cal.c - 9base - revived minimalist port of Plan 9 userland to Unix
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cal.c (4204B)
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1 #include <u.h>
2 #include <libc.h>
3 #include <bio.h>
4
5 char dayw[] =
6 {
7 " S M Tu W Th F S"
8 };
9 char *smon[] =
10 {
11 "January", "February", "March", "April",
12 "May", "June", "July", "August",
13 "September", "October", "November", "December",
14 };
15 char mon[] =
16 {
17 0,
18 31, 29, 31, 30,
19 31, 30, 31, 31,
20 30, 31, 30, 31,
21 };
22 char string[432];
23 Biobuf bout;
24
25 void main(int argc, char *argv[]);
26 int number(char *str);
27 void pstr(char *str, int n);
28 void cal(int m, int y, char *p, int w);
29 int jan1(int yr);
30 int curmo(void);
31 int curyr(void);
32
33 void
34 main(int argc, char *argv[])
35 {
36 int y, i, j, m;
37
38 if(argc > 3) {
39 fprint(2, "usage: cal [month] [year]\n");
40 exits("usage");
41 }
42 Binit(&bout, 1, OWRITE);
43
44 /*
45 * no arg, print current month
46 */
47 if(argc == 1) {
48 m = curmo();
49 y = curyr();
50 goto xshort;
51 }
52
53 /*
54 * one arg
55 * if looks like a month, print month
56 * else print year
57 */
58 if(argc == 2) {
59 y = number(argv[1]);
60 if(y < 0)
61 y = -y;
62 if(y >= 1 && y <= 12) {
63 m = y;
64 y = curyr();
65 goto xshort;
66 }
67 goto xlong;
68 }
69
70 /*
71 * two arg, month and year
72 */
73 m = number(argv[1]);
74 if(m < 0)
75 m = -m;
76 y = number(argv[2]);
77 goto xshort;
78
79 /*
80 * print out just month
81 */
82 xshort:
83 if(m < 1 || m > 12)
84 goto badarg;
85 if(y < 1 || y > 9999)
86 goto badarg;
87 Bprint(&bout, " %s %d\n", smon[m-1], y);
88 Bprint(&bout, "%s\n", dayw);
89 cal(m, y, string, 24);
90 for(i=0; i<6*24; i+=24)
91 pstr(string+i, 24);
92 exits(0);
93
94 /*
95 * print out complete year
96 */
97 xlong:
98 y = number(argv[1]);
99 if(y<1 || y>9999)
100 goto badarg;
101 Bprint(&bout, "\n\n\n");
102 Bprint(&bout, " %d\n", y);
103 Bprint(&bout, "\n");
104 for(i=0; i<12; i+=3) {
105 for(j=0; j<6*72; j++)
106 string[j] = '\0';
107 Bprint(&bout, " %.3s", smon[i]);
108 Bprint(&bout, " %.3s", smon[i+1]);
109 Bprint(&bout, " %.3s\n", smon[i+2]);
110 Bprint(&bout, "%s %s %s\n", dayw, dayw, dayw);
111 cal(i+1, y, string, 72);
112 cal(i+2, y, string+23, 72);
113 cal(i+3, y, string+46, 72);
114 for(j=0; j<6*72; j+=72)
115 pstr(string+j, 72);
116 }
117 Bprint(&bout, "\n\n\n");
118 exits(0);
119
120 badarg:
121 Bprint(&bout, "cal: bad argument\n");
122 }
123
124 struct
125 {
126 char* word;
127 int val;
128 } dict[] =
129 {
130 "jan", 1,
131 "january", 1,
132 "feb", 2,
133 "february", 2,
134 "mar", 3,
135 "march", 3,
136 "apr", 4,
137 "april", 4,
138 "may", 5,
139 "jun", 6,
140 "june", 6,
141 "jul", 7,
142 "july", 7,
143 "aug", 8,
144 "august", 8,
145 "sep", 9,
146 "sept", 9,
147 "september", 9,
148 "oct", 10,
149 "october", 10,
150 "nov", 11,
151 "november", 11,
152 "dec", 12,
153 "december", 12,
154 0
155 };
156
157 /*
158 * convert to a number.
159 * if its a dictionary word,
160 * return negative number
161 */
162 int
163 number(char *str)
164 {
165 int n, c;
166 char *s;
167
168 for(n=0; s=dict[n].word; n++)
169 if(strcmp(s, str) == 0)
170 return -dict[n].val;
171 n = 0;
172 s = str;
173 while(c = *s++) {
174 if(c<'0' || c>'9')
175 return 0;
176 n = n*10 + c-'0';
177 }
178 return n;
179 }
180
181 void
182 pstr(char *str, int n)
183 {
184 int i;
185 char *s;
186
187 s = str;
188 i = n;
189 while(i--)
190 if(*s++ == '\0')
191 s[-1] = ' ';
192 i = n+1;
193 while(i--)
194 if(*--s != ' ')
195 break;
196 s[1] = '\0';
197 Bprint(&bout, "%s\n", str);
198 }
199
200 void
201 cal(int m, int y, char *p, int w)
202 {
203 int d, i;
204 char *s;
205
206 s = p;
207 d = jan1(y);
208 mon[2] = 29;
209 mon[9] = 30;
210
211 switch((jan1(y+1)+7-d)%7) {
212
213 /*
214 * non-leap year
215 */
216 case 1:
217 mon[2] = 28;
218 break;
219
220 /*
221 * 1752
222 */
223 default:
224 mon[9] = 19;
225 break;
226
227 /*
228 * leap year
229 */
230 case 2:
231 ;
232 }
233 for(i=1; i<m; i++)
234 d += mon[i];
235 d %= 7;
236 s += 3*d;
237 for(i=1; i<=mon[m]; i++) {
238 if(i==3 && mon[m]==19) {
239 i += 11;
240 mon[m] += 11;
241 }
242 if(i > 9)
243 *s = i/10+'0';
244 s++;
245 *s++ = i%10+'0';
246 s++;
247 if(++d == 7) {
248 d = 0;
249 s = p+w;
250 p = s;
251 }
252 }
253 }
254
255 /*
256 * return day of the week
257 * of jan 1 of given year
258 */
259 int
260 jan1(int yr)
261 {
262 int y, d;
263
264 /*
265 * normal gregorian calendar
266 * one extra day per four years
267 */
268
269 y = yr;
270 d = 4+y+(y+3)/4;
271
272 /*
273 * julian calendar
274 * regular gregorian
275 * less three days per 400
276 */
277
278 if(y > 1800) {
279 d -= (y-1701)/100;
280 d += (y-1601)/400;
281 }
282
283 /*
284 * great calendar changeover instant
285 */
286
287 if(y > 1752)
288 d += 3;
289
290 return d%7;
291 }
292
293 /*
294 * system dependent
295 * get current month and year
296 */
297 int
298 curmo(void)
299 {
300 Tm *tm;
301
302 tm = localtime(time(0));
303 return tm->mon+1;
304 }
305
306 int
307 curyr(void)
308 {
309 Tm *tm;
310
311 tm = localtime(time(0));
312 return tm->year+1900;
313 }