added cron helper to calculate sun rise and set times

debian/libfn.cron.d

@@ -0,0 +1,2 @@
+0 0 * * * echo 'fnctl stop && fnctl fade -c 000000' | at $(sun rise 55 -6 1)
+0 0 * * * echo 'fnctl start' | at $(sun set 55 -6 1)

src/Makefile.am

@@ -1,7 +1,7 @@
 AM_CFLAGS= -Wall $(FNVUM_DEPS_CFLAGS) $(FNPOM_DEPS_CFLAGS)
 AM_LDFLAGS=
 
-bin_PROGRAMS = fnctl fnvum fnpom fnweb
+bin_PROGRAMS = fnctl fnvum fnpom fnweb sun
 lib_LTLIBRARIES = libfn.la
 include_HEADERS = libfn.h
 
@@ -18,3 +18,5 @@ fnvum_LDADD = -lfn $(FNVUM_DEPS_LIBS)
 
 fnweb_SOURCES = fnweb.c
 fnweb_LDADD = -lfn $(FNWEB_DEPS_LIBS)
+
+sun_SOURCES = sun.c

src/Makefile.in

@@ -37,7 +37,7 @@ POST_UNINSTALL = :
 build_triplet = @build@
 host_triplet = @host@
 bin_PROGRAMS = fnctl$(EXEEXT) fnvum$(EXEEXT) fnpom$(EXEEXT) \
-	fnweb$(EXEEXT)
+	fnweb$(EXEEXT) sun$(EXEEXT)
 subdir = src
 DIST_COMMON = $(include_HEADERS) $(srcdir)/Makefile.am \
 	$(srcdir)/Makefile.in
@@ -90,6 +90,9 @@ fnvum_DEPENDENCIES = $(am__DEPENDENCIES_1)
 am_fnweb_OBJECTS = fnweb.$(OBJEXT)
 fnweb_OBJECTS = $(am_fnweb_OBJECTS)
 fnweb_DEPENDENCIES = $(am__DEPENDENCIES_1)
+am_sun_OBJECTS = sun.$(OBJEXT)
+sun_OBJECTS = $(am_sun_OBJECTS)
+sun_LDADD = $(LDADD)
 DEFAULT_INCLUDES = -I.@am__isrc@ -I$(top_builddir)
 depcomp = $(SHELL) $(top_srcdir)/depcomp
 am__depfiles_maybe = depfiles
@@ -104,9 +107,9 @@ LINK = $(LIBTOOL) --tag=CC $(AM_LIBTOOLFLAGS) $(LIBTOOLFLAGS) \
 	--mode=link $(CCLD) $(AM_CFLAGS) $(CFLAGS) $(AM_LDFLAGS) \
 	$(LDFLAGS) -o $@
 SOURCES = $(libfn_la_SOURCES) $(fnctl_SOURCES) $(fnpom_SOURCES) \
-	$(fnvum_SOURCES) $(fnweb_SOURCES)
+	$(fnvum_SOURCES) $(fnweb_SOURCES) $(sun_SOURCES)
 DIST_SOURCES = $(libfn_la_SOURCES) $(fnctl_SOURCES) $(fnpom_SOURCES) \
-	$(fnvum_SOURCES) $(fnweb_SOURCES)
+	$(fnvum_SOURCES) $(fnweb_SOURCES) $(sun_SOURCES)
 HEADERS = $(include_HEADERS)
 ETAGS = etags
 CTAGS = ctags
@@ -244,6 +247,7 @@ fnvum_SOURCES = fnvum.c
 fnvum_LDADD = -lfn $(FNVUM_DEPS_LIBS)
 fnweb_SOURCES = fnweb.c
 fnweb_LDADD = -lfn $(FNWEB_DEPS_LIBS)
+sun_SOURCES = sun.c
 all: all-am
 
 .SUFFIXES:
@@ -366,6 +370,9 @@ fnvum$(EXEEXT): $(fnvum_OBJECTS) $(fnvum_DEPENDENCIES)
 fnweb$(EXEEXT): $(fnweb_OBJECTS) $(fnweb_DEPENDENCIES) 
 	@rm -f fnweb$(EXEEXT)
 	$(LINK) $(fnweb_OBJECTS) $(fnweb_LDADD) $(LIBS)
+sun$(EXEEXT): $(sun_OBJECTS) $(sun_DEPENDENCIES) 
+	@rm -f sun$(EXEEXT)
+	$(LINK) $(sun_OBJECTS) $(sun_LDADD) $(LIBS)
 
 mostlyclean-compile:
 	-rm -f *.$(OBJEXT)
@@ -378,6 +385,7 @@ distclean-compile:
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/fnvum.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/fnweb.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/libfn.Plo@am__quote@
+@AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/sun.Po@am__quote@
 
 .c.o:
 @am__fastdepCC_TRUE@	$(COMPILE) -MT $@ -MD -MP -MF $(DEPDIR)/$*.Tpo -c -o $@ $<

src/sun.c

@@ -0,0 +1,58 @@
+#include "stdio.h"
+#include "stdlib.h"
+#include "math.h"
+#include "time.h"
+
+double deg2rad(double deg) {
+	return M_PI * deg / 180.0;
+}
+
+enum sun { RISE, SET };
+
+double sun(enum sun mode, double lat, double lon, int timezone) {
+	const double h = -0.0145;
+	const double g = 0.2618;
+
+	time_t t = time(NULL);
+	struct tm *now = localtime(&t);
+	int days = now->tm_yday;
+
+	/* Zeitgleichung */
+	double zgl = -0.171 * sin(0.0337 * days + 0.465) - 0.1299 * sin(0.01787 * days - 0.168) ;
+
+	/* Deklination der Sonne */
+	double dekl = 0.4095 * sin(0.016906 * (days - 80.086));
+
+	/* Zeitdifferenz */
+	double zd = 12 * acos((sin(h) - sin(lat) * sin(dekl)) / (cos(lat) * cos(dekl))) / M_PI;
+
+	switch (mode) {
+		case SET: return 12 + zd - zgl + lon/g + timezone;
+		case RISE: return 12 - zd - zgl + lon/g + timezone;
+		default: return 0;
+	}
+}
+
+int main(int argc, char *argv[]) {
+	enum sun mode;
+
+	if (argc < 5) goto usage;
+
+
+	if (strcmp(argv[1], "rise") == 0) mode = RISE;
+	else if (strcmp(argv[1], "set") == 0) mode = SET;
+	else goto usage;
+
+	int timezone = atoi(argv[4]);
+	double lat = deg2rad(strtod(argv[2], NULL));
+	double lon = deg2rad(strtod(argv[3], NULL));
+	double time = sun(mode, lat, lon, timezone);
+	double intpart;
+
+	printf("%d:%02d\n", (int) floor(time), (int) (modf(time, &intpart)*60));
+	return 0;
+
+usage:
+	fprintf(stderr, "usage: sun (rise|set) LAT LON TIMEZONE\n");
+	return -1;
+}