--- /dev/null
+/**
+ *
+ * strftime.c
+ *
+ * implements the ansi c function strftime()
+ *
+ * written 6 september 1989 by jim nutt
+ * released into the public domain by jim nutt
+ *
+ * modified 21-Oct-89 by Rob Duff
+ *
+ * modified 08-Dec-04 by Tobi Oetiker (added %V)
+**/
+
+#include <stddef.h> /* for size_t */
+#include <stdarg.h> /* for va_arg */
+#include <time.h> /* for struct tm */
+#include "strftime.h"
+
+static char *aday[] = {
+ "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
+};
+
+static char *day[] = {
+ "Sunday", "Monday", "Tuesday", "Wednesday",
+ "Thursday", "Friday", "Saturday"
+};
+
+static char *amonth[] = {
+ "Jan", "Feb", "Mar", "Apr", "May", "Jun",
+ "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
+};
+
+static char *month[] = {
+ "January", "February", "March", "April", "May", "June",
+ "July", "August", "September", "October", "November", "December"
+};
+
+char *tzname_[2] = {"CST", "CDT"}; /* Add your own defaults here */
+
+static char buf[26];
+
+static void strfmt(char *str, const char *fmt, ...);
+
+/**
+ *
+ * size_t strftime_(char *str,
+ * size_t maxs,
+ * const char *fmt,
+ * const struct tm *t)
+ *
+ * this functions acts much like a sprintf for time/date output.
+ * given a pointer to an output buffer, a format string and a
+ * time, it copies the time to the output buffer formatted in
+ * accordance with the format string. the parameters are used
+ * as follows:
+ *
+ * str is a pointer to the output buffer, there should
+ * be at least maxs characters available at the address
+ * pointed to by str.
+ *
+ * maxs is the maximum number of characters to be copied
+ * into the output buffer, included the '\0' terminator
+ *
+ * fmt is the format string. a percent sign (%) is used
+ * to indicate that the following character is a special
+ * format character. the following are valid format
+ * characters:
+ *
+ * %A full weekday name (Monday)
+ * %a abbreviated weekday name (Mon)
+ * %B full month name (January)
+ * %b abbreviated month name (Jan)
+ * %c standard date and time representation
+ * %d day-of-month (01-31)
+ * %H hour (24 hour clock) (00-23)
+ * %I hour (12 hour clock) (01-12)
+ * %j day-of-year (001-366)
+ * %M minute (00-59)
+ * %m month (01-12)
+ * %p local equivalent of AM or PM
+ * %S second (00-59)
+ * %U week-of-year, first day sunday (00-53)
+ * %W week-of-year, first day monday (00-53)
+ * %V ISO 8601 Week number
+ * %w weekday (0-6, sunday is 0)
+ * %X standard time representation
+ * %x standard date representation
+ * %Y year with century
+ * %y year without century (00-99)
+ * %Z timezone name
+ * %% percent sign
+ *
+ * the standard date string is equivalent to:
+ *
+ * %a %b %d %Y
+ *
+ * the standard time string is equivalent to:
+ *
+ * %H:%M:%S
+ *
+ * the standard date and time string is equivalent to:
+ *
+ * %a %b %d %H:%M:%S %Y
+ *
+ * strftime_() returns the number of characters placed in the
+ * buffer, not including the terminating \0, or zero if more
+ * than maxs characters were produced.
+ *
+**/
+
+size_t strftime_(char *s, size_t maxs, const char *f, const struct tm *t)
+{
+ int w,d;
+ char *p, *q, *r;
+
+ p = s;
+ q = s + maxs - 1;
+ while ((*f != '\0'))
+ {
+ if (*f++ == '%')
+ {
+ r = buf;
+ switch (*f++)
+ {
+ case '%' :
+ r = "%";
+ break;
+
+ case 'a' :
+ r = aday[t->tm_wday];
+ break;
+
+ case 'A' :
+ r = day[t->tm_wday];
+ break;
+
+ case 'b' :
+ r = amonth[t->tm_mon];
+ break;
+
+ case 'B' :
+ r = month[t->tm_mon];
+ break;
+
+ case 'c' :
+ strfmt(r, "%0 %0 %2 %2:%2:%2 %4",
+ aday[t->tm_wday], amonth[t->tm_mon],
+ t->tm_mday,t->tm_hour, t->tm_min,
+ t->tm_sec, t->tm_year+1900);
+ break;
+
+ case 'd' :
+ strfmt(r,"%2",t->tm_mday);
+ break;
+
+ case 'H' :
+ strfmt(r,"%2",t->tm_hour);
+ break;
+
+ case 'I' :
+ strfmt(r,"%2",(t->tm_hour%12)?t->tm_hour%12:12);
+ break;
+
+ case 'j' :
+ strfmt(r,"%3",t->tm_yday+1);
+ break;
+
+ case 'm' :
+ strfmt(r,"%2",t->tm_mon+1);
+ break;
+
+ case 'M' :
+ strfmt(r,"%2",t->tm_min);
+ break;
+
+ case 'p' :
+ r = (t->tm_hour>11)?"PM":"AM";
+ break;
+
+ case 'S' :
+ strfmt(r,"%2",t->tm_sec);
+ break;
+
+ case 'U' :
+ w = t->tm_yday/7;
+ if (t->tm_yday%7 > t->tm_wday)
+ w++;
+ strfmt(r, "%2", w);
+ break;
+
+ case 'W' :
+ w = t->tm_yday/7;
+ if (t->tm_yday%7 > (t->tm_wday+6)%7)
+ w++;
+ strfmt(r, "%2", w);
+ break;
+
+ case 'V':
+
+ /* ISO 8601 Week Of Year:
+ If the week (Monday - Sunday) containing January 1 has four or more
+ days in the new year, then it is week 1; otherwise it is week 53 of
+ the previous year and the next week is week one. */
+
+ w = (t->tm_yday + 7 - (t->tm_wday ? t->tm_wday - 1 : 6)) / 7;
+ d = (t->tm_yday + 7 - (t->tm_wday ? t->tm_wday - 1 : 6)) % 7;
+
+ if (d >= 4) { w++; } else if (w == 0) { w = 53; }
+ strfmt(r, "%2", w);
+ break;
+
+ case 'w' :
+ strfmt(r,"%1",t->tm_wday);
+ break;
+
+ case 'x' :
+ strfmt(r, "%3s %3s %2 %4", aday[t->tm_wday],
+ amonth[t->tm_mon], t->tm_mday, t->tm_year+1900);
+ break;
+
+ case 'X' :
+ strfmt(r, "%2:%2:%2", t->tm_hour,
+ t->tm_min, t->tm_sec);
+ break;
+
+ case 'y' :
+ strfmt(r,"%2",t->tm_year%100);
+ break;
+
+ case 'Y' :
+ strfmt(r,"%4",t->tm_year+1900);
+ break;
+
+ case 'Z' :
+ r = (t->tm_isdst && tzname_[1][0]) ?
+ tzname_[1] : tzname_[0];
+ break;
+
+ default:
+ buf[0] = '%'; /* reconstruct the format */
+ buf[1] = f[-1];
+ buf[2] = '\0';
+ if (buf[1] == 0)
+ f--; /* back up if at end of string */
+ }
+ while (*r)
+ {
+ if (p == q)
+ {
+ *q = '\0';
+ return 0;
+ }
+ *p++ = *r++;
+ }
+ }
+ else
+ {
+ if (p == q)
+ {
+ *q = '\0';
+ return 0;
+ }
+ *p++ = f[-1];
+ }
+ }
+ *p = '\0';
+ return p - s;
+}
+
+/*
+ * stdarg.h
+ *
+typedef void *va_list;
+#define va_start(vp,v) (vp=((char*)&v)+sizeof(v))
+#define va_arg(vp,t) (*((t*)(vp))++)
+#define va_end(vp)
+ *
+ */
+
+static int pow[5] = { 1, 10, 100, 1000, 10000 };
+
+/**
+ * static void strfmt(char *str, char *fmt);
+ *
+ * simple sprintf for strftime
+ *
+ * each format descriptor is of the form %n
+ * where n goes from zero to four
+ *
+ * 0 -- string %s
+ * 1..4 -- int %?.?d
+ *
+**/
+
+static void strfmt(char *str, const char *fmt, ...)
+{
+ int ival, ilen;
+ char *sval;
+ va_list vp;
+
+ va_start(vp, fmt);
+ while (*fmt)
+ {
+ if (*fmt++ == '%')
+ {
+ ilen = *fmt++ - '0';
+ if (ilen == 0) /* zero means string arg */
+ {
+ sval = va_arg(vp, char*);
+ while (*sval)
+ *str++ = *sval++;
+ }
+ else /* always leading zeros */
+ {
+ ival = va_arg(vp, int);
+ while (ilen)
+ {
+ ival %= pow[ilen--];
+ *str++ = (char)('0' + ival / pow[ilen]);
+ }
+ }
+ }
+ else *str++ = fmt[-1];
+ }
+ *str = '\0';
+ va_end(vp);
+}
+
+#ifdef TEST
+
+#include <stdio.h> /* for printf */
+#include <time.h> /* for strftime */
+
+char test[80];
+
+int main(int argc, char *argv[])
+{
+ int len;
+ char *fmt;
+ time_t now;
+
+ time(&now);
+
+ fmt = (argc == 1) ? "%I:%M %p\n%c\n" : argv[1];
+ len = strftime_(test,sizeof test, fmt, localtime(&now));
+ printf("%d: %s\n", len, test);
+ return !len;
+}
+
+#endif /* TEST */
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