecek if(Sgl_isone_hidden(result))
327 1.1.2.2 jdolecek {
328 1.1.2.2 jdolecek if(result_exponent==0)
329 1.1.2.2 jdolecek {
330 1.1.2.2 jdolecek /* Denormalized, exponent should be zero. Left operand *
331 1.1.2.2 jdolecek * was normalized, so extent (guard, round) was zero */
332 1.1.2.2 jdolecek goto underflow;
333 1.1.2.2 jdolecek }
334 1.1.2.2 jdolecek else
335 1.1.2.2 jdolecek {
336 1.1.2.2 jdolecek /* No further normalization is needed. */
337 1.1.2.2 jdolecek Sgl_set_sign(result,/*using*/sign_save);
338 1.1.2.2 jdolecek Ext_leftshiftby1(extent);
339 1.1.2.2 jdolecek goto round;
340 1.1.2.2 jdolecek }
341 1.1.2.2 jdolecek }
342 1.1.2.2 jdolecek
343 1.1.2.2 jdolecek /* Check for denormalized, exponent should be zero. Left *
344 1.1.2.2 jdolecek * operand was normalized, so extent (guard, round) was zero */
345 1.1.2.2 jdolecek if(!(underflowtrap = Is_underflowtrap_enabled()) &&
346 1.1.2.2 jdolecek result_exponent==0) goto underflow;
347 1.1.2.2 jdolecek
348 1.1.2.2 jdolecek /* Shift extension to complete one bit of normalization and
349 1.1.2.2 jdolecek * update exponent. */
350 1.1.2.2 jdolecek Ext_leftshiftby1(extent);
351 1.1.2.2 jdolecek
352 1.1.2.2 jdolecek /* Discover first one bit to determine shift amount. Use a
353 1.1.2.2 jdolecek * modified binary search. We have already shifted the result
354 1.1.2.2 jdolecek * one position right and still not found a one so the remainder
355 1.1.2.2 jdolecek * of the extension must be zero and simplifies rounding. */
356 1.1.2.2 jdolecek /* Scan bytes */
357 1.1.2.2 jdolecek while(Sgl_iszero_hiddenhigh7mantissa(result))
358 1.1.2.2 jdolecek {
359 1.1.2.2 jdolecek Sgl_leftshiftby8(result);
360 1.1.2.2 jdolecek if((result_exponent -= 8) <= 0 && !underflowtrap)
361 1.1.2.2 jdolecek goto underflow;
362 1.1.2.2 jdolecek }
363 1.1.2.2 jdolecek /* Now narrow it down to the nibble */
364 1.1.2.2 jdolecek if(Sgl_iszero_hiddenhigh3mantissa(result))
365 1.1.2.2 jdolecek {
366 1.1.2.2 jdolecek /* The lower nibble contains the normalizing one */
367 1.1.2.2 jdolecek Sgl_leftshiftby4(result);
368 1.1.2.2 jdolecek if((result_exponent -= 4) <= 0 && !underflowtrap)
369 1.1.2.2 jdolecek goto underflow;
370 1.1.2.2 jdolecek }
371 1.1.2.2 jdolecek /* Select case were first bit is set (already normalized)
372 1.1.2.2 jdolecek * otherwise select the proper shift. */
373 1.1.2.2 jdolecek if((jumpsize = Sgl_hiddenhigh3mantissa(result)) > 7)
374 1.1.2.2 jdolecek {
375 1.1.2.2 jdolecek /* Already normalized */
376 1.1.2.2 jdolecek if(result_exponent <= 0) goto underflow;
377 1.1.2.2 jdolecek Sgl_set_sign(result,/*using*/sign_save);
378 1.1.2.2 jdolecek Sgl_set_exponent(result,/*using*/result_exponent);
379 1.1.2.2 jdolecek *dstptr = result;
380 1.1.2.2 jdolecek return(NOEXCEPTION);
381 1.1.2.2 jdolecek }
382 1.1.2.2 jdolecek Sgl_sethigh4bits(result,/*using*/sign_save);
383 1.1.2.2 jdolecek switch(jumpsize)
384 1.1.2.2 jdolecek {
385 1.1.2.2 jdolecek case 1:
386 1.1.2.2 jdolecek {
387 1.1.2.2 jdolecek Sgl_leftshiftby3(result);
388 1.1.2.2 jdolecek result_exponent -= 3;
389 1.1.2.2 jdolecek break;
390 1.1.2.2 jdolecek }
391 1.1.2.2 jdolecek case 2:
392 1.1.2.2 jdolecek case 3:
393 1.1.2.2 jdolecek {
394 1.1.2.2 jdolecek Sgl_leftshiftby2(result);
395 1.1.2.2 jdolecek result_exponent -= 2;
396 1.1.2.2 jdolecek break;
397 1.1.2.2 jdolecek }
398 1.1.2.2 jdolecek case 4:
399 1.1.2.2 jdolecek case 5:
400 1.1.2.2 jdolecek case 6:
401 1.1.2.2 jdolecek case 7:
402 1.1.2.2 jdolecek {
403 1.1.2.2 jdolecek Sgl_leftshiftby1(result);
404 1.1.2.2 jdolecek result_exponent -= 1;
405 1.1.2.2 jdolecek break;
406 1.1.2.2 jdolecek }
407 1.1.2.2 jdolecek }
408 1.1.2.2 jdolecek if(result_exponent > 0)
409 1.1.2.2 jdolecek {
410 1.1.2.2 jdolecek Sgl_set_exponent(result,/*using*/result_exponent);
411 1.1.2.2 jdolecek *dstptr = result;
412 1.1.2.2 jdolecek return(NOEXCEPTION); /* Sign bit is already set */
413 1.1.2.2 jdolecek }
414 1.1.2.2 jdolecek /* Fixup potential underflows */
415 1.1.2.2 jdolecek underflow:
416 1.1.2.2 jdolecek if(Is_underflowtrap_enabled())
417 1.1.2.2 jdolecek {
418 1.1.2.2 jdolecek Sgl_set_sign(result,sign_save);
419 1.1.2.2 jdolecek Sgl_setwrapped_exponent(result,result_exponent,unfl);
420 1.1.2.2 jdolecek *dstptr = result;
421 1.1.2.2 jdolecek /* inexact = FALSE; */
422 1.1.2.2 jdolecek return(UNDERFLOWEXCEPTION);
423 1.1.2.2 jdolecek }
424 1.1.2.2 jdolecek /*
425 1.1.2.2 jdolecek * Since we cannot get an inexact denormalized result,
426 1.1.2.2 jdolecek * we can now return.
427 1.1.2.2 jdolecek */
428 1.1.2.2 jdolecek Sgl_right_align(result,/*by*/(1-result_exponent),extent);
429 1.1.2.2 jdolecek Sgl_clear_signexponent(result);
430 1.1.2.2 jdolecek Sgl_set_sign(result,sign_save);
431 1.1.2.2 jdolecek *dstptr = result;
432 1.1.2.2 jdolecek return(NOEXCEPTION);
433 1.1.2.2 jdolecek } /* end if(hidden...)... */
434 1.1.2.2 jdolecek /* Fall through and round */
435 1.1.2.2 jdolecek } /* end if(save < 0)... */
436 1.1.2.2 jdolecek else
437 1.1.2.2 jdolecek {
438 1.1.2.2 jdolecek /* Add magnitudes */
439 1.1.2.2 jdolecek Sgl_addition(left,right,/*to*/result);
440 1.1.2.2 jdolecek if(Sgl_isone_hiddenoverflow(result))
441 1.1.2.2 jdolecek {
442 1.1.2.2 jdolecek /* Prenormalization required. */
443 1.1.2.2 jdolecek Sgl_rightshiftby1_withextent(result,extent,extent);
444 1.1.2.2 jdolecek Sgl_arithrightshiftby1(result);
445 1.1.2.2 jdolecek result_exponent++;
446 1.1.2.2 jdolecek } /* end if hiddenoverflow... */
447 1.1.2.2 jdolecek } /* end else ...add magnitudes... */
448 1.1.2.2 jdolecek
449 1.1.2.2 jdolecek /* Round the result. If the extension is all zeros,then the result is
450 1.1.2.2 jdolecek * exact. Otherwise round in the correct direction. No underflow is
451 1.1.2.2 jdolecek * possible. If a postnormalization is necessary, then the mantissa is
452 1.1.2.2 jdolecek * all zeros so no shift is needed. */
453 1.1.2.2 jdolecek round:
454 1.1.2.2 jdolecek if(Ext_isnotzero(extent))
455 1.1.2.2 jdolecek {
456 1.1.2.2 jdolecek inexact = TRUE;
457 1.1.2.2 jdolecek switch(Rounding_mode())
458 1.1.2.2 jdolecek {
459 1.1.2.2 jdolecek case ROUNDNEAREST: /* The default. */
460 1.1.2.2 jdolecek if(Ext_isone_sign(extent))
461 1.1.2.2 jdolecek {
462 1.1.2.2 jdolecek /* at least 1/2 ulp */
463 1.1.2.2 jdolecek if(Ext_isnotzero_lower(extent) ||
464 1.1.2.2 jdolecek Sgl_isone_lowmantissa(result))
465 1.1.2.2 jdolecek {
466 1.1.2.2 jdolecek /* either exactly half way and odd or more than 1/2ulp */
467 1.1.2.2 jdolecek Sgl_increment(result);
468 1.1.2.2 jdolecek }
469 1.1.2.2 jdolecek }
470 1.1.2.2 jdolecek break;
471 1.1.2.2 jdolecek
472 1.1.2.2 jdolecek case ROUNDPLUS:
473 1.1.2.2 jdolecek if(Sgl_iszero_sign(result))
474 1.1.2.2 jdolecek {
475 1.1.2.2 jdolecek /* Round up positive results */
476 1.1.2.2 jdolecek Sgl_increment(result);
477 1.1.2.2 jdolecek }
478 1.1.2.2 jdolecek break;
479 1.1.2.2 jdolecek
480 1.1.2.2 jdolecek case ROUNDMINUS:
481 1.1.2.2 jdolecek if(Sgl_isone_sign(result))
482 1.1.2.2 jdolecek {
483 1.1.2.2 jdolecek /* Round down negative results */
484 1.1.2.2 jdolecek Sgl_increment(result);
485 1.1.2.2 jdolecek }
486 1.1.2.2 jdolecek
487 1.1.2.2 jdolecek case ROUNDZERO:;
488 1.1.2.2 jdolecek /* truncate is simple */
489 1.1.2.2 jdolecek } /* end switch... */
490 1.1.2.2 jdolecek if(Sgl_isone_hiddenoverflow(result)) result_exponent++;
491 1.1.2.2 jdolecek }
492 1.1.2.2 jdolecek if(result_exponent == SGL_INFINITY_EXPONENT)
493 1.1.2.2 jdolecek {
494 1.1.2.2 jdolecek /* Overflow */
495 1.1.2.2 jdolecek if(Is_overflowtrap_enabled())
496 1.1.2.2 jdolecek {
497 1.1.2.2 jdolecek Sgl_setwrapped_exponent(result,result_exponent,ovfl);
498 1.1.2.2 jdolecek *dstptr = result;
499 1.1.2.2 jdolecek if (inexact) {
500 1.1.2.2 jdolecek if (Is_inexacttrap_enabled())
501 1.1.2.2 jdolecek return(OVERFLOWEXCEPTION | INEXACTEXCEPTION);
502 1.1.2.2 jdolecek else Set_inexactflag();
503 1.1.2.2 jdolecek }
504 1.1.2.2 jdolecek return(OVERFLOWEXCEPTION);
505 1.1.2.2 jdolecek }
506 1.1.2.2 jdolecek else
507 1.1.2.2 jdolecek {
508 1.1.2.2 jdolecek Set_overflowflag();
509 1.1.2.2 jdolecek inexact = TRUE;
510 1.1.2.2 jdolecek Sgl_setoverflow(result);
511 1.1.2.2 jdolecek }
512 1.1.2.2 jdolecek }
513 1.1.2.2 jdolecek else Sgl_set_exponent(result,result_exponent);
514 1.1.2.2 jdolecek *dstptr = result;
515 1.1.2.2 jdolecek if(inexact) {
516 1.1.2.2 jdolecek if(Is_inexacttrap_enabled()) return(INEXACTEXCEPTION);
517 1.1.2.2 jdolecek else Set_inexactflag();
518 1.1.2.2 jdolecek }
519 1.1.2.2 jdolecek return(NOEXCEPTION);
520 1.1.2.2 jdolecek }
521