1 /* **************************************************************************
2 *
3 * --- File: output.c
4 *
5 * --- Purpose: this file provides the functions output(), which outputs
6 * the results of an expression, and my_strtod() that extends
7 * strtod() to handle numbers written in base 2, 8, and 16.
8 *
9 * --- Copyright (C) Guido Gonzato, guido@ibogeo.df.unibo.it
10 *
11 * --- Last updated: 4 February 1999
12 *
13 * This program is free software; you can redistribute it and/or modify
14 * it under the terms of the GNU General Public License as published by
15 * the Free Software Foundation; either version 2 of the License, or
16 * (at your option) any later version.
17 *
18 * This program is distributed in the hope that it will be useful,
19 * but WITHOUT ANY WARRANTY; without even the implied warranty of
20 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
21 * GNU General Public License for more details.
22 *
23 * You should have received a copy of the GNU General Public License
24 * along with this program; if not, write to the Free Software
25 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
26 *
27 * ************************************************************************ */
28
29 #include <stdio.h>
30 #include <string.h>
31 #include <ctype.h>
32 #include <stdlib.h>
33 #include <math.h>
34 #include "gexpr.h"
35
36 #define EPSILON 1e-38
37
38 int output_base;
39 int decimal_pos = 10;
40
41 static int maxpower(double, int);
42 static double topower(double, int);
43 static char *dtostr(double, char *, int);
44
45 /* ----- */
46
output(double f)47 void output(double f)
48 {
49 char s[200];
50
51 dtostr(f, (char *) s, output_base);
52 puts(s);
53
54 } /* output() */
55
56 /* ----- */
57
58 static char *exadigits = "0123456789abcdef";
59
maxpower(double n,int base)60 static int maxpower(double n, int base)
61 /* return the max. power of n in base `base' */
62 {
63 int max = 0;
64
65 while ( (n = floor(n / base)) > 0.0)
66 max++;
67
68 return max;
69
70 } /* maxpower() */
71
72 /* ----- */
73
topower(double n,int power)74 static double topower(double n, int power)
75 /* return n raised to power */
76 {
77 double tmp;
78 int sgn = (power < 0 ? -1 : 1);
79
80 if (power == 0)
81 return(1);
82
83 if (sgn == -1) {
84 tmp = 1. / n;
85 power = -power;
86 }
87 else
88 tmp = n;
89
90 while (--power)
91 if (sgn == 1)
92 tmp *= n;
93 else
94 tmp /= n;
95
96 return tmp;
97
98 } /* topower() */
99
100 /* ----- */
101
dtostr(double n,char * s,int base)102 char *dtostr(double n, char *s, int base)
103 /* return the number n written in base 'base' as string */
104 {
105 int pos = 0, sign, digit, i;
106 double power, remainder, decimals, divisor, d_divisor, d_remainder;
107
108 if (base < 2 || base > 16) {
109 s[0] = '\0';
110 return(s);
111 }
112
113 sign = (n < 0 ? -1: 1);
114 if (sign == -1) {
115 n = -n;
116 s[pos++] = '-';
117 }
118
119 /* now, do the integer part of the number */
120
121 power = maxpower(n, base);
122 divisor = topower(base, power);
123 decimals = n - floor(n);
124
125 do {
126 digit = (int) (floor(n / divisor));
127 remainder = (floor(n - digit * divisor));
128 s[pos++] = exadigits[digit];
129 n = (double) remainder;
130 divisor /= base;
131 } while (divisor >= 1);
132
133 /* if there is a fractional part, do it */
134
135 if (decimals > EPSILON) {
136
137 i = 0;
138 d_divisor = topower(base, -1);
139 n = decimals;
140
141 if (decimal_pos != 0) {
142 s[pos++] = '.';
143 do {
144 digit = (int) (floor(n / d_divisor));
145 d_remainder = n - digit * d_divisor;
146 s[pos++] = exadigits[digit];
147 n = d_remainder;
148 d_divisor /= base;
149 i++;
150 } while ( (i < decimal_pos) && (d_remainder > EPSILON));
151 }
152
153 } /* if decimals */
154
155 s[pos] = '\0';
156 return s;
157
158 } /* dtostr() */
159
160 /* ----- */
161
my_strtod(const char * s,char ** errptr)162 double my_strtod(const char *s, char **errptr)
163 {
164 double d = 0.0, fract = 0.0;
165 int b, base = 10, i, digit;
166 BOOL do_decimals = FALSE;
167
168 /* check what base the number is written in */
169
170 if (s[0] == '0')
171 switch (s[1]) {
172 case 'b': base = 2;
173 break;
174 case 'x': base = 16;
175 break;
176 case '.': base = 10;
177 break;
178 default: base = 8;
179 }
180
181 /* now convert the number using the chosen base */
182
183 if (base == 10)
184 d = strtod(s, errptr);
185 else {
186
187 i = (base == 8 ? 1: 2); /* start from adequate digit */
188 b = base;
189 for (; s[i] != '\0'; i++) {
190
191 if (s[i] == '.')
192 do_decimals = TRUE;
193 else {
194 if (isdigit(s[i]))
195 digit = s[i] - '0';
196 else
197 digit = s[i] - 'a' + 10;
198 if (digit > base - 1) { /* error! */
199 *errptr = (char *) &s[i];
200 return 0;
201 }
202 if (! do_decimals) /* do the integer part */
203 d = d * base + digit;
204 else {
205 fract += (double) digit / (double) b;
206 b *= base;
207 }
208 } /* else */
209
210 } /* for */
211
212 d = d + fract;
213 *errptr = (char *) &s[i];
214
215 } /* else */
216
217 return d;
218
219 } /* my_strtod() */
220
221 /* ----- */
222
223 /* --- End of file output.c --- */
224