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PDP-10 Archives
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SRI_NIC_PERM_FS_1_19910112
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kcc-6/lib/gen/strftm.c
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/*
** STRFTM.C - "strftime()" - Generate formatted date/time string
**
** (c) Copyright Ken Harrenstien 1989
**
** This routine conforms to the draft proposed ANSI C standard as of
** 7-Dec-1988.
**
** Portability considerations:
** The big problem as usual is timezones, which X3J11 completely wimped
** out on. To find the local timezone and print its name,
** the V7/BSD functions ftime() and timezone() are used.
*/
#include <c-env.h>
#include <string.h>
#include <time.h>
#include <sys/time.h> /* For timezone() */
#include <sys/timeb.h> /* For ftime() */
#if __STDC__
#define CONST const
#else
#define CONST
#endif
extern int ftime();
extern char *timezone();
#define alldays \
day("Sunday"), day("Monday"), day("Tuesday"), day("Wednesday"), \
day("Thursday"), day("Friday"), day("Saturday")
#define allmons \
mon("January"), mon("February"), mon("March"), mon("April"), \
mon("May"), mon("June"), mon("July"), mon("August"), \
mon("September"), mon("October"), mon("November"), mon("December")
static char *_tmstday[] = { /* Define table of day names */
#define day(str) str
alldays
#undef day
};
static char _tmltday[] = { /* and size of names */
#define day(str) sizeof(str)-1
alldays
#undef day
};
static char *_tmstmon[] = { /* Define table of month names */
#define mon(str) str
allmons
#undef mon
};
static char _tmltmon[] = { /* and size of names */
#define mon(str) sizeof(str)-1
allmons
#undef mon
};
/* STRFTIME - format date/time string.
**
** This routine may look a little strange to C traditionalists, because
** it attempts to use *++ptr instead of *ptr++ as much as possible. This
** is so the code will be optimally efficient on PDP-10s.
*/
size_t
strftime(to, maxlen, fmt, t)
char *to;
size_t maxlen;
CONST char *fmt;
CONST struct tm *t;
{
static char errstr[] = "???"; /* For use with wild indices */
register int n = maxlen; /* Our countdown */
register char *s;
int cols, i, max;
if (!maxlen || !t) return 0; /* Ensure can write at least 1 char! */
for (*to = *fmt;; *++to = *++fmt) switch (*to) {
default:
if (--n > 0) continue; /* If still room, keep going */
return 0; /* Nope, fail. */
case 0: /* Done! Already null-terminated, */
return maxlen - n; /* so just return count. */
case '%':
/* Start big switch to handle format command.
** "to" points to the first place to deposit into, overwriting
** the '%' that was already put there.
** "n" has the # chars of room left.
*/
s = NULL;
switch (*++fmt) { /* Check next char */
case 0: /* Ugh, premature EOF! */
default: /* Or unknown format char! */
--fmt; /* Fake out and pretend saw %% */
case '%': /* %% - OK, leave % in dest str */
if (--n > 0)
continue;
return 0; /* Fail */
case 'a': /* Abbrev weekday name */
s = (t->tm_wday >= 0 && t->tm_wday < 7)
? _tmstday[t->tm_wday] : errstr;
cols = 3;
break;
case 'b': /* Abbrev month name */
s = (t->tm_mon >= 0 && t->tm_mon < 12)
? _tmstmon[t->tm_mon] : errstr;
cols = 3;
break;
case 'A': /* Full weekday name */
if (t->tm_wday >= 0 && t->tm_wday < 7)
s = _tmstday[t->tm_wday], cols = _tmltday[t->tm_wday];
else s = errstr, cols = 3;
break;
case 'B': /* Full month name */
if (t->tm_mon >= 0 && t->tm_mon < 12)
s = _tmstmon[t->tm_mon], cols = _tmltmon[t->tm_mon];
else s = errstr, cols = 3;
break;
case 'p': /* AM/PM designations for 12-hr clock */
cols = 2;
s = (t->tm_hour < 12) ? "am" : "pm";
if (t->tm_sec == 0 && t->tm_min == 0) {
if (t->tm_hour == 0) s = "midnight", cols = 8;
else if (t->tm_hour == 12) s = "noon", cols = 4;
}
break;
/* Simple numerical stuff */
case 'H': cols=2, max=23, i = t->tm_hour; break; /* hh (00-) */
case 'M': cols=2, max=59, i = t->tm_min; break; /* mm (00-) */
case 'S': cols=2, max=61, i = t->tm_sec; break; /* ss (00-) */
case 'd': cols=2, max=31, i = t->tm_mday; break; /* DD (01-) */
case 'm': cols=2, max=12, i = t->tm_mon+1; break; /* MM (01-) */
case 'y': cols=2, max=99, i = t->tm_year%100; break; /* YY (00-) */
case 'Y': cols=4, max=9999,i= t->tm_year+1900; break; /* YYYY (0000-)*/
case 'w': cols=1, max=6, i = t->tm_wday; break; /* Weekday (0-) */
case 'j': cols=3, max=366,i = t->tm_yday+1; break; /* Julian (001-) */
case 'I': /* Hour (12-hr clock) (01-12) */
cols = 2, max = 12;
i = (t->tm_hour > 12) ? (t->tm_hour - 12)
: (t->tm_hour==0 ? 12 : t->tm_hour);
break;
case 'U': /* Wk # of yr (1st Sun starts wk 1) (00-53) */
if (1) i = t->tm_wday;
else /* Note skip over code! */
case 'W': /* Wk # of yr (1st Mon starts wk 1) (00-53) */
i = (i = t->tm_wday-1) < 0 /* Modular subtract */
? i = 6 : i;
if ((i = t->tm_yday - i) < 0)
i = 0;
else i = (i/7) + 1;
cols = 2, max = 53;
break;
/* Handle "appropriate" date & time representations. Note
** hack of using case labels and ifs in order to initialize
** the format string "s" and thereafter share code.
*/
if (0)
case 'c': s = "%d-%b-%Y %H:%M:%S"; /* Date and Time */
else if (0)
case 'x': s = "%d-%b-%Y"; /* Date only */
else if (0)
case 'X': s = "%H:%M:%S"; /* Time only */
i = strftime(to, n, s, t);
if (!i || (n -= i) <= 0)
return 0;
to += i-1;
continue;
case 'Z': /* Time zone name or abbrev */
{ struct timeb tmb;
if (ftime(&tmb) !=0 || !(s = timezone(tmb.timezone, t->tm_isdst)))
s = "TwilightZone"; /* What else to do??? */
cols = strlen(s); /* Won, got timezone name */
break;
}
}
/* If we come here, "cols" has the # columns we need.
** If "s" is NULL, then "max" and "i" are arguments for the
** decimal printer, else "s" is copied.
** If a number is out of range, asterisks are substituted so that
** the field width is still filled out.
*/
if ((n -= cols) <= 0)
return 0;
if (!s) {
if (i < 0 || max < i) s = "****"; /* Overflow, subst string */
else switch (cols) {
case 4: *to++ = (i/1000) + '0'; i %= 1000;
case 3: *to++ = (i/100) + '0'; i %= 100;
case 2: *to++ = (i/10) + '0'; i %= 10;
case 1: *to = i + '0';
continue;
}
}
for (*to = *s; --cols > 0; *++to = *++s); /* Copy string! */
/* "to" is left pointing to last char written! */
} /* Resume big loop, never breaks out. */
}