misc/efgcvt.c

   1 /* Compatibility functions for floating point formatting.
   2    Copyright (C) 1995, 1996, 1997, 1999, 2002 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, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <math.h>
  21 #include <stdio.h>
  22 #include <stdlib.h>
  23 #include <sys/param.h>
  24 #include <float.h>
  25 #include <bits/libc-lock.h>
  26
  27 #ifndef FLOAT_TYPE
  28 # define FLOAT_TYPE double
  29 # define FUNC_PREFIX
  30 # define FLOAT_FMT_FLAG
  31 /* Actually we have to write (DBL_DIG + log10 (DBL_MAX_10_EXP)) but we
  32    don't have log10 available in the preprocessor.  */
  33 # define MAXDIG (NDIGIT_MAX + 3)
  34 # define FCVT_MAXDIG (DBL_MAX_10_EXP + MAXDIG)
  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 #endif
  48
  49 #define APPEND(a, b) APPEND2 (a, b)
  50 #define APPEND2(a, b) a##b
  51
  52
  53 #define FCVT_BUFFER APPEND (FUNC_PREFIX, fcvt_buffer)
  54 #define FCVT_BUFPTR APPEND (FUNC_PREFIX, fcvt_bufptr)
  55 #define ECVT_BUFFER APPEND (FUNC_PREFIX, ecvt_buffer)
  56
  57
  58 static char FCVT_BUFFER[MAXDIG];
  59 static char ECVT_BUFFER[MAXDIG];
  60 libc_freeres_ptr (static char *FCVT_BUFPTR);
  61
  62 char *
  63 APPEND (FUNC_PREFIX, fcvt) (value, ndigit, decpt, sign)
  64      FLOAT_TYPE value;
  65      int ndigit, *decpt, *sign;
  66 {
  67   if (FCVT_BUFPTR == NULL)
  68     {
  69       if (APPEND (FUNC_PREFIX, fcvt_r) (value, ndigit, decpt, sign,
  70                                         FCVT_BUFFER, MAXDIG) != -1)
  71         return FCVT_BUFFER;
  72
  73       FCVT_BUFPTR = (char *) malloc (FCVT_MAXDIG);
  74       if (FCVT_BUFPTR == NULL)
  75         return FCVT_BUFFER;
  76     }
  77
  78   (void) APPEND (FUNC_PREFIX, fcvt_r) (value, ndigit, decpt, sign,
  79                                        FCVT_BUFPTR, FCVT_MAXDIG);
  80
  81   return FCVT_BUFPTR;
  82 }
  83
  84
  85 char *
  86 APPEND (FUNC_PREFIX, ecvt) (value, ndigit, decpt, sign)
  87      FLOAT_TYPE value;
  88      int ndigit, *decpt, *sign;
  89 {
  90   (void) APPEND (FUNC_PREFIX, ecvt_r) (value, ndigit, decpt, sign,
  91                                        ECVT_BUFFER, MAXDIG);
  92
  93   return ECVT_BUFFER;
  94 }
  95
  96 char *
  97 APPEND (FUNC_PREFIX, gcvt) (value, ndigit, buf)
  98      FLOAT_TYPE value;
  99      int ndigit;
 100      char *buf;
 101 {
 102   sprintf (buf, "%.*" FLOAT_FMT_FLAG "g", MIN (ndigit, NDIGIT_MAX), value);
 103   return buf;
 104 }