2 * Copyright (c) 1992, 1993
3 * The Regents of the University of California. All rights reserved.
5 * This software was developed by the Computer Systems Engineering group
6 * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
7 * contributed to Berkeley.
9 * All advertising materials mentioning features or use of this software
10 * must display the following acknowledgement:
11 * This product includes software developed by the University of
12 * California, Lawrence Berkeley Laboratory.
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15 * modification, are permitted provided that the following conditions
17 * 1. Redistributions of source code must retain the above copyright
18 * notice, this list of conditions and the following disclaimer.
19 * 2. Redistributions in binary form must reproduce the above copyright
20 * notice, this list of conditions and the following disclaimer in the
21 * documentation and/or other materials provided with the distribution.
22 * 4. Neither the name of the University nor the names of its contributors
23 * may be used to endorse or promote products derived from this software
24 * without specific prior written permission.
26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
38 * @(#)fpu_subr.c 8.1 (Berkeley) 6/11/93
39 * $NetBSD: fpu_subr.c,v 1.3 1996/03/14 19:42:01 christos Exp $
42 #include <sys/cdefs.h>
43 __FBSDID("$FreeBSD$");
49 #include <sys/param.h>
51 #include <machine/frame.h>
52 #include <machine/fp.h>
53 #include <machine/fsr.h>
54 #include <machine/instr.h>
56 #include "fpu_arith.h"
58 #include "fpu_extern.h"
59 #include "__sparc_utrap_private.h"
62 * Shift the given number right rsh bits. Any bits that `fall off' will get
63 * shoved into the sticky field; we return the resulting sticky. Note that
64 * shifting NaNs is legal (this will never shift all bits out); a NaN's
65 * sticky field is ignored anyway.
68 __fpu_shr(struct fpn *fp, int rsh)
70 u_int m0, m1, m2, m3, s;
74 if (rsh <= 0 || (fp->fp_class != FPC_NUM && !ISNAN(fp)))
75 __utrap_panic("fpu_rightshift 1");
83 /* If shifting all the bits out, take a shortcut. */
84 if (rsh >= FP_NMANT) {
86 if ((m0 | m1 | m2 | m3) == 0)
87 __utrap_panic("fpu_rightshift 2");
94 if ((m0 | m1 | m2 | m3) == 0)
95 fp->fp_class = FPC_ZERO;
102 /* Squish out full words. */
106 m3 = m0, m2 = 0, m1 = 0, m0 = 0;
107 } else if (rsh >= 32 * 2) {
109 m3 = m1, m2 = m0, m1 = 0, m0 = 0;
110 } else if (rsh >= 32) {
112 m3 = m2, m2 = m1, m1 = m0, m0 = 0;
115 /* Handle any remaining partial word. */
116 if ((rsh &= 31) != 0) {
119 m3 = (m3 >> rsh) | (m2 << lsh);
120 m2 = (m2 >> rsh) | (m1 << lsh);
121 m1 = (m1 >> rsh) | (m0 << lsh);
133 * Force a number to be normal, i.e., make its fraction have all zero
134 * bits before FP_1, then FP_1, then all 1 bits. This is used for denorms
135 * and (sometimes) for intermediate results.
137 * Internally, this may use a `supernormal' -- a number whose fp_mant
138 * is greater than or equal to 2.0 -- so as a side effect you can hand it
139 * a supernormal and it will fix it (provided fp->fp_mant[3] == 0).
142 __fpu_norm(struct fpn *fp)
144 u_int m0, m1, m2, m3, top, sup, nrm;
153 /* Handle severe subnormals with 32-bit moves. */
156 m0 = m1, m1 = m2, m2 = m3, m3 = 0, exp -= 32;
158 m0 = m2, m1 = m3, m2 = 0, m3 = 0, exp -= 2 * 32;
160 m0 = m3, m1 = 0, m2 = 0, m3 = 0, exp -= 3 * 32;
162 fp->fp_class = FPC_ZERO;
167 /* Now fix any supernormal or remaining subnormal. */
172 * We have a supernormal number. We need to shift it right.
173 * We may assume m3==0.
175 for (rsh = 1, top = m0 >> 1; top >= sup; rsh++) /* XXX slow */
180 m2 = (m2 >> rsh) | (m1 << lsh);
181 m1 = (m1 >> rsh) | (m0 << lsh);
183 } else if (m0 < nrm) {
185 * We have a regular denorm (a subnormal number), and need
188 for (lsh = 1, top = m0 << 1; top < nrm; lsh++) /* XXX slow */
192 m0 = top | (m1 >> rsh);
193 m1 = (m1 << lsh) | (m2 >> rsh);
194 m2 = (m2 << lsh) | (m3 >> rsh);
206 * Concoct a `fresh' Quiet NaN per Appendix N.
207 * As a side effect, we set NV (invalid) for the current exceptions.
210 __fpu_newnan(struct fpemu *fe)
216 fp->fp_class = FPC_QNAN;
218 fp->fp_mant[0] = FP_1 - 1;
219 fp->fp_mant[1] = fp->fp_mant[2] = fp->fp_mant[3] = ~0;