xref: /illumos-gate/usr/src/lib/libc/port/fp/hex_bin.c (revision 1da57d551424de5a9d469760be7c4b4d4f10a755)
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 (the "License").
6  * You may not use this file except in compliance with the License.
7  *
8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9  * or http://www.opensolaris.org/os/licensing.
10  * See the License for the specific language governing permissions
11  * and limitations under the License.
12  *
13  * When distributing Covered Code, include this CDDL HEADER in each
14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15  * If applicable, add the following below this CDDL HEADER, with the
16  * fields enclosed by brackets "[]" replaced with your own identifying
17  * information: Portions Copyright [yyyy] [name of copyright owner]
18  *
19  * CDDL HEADER END
20  */
21 
22 /*
23  * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
24  * Use is subject to license terms.
25  */
26 
27 #include "lint.h"
28 #include "base_conversion.h"
29 
30 /* conversion from hex chars to hex values */
31 #define	HEXVAL(c)	(('0' <= c && c <= '9')? c - '0' : \
32 			10 + (('a' <= c && c <= 'f')? c - 'a' : c - 'A'))
33 
34 /*
35  * Convert a hexadecimal record in *pd to unpacked form in *pu.
36  *
37  * Up to 30 hexadecimal digits from pd->ds are converted to a binary
38  * value in px->significand, which is then normalized so that the most
39  * significant bit is 1.  If there are additional, unused digits in
40  * pd->ds, the least significant bit of px->significand will be set.
41  */
42 static void
__hex_to_unpacked(decimal_record * pd,unpacked * pu)43 __hex_to_unpacked(decimal_record *pd, unpacked *pu)
44 {
45 	int	i, n;
46 
47 	pu->sign = pd->sign;
48 	pu->fpclass = pd->fpclass;
49 
50 	/*
51 	 * Adjust the (base two) exponent to reflect the fact that the
52 	 * radix point in *pd lies to the right of the last (base sixteen)
53 	 * digit while the radix point in *pu lies to the right of the
54 	 * most significant bit.
55 	 */
56 	pu->exponent = pd->exponent + (pd->ndigits << 2) - 1;
57 
58 	/* fill in the significand */
59 	for (i = 0; i < 5; i++)
60 		pu->significand[i] = 0;
61 
62 	n = pd->ndigits;
63 	if (n > 30)
64 		n = 30;
65 	for (i = 0; i < n; i++) {
66 		pu->significand[i >> 3] |= HEXVAL(pd->ds[i]) <<
67 		    ((7 - (i & 7)) << 2);
68 	}
69 
70 	/* sanity check */
71 	if (pu->significand[0] == 0) {
72 		pu->fpclass = fp_zero;
73 		return;
74 	}
75 
76 	/* normalize so the most significant bit is set */
77 	while (pu->significand[0] < 0x80000000u) {
78 		pu->significand[0] = (pu->significand[0] << 1) |
79 		    (pu->significand[1] >> 31);
80 		pu->significand[1] = (pu->significand[1] << 1) |
81 		    (pu->significand[2] >> 31);
82 		pu->significand[2] = (pu->significand[2] << 1) |
83 		    (pu->significand[3] >> 31);
84 		pu->significand[3] <<= 1;
85 		pu->exponent--;
86 	}
87 
88 	/* if there are any unused digits, set a sticky bit */
89 	if (pd->ndigits > 30 || pd->more)
90 		pu->significand[4] = 1;
91 }
92 
93 /*
94  * The following routines convert the hexadecimal value encoded in the
95  * decimal record *pd to a floating point value *px observing the round-
96  * ing mode specified in rd and passing back any exceptions raised via
97  * *ps.
98  *
99  * These routines assume pd->fpclass is either fp_zero or fp_normal.
100  * If pd->fpclass is fp_zero, *px is set to zero with the sign indicated
101  * by pd->sign and no exceptions are raised.  Otherwise, pd->ds must
102  * contain a string of hexadecimal digits of length pd->ndigits > 0, and
103  * the first digit must be nonzero.  Let m be the integer represented by
104  * this string.  Then *px is set to a correctly rounded approximation to
105  *
106  *  (-1)^(pd->sign) * m * 2^(pd->exponent)
107  *
108  * with inexact, underflow, and/or overflow raised as appropriate.
109  */
110 
111 void
__hex_to_single(decimal_record * pd,enum fp_direction_type rd,single * px,fp_exception_field_type * ps)112 __hex_to_single(decimal_record *pd, enum fp_direction_type rd, single *px,
113     fp_exception_field_type *ps)
114 {
115 	single_equivalence	kluge;
116 	unpacked		u;
117 
118 	*ps = 0;
119 	if (pd->fpclass == fp_zero) {
120 		kluge.f.msw.sign = pd->sign? 1 : 0;
121 		kluge.f.msw.exponent = 0;
122 		kluge.f.msw.significand = 0;
123 		*px = kluge.x;
124 	} else {
125 		__hex_to_unpacked(pd, &u);
126 		__pack_single(&u, px, rd, ps);
127 		if (*ps != 0)
128 			__base_conversion_set_exception(*ps);
129 	}
130 }
131 
132 void
__hex_to_double(decimal_record * pd,enum fp_direction_type rd,double * px,fp_exception_field_type * ps)133 __hex_to_double(decimal_record *pd, enum fp_direction_type rd, double *px,
134     fp_exception_field_type *ps)
135 {
136 	double_equivalence	kluge;
137 	unpacked		u;
138 
139 	*ps = 0;
140 	if (pd->fpclass == fp_zero) {
141 		kluge.f.msw.sign = pd->sign? 1 : 0;
142 		kluge.f.msw.exponent = 0;
143 		kluge.f.msw.significand = 0;
144 		kluge.f.significand2 = 0;
145 		*px = kluge.x;
146 	} else {
147 		__hex_to_unpacked(pd, &u);
148 		__pack_double(&u, px, rd, ps);
149 		if (*ps != 0)
150 			__base_conversion_set_exception(*ps);
151 	}
152 }
153 
154 #if defined(__sparc)
155 
156 void
__hex_to_quadruple(decimal_record * pd,enum fp_direction_type rd,quadruple * px,fp_exception_field_type * ps)157 __hex_to_quadruple(decimal_record *pd, enum fp_direction_type rd, quadruple *px,
158     fp_exception_field_type *ps)
159 {
160 	quadruple_equivalence	kluge;
161 	unpacked		u;
162 
163 	*ps = 0;
164 	if (pd->fpclass == fp_zero) {
165 		kluge.f.msw.sign = pd->sign? 1 : 0;
166 		kluge.f.msw.exponent = 0;
167 		kluge.f.msw.significand = 0;
168 		kluge.f.significand2 = 0;
169 		kluge.f.significand3 = 0;
170 		kluge.f.significand4 = 0;
171 		*px = kluge.x;
172 	} else {
173 		__hex_to_unpacked(pd, &u);
174 		__pack_quadruple(&u, px, rd, ps);
175 		if (*ps != 0)
176 			__base_conversion_set_exception(*ps);
177 	}
178 }
179 
180 #elif defined(__i386) || defined(__amd64)
181 
182 void
__hex_to_extended(decimal_record * pd,enum fp_direction_type rd,extended * px,fp_exception_field_type * ps)183 __hex_to_extended(decimal_record *pd, enum fp_direction_type rd, extended *px,
184     fp_exception_field_type *ps)
185 {
186 	extended_equivalence	kluge;
187 	unpacked		u;
188 
189 	*ps = 0;
190 	if (pd->fpclass == fp_zero) {
191 		kluge.f.msw.sign = pd->sign? 1 : 0;
192 		kluge.f.msw.exponent = 0;
193 		kluge.f.significand = 0;
194 		kluge.f.significand2 = 0;
195 		(*px)[0] = kluge.x[0];
196 		(*px)[1] = kluge.x[1];
197 		(*px)[2] = kluge.x[2];
198 	} else {
199 		__hex_to_unpacked(pd, &u);
200 		__pack_extended(&u, px, rd, ps);
201 		if (*ps != 0)
202 			__base_conversion_set_exception(*ps);
203 	}
204 }
205 
206 #else
207 #error Unknown architecture
208 #endif
209