xref: /reactos/sdk/lib/crt/stdlib/fcvtbuf.c (revision 1734f297)
1 #include <stdlib.h>
2 #include <stdio.h>
3 #include <string.h>
4 #include <float.h>
5 #include <math.h>
6 #include <malloc.h>
7 // #include <msvcrt/locale.h>
8 
9 // replace fjgpp fcvtbuf from project  http://www.jbox.dk/sanos/source/lib/fcvt.c.html
10 // with small modification's to match ReactOS arch
11 
12 // Floating point to string conversion routines
13 //
14 // Copyright (C) 2002 Michael Ringgaard. All rights reserved.
15 //
16 // Redistribution and use in source and binary forms, with or without
17 // modification, are permitted provided that the following conditions
18 // are met:
19 //
20 // 1. Redistributions of source code must retain the above copyright
21 //    notice, this list of conditions and the following disclaimer.
22 // 2. Redistributions in binary form must reproduce the above copyright
23 //    notice, this list of conditions and the following disclaimer in the
24 //    documentation and/or other materials provided with the distribution.
25 // 3. Neither the name of the project nor the names of its contributors
26 //    may be used to endorse or promote products derived from this software
27 //    without specific prior written permission.
28 //
29 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
30 // ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
31 // IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
32 // ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
33 // FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
34 // DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
35 // OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
36 // HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
37 // LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
38 // OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
39 // SUCH DAMAGE.
40 //
41 
42 
43 //#include <math.h>
44 #define CVTBUFSIZE  2 * DBL_MAX_10_EXP + 10
45 static char *cvt(double arg, int ndigits, int *decpt, int *sign, char *buf, int eflag)
46 {
47   int r2;
48   double fi, fj;
49   char *p, *p1;
50 
51   if (ndigits >= CVTBUFSIZE - 1) ndigits = CVTBUFSIZE - 2;
52   r2 = 0;
53   *sign = 0;
54   p = &buf[0];
55   if (arg < 0)
56   {
57     *sign = 1;
58     arg = -arg;
59   }
60   arg = modf(arg, &fi);
61   p1 = &buf[CVTBUFSIZE];
62 
63   if (fi != 0)
64   {
65     p1 = &buf[CVTBUFSIZE];
66     while (fi != 0)
67     {
68       fj = modf(fi / 10, &fi);
69       *--p1 = (int)((fj + .03) * 10) + '0';
70       r2++;
71     }
72     while (p1 < &buf[CVTBUFSIZE]) *p++ = *p1++;
73   }
74   else if (arg > 0)
75   {
76     while ((fj = arg * 10) < 1)
77     {
78       arg = fj;
79       r2--;
80     }
81   }
82   p1 = &buf[ndigits];
83   if (eflag == 0) p1 += r2;
84   *decpt = r2;
85   if (p1 < &buf[0])
86   {
87     buf[0] = '\0';
88     return buf;
89   }
90   while (p <= p1 && p < &buf[CVTBUFSIZE])
91   {
92     arg *= 10;
93     arg = modf(arg, &fj);
94     *p++ = (int) fj + '0';
95   }
96   if (p1 >= &buf[CVTBUFSIZE])
97   {
98     buf[CVTBUFSIZE - 1] = '\0';
99     return buf;
100   }
101   p = p1;
102   *p1 += 5;
103   while (*p1 > '9')
104   {
105     *p1 = '0';
106     if (p1 > buf)
107       ++*--p1;
108     else
109     {
110       *p1 = '1';
111       (*decpt)++;
112       if (eflag == 0)
113       {
114         if (p > buf) *p = '0';
115         p++;
116       }
117     }
118   }
119   *p = '\0';
120   return buf;
121 }
122 
123 char *fcvtbuf(double arg, int ndigits, int *decpt, int *sign, char *buf)
124 {
125   return cvt(arg, ndigits, decpt, sign, buf, 0);
126 }
127