1 /*
2 * Copyright (c) 1989, 1993
3 * The Regents of the University of California. All rights reserved.
4 *
5 * This code is derived from software posted to USENET.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the University nor the names of its contributors
16 * may be used to endorse or promote products derived from this software
17 * without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32 #if 0
33 #ifndef lint
34 static const char copyright[] =
35 "@(#) Copyright (c) 1989, 1993\n\
36 The Regents of the University of California. All rights reserved.\n";
37 #endif /* not lint */
38
39 #ifndef lint
40 static const char sccsid[] = "@(#)pom.c 8.1 (Berkeley) 5/31/93";
41 #endif /* not lint */
42 #endif
43 #include <sys/cdefs.h>
44 /*
45 * Phase of the Moon. Calculates the current phase of the moon.
46 * Based on routines from `Practical Astronomy with Your Calculator',
47 * by Duffett-Smith. Comments give the section from the book that
48 * particular piece of code was adapted from.
49 *
50 * -- Keith E. Brandt VIII 1984
51 *
52 */
53
54 #include <sys/capsicum.h>
55 #include <capsicum_helpers.h>
56
57 #include <err.h>
58 #include <errno.h>
59 #include <stdio.h>
60 #include <stdlib.h>
61 #include <math.h>
62 #include <string.h>
63 #include <sysexits.h>
64 #include <time.h>
65 #include <unistd.h>
66
67 #ifndef PI
68 #define PI 3.14159265358979323846
69 #endif
70 #define EPOCH 85
71 #define EPSILONg 279.611371 /* solar ecliptic long at EPOCH */
72 #define RHOg 282.680403 /* solar ecliptic long of perigee at EPOCH */
73 #define ECCEN 0.01671542 /* solar orbit eccentricity */
74 #define lzero 18.251907 /* lunar mean long at EPOCH */
75 #define Pzero 192.917585 /* lunar mean long of perigee at EPOCH */
76 #define Nzero 55.204723 /* lunar mean long of node at EPOCH */
77 #define isleap(y) ((((y) % 4) == 0 && ((y) % 100) != 0) || ((y) % 400) == 0)
78
79 static void adj360(double *);
80 static double dtor(double);
81 static double potm(double);
82 static void usage(char *progname);
83
84 int
main(int argc,char ** argv)85 main(int argc, char **argv)
86 {
87 time_t tt;
88 struct tm GMT, tmd;
89 double days, today, tomorrow;
90 int ch, cnt, pflag = 0;
91 char *odate = NULL, *otime = NULL;
92 char *progname = argv[0];
93
94 if (caph_limit_stdio() < 0)
95 err(1, "unable to limit capabitilities for stdio");
96
97 caph_cache_catpages();
98 if (caph_enter() < 0)
99 err(1, "unable to enter capability mode");
100
101 while ((ch = getopt(argc, argv, "d:pt:")) != -1)
102 switch (ch) {
103 case 'd':
104 odate = optarg;
105 break;
106 case 'p':
107 pflag = 1;
108 break;
109 case 't':
110 otime = optarg;
111 break;
112 default:
113 usage(progname);
114 }
115
116 argc -= optind;
117 argv += optind;
118
119 if (argc)
120 usage(progname);
121
122 /* Adjust based on users preferences */
123 time(&tt);
124 if (otime != NULL || odate != NULL) {
125 /* Save today in case -d isn't specified */
126 localtime_r(&tt, &tmd);
127
128 if (odate != NULL) {
129 tmd.tm_year = strtol(odate, NULL, 10) - 1900;
130 tmd.tm_mon = strtol(odate + 5, NULL, 10) - 1;
131 tmd.tm_mday = strtol(odate + 8, NULL, 10);
132 /* Use midnight as the middle of the night */
133 tmd.tm_hour = 0;
134 tmd.tm_min = 0;
135 tmd.tm_sec = 0;
136 tmd.tm_isdst = -1;
137 }
138 if (otime != NULL) {
139 tmd.tm_hour = strtol(otime, NULL, 10);
140 tmd.tm_min = strtol(otime + 3, NULL, 10);
141 tmd.tm_sec = strtol(otime + 6, NULL, 10);
142 tmd.tm_isdst = -1;
143 }
144 tt = mktime(&tmd);
145 }
146
147 gmtime_r(&tt, &GMT);
148 days = (GMT.tm_yday + 1) + ((GMT.tm_hour +
149 (GMT.tm_min / 60.0) + (GMT.tm_sec / 3600.0)) / 24.0);
150 for (cnt = EPOCH; cnt < GMT.tm_year; ++cnt)
151 days += isleap(1900 + cnt) ? 366 : 365;
152 today = potm(days);
153 if (pflag) {
154 (void)printf("%1.0f\n", today);
155 return (0);
156 }
157 (void)printf("The Moon is ");
158 if (today >= 99.5)
159 (void)printf("Full\n");
160 else if (today < 0.5)
161 (void)printf("New\n");
162 else {
163 tomorrow = potm(days + 1);
164 if (today >= 49.5 && today < 50.5)
165 (void)printf("%s\n", tomorrow > today ?
166 "at the First Quarter" : "at the Last Quarter");
167 else {
168 (void)printf("%s ", tomorrow > today ?
169 "Waxing" : "Waning");
170 if (today > 50)
171 (void)printf("Gibbous (%1.0f%% of Full)\n",
172 today);
173 else if (today < 50)
174 (void)printf("Crescent (%1.0f%% of Full)\n",
175 today);
176 }
177 }
178
179 return 0;
180 }
181
182 /*
183 * potm --
184 * return phase of the moon
185 */
186 static double
potm(double days)187 potm(double days)
188 {
189 double N, Msol, Ec, LambdaSol, l, Mm, Ev, Ac, A3, Mmprime;
190 double A4, lprime, V, ldprime, D, Nm;
191
192 N = 360 * days / 365.2422; /* sec 42 #3 */
193 adj360(&N);
194 Msol = N + EPSILONg - RHOg; /* sec 42 #4 */
195 adj360(&Msol);
196 Ec = 360 / PI * ECCEN * sin(dtor(Msol)); /* sec 42 #5 */
197 LambdaSol = N + Ec + EPSILONg; /* sec 42 #6 */
198 adj360(&LambdaSol);
199 l = 13.1763966 * days + lzero; /* sec 61 #4 */
200 adj360(&l);
201 Mm = l - (0.1114041 * days) - Pzero; /* sec 61 #5 */
202 adj360(&Mm);
203 Nm = Nzero - (0.0529539 * days); /* sec 61 #6 */
204 adj360(&Nm);
205 Ev = 1.2739 * sin(dtor(2*(l - LambdaSol) - Mm)); /* sec 61 #7 */
206 Ac = 0.1858 * sin(dtor(Msol)); /* sec 61 #8 */
207 A3 = 0.37 * sin(dtor(Msol));
208 Mmprime = Mm + Ev - Ac - A3; /* sec 61 #9 */
209 Ec = 6.2886 * sin(dtor(Mmprime)); /* sec 61 #10 */
210 A4 = 0.214 * sin(dtor(2 * Mmprime)); /* sec 61 #11 */
211 lprime = l + Ev + Ec - Ac + A4; /* sec 61 #12 */
212 V = 0.6583 * sin(dtor(2 * (lprime - LambdaSol))); /* sec 61 #13 */
213 ldprime = lprime + V; /* sec 61 #14 */
214 D = ldprime - LambdaSol; /* sec 63 #2 */
215 return(50 * (1 - cos(dtor(D)))); /* sec 63 #3 */
216 }
217
218 /*
219 * dtor --
220 * convert degrees to radians
221 */
222 static double
dtor(double deg)223 dtor(double deg)
224 {
225
226 return(deg * PI / 180);
227 }
228
229 /*
230 * adj360 --
231 * adjust value so 0 <= deg <= 360
232 */
233 static void
adj360(double * deg)234 adj360(double *deg)
235 {
236
237 for (;;)
238 if (*deg < 0)
239 *deg += 360;
240 else if (*deg > 360)
241 *deg -= 360;
242 else
243 break;
244 }
245
246 static void
usage(char * progname)247 usage(char *progname)
248 {
249
250 fprintf(stderr, "Usage: %s [-p] [-d yyyy.mm.dd] [-t hh:mm:ss]\n",
251 progname);
252 exit(EX_USAGE);
253 }
254