Update.
[glibc.git] / misc / efgcvt_r.c
blobac2a5c45bf6cdaf1e972d3dceb114432bd101f4e
1 /* Compatibility functions for floating point formatting, reentrant versions.
2 Copyright (C) 1995,96,97,98,99,2000,01,02 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
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.
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.
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, write to the Free
17 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
18 02111-1307 USA. */
20 #include <errno.h>
21 #include <float.h>
22 #include <stdio.h>
23 #include <string.h>
24 #include <ctype.h>
25 #include <math.h>
26 #include <stdlib.h>
27 #include <sys/param.h>
29 #ifndef FLOAT_TYPE
30 # define FLOAT_TYPE double
31 # define FUNC_PREFIX
32 # define FLOAT_FMT_FLAG
33 # define FLOAT_NAME_EXT
34 # if DBL_MANT_DIG == 53
35 # define NDIGIT_MAX 17
36 # elif DBL_MANT_DIG == 24
37 # define NDIGIT_MAX 9
38 # elif DBL_MANT_DIG == 56
39 # define NDIGIT_MAX 18
40 # else
41 /* See IEEE 854 5.6, table 2 for this formula. Unfortunately we need a
42 compile time constant here, so we cannot use it. */
43 # error "NDIGIT_MAX must be precomputed"
44 # define NDIGIT_MAX (lrint (ceil (M_LN2 / M_LN10 * DBL_MANT_DIG + 1.0)))
45 # endif
46 #endif
48 #define APPEND(a, b) APPEND2 (a, b)
49 #define APPEND2(a, b) a##b
51 #define FLOOR APPEND(floor, FLOAT_NAME_EXT)
52 #define FABS APPEND(fabs, FLOAT_NAME_EXT)
53 #define LOG10 APPEND(log10, FLOAT_NAME_EXT)
54 #define EXP APPEND(exp, FLOAT_NAME_EXT)
57 int
58 APPEND (FUNC_PREFIX, fcvt_r) (value, ndigit, decpt, sign, buf, len)
59 FLOAT_TYPE value;
60 int ndigit, *decpt, *sign;
61 char *buf;
62 size_t len;
64 ssize_t n;
65 ssize_t i;
66 int left;
68 if (buf == NULL)
70 __set_errno (EINVAL);
71 return -1;
74 left = 0;
75 if (isfinite (value))
77 *sign = signbit (value) != 0;
78 if (*sign)
79 value = -value;
81 if (ndigit < 0)
83 /* Rounding to the left of the decimal point. */
84 while (ndigit < 0)
86 FLOAT_TYPE new_value = value * 0.1;
88 if (new_value < 1.0)
90 ndigit = 0;
91 break;
94 value = new_value;
95 ++left;
96 ++ndigit;
100 else
101 /* Value is Inf or NaN. */
102 *sign = 0;
104 n = __snprintf (buf, len, "%.*" FLOAT_FMT_FLAG "f", MIN (ndigit, NDIGIT_MAX),
105 value);
106 /* Check for a too small buffer. */
107 if (n >= (ssize_t) len)
108 return -1;
110 i = 0;
111 while (i < n && isdigit (buf[i]))
112 ++i;
113 *decpt = i;
115 if (i == 0)
116 /* Value is Inf or NaN. */
117 return 0;
119 if (i < n)
122 ++i;
123 while (i < n && !isdigit (buf[i]));
125 if (*decpt == 1 && buf[0] == '0' && value != 0.0)
127 /* We must not have leading zeroes. Strip them all out and
128 adjust *DECPT if necessary. */
129 --*decpt;
130 while (i < n && buf[i] == '0')
132 --*decpt;
133 ++i;
137 memmove (&buf[MAX (*decpt, 0)], &buf[i], n - i);
138 buf[n - (i - MAX (*decpt, 0))] = '\0';
141 if (left)
143 *decpt += left;
144 if ((ssize_t) --len > n)
146 while (left-- > 0 && n < (ssize_t) len)
147 buf[n++] = '0';
148 buf[n] = '\0';
152 return 0;
154 libc_hidden_def (APPEND (FUNC_PREFIX, fcvt_r))
157 APPEND (FUNC_PREFIX, ecvt_r) (value, ndigit, decpt, sign, buf, len)
158 FLOAT_TYPE value;
159 int ndigit, *decpt, *sign;
160 char *buf;
161 size_t len;
163 int exponent = 0;
165 if (isfinite (value) && value != 0.0)
167 /* Slow code that doesn't require -lm functions. */
168 FLOAT_TYPE d;
169 FLOAT_TYPE f = 1.0;
170 if (value < 0.0)
171 d = -value;
172 else
173 d = value;
174 if (d < 1.0)
178 f *= 10.0;
179 --exponent;
181 while (d * f < 1.0);
183 value *= f;
185 else if (d >= 10.0)
189 f *= 10;
190 ++exponent;
192 while (d >= f * 10.0);
194 value /= f;
197 else if (value == 0.0)
198 /* SUSv2 leaves it unspecified whether *DECPT is 0 or 1 for 0.0.
199 This could be changed to -1 if we want to return 0. */
200 exponent = 0;
202 if (ndigit <= 0 && len > 0)
204 buf[0] = '\0';
205 *decpt = 1;
206 *sign = isfinite (value) ? signbit (value) != 0 : 0;
208 else
209 if (APPEND (FUNC_PREFIX, fcvt_r) (value, MIN (ndigit, NDIGIT_MAX) - 1,
210 decpt, sign, buf, len))
211 return -1;
213 *decpt += exponent;
214 return 0;
216 libc_hidden_def (APPEND (FUNC_PREFIX, ecvt_r))