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 | |
73 | int |
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 | |
168 | int |
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 |
256 | cvt_symbol(fcvt_r); |
257 | cvt_symbol(ecvt_r); |
258 | |