summaryrefslogtreecommitdiff
path: root/misc/efgcvt_r.c
blob: 69caef01d71250d0624afcb3e94281a98655a6c4 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
/* Compatibility functions for floating point formatting, reentrant versions.
   Copyright (C) 1995, 1996, 1997 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Library General Public License as
   published by the Free Software Foundation; either version 2 of the
   License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public
   License along with the GNU C Library; see the file COPYING.LIB.  If not,
   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */

#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include <math.h>
#include <stdlib.h>

#ifndef FLOAT_TYPE
#define FLOAT_TYPE double
#define FUNC_PREFIX
#define FLOAT_FMT_FLAG
#define FLOAT_NAME_EXT
#endif

#define APPEND(a, b) APPEND2 (a, b)
#define APPEND2(a, b) a##b

#define FLOOR APPEND(floor, FLOAT_NAME_EXT)
#define FABS APPEND(fabs, FLOAT_NAME_EXT)
#define LOG10 APPEND(log10, FLOAT_NAME_EXT)
#define EXP APPEND(exp, FLOAT_NAME_EXT)


int
APPEND (FUNC_PREFIX, fcvt_r) (value, ndigit, decpt, sign, buf, len)
     FLOAT_TYPE value;
     int ndigit, *decpt, *sign;
     char *buf;
     size_t len;
{
  int n, i;

  if (buf == NULL)
    {
      __set_errno (EINVAL);
      return -1;
    }

  if (isfinite (value))
    {
      *sign = signbit (value) != 0;
      if (*sign)
	value = -value;
    }

  n = snprintf (buf, len, "%.*" FLOAT_FMT_FLAG "f", ndigit, value);
  if (n < 0)
    return -1;

  i = 0;
  while (i < n && isdigit (buf[i]))
    ++i;
  *decpt = i;

  if (i == 0)
    {
      /* Value is Inf or NaN.  */
      *sign = 0;
      return 0;
    }

  if (i < n)
    {
      do
	++i;
      while (i < n && !isdigit (buf[i]));
      memmove (&buf[*decpt], &buf[i], n - i);
      buf[n - (i - *decpt)] = 0;
    }

  return 0;
}

#define weak_extern2(name) weak_extern (name)
weak_extern2 (FLOOR) weak_extern2 (LOG10) weak_extern2 (FABS)
weak_extern2 (EXP)

int
APPEND (FUNC_PREFIX, ecvt_r) (value, ndigit, decpt, sign, buf, len)
     FLOAT_TYPE value;
     int ndigit, *decpt, *sign;
     char *buf;
     size_t len;
{
  int exponent = 0;

  if (isfinite (value) && value != 0.0)
    {
      FLOAT_TYPE (*log10_function) (FLOAT_TYPE) = &LOG10;

      if (log10_function)
	{
	  /* Use the reasonable code if -lm is included.  */
	  FLOAT_TYPE dexponent;
	  dexponent = FLOOR (LOG10 (FABS (value)));
	  value *= EXP (dexponent * -M_LN10);
	  exponent = (int) dexponent;
	}
      else
	{
	  /* Slow code that doesn't require -lm functions.  */
	  FLOAT_TYPE d;
	  if (value < 0.0)
	    d = -value;
	  else
	    d = value;
	  if (d < 1.0)
	    {
	      do
		{
		  d *= 10.0;
		  exponent--;
		}
	      while (d < 1.0);
	    }
	  else if (d >= 10.0)
	    {
	      do
		{
		  d *= 0.1;
		  exponent++;
		}
	      while (d >= 10.0);
	    }
	  if (value < 0.0)
	    value = -d;
	  else
	    value = d;
	}
    }

  if (APPEND (FUNC_PREFIX, fcvt_r) (value, ndigit - 1, decpt, sign, buf, len))
    return -1;
  *decpt += exponent;
  return 0;
}