misc/efgcvt_r.c

   1 /* Compatibility functions for floating point formatting, reentrant versions.
   2    Copyright (C) 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2004, 2006
   3    Free Software Foundation, Inc.
   4    This file is part of the GNU C Library.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, write to the Free
  18    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19    02111-1307 USA.  */
  20
  21 #include <errno.h>
  22 #include <float.h>
  23 #include <stdio.h>
  24 #include <string.h>
  25 #include <ctype.h>
  26 #include <math.h>
  27 #include <stdlib.h>
  28 #include <sys/param.h>
  29 #include <math_ldbl_opt.h>
  30
  31 #ifndef FLOAT_TYPE
  32 # define FLOAT_TYPE double
  33 # define FUNC_PREFIX
  34 # define FLOAT_FMT_FLAG
  35 # define FLOAT_NAME_EXT
  36 # define FLOAT_MIN_10_EXP DBL_MIN_10_EXP
  37 # if DBL_MANT_DIG == 53
  38 #  define NDIGIT_MAX 17
  39 # elif DBL_MANT_DIG == 24
  40 #  define NDIGIT_MAX 9
  41 # elif DBL_MANT_DIG == 56
  42 #  define NDIGIT_MAX 18
  43 # else
  44 /* See IEEE 854 5.6, table 2 for this formula.  Unfortunately we need a
  45    compile time constant here, so we cannot use it.  */
  46 #  error "NDIGIT_MAX must be precomputed"
  47 #  define NDIGIT_MAX (lrint (ceil (M_LN2 / M_LN10 * DBL_MANT_DIG + 1.0)))
  48 # endif
  49 # if DBL_MIN_10_EXP == -37
  50 #  define FLOAT_MIN_10_NORM     1.0e-37
  51 # elif DBL_MIN_10_EXP == -307
  52 #  define FLOAT_MIN_10_NORM     1.0e-307
  53 # elif DBL_MIN_10_EXP == -4931
  54 #  define FLOAT_MIN_10_NORM     1.0e-4931
  55 # else
  56 /* libc can't depend on libm.  */
  57 #  error "FLOAT_MIN_10_NORM must be precomputed"
  58 #  define FLOAT_MIN_10_NORM     exp10 (DBL_MIN_10_EXP)
  59 # endif
  60 #else
  61 # define LONG_DOUBLE_CVT
  62 #endif
  63
  64 #define APPEND(a, b) APPEND2 (a, b)
  65 #define APPEND2(a, b) a##b
  66 #define __APPEND(a, b) __APPEND2 (a, b)
  67 #define __APPEND2(a, b) __##a##b
  68
  69 #define FLOOR APPEND(floor, FLOAT_NAME_EXT)
  70 #define FABS APPEND(fabs, FLOAT_NAME_EXT)
  71 #define LOG10 APPEND(log10, FLOAT_NAME_EXT)
  72 #define EXP APPEND(exp, FLOAT_NAME_EXT)
  73
  74
  75 int
  76 __APPEND (FUNC_PREFIX, fcvt_r) (value, ndigit, decpt, sign, buf, len)
  77      FLOAT_TYPE value;
  78      int ndigit, *decpt, *sign;
  79      char *buf;
  80      size_t len;
  81 {
  82   ssize_t n;
  83   ssize_t i;
  84   int left;
  85
  86   if (buf == NULL)
  87     {
  88       __set_errno (EINVAL);
  89       return -1;
  90     }
  91
  92   left = 0;
  93   if (isfinite (value))
  94     {
  95       *sign = signbit (value) != 0;
  96       if (*sign)
  97         value = -value;
  98
  99       if (ndigit < 0)
 100         {
 101           /* Rounding to the left of the decimal point.  */
 102           while (ndigit < 0)
 103             {
 104               FLOAT_TYPE new_value = value * 0.1;
 105
 106               if (new_value < 1.0)
 107                 {
 108                   ndigit = 0;
 109                   break;
 110                 }
 111
 112               value = new_value;
 113               ++left;
 114               ++ndigit;
 115             }
 116         }
 117     }
 118   else
 119     /* Value is Inf or NaN.  */
 120     *sign = 0;
 121
 122   n = __snprintf (buf, len, "%.*" FLOAT_FMT_FLAG "f", MIN (ndigit, NDIGIT_MAX),
 123                   value);
 124   /* Check for a too small buffer.  */
 125   if (n >= (ssize_t) len)
 126     return -1;
 127
 128   i = 0;
 129   while (i < n && isdigit (buf[i]))
 130     ++i;
 131   *decpt = i;
 132
 133   if (i == 0)
 134     /* Value is Inf or NaN.  */
 135     return 0;
 136
 137   if (i < n)
 138     {
 139       do
 140         ++i;
 141       while (i < n && !isdigit (buf[i]));
 142
 143       if (*decpt == 1 && buf[0] == '0' && value != 0.0)
 144         {
 145           /* We must not have leading zeroes.  Strip them all out and
 146              adjust *DECPT if necessary.  */
 147           --*decpt;
 148           while (i < n && buf[i] == '0')
 149             {
 150               --*decpt;
 151               ++i;
 152             }
 153         }
 154
 155       memmove (&buf[MAX (*decpt, 0)], &buf[i], n - i);
 156       buf[n - (i - MAX (*decpt, 0))] = '\0';
 157     }
 158
 159   if (left)
 160     {
 161       *decpt += left;
 162       if ((ssize_t) --len > n)
 163         {
 164           while (left-- > 0 && n < (ssize_t) len)
 165             buf[n++] = '0';
 166           buf[n] = '\0';
 167         }
 168     }
 169
 170   return 0;
 171 }
 172
 173 int
 174 __APPEND (FUNC_PREFIX, ecvt_r) (value, ndigit, decpt, sign, buf, len)
 175      FLOAT_TYPE value;
 176      int ndigit, *decpt, *sign;
 177      char *buf;
 178      size_t len;
 179 {
 180   int exponent = 0;
 181
 182   if (isfinite (value) && value != 0.0)
 183     {
 184       /* Slow code that doesn't require -lm functions.  */
 185       FLOAT_TYPE d;
 186       FLOAT_TYPE f = 1.0;
 187       if (value < 0.0)
 188         d = -value;
 189       else
 190         d = value;
 191       /* For denormalized numbers the d < 1.0 case below won't work,
 192          as f can overflow to +Inf.  */
 193       if (d < FLOAT_MIN_10_NORM)
 194         {
 195           value /= FLOAT_MIN_10_NORM;
 196           if (value < 0.0)
 197             d = -value;
 198           else
 199             d = value;
 200           exponent += FLOAT_MIN_10_EXP;
 201         }
 202       if (d < 1.0)
 203         {
 204           do
 205             {
 206               f *= 10.0;
 207               --exponent;
 208             }
 209           while (d * f < 1.0);
 210
 211           value *= f;
 212         }
 213       else if (d >= 10.0)
 214         {
 215           do
 216             {
 217               f *= 10;
 218               ++exponent;
 219             }
 220           while (d >= f * 10.0);
 221
 222           value /= f;
 223         }
 224     }
 225   else if (value == 0.0)
 226     /* SUSv2 leaves it unspecified whether *DECPT is 0 or 1 for 0.0.
 227        This could be changed to -1 if we want to return 0.  */
 228     exponent = 0;
 229
 230   if (ndigit <= 0 && len > 0)
 231     {
 232       buf[0] = '\0';
 233       *decpt = 1;
 234       *sign = isfinite (value) ? signbit (value) != 0 : 0;
 235     }
 236   else
 237     if (__APPEND (FUNC_PREFIX, fcvt_r) (value, MIN (ndigit, NDIGIT_MAX) - 1,
 238                                         decpt, sign, buf, len))
 239       return -1;
 240
 241   *decpt += exponent;
 242   return 0;
 243 }
 244
 245 #if LONG_DOUBLE_COMPAT (libc, GLIBC_2_0)
 246 # ifdef LONG_DOUBLE_CVT
 247 #  define cvt_symbol(symbol) \
 248   cvt_symbol_1 (libc, __APPEND (FUNC_PREFIX, symbol), \
 249               APPEND (FUNC_PREFIX, symbol), GLIBC_2_4)
 250 #  define cvt_symbol_1(lib, local, symbol, version) \
 251     versioned_symbol (lib, local, symbol, version)
 252 # else
 253 #  define cvt_symbol(symbol) \
 254   cvt_symbol_1 (libc, __APPEND (FUNC_PREFIX, symbol), \
 255               APPEND (q, symbol), GLIBC_2_0); \
 256   strong_alias (__APPEND (FUNC_PREFIX, symbol), APPEND (FUNC_PREFIX, symbol))
 257 #  define cvt_symbol_1(lib, local, symbol, version) \
 258   compat_symbol (lib, local, symbol, version)
 259 # endif
 260 #else
 261 # define cvt_symbol(symbol) \
 262   strong_alias (__APPEND (FUNC_PREFIX, symbol), APPEND (FUNC_PREFIX, symbol))
 263 #endif
 264 cvt_symbol(fcvt_r);
 265 cvt_symbol(ecvt_r);