1 /****************************************************************
2 *
3 * The author of this software is David M. Gay.
4 *
5 * Copyright (c) 1991, 1996 by Lucent Technologies.
6 *
7 * Permission to use, copy, modify, and distribute this software for any
8 * purpose without fee is hereby granted, provided that this entire notice
9 * is included in all copies of any software which is or includes a copy
10 * or modification of this software and in all copies of the supporting
11 * documentation for such software.
12 *
13 * THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR IMPLIED
14 * WARRANTY. IN PARTICULAR, NEITHER THE AUTHOR NOR LUCENT MAKES ANY
15 * REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE MERCHANTABILITY
16 * OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR PURPOSE.
17 *
18 ***************************************************************/
19
20 /* g_fmt(buf,x) stores the closest decimal approximation to x in buf;
21 * it suffices to declare buf
22 * char buf[32];
23 */
24
25 #include "dmg_fp.h"
26
27 namespace dmg_fp {
28
29 char *
g_fmt(register char * b,double x)30 g_fmt(register char *b, double x)
31 {
32 register int i, k;
33 register char *s;
34 int decpt, j, sign;
35 char *b0, *s0, *se;
36
37 b0 = b;
38 #ifdef IGNORE_ZERO_SIGN
39 if (!x) {
40 *b++ = '0';
41 *b = 0;
42 goto done;
43 }
44 #endif
45 s = s0 = dtoa(x, 0, 0, &decpt, &sign, &se);
46 if (sign)
47 *b++ = '-';
48 if (decpt == 9999) /* Infinity or Nan */ {
49 while((*b++ = *s++)) {}
50 goto done0;
51 }
52 if (decpt <= -4 || decpt > se - s + 5) {
53 *b++ = *s++;
54 if (*s) {
55 *b++ = '.';
56 while((*b = *s++))
57 b++;
58 }
59 *b++ = 'e';
60 /* sprintf(b, "%+.2d", decpt - 1); */
61 if (--decpt < 0) {
62 *b++ = '-';
63 decpt = -decpt;
64 }
65 else
66 *b++ = '+';
67 for(j = 2, k = 10; 10*k <= decpt; j++, k *= 10) {}
68 for(;;) {
69 i = decpt / k;
70 *b++ = i + '0';
71 if (--j <= 0)
72 break;
73 decpt -= i*k;
74 decpt *= 10;
75 }
76 *b = 0;
77 }
78 else if (decpt <= 0) {
79 *b++ = '.';
80 for(; decpt < 0; decpt++)
81 *b++ = '0';
82 while((*b++ = *s++)) {}
83 }
84 else {
85 while((*b = *s++)) {
86 b++;
87 if (--decpt == 0 && *s)
88 *b++ = '.';
89 }
90 for(; decpt > 0; decpt--)
91 *b++ = '0';
92 *b = 0;
93 }
94 done0:
95 freedtoa(s0);
96 #ifdef IGNORE_ZERO_SIGN
97 done:
98 #endif
99 return b0;
100 }
101
102 } // namespace dmg_fp
103