| 1 | /* cal - print a calendar Author: Maritn Minow */
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| 2 |
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| 3 | #include <stdlib.h>
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| 4 | #include <string.h>
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| 5 | #include <stdio.h>
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| 6 |
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| 7 | #define do3months domonth
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| 8 | #define IO_SUCCESS 0 /* Unix definitions */
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| 9 | #define IO_ERROR 1
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| 10 | #define EOS 0
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| 11 |
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| 12 | #define ENTRY_SIZE 3 /* 3 bytes per value */
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| 13 | #define DAYS_PER_WEEK 7 /* Sunday, etc. */
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| 14 | #define WEEKS_PER_MONTH 6 /* Max. weeks in a month */
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| 15 | #define MONTHS_PER_LINE 3 /* Three months across */
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| 16 | #define MONTH_SPACE 3 /* Between each month */
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| 17 |
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| 18 | char *badarg = {"Bad argument\n"};
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| 19 | char *how = {"Usage: cal [month] year\n"};
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| 20 |
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| 21 | /* Calendar() stuffs data into layout[],
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| 22 | * output() copies from layout[] to outline[], (then trims blanks).
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| 23 | */
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| 24 | char layout[MONTHS_PER_LINE][WEEKS_PER_MONTH][DAYS_PER_WEEK][ENTRY_SIZE];
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| 25 | char outline[(MONTHS_PER_LINE * DAYS_PER_WEEK * ENTRY_SIZE)
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| 26 | + (MONTHS_PER_LINE * MONTH_SPACE)
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| 27 | + 1];
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| 28 |
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| 29 | char *weekday = " S M Tu W Th F S";
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| 30 | char *monthname[] = {
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| 31 | "???", /* No month 0 */
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| 32 | "Jan", "Feb", "Mar", "Apr", "May", "Jun",
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| 33 | "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
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| 34 | };
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| 35 |
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| 36 | _PROTOTYPE(int main, (int argc, char **argv));
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| 37 | _PROTOTYPE(void doyear, (int year));
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| 38 | _PROTOTYPE(void domonth, (int year, int month));
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| 39 | _PROTOTYPE(void output, (int nmonths));
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| 40 | _PROTOTYPE(void calendar, (int year, int month, int indx));
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| 41 | _PROTOTYPE(void usage, (char *s));
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| 42 | _PROTOTYPE(int date, (int year, int month, int week, int wday));
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| 43 | _PROTOTYPE(void setmonth, (int year, int month));
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| 44 | _PROTOTYPE(int getdate, (int week, int wday));
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| 45 | _PROTOTYPE(static int Jan1, (int year));
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| 46 |
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| 47 | int main(argc, argv)
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| 48 | int argc;
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| 49 | char *argv[];
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| 50 | {
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| 51 | register int year;
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| 52 |
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| 53 | register int arg1val;
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| 54 | int arg1len;
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| 55 | int arg2val;
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| 56 |
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| 57 | if (argc <= 1) {
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| 58 | usage(how);
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| 59 | } else {
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| 60 | arg1val = atoi(argv[1]);
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| 61 | arg1len = strlen(argv[1]);
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| 62 | if (argc == 2) {
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| 63 | /* Only one argument, if small, it's a month. If
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| 64 | * large, it's a year. Note: cal 0082 Year
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| 65 | * 0082 cal 82 Year 0082 */
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| 66 | if (arg1len <= 2 && arg1val <= 12)
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| 67 | do3months(year, arg1val);
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| 68 | else
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| 69 | doyear(arg1val);
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| 70 | } else {
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| 71 | /* Two arguments, allow 1980 12 or 12 1980 */
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| 72 | arg2val = atoi(argv[2]);
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| 73 | if (arg1len > 2)
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| 74 | do3months(arg1val, arg2val);
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| 75 | else
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| 76 | do3months(arg2val, arg1val);
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| 77 | }
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| 78 | }
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| 79 | return(IO_SUCCESS);
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| 80 | }
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| 81 |
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| 82 | void doyear(year)
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| 83 | int year;
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| 84 | /* Print the calendar for an entire year. */
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| 85 | {
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| 86 | register int month;
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| 87 |
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| 88 | if (year < 1 || year > 9999) usage(badarg);
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| 89 | if (year < 100)
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| 90 | printf("\n\n\n 00%2d\n\n", year);
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| 91 | else
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| 92 | printf("\n\n\n%35d\n\n", year);
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| 93 | for (month = 1; month <= 12; month += MONTHS_PER_LINE) {
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| 94 | printf("%12s%23s%23s\n",
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| 95 | monthname[month],
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| 96 | monthname[month + 1],
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| 97 | monthname[month + 2]);
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| 98 | printf("%s %s %s\n", weekday, weekday, weekday);
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| 99 | calendar(year, month + 0, 0);
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| 100 | calendar(year, month + 1, 1);
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| 101 | calendar(year, month + 2, 2);
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| 102 | output(3);
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| 103 | #if MONTHS_PER_LINE != 3
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| 104 | #error "the above will not work"
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| 105 | #endif
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| 106 | }
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| 107 | printf("\n\n\n");
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| 108 | }
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| 109 |
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| 110 | void domonth(year, month)
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| 111 | int year;
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| 112 | int month;
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| 113 | /* Do one specific month -- note: no longer used */
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| 114 | {
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| 115 | if (year < 1 || year > 9999) usage(badarg);
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| 116 | if (month <= 0 || month > 12) usage(badarg);
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| 117 | printf("%9s%5d\n\n%s\n", monthname[month], year, weekday);
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| 118 | calendar(year, month, 0);
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| 119 | output(1);
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| 120 | printf("\n\n");
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| 121 | }
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| 122 |
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| 123 | void output(nmonths)
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| 124 | int nmonths; /* Number of months to do */
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| 125 | /* Clean up and output the text. */
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| 126 | {
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| 127 | register int week;
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| 128 | register int month;
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| 129 | register char *outp;
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| 130 | int i;
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| 131 | char tmpbuf[21], *p;
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| 132 |
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| 133 | for (week = 0; week < WEEKS_PER_MONTH; week++) {
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| 134 | outp = outline;
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| 135 | for (month = 0; month < nmonths; month++) {
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| 136 | /* The -1 in the following removes the unwanted
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| 137 | * leading blank from the entry for Sunday. */
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| 138 | p = &layout[month][week][0][1];
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| 139 | for (i = 0; i < 20; i++) tmpbuf[i] = *p++;
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| 140 | tmpbuf[20] = 0;
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| 141 | sprintf(outp, "%s ", tmpbuf);
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| 142 | outp += (DAYS_PER_WEEK * ENTRY_SIZE) + MONTH_SPACE - 1;
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| 143 | }
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| 144 | while (outp > outline && outp[-1] == ' ') outp--;
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| 145 | *outp = EOS;
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| 146 | printf("%s\n", outline);
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| 147 | }
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| 148 | }
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| 149 |
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| 150 | void calendar(year, month, indx)
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| 151 | int year;
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| 152 | int month;
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| 153 | int indx; /* Which of the three months */
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| 154 | /* Actually build the calendar for this month. */
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| 155 | {
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| 156 | register char *tp;
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| 157 | int week;
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| 158 | register int wday;
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| 159 | register int today;
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| 160 |
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| 161 | setmonth(year, month);
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| 162 | for (week = 0; week < WEEKS_PER_MONTH; week++) {
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| 163 | for (wday = 0; wday < DAYS_PER_WEEK; wday++) {
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| 164 | tp = &layout[indx][week][wday][0];
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| 165 | *tp++ = ' ';
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| 166 | today = getdate(week, wday);
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| 167 | if (today <= 0) {
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| 168 | *tp++ = ' ';
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| 169 | *tp++ = ' ';
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| 170 | } else if (today < 10) {
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| 171 | *tp++ = ' ';
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| 172 | *tp = (today + '0');
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| 173 | } else {
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| 174 | *tp++ = (today / 10) + '0';
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| 175 | *tp = (today % 10) + '0';
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| 176 | }
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| 177 | }
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| 178 | }
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| 179 | }
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| 180 |
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| 181 | void usage(s)
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| 182 | char *s;
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| 183 | {
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| 184 | /* Fatal parameter error. */
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| 185 |
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| 186 | fprintf(stderr, "%s", s);
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| 187 | exit(IO_ERROR);
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| 188 | }
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| 189 |
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| 190 | /* Calendar routines, intended for eventual porting to TeX
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| 191 | *
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| 192 | * date(year, month, week, wday)
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| 193 | * Returns the date on this week (0 is first, 5 last possible)
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| 194 | * and day of the week (Sunday == 0)
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| 195 | * Note: January is month 1.
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| 196 | *
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| 197 | * setmonth(year, month)
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| 198 | * Parameters are as above, sets getdate() for this month.
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| 199 | *
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| 200 | * int
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| 201 | * getdate(week, wday)
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| 202 | * Parameters are as above, uses the data set by setmonth()
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| 203 | */
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| 204 |
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| 205 | /* This structure is used to pass data between setmonth() and getdate().
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| 206 | * It needs considerable expansion if the Julian->Gregorian change is
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| 207 | * to be extended to other countries.
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| 208 | */
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| 209 |
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| 210 | static struct {
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| 211 | int this_month; /* month number used in 1752 checking */
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| 212 | int feb; /* Days in February for this month */
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| 213 | int sept; /* Days in September for this month */
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| 214 | int days_in_month; /* Number of days in this month */
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| 215 | int dow_first; /* Day of week of the 1st day in month */
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| 216 | } info;
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| 217 |
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| 218 | static int day_month[] = { /* 30 days hath September... */
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| 219 | 0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
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| 220 | };
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| 221 |
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| 222 | int date(year, month, week, wday)
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| 223 | int year; /* Calendar date being computed */
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| 224 | int month; /* January == 1 */
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| 225 | int week; /* Week in the month 0..5 inclusive */
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| 226 | int wday; /* Weekday, Sunday == 0 */
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| 227 | /* Return the date of the month that fell on this week and weekday.
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| 228 | * Return zero if it's out of range.
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| 229 | */
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| 230 | {
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| 231 | setmonth(year, month);
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| 232 | return(getdate(week, wday));
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| 233 | }
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| 234 |
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| 235 | void setmonth(year, month)
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| 236 | int year; /* Year to compute */
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| 237 | int month; /* Month, January is month 1 */
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| 238 | /* Setup the parameters needed to compute this month
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| 239 | * (stored in the info structure).
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| 240 | */
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| 241 | {
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| 242 | register int i;
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| 243 |
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| 244 | if (month < 1 || month > 12) {/* Verify caller's parameters */
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| 245 | info.days_in_month = 0; /* Garbage flag */
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| 246 | return;
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| 247 | }
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| 248 | info.this_month = month; /* used in 1752 checking */
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| 249 | info.dow_first = Jan1(year); /* Day of January 1st for now */
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| 250 | info.feb = 29; /* Assume leap year */
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| 251 | info.sept = 30; /* Assume normal year */
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| 252 | /* Determine whether it's an ordinary year, a leap year or the
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| 253 | * magical calendar switch year of 1752. */
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| 254 | switch ((Jan1(year + 1) + 7 - info.dow_first) % 7) {
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| 255 | case 1: /* Not a leap year */
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| 256 | info.feb = 28;
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| 257 | case 2: /* Ordinary leap year */
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| 258 | break;
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| 259 |
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| 260 | default: /* The magical moment arrives */
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| 261 | info.sept = 19; /* 19 days hath September */
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| 262 | break;
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| 263 | }
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| 264 | info.days_in_month =
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| 265 | (month == 2) ? info.feb
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| 266 | : (month == 9) ? info.sept
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| 267 | : day_month[month];
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| 268 | for (i = 1; i < month; i++) {
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| 269 | switch (i) { /* Special months? */
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| 270 | case 2: /* February */
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| 271 | info.dow_first += info.feb;
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| 272 | break;
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| 273 |
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| 274 | case 9: info.dow_first += info.sept; break;
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| 275 |
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| 276 | default:
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| 277 | info.dow_first += day_month[i];
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| 278 | break;
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| 279 | }
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| 280 | }
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| 281 | info.dow_first %= 7; /* Now it's Sunday to Saturday */
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| 282 | }
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| 283 |
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| 284 | int getdate(week, wday)
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| 285 | int week;
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| 286 | int wday;
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| 287 | {
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| 288 | register int today;
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| 289 |
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| 290 | /* Get a first guess at today's date and make sure it's in range. */
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| 291 | today = (week * 7) + wday - info.dow_first + 1;
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| 292 | if (today <= 0 || today > info.days_in_month)
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| 293 | return(0);
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| 294 | else if (info.sept == 19 && info.this_month == 9
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| 295 | && today >= 3) /* The magical month? */
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| 296 | return(today + 11); /* If so, some dates changed */
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| 297 | else /* Otherwise, */
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| 298 | return(today); /* Return the date */
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| 299 | }
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| 300 |
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| 301 | static int Jan1(year)
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| 302 | int year;
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| 303 | /* Return day of the week for Jan 1 of the specified year. */
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| 304 | {
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| 305 | register int day;
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| 306 |
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| 307 | day = year + 4 + ((year + 3) / 4); /* Julian Calendar */
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| 308 | if (year > 1800) { /* If it's recent, do */
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| 309 | day -= ((year - 1701) / 100); /* Clavian correction */
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| 310 | day += ((year - 1601) / 400); /* Gregorian correction */
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| 311 | }
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| 312 | if (year > 1752) /* Adjust for Gregorian */
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| 313 | day += 3; /* calendar */
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| 314 | return(day % 7);
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| 315 | }
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