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 #include "quad.h"
28
29 #ifdef __sparcv9
30 #define _Q_qtod _Qp_qtod
31 #endif
32
33 /*
34 * _Q_qtod(x) returns (double)*x.
35 */
36 double
_Q_qtod(const union longdouble * x)37 _Q_qtod(const union longdouble *x)
38 {
39 union xdouble u;
40 unsigned int xm, round, sticky, fsr, rm;
41 int subnormal, e;
42
43 xm = x->l.msw & 0x7fffffff;
44
45 /* get the rounding mode, fudging directed rounding modes */
46 /* as though the result were positive */
47 __quad_getfsrp(&fsr);
48 rm = fsr >> 30;
49 if (x->l.msw & 0x80000000)
50 rm ^= (rm >> 1);
51
52 /* handle nan, inf, and out-of-range cases */
53 if (xm >= 0x43ff0000) {
54 if (xm >= 0x7fff0000) {
55 if ((xm & 0xffff) | x->l.frac2 | x->l.frac3 |
56 x->l.frac4) {
57 /* x is nan */
58 u.l.hi = (x->l.msw & 0x80000000) | 0x7ff80000;
59 u.l.hi |= ((xm & 0x7fff) << 4) |
60 (x->l.frac2 >> 28);
61 u.l.lo = (x->l.frac2 << 4) |
62 (x->l.frac3 >> 28);
63 if (!(xm & 0x8000)) {
64 /* snan, signal invalid */
65 if (fsr & FSR_NVM) {
66 __quad_fqtod(x, &u.d);
67 } else {
68 fsr = (fsr & ~FSR_CEXC) |
69 FSR_NVA | FSR_NVC;
70 __quad_setfsrp(&fsr);
71 }
72 }
73 return (u.d);
74 }
75 /* x is inf */
76 u.l.hi = (x->l.msw & 0x80000000) | 0x7ff00000;
77 u.l.lo = 0;
78 return (u.d);
79 }
80 /* x is too big, overflow */
81 if (rm == FSR_RN || rm == FSR_RP) {
82 u.l.hi = 0x7ff00000;
83 u.l.lo = 0;
84 } else {
85 u.l.hi = 0x7fefffff;
86 u.l.lo = 0xffffffff;
87 }
88 u.l.hi |= (x->l.msw & 0x80000000);
89 if (fsr & (FSR_OFM | FSR_NXM)) {
90 __quad_fqtod(x, &u.d);
91 } else {
92 fsr = (fsr & ~FSR_CEXC) | FSR_OFA | FSR_OFC |
93 FSR_NXA | FSR_NXC;
94 __quad_setfsrp(&fsr);
95 }
96 return (u.d);
97 }
98
99 subnormal = 0;
100 if (xm < 0x3c010000) {
101 if (xm < 0x3bcc0000) {
102 if (QUAD_ISZERO(*x)) {
103 u.l.hi = (x->l.msw & 0x80000000);
104 u.l.lo = 0;
105 return (u.d);
106 }
107 /* x is too small, underflow */
108 u.l.hi = (x->l.msw & 0x80000000);
109 u.l.lo = ((rm == FSR_RP)? 1 : 0);
110 if (fsr & (FSR_UFM | FSR_NXM)) {
111 __quad_fqtod(x, &u.d);
112 } else {
113 fsr = (fsr & ~FSR_CEXC) | FSR_UFA | FSR_UFC |
114 FSR_NXA | FSR_NXC;
115 __quad_setfsrp(&fsr);
116 }
117 return (u.d);
118 }
119
120 /* x is in the subnormal range for double */
121 subnormal = 1;
122 u.l.hi = 0x80000 | ((xm & 0xffff) << 3) | (x->l.frac2 >> 29);
123 u.l.lo = (x->l.frac2 << 3) | (x->l.frac3 >> 29);
124 round = x->l.frac3 & 0x10000000;
125 sticky = (x->l.frac3 & 0xfffffff) | x->l.frac4;
126 e = 0x3c00 - (xm >> 16);
127 if (e >= 32) {
128 sticky |= round | (u.l.lo & 0x7fffffff);
129 round = u.l.lo & 0x80000000;
130 u.l.lo = u.l.hi;
131 u.l.hi = 0;
132 e -= 32;
133 }
134 if (e) {
135 sticky |= round | (u.l.lo & ((1 << (e - 1)) - 1));
136 round = u.l.lo & (1 << (e - 1));
137 u.l.lo = (u.l.lo >> e) | (u.l.hi << (32 - e));
138 u.l.hi >>= e;
139 }
140 } else {
141 /* x is in the normal range for double */
142 u.l.hi = ((xm - 0x3c000000) << 4) | (x->l.frac2 >> 28);
143 u.l.lo = (x->l.frac2 << 4) | (x->l.frac3 >> 28);
144 round = x->l.frac3 & 0x8000000;
145 sticky = (x->l.frac3 & 0x7ffffff) | x->l.frac4;
146 }
147
148 /* see if we need to round */
149 fsr &= ~FSR_CEXC;
150 if (round | sticky) {
151 fsr |= FSR_NXC;
152 if (subnormal)
153 fsr |= FSR_UFC;
154
155 /* round up if necessary */
156 if (rm == FSR_RP || (rm == FSR_RN && round && (sticky ||
157 (u.l.lo & 1)))) {
158 /* round up and check for overflow */
159 if (++u.l.lo == 0)
160 if (++u.l.hi >= 0x7ff00000)
161 fsr |= FSR_OFC;
162 }
163 }
164
165 /* if result is exact and subnormal but underflow trapping is */
166 /* enabled, signal underflow */
167 else if (subnormal && (fsr & FSR_UFM))
168 fsr |= FSR_UFC;
169
170 /* attach the sign and raise exceptions as need be */
171 u.l.hi |= (x->l.msw & 0x80000000);
172 if ((fsr & FSR_CEXC) & (fsr >> 23)) {
173 __quad_setfsrp(&fsr);
174 __quad_fqtod(x, &u.d);
175 } else {
176 fsr |= (fsr & 0x1f) << 5;
177 __quad_setfsrp(&fsr);
178 }
179 return (u.d);
180 }
181