1 #include "../hdr/macros.h"
2
3 SCCSID(@(#)ctime.c 4.3);
4
5 /*
6 * This routine converts time as follows.
7 * The epoch is 0000 Jan 1 1970 GMT.
8 * The argument time is in seconds since then.
9 * The localtime(t) entry returns a pointer to an array
10 * containing
11 * seconds (0-59)
12 * minutes (0-59)
13 * hours (0-23)
14 * day of month (1-31)
15 * month (0-11)
16 * year-1970
17 * weekday (0-6, Sun is 0)
18 * day of the year
19 * daylight savings flag
20 *
21 * The routine calls the system to determine the local
22 * timezone and whether Daylight Saving Time is permitted locally.
23 * (DST is then determined by the current US standard rules)
24 * There is a table that accounts for the peculiarities
25 * undergone by daylight time in 1974-1975.
26 *
27 * The routine does not work
28 * in Saudi Arabia which runs on Solar time.
29 *
30 * asctime(tvec))
31 * where tvec is produced by localtime
32 * returns a ptr to a character string
33 * that has the ascii time in the form
34 * Thu Jan 01 00:00:00 1970n0\\
35 * 01234567890123456789012345
36 * 0 1 2
37 *
38 * ctime(t) just calls localtime, then asctime.
39 */
40
41 #ifdef notdef
42 #include <sys/types.h> /* included by macros.h above */
43 #endif
44 #include <sys/time.h>
45 #include <sys/timeb.h>
46
47 static char cbuf[26];
48 int dmsize[12] =
49 {
50 31,
51 28,
52 31,
53 30,
54 31,
55 30,
56 31,
57 31,
58 30,
59 31,
60 30,
61 31
62 };
63
64 /*
65 * The following table is used for 1974 and 1975 and
66 * gives the day number of the first day after the Sunday of the
67 * change.
68 */
69 static struct {
70 int daylb;
71 int dayle;
72 } daytab[] = {
73 5, 333, /* 1974: Jan 6 - last Sun. in Nov */
74 58, 303, /* 1975: Last Sun. in Feb - last Sun in Oct */
75 };
76
77 struct tm *gmtime();
78 char *ct_numb();
79 struct tm *localtime();
80 char *ctime();
81 char *ct_num();
82 char *asctime();
83
84 char *
ctime(t)85 ctime(t)
86 long *t;
87 {
88 return(asctime(localtime(t)));
89 }
90
91 struct tm *
localtime(tim)92 localtime(tim)
93 long *tim;
94 {
95 register int dayno;
96 register struct tm *ct;
97 register daylbegin, daylend;
98 long copyt;
99 struct timeb systime;
100
101 ftime(&systime);
102 copyt = *tim - (long)systime.timezone*60;
103 ct = gmtime(©t);
104 dayno = ct->tm_yday;
105 daylbegin = 119; /* last Sun in Apr */
106 daylend = 303; /* Last Sun in Oct */
107 if (ct->tm_year==74 || ct->tm_year==75) {
108 daylbegin = daytab[ct->tm_year-74].daylb;
109 daylend = daytab[ct->tm_year-74].dayle;
110 }
111 daylbegin = sunday(ct, daylbegin);
112 daylend = sunday(ct, daylend);
113 if (systime.dstflag &&
114 (dayno>daylbegin || (dayno==daylbegin && ct->tm_hour>=2)) &&
115 (dayno<daylend || (dayno==daylend && ct->tm_hour<1))) {
116 copyt += 1*60*60;
117 ct = gmtime(©t);
118 ct->tm_isdst++;
119 }
120 return(ct);
121 }
122
123 /*
124 * The argument is a 0-origin day number.
125 * The value is the day number of the first
126 * Sunday on or after the day.
127 */
128 static
sunday(t,d)129 sunday(t, d)
130 register struct tm *t;
131 register int d;
132 {
133 if (d >= 58)
134 d += dysize(t->tm_year) - 365;
135 return(d - (d - t->tm_yday + t->tm_wday + 700) % 7);
136 }
137
138 struct tm *
gmtime(tim)139 gmtime(tim)
140 long *tim;
141 {
142 register int d0, d1;
143 long hms, day;
144 register int *tp;
145 static struct tm xtime;
146
147 /*
148 * break initial number into days
149 */
150 hms = *tim % 86400;
151 day = *tim / 86400;
152 if (hms<0) {
153 hms += 86400;
154 day -= 1;
155 }
156 tp = (int *)&xtime;
157
158 /*
159 * generate hours:minutes:seconds
160 */
161 *tp++ = hms%60;
162 d1 = hms/60;
163 *tp++ = d1%60;
164 d1 /= 60;
165 *tp++ = d1;
166
167 /*
168 * day is the day number.
169 * generate day of the week.
170 * The addend is 4 mod 7 (1/1/1970 was Thursday)
171 */
172
173 xtime.tm_wday = (day+7340036)%7;
174
175 /*
176 * year number
177 */
178 if (day>=0) for(d1=70; day >= dysize(d1); d1++)
179 day -= dysize(d1);
180 else for (d1=70; day<0; d1--)
181 day += dysize(d1-1);
182 xtime.tm_year = d1;
183 xtime.tm_yday = d0 = day;
184
185 /*
186 * generate month
187 */
188
189 if (dysize(d1)==366)
190 dmsize[1] = 29;
191 for(d1=0; d0 >= dmsize[d1]; d1++)
192 d0 -= dmsize[d1];
193 dmsize[1] = 28;
194 *tp++ = d0+1;
195 *tp++ = d1;
196 xtime.tm_isdst = 0;
197 return(&xtime);
198 }
199
200 char *
asctime(t)201 asctime(t)
202 struct tm *t;
203 {
204 register char *cp, *ncp;
205 register int *tp;
206
207 cp = cbuf;
208 for (ncp = "Day Mon 00 00:00:00 1900\n"; *cp++ = *ncp++;);
209 ncp = &"SunMonTueWedThuFriSat"[3*t->tm_wday];
210 cp = cbuf;
211 *cp++ = *ncp++;
212 *cp++ = *ncp++;
213 *cp++ = *ncp++;
214 cp++;
215 tp = &t->tm_mon;
216 ncp = &"JanFebMarAprMayJunJulAugSepOctNovDec"[(*tp)*3];
217 *cp++ = *ncp++;
218 *cp++ = *ncp++;
219 *cp++ = *ncp++;
220 cp = ct_numb(cp, *--tp);
221 cp = ct_numb(cp, *--tp+100);
222 cp = ct_numb(cp, *--tp+100);
223 cp = ct_numb(cp, *--tp+100);
224 if (t->tm_year>=100) {
225 cp[1] = '2';
226 cp[2] = '0';
227 }
228 cp += 2;
229 cp = ct_numb(cp, t->tm_year+100);
230 return(cbuf);
231 }
232
dysize(y)233 dysize(y)
234 {
235 if((y%4) == 0)
236 return(366);
237 return(365);
238 }
239
240 static char *
ct_numb(cp,n)241 ct_numb(cp, n)
242 register char *cp;
243 {
244 cp++;
245 if (n>=10)
246 *cp++ = (n/10)%10 + '0';
247 else
248 *cp++ = ' ';
249 *cp++ = n%10 + '0';
250 return(cp);
251 }
252