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.
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11 * This product includes software developed by the University of
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23 * must display the following acknowledgement:
24 * This product includes software developed by the University of
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42 * @(#)fpu_subr.c 8.1 (Berkeley) 6/11/93
43 * $NetBSD: fpu_subr.c,v 1.3 1996/03/14 19:42:01 christos Exp $
46 #include <sys/cdefs.h>
47 __FBSDID("$FreeBSD$");
53 #include <sys/param.h>
55 #include <machine/frame.h>
56 #include <machine/fp.h>
57 #include <machine/fsr.h>
58 #include <machine/instr.h>
60 #include "fpu_arith.h"
62 #include "fpu_extern.h"
63 #include "__sparc_utrap_private.h"
66 * Shift the given number right rsh bits. Any bits that `fall off' will get
67 * shoved into the sticky field; we return the resulting sticky. Note that
68 * shifting NaNs is legal (this will never shift all bits out); a NaN's
69 * sticky field is ignored anyway.
72 __fpu_shr(struct fpn *fp, int rsh)
74 u_int m0, m1, m2, m3, s;
78 if (rsh <= 0 || (fp->fp_class != FPC_NUM && !ISNAN(fp)))
79 __utrap_panic("fpu_rightshift 1");
87 /* If shifting all the bits out, take a shortcut. */
88 if (rsh >= FP_NMANT) {
90 if ((m0 | m1 | m2 | m3) == 0)
91 __utrap_panic("fpu_rightshift 2");
98 if ((m0 | m1 | m2 | m3) == 0)
99 fp->fp_class = FPC_ZERO;
106 /* Squish out full words. */
110 m3 = m0, m2 = 0, m1 = 0, m0 = 0;
111 } else if (rsh >= 32 * 2) {
113 m3 = m1, m2 = m0, m1 = 0, m0 = 0;
114 } else if (rsh >= 32) {
116 m3 = m2, m2 = m1, m1 = m0, m0 = 0;
119 /* Handle any remaining partial word. */
120 if ((rsh &= 31) != 0) {
123 m3 = (m3 >> rsh) | (m2 << lsh);
124 m2 = (m2 >> rsh) | (m1 << lsh);
125 m1 = (m1 >> rsh) | (m0 << lsh);
137 * Force a number to be normal, i.e., make its fraction have all zero
138 * bits before FP_1, then FP_1, then all 1 bits. This is used for denorms
139 * and (sometimes) for intermediate results.
141 * Internally, this may use a `supernormal' -- a number whose fp_mant
142 * is greater than or equal to 2.0 -- so as a side effect you can hand it
143 * a supernormal and it will fix it (provided fp->fp_mant[3] == 0).
146 __fpu_norm(struct fpn *fp)
148 u_int m0, m1, m2, m3, top, sup, nrm;
157 /* Handle severe subnormals with 32-bit moves. */
160 m0 = m1, m1 = m2, m2 = m3, m3 = 0, exp -= 32;
162 m0 = m2, m1 = m3, m2 = 0, m3 = 0, exp -= 2 * 32;
164 m0 = m3, m1 = 0, m2 = 0, m3 = 0, exp -= 3 * 32;
166 fp->fp_class = FPC_ZERO;
171 /* Now fix any supernormal or remaining subnormal. */
176 * We have a supernormal number. We need to shift it right.
177 * We may assume m3==0.
179 for (rsh = 1, top = m0 >> 1; top >= sup; rsh++) /* XXX slow */
184 m2 = (m2 >> rsh) | (m1 << lsh);
185 m1 = (m1 >> rsh) | (m0 << lsh);
187 } else if (m0 < nrm) {
189 * We have a regular denorm (a subnormal number), and need
192 for (lsh = 1, top = m0 << 1; top < nrm; lsh++) /* XXX slow */
196 m0 = top | (m1 >> rsh);
197 m1 = (m1 << lsh) | (m2 >> rsh);
198 m2 = (m2 << lsh) | (m3 >> rsh);
210 * Concoct a `fresh' Quiet NaN per Appendix N.
211 * As a side effect, we set NV (invalid) for the current exceptions.
214 __fpu_newnan(struct fpemu *fe)
220 fp->fp_class = FPC_QNAN;
222 fp->fp_mant[0] = FP_1 - 1;
223 fp->fp_mant[1] = fp->fp_mant[2] = fp->fp_mant[3] = ~0;