misc/efgcvt.c

   1 /* Compatibility functions for floating point formatting.
   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 <math.h>
  20 #include <stdio.h>
  21 #include <stdlib.h>
  22 #include <sys/param.h>
  23 #include <float.h>
  24 #include <libc-lock.h>
  25 #include <math_ldbl_opt.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 #else
  48 # define LONG_DOUBLE_CVT
  49 #endif
  50
  51 #define APPEND(a, b) APPEND2 (a, b)
  52 #define APPEND2(a, b) a##b
  53 #define __APPEND(a, b) __APPEND2 (a, b)
  54 #define __APPEND2(a, b) __##a##b
  55
  56
  57 #define FCVT_BUFFER APPEND (FUNC_PREFIX, fcvt_buffer)
  58 #define FCVT_BUFPTR APPEND (FUNC_PREFIX, fcvt_bufptr)
  59 #define ECVT_BUFFER APPEND (FUNC_PREFIX, ecvt_buffer)
  60
  61
  62 static char FCVT_BUFFER[MAXDIG];
  63 static char ECVT_BUFFER[MAXDIG];
  64 libc_freeres_ptr (static char *FCVT_BUFPTR);
  65
  66 char *
  67 __APPEND (FUNC_PREFIX, fcvt) (FLOAT_TYPE value, int ndigit, int *decpt,
  68                               int *sign)
  69 {
  70   if (FCVT_BUFPTR == NULL)
  71     {
  72       if (__APPEND (FUNC_PREFIX, fcvt_r) (value, ndigit, decpt, sign,
  73                                           FCVT_BUFFER, MAXDIG) != -1)
  74         return FCVT_BUFFER;
  75
  76       FCVT_BUFPTR = (char *) malloc (FCVT_MAXDIG);
  77       if (FCVT_BUFPTR == NULL)
  78         return FCVT_BUFFER;
  79     }
  80
  81   (void) __APPEND (FUNC_PREFIX, fcvt_r) (value, ndigit, decpt, sign,
  82                                          FCVT_BUFPTR, FCVT_MAXDIG);
  83
  84   return FCVT_BUFPTR;
  85 }
  86
  87
  88 char *
  89 __APPEND (FUNC_PREFIX, ecvt) (FLOAT_TYPE value, int ndigit, int *decpt,
  90                               int *sign)
  91 {
  92   (void) __APPEND (FUNC_PREFIX, ecvt_r) (value, ndigit, decpt, sign,
  93                                          ECVT_BUFFER, MAXDIG);
  94
  95   return ECVT_BUFFER;
  96 }
  97
  98 char *
  99 __APPEND (FUNC_PREFIX, gcvt) (FLOAT_TYPE value, int ndigit, char *buf)
 100 {
 101   sprintf (buf, "%.*" FLOAT_FMT_FLAG "g", MIN (ndigit, NDIGIT_MAX), value);
 102   return buf;
 103 }
 104
 105 #if LONG_DOUBLE_COMPAT (libc, GLIBC_2_0)
 106 # ifdef LONG_DOUBLE_CVT
 107 #  define cvt_symbol(symbol) \
 108   cvt_symbol_1 (libc, __APPEND (FUNC_PREFIX, symbol), \
 109               APPEND (FUNC_PREFIX, symbol), GLIBC_2_4)
 110 #  define cvt_symbol_1(lib, local, symbol, version) \
 111     versioned_symbol (lib, local, symbol, version)
 112 # else
 113 #  define cvt_symbol(symbol) \
 114   cvt_symbol_1 (libc, __APPEND (FUNC_PREFIX, symbol), \
 115               APPEND (q, symbol), GLIBC_2_0); \
 116   strong_alias (__APPEND (FUNC_PREFIX, symbol), APPEND (FUNC_PREFIX, symbol))
 117 #  define cvt_symbol_1(lib, local, symbol, version) \
 118   compat_symbol (lib, local, symbol, version)
 119 # endif
 120 #else
 121 # define cvt_symbol(symbol) \
 122   strong_alias (__APPEND (FUNC_PREFIX, symbol), APPEND (FUNC_PREFIX, symbol))
 123 #endif
 124 cvt_symbol(fcvt);
 125 cvt_symbol(ecvt);
 126 cvt_symbol(gcvt);