1/* Compatibility functions for floating point formatting, reentrant versions.
2 Copyright (C) 1995-2017 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <http://www.gnu.org/licenses/>. */
18
19#include <errno.h>
20#include <float.h>
21#include <stdio.h>
22#include <string.h>
23#include <ctype.h>
24#include <math.h>
25#include <stdlib.h>
26#include <sys/param.h>
27#include <math_ldbl_opt.h>
28
29#ifndef FLOAT_TYPE
30# define FLOAT_TYPE double
31# define FUNC_PREFIX
32# define FLOAT_FMT_FLAG
33# define FLOAT_NAME_EXT
34# define FLOAT_MIN_10_EXP DBL_MIN_10_EXP
35# if DBL_MANT_DIG == 53
36# define NDIGIT_MAX 17
37# elif DBL_MANT_DIG == 24
38# define NDIGIT_MAX 9
39# elif DBL_MANT_DIG == 56
40# define NDIGIT_MAX 18
41# else
42/* See IEEE 854 5.6, table 2 for this formula. Unfortunately we need a
43 compile time constant here, so we cannot use it. */
44# error "NDIGIT_MAX must be precomputed"
45# define NDIGIT_MAX (lrint (ceil (M_LN2 / M_LN10 * DBL_MANT_DIG + 1.0)))
46# endif
47# if DBL_MIN_10_EXP == -37
48# define FLOAT_MIN_10_NORM 1.0e-37
49# elif DBL_MIN_10_EXP == -307
50# define FLOAT_MIN_10_NORM 1.0e-307
51# elif DBL_MIN_10_EXP == -4931
52# define FLOAT_MIN_10_NORM 1.0e-4931
53# else
54/* libc can't depend on libm. */
55# error "FLOAT_MIN_10_NORM must be precomputed"
56# define FLOAT_MIN_10_NORM exp10 (DBL_MIN_10_EXP)
57# endif
58#else
59# define LONG_DOUBLE_CVT
60#endif
61
62#define APPEND(a, b) APPEND2 (a, b)
63#define APPEND2(a, b) a##b
64#define __APPEND(a, b) __APPEND2 (a, b)
65#define __APPEND2(a, b) __##a##b
66
67#define FLOOR APPEND(floor, FLOAT_NAME_EXT)
68#define FABS APPEND(fabs, FLOAT_NAME_EXT)
69#define LOG10 APPEND(log10, FLOAT_NAME_EXT)
70#define EXP APPEND(exp, FLOAT_NAME_EXT)
71
72
73int
74__APPEND (FUNC_PREFIX, fcvt_r) (FLOAT_TYPE value, int ndigit, int *decpt,
75 int *sign, char *buf, size_t len)
76{
77 ssize_t n;
78 ssize_t i;
79 int left;
80
81 if (buf == NULL)
82 {
83 __set_errno (EINVAL);
84 return -1;
85 }
86
87 left = 0;
88 if (isfinite (value))
89 {
90 *sign = signbit (value) != 0;
91 if (*sign)
92 value = -value;
93
94 if (ndigit < 0)
95 {
96 /* Rounding to the left of the decimal point. */
97 while (ndigit < 0)
98 {
99 FLOAT_TYPE new_value = value * 0.1;
100
101 if (new_value < 1.0)
102 {
103 ndigit = 0;
104 break;
105 }
106
107 value = new_value;
108 ++left;
109 ++ndigit;
110 }
111 }
112 }
113 else
114 /* Value is Inf or NaN. */
115 *sign = 0;
116
117 n = __snprintf (buf, len, "%.*" FLOAT_FMT_FLAG "f", MIN (ndigit, NDIGIT_MAX),
118 value);
119 /* Check for a too small buffer. */
120 if (n >= (ssize_t) len)
121 return -1;
122
123 i = 0;
124 while (i < n && isdigit (buf[i]))
125 ++i;
126 *decpt = i;
127
128 if (i == 0)
129 /* Value is Inf or NaN. */
130 return 0;
131
132 if (i < n)
133 {
134 do
135 ++i;
136 while (i < n && !isdigit (buf[i]));
137
138 if (*decpt == 1 && buf[0] == '0' && value != 0.0)
139 {
140 /* We must not have leading zeroes. Strip them all out and
141 adjust *DECPT if necessary. */
142 --*decpt;
143 while (i < n && buf[i] == '0')
144 {
145 --*decpt;
146 ++i;
147 }
148 }
149
150 memmove (&buf[MAX (*decpt, 0)], &buf[i], n - i);
151 buf[n - (i - MAX (*decpt, 0))] = '\0';
152 }
153
154 if (left)
155 {
156 *decpt += left;
157 if ((ssize_t) --len > n)
158 {
159 while (left-- > 0 && n < (ssize_t) len)
160 buf[n++] = '0';
161 buf[n] = '\0';
162 }
163 }
164
165 return 0;
166}
167
168int
169__APPEND (FUNC_PREFIX, ecvt_r) (FLOAT_TYPE value, int ndigit, int *decpt,
170 int *sign, char *buf, size_t len)
171{
172 int exponent = 0;
173
174 if (isfinite (value) && value != 0.0)
175 {
176 /* Slow code that doesn't require -lm functions. */
177 FLOAT_TYPE d;
178 FLOAT_TYPE f = 1.0;
179 if (value < 0.0)
180 d = -value;
181 else
182 d = value;
183 /* For denormalized numbers the d < 1.0 case below won't work,
184 as f can overflow to +Inf. */
185 if (d < FLOAT_MIN_10_NORM)
186 {
187 value /= FLOAT_MIN_10_NORM;
188 if (value < 0.0)
189 d = -value;
190 else
191 d = value;
192 exponent += FLOAT_MIN_10_EXP;
193 }
194 if (d < 1.0)
195 {
196 do
197 {
198 f *= 10.0;
199 --exponent;
200 }
201 while (d * f < 1.0);
202
203 value *= f;
204 }
205 else if (d >= 10.0)
206 {
207 do
208 {
209 f *= 10;
210 ++exponent;
211 }
212 while (d >= f * 10.0);
213
214 value /= f;
215 }
216 }
217 else if (value == 0.0)
218 /* SUSv2 leaves it unspecified whether *DECPT is 0 or 1 for 0.0.
219 This could be changed to -1 if we want to return 0. */
220 exponent = 0;
221
222 if (ndigit <= 0 && len > 0)
223 {
224 buf[0] = '\0';
225 *decpt = 1;
226 *sign = isfinite (value) ? signbit (value) != 0 : 0;
227 }
228 else
229 if (__APPEND (FUNC_PREFIX, fcvt_r) (value, MIN (ndigit, NDIGIT_MAX) - 1,
230 decpt, sign, buf, len))
231 return -1;
232
233 *decpt += exponent;
234 return 0;
235}
236
237#if LONG_DOUBLE_COMPAT (libc, GLIBC_2_0)
238# ifdef LONG_DOUBLE_CVT
239# define cvt_symbol(symbol) \
240 cvt_symbol_1 (libc, __APPEND (FUNC_PREFIX, symbol), \
241 APPEND (FUNC_PREFIX, symbol), GLIBC_2_4)
242# define cvt_symbol_1(lib, local, symbol, version) \
243 versioned_symbol (lib, local, symbol, version)
244# else
245# define cvt_symbol(symbol) \
246 cvt_symbol_1 (libc, __APPEND (FUNC_PREFIX, symbol), \
247 APPEND (q, symbol), GLIBC_2_0); \
248 weak_alias (__APPEND (FUNC_PREFIX, symbol), APPEND (FUNC_PREFIX, symbol))
249# define cvt_symbol_1(lib, local, symbol, version) \
250 compat_symbol (lib, local, symbol, version)
251# endif
252#else
253# define cvt_symbol(symbol) \
254 weak_alias (__APPEND (FUNC_PREFIX, symbol), APPEND (FUNC_PREFIX, symbol))
255#endif
256cvt_symbol(fcvt_r);
257cvt_symbol(ecvt_r);
258