--- /dev/null
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include "calendar.h"
+
+struct _Breviary {
+
+ time_t time;
+
+ /**
+ * Whether this is Year 1 or 2.
+ */
+ unsigned int year1or2: 2;
+
+ unsigned int hour:6;
+
+ /* Flags */
+ unsigned int debug:1;
+ unsigned int bvmblue:1;
+ unsigned int adventblue:1;
+ unsigned int rose:1;
+
+ unsigned int facets[5];
+
+};
+
+Breviary *
+breviary_new (time_t when)
+{
+ Breviary *result = malloc (sizeof (Breviary));
+
+ result->time = when;
+ result->facets[0] = 0;
+
+ result->debug = 0;
+ result->bvmblue = 0;
+ result->adventblue = 0;
+ result->rose = 0;
+
+ return result;
+}
+
+void
+breviary_set_flag (Breviary *breviary,
+ const char *flag,
+ int value)
+{
+ value = !!value;
+
+ if (strcmp("debug", flag)==0) {
+ breviary->debug = value;
+ } else if (strcmp("bvmblue", flag)==0) {
+ breviary->bvmblue = value;
+ } else if (strcmp("adventblue", flag)==0) {
+ breviary->adventblue = value;
+ } else if (strcmp("rose", flag)==0) {
+ breviary->rose = value;
+ }
+}
+
+long
+ymd_to_serial (int y, int m, int d)
+{
+ struct tm time;
+
+ time.tm_sec = 0;
+ time.tm_min = 0;
+ time.tm_hour = 0;
+ time.tm_mday = d;
+ time.tm_mon = m-1; /* January is 0 */
+ time.tm_year = y;
+ time.tm_wday = 0;
+ time.tm_yday = 0;
+ time.tm_isdst = 0;
+
+ return mktime(&time) / (60*60*24);
+}
+
+/**
+ * Returns the serial number of the Sunday immediately
+ * before the parameter, unless the parameter represents
+ * a Sunday, in which case it is returned unchanged.
+ *
+ * \param serial The serial number of a day.
+ * \result A Sunday within a week before "serial".
+ */
+long
+rewind_to_sunday (long serial)
+{
+ serial += 4;
+ return (serial - (serial%7)) - 4;
+}
+
+/**
+ * Returns the date of Easter for the given calendar year.
+ *
+ * \param y The number of years after 1900 (for
+ * example, 2010 is 110).
+ * \result The date of Easter for the given year,
+ * expressed as a number of days after
+ * 1 January 1970.
+ */
+unsigned long
+year_to_easter (int y)
+{
+ int c, g, k, l, i, j, m, d;
+
+ y = y + 1900;
+ c = y/100;
+ g = y%19;
+ k = (c-17) / 25;
+ i = (c - c/4 - (c-k)/3 + 19*g + 15) % 30;
+ i = i - (i/28)*(1- (i/28)*(29/(i+1))*((21-g)/11));
+ j = (y + y/4 + i + 2 - c + c/4) % 7;
+ l = i - j;
+ m = 3 + (l+40)/44;
+ d = l + 28 - 31*(m/4);
+
+ return ymd_to_serial (y-1900, m, d);
+}
+
+/**
+ * Returns the date of Advent Sunday, the first
+ * day of the liturgical year, for the given calendar year.
+ *
+ * \param y The number of years after 1900 (for
+ * example, 2010 is 110).
+ * \result The date of Advent Sunday for the given
+ * year, expressed as a number of days
+ * after 1 January 1970.
+ */
+unsigned long
+year_to_advent_sunday (int y)
+{
+ /* Firstly, discover which day Christmas falls on */
+ struct tm time;
+ long result = ymd_to_serial (y, 12, 25);
+ time_t christmas = result * (60*60*24);
+
+ gmtime_r (&christmas,
+ &time);
+
+ if (time.tm_wday==0)
+ {
+ /* Christmas falls on a Sunday */
+ result -= 7;
+ }
+ else
+ {
+ /*
+ * It was that many days after the
+ * Sunday we want.
+ */
+ result -= time.tm_wday;
+ }
+
+ /* Now skip backwards three more weeks */
+ result -= (3*7);
+
+ return result;
+
+}
+
+static void
+dump_date (const char* message,
+ long serial)
+{
+ struct tm tm;
+ time_t time = serial * (24*60*60);
+
+ gmtime_r (&time,
+ &tm);
+
+ printf ("%s - %ld - %d-%d-%d\n",
+ message,
+ serial,
+ tm.tm_year+1900, tm.tm_mon+1, tm.tm_mday);
+}
+
+void
+breviary_ensure_initialised (Breviary *breviary)
+{
+ struct tm tm;
+ long target_serial,
+ easter_serial,
+ advent_sunday_serial,
+ week_count_start_serial,
+ season_start_serial,
+ sunday_before_season_start_serial;
+ int season = SEASON_NONE;
+ int days_after_easter;
+ int days_after_week_count_start;
+
+ if (breviary->facets[0]!=0)
+ return;
+
+#if 0
+ printf ("Breviary is not initialised; doing it now.\n");
+#endif
+
+ breviary->facets[0] = 1;
+ breviary->facets[1] = 1;
+ breviary->facets[2] = 1;
+ breviary->facets[3] = 1;
+ breviary->facets[4] = 0;
+
+ gmtime_r (&(breviary->time),
+ &tm);
+
+ breviary->hour = tm.tm_hour;
+
+ breviary->facets[0] =
+ 10100 +
+ tm.tm_mon*100 +
+ tm.tm_mday;
+
+ target_serial =
+ ymd_to_serial (tm.tm_year,
+ tm.tm_mon+1,
+ tm.tm_mday);
+
+#if 0
+ dump_date ("Target date",
+ target_serial);
+#endif
+
+ easter_serial = year_to_easter (tm.tm_year);
+
+#if 0
+ dump_date ("Easter",
+ easter_serial);
+#endif
+
+ days_after_easter = target_serial - easter_serial;
+
+ breviary->facets[3] =
+ 40500 +
+ days_after_easter;
+
+ week_count_start_serial =
+ rewind_to_sunday (ymd_to_serial (tm.tm_year,
+ 1, 1));
+
+#if 0
+ dump_date ("Measuring weeks from",
+ week_count_start_serial);
+#endif
+
+ days_after_week_count_start =
+ target_serial - week_count_start_serial;
+
+ breviary->facets[1] =
+ 20000 +
+ 10 * (days_after_week_count_start/7) +
+ days_after_week_count_start%7;
+
+ advent_sunday_serial =
+ year_to_advent_sunday (tm.tm_year);
+
+#if 0
+ dump_date ("Advent Sunday",
+ advent_sunday_serial);
+#endif
+
+ /* Now to calculate the season */
+
+ if (days_after_easter > -47 &&
+ days_after_easter < 0)
+ {
+ breviary->facets[2] =
+ SEASON_LENT;
+ season_start_serial =
+ easter_serial - 47;
+ }
+ else if (days_after_easter >= 0 &&
+ days_after_easter <= 49)
+ {
+ /*
+ * yes, this is correct: Pentecost
+ * itself is in Easter season, not
+ * Pentecost season
+ */
+
+ breviary->facets[2] =
+ SEASON_EASTER;
+ season_start_serial =
+ easter_serial;
+ }
+ else if (target_serial >= advent_sunday_serial &&
+ breviary->facets[0] < 11225)
+ {
+ breviary->facets[2] =
+ SEASON_ADVENT;
+ season_start_serial =
+ advent_sunday_serial;
+ }
+ else if (breviary->facets[0] >= 11225 ||
+ breviary->facets[0] <= 10105)
+ {
+ int year = tm.tm_year;
+
+ if (breviary->facets[0] <= 10105)
+ {
+ year--;
+ }
+
+ breviary->facets[2] =
+ SEASON_CHRISTMAS;
+ season_start_serial =
+ ymd_to_serial (year, 12, 25);
+ }
+ else if (days_after_easter <= -47)
+ {
+ breviary->facets[2] =
+ SEASON_EPIPHANY;
+ season_start_serial =
+ ymd_to_serial (tm.tm_year,
+ 1, 6);
+ }
+ else
+ {
+ breviary->facets[2] =
+ SEASON_PENTECOST;
+ season_start_serial =
+ easter_serial + 50;
+ }
+
+#if 0
+ dump_date ("Season starts on",
+ season_start_serial);
+#endif
+
+ sunday_before_season_start_serial =
+ rewind_to_sunday (season_start_serial);
+
+ if (sunday_before_season_start_serial ==
+ season_start_serial)
+ {
+ /*
+ * If the season begins on a Sunday,
+ * the first week is 1, not 0.
+ */
+ sunday_before_season_start_serial -= 7;
+ }
+
+ if (target_serial ==
+ advent_sunday_serial-7)
+ {
+ /*
+ * The feast of Christ the King gets a
+ * special case: it's coded as week
+ * 99 of Pentecost season. (See the
+ * docs for a discussion of why.)
+ */
+
+ breviary->facets[2] += 990;
+ }
+ else
+ {
+ breviary->facets[2] += 10 *
+ ((target_serial - sunday_before_season_start_serial)/7);
+ }
+
+ /* And lastly, add the day of the week. */
+ breviary->facets[2] +=
+ days_after_week_count_start%7;
+
+#if 0
+
+ /* Year 1 or 2? */
+
+ breviary->year1or2 = 1 + (tm.tm_year%2);
+ if (target_serial >= advent_sunday_serial)
+ {
+ /*
+ * If we're on or after Advent Sunday, we're
+ * into the following year, so flip the
+ * year number.
+ */
+ breviary->year1or2 = 3 - breviary->year1or2;
+ }
+
+ printf ("Year 1 or 2? %d\n", breviary->year1or2);
+
+ /* Calculate the season. */
+#endif
+
+}
+
+const int*
+breviary_get_facets (Breviary *breviary)
+{
+ breviary_ensure_initialised (breviary);
+
+ return &(breviary->facets[0]);
+}
+
+void
+breviary_free (Breviary *breviary)
+{
+ free (breviary);
+}
+
+static void
+dump_sundays (void)
+{
+ long current = ymd_to_serial (75, 1, 1);
+ int day;
+
+ printf ("# Dump Sundays\n");
+
+ for (day=1; day<32; day++) {
+ struct tm tm;
+ char *is_sunday = "";
+ time_t time;
+
+ time = current * (60*60*24);
+
+ gmtime_r (&time,
+ &tm);
+
+ if (tm.tm_wday==0)
+ {
+ is_sunday = " (Sunday)";
+ }
+
+ printf ("%d-%02d-%02d %10ld %10ld%s\n",
+ tm.tm_year+1900,
+ tm.tm_mon+1,
+ tm.tm_mday,
+ current,
+ rewind_to_sunday (current),
+ is_sunday);
+
+ current++;
+ }
+}
+
+char *
+breviary_explain_facet (int facet)
+{
+ const size_t size = 15;
+ char *result = malloc (size);
+
+ result[0] = 0;
+
+ switch (facet / 10000)
+ {
+ case 1: /* Gregorian */
+ {
+ int month = (facet%10000)/100;
+ int day = facet%100;
+ char *month_name = NULL;
+
+ switch (month)
+ {
+ case 1: month_name = "Jan"; break;
+ case 2: month_name = "Feb"; break;
+ case 3: month_name = "Mar"; break;
+ case 4: month_name = "Apr"; break;
+ case 5: month_name = "May"; break;
+ case 6: month_name = "Jun"; break;
+ case 7: month_name = "Jul"; break;
+ case 8: month_name = "Aug"; break;
+ case 9: month_name = "Sep"; break;
+ case 10: month_name = "Oct"; break;
+ case 11: month_name = "Nov"; break;
+ case 12: month_name = "Dec"; break;
+ }
+
+ if (month_name)
+ {
+ snprintf (result, size,
+ "%s %2d",
+ month_name, day);
+ }
+ }
+ break;
+
+ case 2: /* Week number */
+ {
+ int week = (facet-20000) / 10;
+ int day = facet % 10;
+ char* day_name = NULL;
+
+ switch (day)
+ {
+ case 0: day_name = "Sun"; break;
+ case 1: day_name = "Mon"; break;
+ case 2: day_name = "Tue"; break;
+ case 3: day_name = "Wed"; break;
+ case 4: day_name = "Thu"; break;
+ case 5: day_name = "Fri"; break;
+ case 6: day_name = "Sat"; break;
+ }
+
+ if (day_name)
+ {
+ snprintf (result, size,
+ "%s, week %d",
+ day_name,
+ week);
+ }
+ }
+ break;
+
+ case 3: /* Season */
+ {
+ int season = (facet / 1000) * 1000;
+ int week = (facet/10) % 100;
+ char *season_name = NULL;
+
+ switch (season)
+ {
+ case SEASON_ADVENT:
+ season_name = "Adve";
+ break;
+
+ case SEASON_CHRISTMAS:
+ season_name = "Chri";
+ break;
+
+ case SEASON_EPIPHANY:
+ season_name = "Ephi";
+ break;
+
+ case SEASON_LENT:
+ season_name = "Lent";
+ break;
+
+ case SEASON_EASTER:
+ season_name = "East";
+ break;
+
+ case SEASON_PENTECOST:
+ season_name = "Pent";
+ break;
+ }
+
+ if (season_name)
+ {
+ snprintf (result, size,
+ "%s %d",
+ season_name, week);
+ }
+ }
+ break;
+
+ case 4: /* Easter */
+ {
+ int value = facet - 40500;
+ char sign = '+';
+
+ if (value<0)
+ {
+ value = -value;
+ sign = '-';
+ }
+
+ snprintf (result, size,
+ "Easter%c%03d",
+ sign, value);
+ }
+ break;
+ }
+
+ if (result[0]==0)
+ {
+ snprintf (result, size,
+ "Unknown");
+ }
+
+ return result;
+}
+
+void
+breviary_free_string (char *string)
+{
+ if (string==NULL)
+ {
+ return;
+ }
+
+ free (string);
+}
+
+static void
+dump_facets (void)
+{
+ long current = ymd_to_serial (75, 1, 1);
+ int i;
+ const int *cursor;
+ Breviary *breviary;
+
+ printf ("# Dump facets\n");
+
+ for (i=0; i<365; i++) {
+ struct tm tm;
+ time_t time;
+
+ time = current * (60*60*24);
+
+ gmtime_r (&time,
+ &tm);
+
+ printf ("%d-%02d-%02d",
+ tm.tm_year+1900,
+ tm.tm_mon+1,
+ tm.tm_mday);
+
+ breviary = breviary_new (time);
+
+ cursor = breviary_get_facets (breviary);
+
+ while (*cursor)
+ {
+ char *explanation =
+ breviary_explain_facet (*cursor);
+ printf (" %d %-15s", *cursor,
+ explanation);
+ breviary_free_string (explanation);
+ cursor++;
+ }
+
+ breviary_free (breviary);
+
+ printf ("\n");
+
+ current++;
+ }
+
+}
+
+int
+breviary_test_dump_feast (unsigned int feast)
+{
+ int year;
+ struct tm tm;
+
+ switch (feast)
+ {
+ case 1:
+ dump_sundays ();
+ return;
+
+ case 2:
+ dump_facets ();
+ return;
+
+ case 3:
+ case 4:
+ break;
+
+ default:
+ printf ("# Unknown request %d\n", feast);
+ return;
+ }
+
+ for (year=70; year<=120; year++)
+ {
+ int date;
+ time_t time;
+
+ if (feast==3)
+ date = year_to_easter (year);
+ else
+ date = year_to_advent_sunday (year);
+
+ time = (time_t) date * (24*60*60);
+
+ gmtime_r (&time,
+ &tm);
+
+ printf ("%d-%d-%d\n",
+ tm.tm_year+1900, tm.tm_mon+1, tm.tm_mday);
+ }
+}
+
+/* EOF calendar.c */
~tthurman / breviary.git / commitdiff