1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (c) 2004-2008 David Schultz <das@FreeBSD.ORG>
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29 #include <float.h>
30 #include <limits.h>
31 #include <math.h>
32 #include <stdint.h>
33
34 #ifdef __i386__
35 #include <ieeefp.h>
36 #endif
37
38 #include "../stdio/floatio.h"
39 #include "fpmath.h"
40 #include "gdtoaimp.h"
41
42 #if (LDBL_MANT_DIG > DBL_MANT_DIG)
43
44 /* Strings values used by dtoa() */
45 #define INFSTR "Infinity"
46 #define NANSTR "NaN"
47
48 #ifdef LDBL_IMPLICIT_NBIT
49 #define MANH_SIZE LDBL_MANH_SIZE
50 #else
51 #define MANH_SIZE (LDBL_MANH_SIZE - 1)
52 #endif
53
54 #if MANH_SIZE > 32
55 typedef uint64_t manh_t;
56 #else
57 typedef uint32_t manh_t;
58 #endif
59
60 #if LDBL_MANL_SIZE > 32
61 typedef uint64_t manl_t;
62 #else
63 typedef uint32_t manl_t;
64 #endif
65
66 #define LDBL_ADJ (LDBL_MAX_EXP - 2)
67 #define SIGFIGS ((LDBL_MANT_DIG + 3) / 4 + 1)
68
69 static const float one[] = { 1.0f, -1.0f };
70
71 /*
72 * This is the long double version of __hdtoa().
73 */
74 char *
__hldtoa(long double e,const char * xdigs,int ndigits,int * decpt,int * sign,char ** rve)75 __hldtoa(long double e, const char *xdigs, int ndigits, int *decpt, int *sign,
76 char **rve)
77 {
78 union IEEEl2bits u;
79 char *s, *s0;
80 manh_t manh;
81 manl_t manl;
82 int bufsize;
83 #ifdef __i386__
84 fp_prec_t oldprec;
85 #endif
86
87 u.e = e;
88 *sign = u.bits.sign;
89
90 switch (fpclassify(e)) {
91 case FP_NORMAL:
92 *decpt = u.bits.exp - LDBL_ADJ;
93 break;
94 case FP_ZERO:
95 *decpt = 1;
96 return (nrv_alloc("0", rve, 1));
97 case FP_SUBNORMAL:
98 #ifdef __i386__
99 oldprec = fpsetprec(FP_PE);
100 #endif
101 u.e *= 0x1p514L;
102 *decpt = u.bits.exp - (514 + LDBL_ADJ);
103 #ifdef __i386__
104 fpsetprec(oldprec);
105 #endif
106 break;
107 case FP_INFINITE:
108 *decpt = INT_MAX;
109 return (nrv_alloc(INFSTR, rve, sizeof(INFSTR) - 1));
110 default: /* FP_NAN or unrecognized */
111 *decpt = INT_MAX;
112 return (nrv_alloc(NANSTR, rve, sizeof(NANSTR) - 1));
113 }
114
115 /* FP_NORMAL or FP_SUBNORMAL */
116
117 if (ndigits == 0) /* dtoa() compatibility */
118 ndigits = 1;
119
120 /*
121 * If ndigits < 0, we are expected to auto-size, so we allocate
122 * enough space for all the digits.
123 */
124 bufsize = (ndigits > 0) ? ndigits : SIGFIGS;
125 s0 = rv_alloc(bufsize);
126
127 /* Round to the desired number of digits. */
128 if (SIGFIGS > ndigits && ndigits > 0) {
129 float redux = one[u.bits.sign];
130 int offset = 4 * ndigits + LDBL_MAX_EXP - 4 - LDBL_MANT_DIG;
131 #ifdef __i386__
132 oldprec = fpsetprec(FP_PE);
133 #endif
134 u.bits.exp = offset;
135 u.e += redux;
136 u.e -= redux;
137 *decpt += u.bits.exp - offset;
138 #ifdef __i386__
139 fpsetprec(oldprec);
140 #endif
141 }
142
143 mask_nbit_l(u);
144 manh = u.bits.manh;
145 manl = u.bits.manl;
146 *s0 = '1';
147 for (s = s0 + 1; s < s0 + bufsize; s++) {
148 *s = xdigs[(manh >> (MANH_SIZE - 4)) & 0xf];
149 manh = (manh << 4) | (manl >> (LDBL_MANL_SIZE - 4));
150 manl <<= 4;
151 }
152
153 /* If ndigits < 0, we are expected to auto-size the precision. */
154 if (ndigits < 0) {
155 for (ndigits = SIGFIGS; s0[ndigits - 1] == '0'; ndigits--)
156 ;
157 }
158
159 s = s0 + ndigits;
160 *s = '\0';
161 if (rve != NULL)
162 *rve = s;
163 return (s0);
164 }
165
166 #else /* (LDBL_MANT_DIG == DBL_MANT_DIG) */
167
168 char *
__hldtoa(long double e,const char * xdigs,int ndigits,int * decpt,int * sign,char ** rve)169 __hldtoa(long double e, const char *xdigs, int ndigits, int *decpt, int *sign,
170 char **rve)
171 {
172
173 return (__hdtoa((double)e, xdigs, ndigits, decpt, sign, rve));
174 }
175
176 #endif /* (LDBL_MANT_DIG == DBL_MANT_DIG) */
177