libgm2/libm2pim/dtoa.cc

   1 /* dtoa.cc convert double to ascii and visa versa.
   2
   3 Copyright (C) 2009-2022 Free Software Foundation, Inc.
   4 Contributed by Gaius Mulley <gaius.mulley@southwales.ac.uk>.
   5
   6 This file is part of GNU Modula-2.
   7
   8 GNU Modula-2 is free software; you can redistribute it and/or modify
   9 it under the terms of the GNU General Public License as published by
  10 the Free Software Foundation; either version 3, or (at your option)
  11 any later version.
  12
  13 GNU Modula-2 is distributed in the hope that it will be useful, but
  14 WITHOUT ANY WARRANTY; without even the implied warranty of
  15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16 General Public License for more details.
  17
  18 Under Section 7 of GPL version 3, you are granted additional
  19 permissions described in the GCC Runtime Library Exception, version
  20 3.1, as published by the Free Software Foundation.
  21
  22 You should have received a copy of the GNU General Public License and
  23 a copy of the GCC Runtime Library Exception along with this program;
  24 see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  25 <http://www.gnu.org/licenses/>.  */
  26
  27 #define GM2
  28
  29 #include <config.h>
  30 #include <m2rts.h>
  31
  32 #define EXPORT(FUNC) m2pim ## _dtoa_ ## FUNC
  33 #define M2EXPORT(FUNC) m2pim ## _M2_dtoa_ ## FUNC
  34 #define M2LIBNAME "m2pim"
  35
  36 #if defined(HAVE_STRINGS)
  37 #include <strings.h>
  38 #endif
  39
  40 #if defined(HAVE_STRING)
  41 #include <string.h>
  42 #endif
  43
  44 #if defined(HAVE_STDDEF_H)
  45 /* Obtain a definition for NULL.  */
  46 #include <stddef.h>
  47 #endif
  48
  49 #if defined(HAVE_STDIO_H)
  50 /* Obtain a definition for NULL.  */
  51 #include <stdio.h>
  52 #endif
  53
  54 #if defined(HAVE_TIME_H)
  55 /* Obtain a definition for NULL.  */
  56 #include <time.h>
  57 #endif
  58
  59 #if defined(HAVE_STRING_H)
  60 /* Obtain a definition for NULL.  */
  61 #include <string.h>
  62 #endif
  63
  64 #if defined(HAVE_WCHAR_H)
  65 /* Obtain a definition for NULL.  */
  66 #include <wchar.h>
  67 #endif
  68
  69 #if defined(HAVE_STDLIB_H)
  70 /* Obtain a prototype for free and malloc.  */
  71 #include <stdlib.h>
  72 #endif
  73
  74 #if !defined(NULL)
  75 #define NULL (void *)0
  76 #endif
  77
  78 #if defined(HAVE_STDLIB_H)
  79 #if !defined(_ISOC99_SOURCE)
  80 #define _ISOC99_SOURCE
  81 #endif
  82 #include <stdlib.h>
  83 #endif
  84
  85 #if defined(HAVE_ERRNO_H)
  86 #include <errno.h>
  87 #endif
  88
  89 #if defined(HAVE_SYS_ERRNO_H)
  90 #include <sys/errno.h>
  91 #endif
  92
  93 #if defined(HAVE_STRING_H)
  94
  95 #define MAX_FP_DIGITS 500
  96
  97 typedef enum Mode { maxsignicant, decimaldigits } Mode;
  98
  99 /* maxsignicant:  return a string containing max(1,ndigits) significant
 100    digits.  The return string contains the string produced by ecvt.
 101
 102    decimaldigits: return a string produced by fcvt.  The string will
 103    contain ndigits past the decimal point (ndigits may be negative).  */
 104
 105 extern "C" double
 106 EXPORT(strtod) (const char *s, bool *error)
 107 {
 108   char *endp;
 109   double d;
 110
 111 #if defined(HAVE_ERRNO_H)
 112   errno = 0;
 113 #endif
 114   d = strtod (s, &endp);
 115   if (endp != NULL && (*endp == '\0'))
 116 #if defined(HAVE_ERRNO_H)
 117     *error = (errno != 0);
 118 #else
 119     *error = false;
 120 #endif
 121   else
 122     *error = true;
 123   return d;
 124 }
 125
 126 /* dtoa_calcmaxsig calculates the position of the decimal point
 127    it also removes the decimal point and exponent from string, p.  */
 128
 129 extern "C" int
 130 EXPORT(calcmaxsig) (char *p, int ndigits)
 131 {
 132   char *e;
 133   char *o;
 134   int x;
 135
 136   e = strchr (p, 'E');
 137   if (e == NULL)
 138     x = 0;
 139   else
 140     {
 141       *e = (char)0;
 142       x = atoi (e + 1);
 143     }
 144
 145   o = strchr (p, '.');
 146   if (o == NULL)
 147     return strlen (p) + x;
 148   else
 149     {
 150       memmove (o, o + 1, ndigits - (o - p));
 151       return o - p + x;
 152     }
 153 }
 154
 155 /* dtoa_calcdecimal calculates the position of the decimal point
 156    it also removes the decimal point and exponent from string, p.
 157    It truncates the digits in p accordingly to ndigits.
 158    Ie ndigits is the number of digits after the '.'.  */
 159
 160 extern "C" int
 161 EXPORT(calcdecimal) (char *p, int str_size, int ndigits)
 162 {
 163   char *e;
 164   char *o;
 165   int x;
 166   int l;
 167
 168   e = strchr (p, 'E');
 169   if (e == NULL)
 170     x = 0;
 171   else
 172     {
 173       *e = (char)0;
 174       x = atoi (e + 1);
 175     }
 176
 177   l = strlen (p);
 178   o = strchr (p, '.');
 179   if (o == NULL)
 180     x += strlen (p);
 181   else
 182     {
 183       int m = strlen (o);
 184       memmove (o, o + 1, l - (o - p));
 185       if (m > 0)
 186         o[m - 1] = '0';
 187       x += o - p;
 188     }
 189   if ((x + ndigits >= 0) && (x + ndigits < str_size))
 190     p[x + ndigits] = (char)0;
 191   return x;
 192 }
 193
 194 extern "C" bool
 195 EXPORT(calcsign) (char *p, int str_size)
 196 {
 197   if (p[0] == '-')
 198     {
 199       memmove (p, p + 1, str_size - 1);
 200       return true;
 201     }
 202   else
 203     return false;
 204 }
 205
 206 extern "C" char *
 207 EXPORT(dtoa) (double d, int mode, int ndigits, int *decpt, bool *sign)
 208 {
 209   char format[50];
 210   char *p;
 211   int r;
 212   switch (mode)
 213     {
 214
 215     case maxsignicant:
 216       ndigits += 20; /* Enough for exponent.  */
 217       p = (char *) malloc (ndigits);
 218       snprintf (format, 50, "%s%d%s", "%.", ndigits - 20, "E");
 219       snprintf (p, ndigits, format, d);
 220       *sign = EXPORT(calcsign) (p, ndigits);
 221       *decpt = EXPORT(calcmaxsig) (p, ndigits);
 222       return p;
 223     case decimaldigits:
 224       p = (char *) malloc (MAX_FP_DIGITS + 20);
 225       snprintf (format, 50, "%s%d%s", "%.", MAX_FP_DIGITS, "E");
 226       snprintf (p, MAX_FP_DIGITS + 20, format, d);
 227       *sign = EXPORT(calcsign) (p, MAX_FP_DIGITS + 20);
 228       *decpt = EXPORT(calcdecimal) (p, MAX_FP_DIGITS + 20, ndigits);
 229       return p;
 230     default:
 231       abort ();
 232     }
 233 }
 234
 235 #endif
 236
 237 #if defined(GM2)
 238 /* GNU Modula-2 linking hooks.  */
 239
 240 extern "C" void
 241 M2EXPORT(init) (int, char **, char **)
 242 {
 243 }
 244
 245 extern "C" void
 246 M2EXPORT(fini) (int, char **, char **)
 247 {
 248 }
 249
 250 extern "C" void
 251 M2EXPORT(dep) (void)
 252 {
 253 }
 254
 255 extern "C" void __attribute__((__constructor__))
 256 M2EXPORT(ctor) (void)
 257 {
 258   m2pim_M2RTS_RegisterModule ("dtoa", M2LIBNAME,
 259                               M2EXPORT(init), M2EXPORT(fini),
 260                               M2EXPORT(dep));
 261 }
 262 #endif