1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License, Version 1.0 only
6 * (the "License"). You may not use this file except in compliance
7 * with the License.
8 *
9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10 * or http://www.opensolaris.org/os/licensing.
11 * See the License for the specific language governing permissions
12 * and limitations under the License.
13 *
14 * When distributing Covered Code, include this CDDL HEADER in each
15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16 * If applicable, add the following below this CDDL HEADER, with the
17 * fields enclosed by brackets "[]" replaced with your own identifying
18 * information: Portions Copyright [yyyy] [name of copyright owner]
19 *
20 * CDDL HEADER END
21 */
22 /*
23 * Copyright (c) 1994-1997, by Sun Microsystems, Inc.
24 * All rights reserved.
25 */
26
27 #pragma ident "%Z%%M% %I% %E% SMI"
28
29 #include "quad.h"
30
31 #ifdef __sparcv9
32 #define _Q_qtod _Qp_qtod
33 #endif
34
35 /*
36 * _Q_qtod(x) returns (double)*x.
37 */
38 double
_Q_qtod(const union longdouble * x)39 _Q_qtod(const union longdouble *x)
40 {
41 union xdouble u;
42 unsigned int xm, round, sticky, fsr, rm;
43 int subnormal, e;
44
45 xm = x->l.msw & 0x7fffffff;
46
47 /* get the rounding mode, fudging directed rounding modes */
48 /* as though the result were positive */
49 __quad_getfsrp(&fsr);
50 rm = fsr >> 30;
51 if (x->l.msw & 0x80000000)
52 rm ^= (rm >> 1);
53
54 /* handle nan, inf, and out-of-range cases */
55 if (xm >= 0x43ff0000) {
56 if (xm >= 0x7fff0000) {
57 if ((xm & 0xffff) | x->l.frac2 | x->l.frac3 |
58 x->l.frac4) {
59 /* x is nan */
60 u.l.hi = (x->l.msw & 0x80000000) | 0x7ff80000;
61 u.l.hi |= ((xm & 0x7fff) << 4) |
62 (x->l.frac2 >> 28);
63 u.l.lo = (x->l.frac2 << 4) |
64 (x->l.frac3 >> 28);
65 if (!(xm & 0x8000)) {
66 /* snan, signal invalid */
67 if (fsr & FSR_NVM) {
68 __quad_fqtod(x, &u.d);
69 } else {
70 fsr = (fsr & ~FSR_CEXC) |
71 FSR_NVA | FSR_NVC;
72 __quad_setfsrp(&fsr);
73 }
74 }
75 return (u.d);
76 }
77 /* x is inf */
78 u.l.hi = (x->l.msw & 0x80000000) | 0x7ff00000;
79 u.l.lo = 0;
80 return (u.d);
81 }
82 /* x is too big, overflow */
83 if (rm == FSR_RN || rm == FSR_RP) {
84 u.l.hi = 0x7ff00000;
85 u.l.lo = 0;
86 } else {
87 u.l.hi = 0x7fefffff;
88 u.l.lo = 0xffffffff;
89 }
90 u.l.hi |= (x->l.msw & 0x80000000);
91 if (fsr & (FSR_OFM | FSR_NXM)) {
92 __quad_fqtod(x, &u.d);
93 } else {
94 fsr = (fsr & ~FSR_CEXC) | FSR_OFA | FSR_OFC |
95 FSR_NXA | FSR_NXC;
96 __quad_setfsrp(&fsr);
97 }
98 return (u.d);
99 }
100
101 subnormal = 0;
102 if (xm < 0x3c010000) {
103 if (xm < 0x3bcc0000) {
104 if (QUAD_ISZERO(*x)) {
105 u.l.hi = (x->l.msw & 0x80000000);
106 u.l.lo = 0;
107 return (u.d);
108 }
109 /* x is too small, underflow */
110 u.l.hi = (x->l.msw & 0x80000000);
111 u.l.lo = ((rm == FSR_RP)? 1 : 0);
112 if (fsr & (FSR_UFM | FSR_NXM)) {
113 __quad_fqtod(x, &u.d);
114 } else {
115 fsr = (fsr & ~FSR_CEXC) | FSR_UFA | FSR_UFC |
116 FSR_NXA | FSR_NXC;
117 __quad_setfsrp(&fsr);
118 }
119 return (u.d);
120 }
121
122 /* x is in the subnormal range for double */
123 subnormal = 1;
124 u.l.hi = 0x80000 | ((xm & 0xffff) << 3) | (x->l.frac2 >> 29);
125 u.l.lo = (x->l.frac2 << 3) | (x->l.frac3 >> 29);
126 round = x->l.frac3 & 0x10000000;
127 sticky = (x->l.frac3 & 0xfffffff) | x->l.frac4;
128 e = 0x3c00 - (xm >> 16);
129 if (e >= 32) {
130 sticky |= round | (u.l.lo & 0x7fffffff);
131 round = u.l.lo & 0x80000000;
132 u.l.lo = u.l.hi;
133 u.l.hi = 0;
134 e -= 32;
135 }
136 if (e) {
137 sticky |= round | (u.l.lo & ((1 << (e - 1)) - 1));
138 round = u.l.lo & (1 << (e - 1));
139 u.l.lo = (u.l.lo >> e) | (u.l.hi << (32 - e));
140 u.l.hi >>= e;
141 }
142 } else {
143 /* x is in the normal range for double */
144 u.l.hi = ((xm - 0x3c000000) << 4) | (x->l.frac2 >> 28);
145 u.l.lo = (x->l.frac2 << 4) | (x->l.frac3 >> 28);
146 round = x->l.frac3 & 0x8000000;
147 sticky = (x->l.frac3 & 0x7ffffff) | x->l.frac4;
148 }
149
150 /* see if we need to round */
151 fsr &= ~FSR_CEXC;
152 if (round | sticky) {
153 fsr |= FSR_NXC;
154 if (subnormal)
155 fsr |= FSR_UFC;
156
157 /* round up if necessary */
158 if (rm == FSR_RP || (rm == FSR_RN && round && (sticky ||
159 (u.l.lo & 1)))) {
160 /* round up and check for overflow */
161 if (++u.l.lo == 0)
162 if (++u.l.hi >= 0x7ff00000)
163 fsr |= FSR_OFC;
164 }
165 }
166
167 /* if result is exact and subnormal but underflow trapping is */
168 /* enabled, signal underflow */
169 else if (subnormal && (fsr & FSR_UFM))
170 fsr |= FSR_UFC;
171
172 /* attach the sign and raise exceptions as need be */
173 u.l.hi |= (x->l.msw & 0x80000000);
174 if ((fsr & FSR_CEXC) & (fsr >> 23)) {
175 __quad_setfsrp(&fsr);
176 __quad_fqtod(x, &u.d);
177 } else {
178 fsr |= (fsr & 0x1f) << 5;
179 __quad_setfsrp(&fsr);
180 }
181 return (u.d);
182 }
183