sbase/cal.c

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C
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/* See LICENSE file for copyright and license details. */
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include "util.h"
#define MONTHMAX 100
static void drawcal(int, int, int, int, int, int);
static int dayofweek(int, int, int, int);
static bool isleap(int);
static void usage(void);
static void
drawcal(int year, int month, int day, int ncols, int nmons, int fday)
{
char str[21];
int count[MONTHMAX];
int d, i, r, j;
int moff, yoff, cur, last, ndays, day1;
char *smon[] = {
" January", " February", " March",
" April", " May", " June",
" July", " August", " September",
" October", " November", " December" };
int mdays[] = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
int row = 0;
char *days[] = { "Su", "Mo", "Tu", "We", "Th", "Fr", "Sa", };
while(nmons > 0) {
last = MIN(nmons, ncols);
for(i = 0; i < last; i++) {
moff = month + ncols * row + i - 1;
cur = moff % 12;
yoff = year + moff / 12;
sprintf(str, "%s %d", smon[cur], yoff);
printf("%-20s ", str);
count[i] = 1;
}
printf("\n");
for(i = 0; i < last; i++) {
for(j = fday; j < LEN(days); j++)
printf("%s ", days[j]);
for(j = 0; j < fday; j++)
printf("%s ", days[j]);
printf(" ");
}
printf("\n");
for(r = 0; r < 6; r++) {
for(i = 0; i < last; i++) {
moff = month + ncols * row + i - 1;
cur = moff % 12;
yoff = year + moff / 12;
ndays = mdays[cur] + ((cur == 1) & isleap(yoff));
day1 = dayofweek(year, cur, 1, fday);
for(d = 0; d < 7; d++) {
if((r || d >= day1) && count[i] <= ndays)
printf("%2d ", count[i]++);
else
printf(" ");
}
printf(" ");
}
printf("\n");
}
nmons -= ncols;
row++;
}
}
static int
dayofweek(int year, int month, int day, int fday)
{
int a, y, m, d;
month++;
a = (14 - month) / 12;
y = year + 4800 - a;
m = month + 12 * a - 3;
d = (day + (153 * m + 2) / 5 + 365 * y + y / 4 - y / 100 + y \
/ 400 - 32045 + 1) % 7;
return (fday > d)? (7 - d) : (d - fday);
}
static bool
isleap(int year)
{
bool leap = false;
if(year % 4 == 0)
leap = true;
if(year % 100 == 0)
leap = false;
if(year % 400 == 0)
leap = true;
return leap;
}
static void
usage(void)
{
eprintf("usage: %s [-c columns] [-m month] [-n number] [-y year]\n",
argv0);
}
int
main(int argc, char *argv[])
{
int year, month, day, ncols, nmons, fday;
struct tm *ltime;
time_t now;
now = time(NULL);
ltime = localtime(&now);
year = ltime->tm_year + 1900;
month = ltime->tm_mon + 1;
day = ltime->tm_mday;
fday = 0;
ncols = 3;
nmons = 1;
ARGBEGIN {
case '1':
nmons = 1;
break;
case '3':
nmons = 3;
month -= 1;
if(month == 0) {
month = 12;
year--;
}
break;
case 'c':
ncols = estrtol(EARGF(usage()), 0);
break;
case 'f':
fday = estrtol(EARGF(usage()), 0);
break;
case 'm': /* Monday */
fday = 1;
break;
case 'n':
nmons = estrtol(EARGF(usage()), 0);
break;
case 's': /* Sunday */
fday = 0;
break;
case 'y':
month = 1;
nmons = 12;
break;
default:
usage();
} ARGEND;
switch(argc) {
case 3:
day = estrtol(argv[0], 0);
argv++;
case 2:
month = estrtol(argv[0], 0);
argv++;
case 1:
year = estrtol(argv[0], 0);
break;
case 0:
break;
default:
usage();
}
if(ncols < 0 || ncols > MONTHMAX || month < 1 || month > 12 \
|| nmons < 1 || fday < 0 || fday > 6) {
usage();
}
drawcal(year, month, day, ncols, nmons, fday);
exit(0);
}