NetBSD-5.0.2/games/pom/pom.c
/* $NetBSD: pom.c,v 1.17 2008/07/20 01:03:22 lukem Exp $ */
/*
* Copyright (c) 1989, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software posted to USENET.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/cdefs.h>
#ifndef lint
__COPYRIGHT("@(#) Copyright (c) 1989, 1993\
The Regents of the University of California. All rights reserved.");
#endif /* not lint */
#ifndef lint
#if 0
static char sccsid[] = "@(#)pom.c 8.1 (Berkeley) 5/31/93";
#else
__RCSID("$NetBSD: pom.c,v 1.17 2008/07/20 01:03:22 lukem Exp $");
#endif
#endif /* not lint */
/*
* Phase of the Moon. Calculates the current phase of the moon.
* Based on routines from `Practical Astronomy with Your Calculator',
* by Duffett-Smith. Comments give the section from the book that
* particular piece of code was adapted from.
*
* -- Keith E. Brandt VIII 1984
*
* Updated to the Third Edition of Duffett-Smith's book, Paul Janzen, IX 1998
*
*/
#include <ctype.h>
#include <err.h>
#include <math.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <time.h>
#include <unistd.h>
#ifndef PI
#define PI 3.14159265358979323846
#endif
/*
* The EPOCH in the third edition of the book is 1990 Jan 0.0 TDT.
* In this program, we do not bother to correct for the differences
* between UTC (as shown by the UNIX clock) and TDT. (TDT = TAI + 32.184s;
* TAI-UTC = 32s in Jan 1999.)
*/
#define EPOCH_MINUS_1970 (20 * 365 + 5 - 1) /* 20 years, 5 leaps, back 1 day to Jan 0 */
#define EPSILONg 279.403303 /* solar ecliptic long at EPOCH */
#define RHOg 282.768422 /* solar ecliptic long of perigee at EPOCH */
#define ECCEN 0.016713 /* solar orbit eccentricity */
#define lzero 318.351648 /* lunar mean long at EPOCH */
#define Pzero 36.340410 /* lunar mean long of perigee at EPOCH */
#define Nzero 318.510107 /* lunar mean long of node at EPOCH */
void adj360(double *);
double dtor(double);
int main(int, char *[]);
double potm(double);
time_t parsetime(char *);
void badformat(void) __dead;
int
main(int argc, char *argv[])
{
time_t tmpt, now;
double days, today, tomorrow;
char buf[1024];
if (time(&now) == (time_t)-1)
err(1, "time");
if (argc > 1) {
tmpt = parsetime(argv[1]);
strftime(buf, sizeof(buf), "%a %Y %b %e %H:%M:%S (%Z)",
localtime(&tmpt));
printf("%s: ", buf);
} else {
tmpt = now;
}
days = (tmpt - EPOCH_MINUS_1970 * 86400) / 86400.0;
today = potm(days) + .5;
if (tmpt < now)
(void)printf("The Moon was ");
else if (tmpt == now)
(void)printf("The Moon is ");
else
(void)printf("The Moon will be ");
if ((int)today == 100)
(void)printf("Full\n");
else if (!(int)today)
(void)printf("New\n");
else {
tomorrow = potm(days + 1);
if ((int)today == 50)
(void)printf("%s\n", tomorrow > today ?
"at the First Quarter" : "at the Last Quarter");
/* today is 0.5 too big, but it doesn't matter here
* since the phase is changing fast enough
*/
else {
today -= 0.5; /* Now it might matter */
(void)printf("%s ", tomorrow > today ?
"Waxing" : "Waning");
if (today > 50)
(void)printf("Gibbous (%1.0f%% of Full)\n",
today);
else if (today < 50)
(void)printf("Crescent (%1.0f%% of Full)\n",
today);
}
}
return EXIT_SUCCESS;
}
/*
* potm --
* return phase of the moon
*/
double
potm(double days)
{
double N, Msol, Ec, LambdaSol, l, Mm, Ev, Ac, A3, Mmprime;
double A4, lprime, V, ldprime, D, Nm;
N = 360 * days / 365.242191; /* sec 46 #3 */
adj360(&N);
Msol = N + EPSILONg - RHOg; /* sec 46 #4 */
adj360(&Msol);
Ec = 360 / PI * ECCEN * sin(dtor(Msol)); /* sec 46 #5 */
LambdaSol = N + Ec + EPSILONg; /* sec 46 #6 */
adj360(&LambdaSol);
l = 13.1763966 * days + lzero; /* sec 65 #4 */
adj360(&l);
Mm = l - (0.1114041 * days) - Pzero; /* sec 65 #5 */
adj360(&Mm);
Nm = Nzero - (0.0529539 * days); /* sec 65 #6 */
adj360(&Nm);
Ev = 1.2739 * sin(dtor(2*(l - LambdaSol) - Mm)); /* sec 65 #7 */
Ac = 0.1858 * sin(dtor(Msol)); /* sec 65 #8 */
A3 = 0.37 * sin(dtor(Msol));
Mmprime = Mm + Ev - Ac - A3; /* sec 65 #9 */
Ec = 6.2886 * sin(dtor(Mmprime)); /* sec 65 #10 */
A4 = 0.214 * sin(dtor(2 * Mmprime)); /* sec 65 #11 */
lprime = l + Ev + Ec - Ac + A4; /* sec 65 #12 */
V = 0.6583 * sin(dtor(2 * (lprime - LambdaSol))); /* sec 65 #13 */
ldprime = lprime + V; /* sec 65 #14 */
D = ldprime - LambdaSol; /* sec 67 #2 */
return(50.0 * (1 - cos(dtor(D)))); /* sec 67 #3 */
}
/*
* dtor --
* convert degrees to radians
*/
double
dtor(double deg)
{
return(deg * PI / 180);
}
/*
* adj360 --
* adjust value so 0 <= deg <= 360
*/
void
adj360(double *deg)
{
for (;;)
if (*deg < 0)
*deg += 360;
else if (*deg > 360)
*deg -= 360;
else
break;
}
#define ATOI2(ar) ((ar)[0] - '0') * 10 + ((ar)[1] - '0'); (ar) += 2;
time_t
parsetime(char *p)
{
struct tm *lt;
int bigyear;
int yearset = 0;
time_t tval;
unsigned char *t;
for (t = p; *t; ++t) {
if (isdigit(*t))
continue;
badformat();
}
tval = time(NULL);
lt = localtime(&tval);
lt->tm_sec = 0;
lt->tm_min = 0;
switch (strlen(p)) {
case 10: /* yyyy */
bigyear = ATOI2(p);
lt->tm_year = bigyear * 100 - 1900;
yearset = 1;
/* FALLTHROUGH */
case 8: /* yy */
if (yearset) {
lt->tm_year += ATOI2(p);
} else {
lt->tm_year = ATOI2(p);
if (lt->tm_year < 69) /* hack for 2000 */
lt->tm_year += 100;
}
/* FALLTHROUGH */
case 6: /* mm */
lt->tm_mon = ATOI2(p);
if ((lt->tm_mon > 12) || !lt->tm_mon)
badformat();
--lt->tm_mon; /* time struct is 0 - 11 */
/* FALLTHROUGH */
case 4: /* dd */
lt->tm_mday = ATOI2(p);
if ((lt->tm_mday > 31) || !lt->tm_mday)
badformat();
/* FALLTHROUGH */
case 2: /* HH */
lt->tm_hour = ATOI2(p);
if (lt->tm_hour > 23)
badformat();
break;
default:
badformat();
}
/* The calling code needs a valid tm_ydays and this is the easiest
* way to get one */
if ((tval = mktime(lt)) == -1)
errx(1, "specified date is outside allowed range");
return (tval);
}
void
badformat(void)
{
warnx("illegal time format");
(void)fprintf(stderr, "usage: pom [[[[[cc]yy]mm]dd]HH]\n");
exit(EXIT_FAILURE);
}