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 #define MAX_HEX_DIGITS ((LDBL_MANT_DIG + 3 - 1) / 4 + 1)
69
70 static const float one[] = { 1.0f, -1.0f };
71
72 /*
73 * This is the long double version of __hdtoa().
74 */
75 char *
__hldtoa(long double e,const char * xdigs,int ndigits,int * decpt,int * sign,char ** rve)76 __hldtoa(long double e, const char *xdigs, int ndigits, int *decpt, int *sign,
77 char **rve)
78 {
79 union IEEEl2bits u;
80 char *s, *s0;
81 manh_t manh;
82 manl_t manl;
83 int bufsize;
84 #ifdef __i386__
85 fp_prec_t oldprec;
86 #endif
87
88 u.e = e;
89 *sign = u.bits.sign;
90
91 switch (fpclassify(e)) {
92 case FP_NORMAL:
93 *decpt = u.bits.exp - LDBL_ADJ;
94 break;
95 case FP_ZERO:
96 *decpt = 1;
97 return (nrv_alloc("0", rve, 1));
98 case FP_SUBNORMAL:
99 #ifdef __i386__
100 oldprec = fpsetprec(FP_PE);
101 #endif
102 u.e *= 0x1p514L;
103 *decpt = u.bits.exp - (514 + LDBL_ADJ);
104 #ifdef __i386__
105 fpsetprec(oldprec);
106 #endif
107 break;
108 case FP_INFINITE:
109 *decpt = INT_MAX;
110 return (nrv_alloc(INFSTR, rve, sizeof(INFSTR) - 1));
111 default: /* FP_NAN or unrecognized */
112 *decpt = INT_MAX;
113 return (nrv_alloc(NANSTR, rve, sizeof(NANSTR) - 1));
114 }
115
116 /* FP_NORMAL or FP_SUBNORMAL */
117
118 if (ndigits == 0) /* dtoa() compatibility */
119 ndigits = 1;
120
121 /*
122 * If ndigits < 0, we are expected to auto-size, so we allocate
123 * enough space for all the digits.
124 */
125 bufsize = (ndigits > 0) ? ndigits : SIGFIGS;
126 s0 = rv_alloc(bufsize);
127
128 /* Round to the desired number of digits. */
129 if (MAX_HEX_DIGITS > ndigits && ndigits > 0) {
130 float redux = one[u.bits.sign];
131 int offset = 4 * ndigits + LDBL_MAX_EXP - 4 - LDBL_MANT_DIG;
132 #ifdef __i386__
133 oldprec = fpsetprec(FP_PE);
134 #endif
135 u.bits.exp = offset;
136 u.e += redux;
137 u.e -= redux;
138 *decpt += u.bits.exp - offset;
139 #ifdef __i386__
140 fpsetprec(oldprec);
141 #endif
142 }
143
144 mask_nbit_l(u);
145 manh = u.bits.manh;
146 manl = u.bits.manl;
147 *s0 = '1';
148 for (s = s0 + 1; s < s0 + bufsize; s++) {
149 *s = xdigs[(manh >> (MANH_SIZE - 4)) & 0xf];
150 manh = (manh << 4) | (manl >> (LDBL_MANL_SIZE - 4));
151 manl <<= 4;
152 }
153
154 /* If ndigits < 0, we are expected to auto-size the precision. */
155 if (ndigits < 0) {
156 for (ndigits = SIGFIGS; s0[ndigits - 1] == '0'; ndigits--)
157 ;
158 }
159
160 s = s0 + ndigits;
161 *s = '\0';
162 if (rve != NULL)
163 *rve = s;
164 return (s0);
165 }
166
167 #else /* (LDBL_MANT_DIG == DBL_MANT_DIG) */
168
169 char *
__hldtoa(long double e,const char * xdigs,int ndigits,int * decpt,int * sign,char ** rve)170 __hldtoa(long double e, const char *xdigs, int ndigits, int *decpt, int *sign,
171 char **rve)
172 {
173
174 return (__hdtoa((double)e, xdigs, ndigits, decpt, sign, rve));
175 }
176
177 #endif /* (LDBL_MANT_DIG == DBL_MANT_DIG) */
178