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authorErik Andersen <andersen@codepoet.org>2000-05-14 04:16:35 +0000
committerErik Andersen <andersen@codepoet.org>2000-05-14 04:16:35 +0000
commit64bc6412188b141c010ac3b8e813b837dd991e80 (patch)
treeffa12b79ea4b13191754f54b872eb1a4f9e3a04b /libc/misc/time/tm_conv.c
Initial revision
Diffstat (limited to 'libc/misc/time/tm_conv.c')
-rw-r--r--libc/misc/time/tm_conv.c138
1 files changed, 138 insertions, 0 deletions
diff --git a/libc/misc/time/tm_conv.c b/libc/misc/time/tm_conv.c
new file mode 100644
index 000000000..ffd524c4b
--- /dev/null
+++ b/libc/misc/time/tm_conv.c
@@ -0,0 +1,138 @@
+
+#if 0
+#include <time.h>
+
+/* This is a translation from ALGOL in Collected Algorithms of CACM. */
+/* Copied from Algorithm 199, Author: Robert G. Tantzen */
+
+void
+__tm_conv(tmbuf, timep, offset)
+struct tm *tmbuf;
+time_t *timep;
+time_t offset;
+{
+static int moffset[] =
+ {0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334};
+
+ long s;
+ long j, d, m, y;
+
+ offset += *timep;
+
+ tmbuf->tm_isdst = 0; /* Someone else can set this */
+
+ j = offset / 86400L + 719469;
+ s = offset % 86400L;
+
+ if( s < 0 ) { s += 86400L; j--; }
+
+ tmbuf->tm_sec = s % 60;
+ tmbuf->tm_min = (s / 60) % 60;
+ tmbuf->tm_hour = s / 3600;
+
+ tmbuf->tm_wday = (j+2) % 7;
+
+ /*
+ * Julian date converter. Takes a julian date (the number of days since
+ * some distant epoch or other), and fills tmbuf.
+ */
+
+ y = (4L * j - 1L) / 146097L;
+ j = 4L * j - 1L - 146097L * y;
+ d = j / 4L;
+ j = (4L * d + 3L) / 1461L;
+ d = 4L * d + 3L - 1461L * j;
+ d = (d + 4L) / 4L;
+ m = (5L * d - 3L) / 153L;
+ d = 5L * d - 3 - 153L * m;
+ d = (d + 5L) / 5L;
+ y = 100L * y + j;
+ if (m < 10)
+ m += 2;
+ else
+ {
+ m -= 10;
+ ++y;
+ }
+
+ tmbuf->tm_year = y - 1900;
+ tmbuf->tm_mon = m;
+ tmbuf->tm_mday = d;
+
+ tmbuf->tm_yday = d + moffset[m];
+ if (m > 1 && ((y) % 4 == 0 && ((y) % 100 != 0 || (y) % 400 == 0)))
+ tmbuf->tm_yday++;
+}
+
+#else
+
+/* This is adapted from glibc */
+/* Copyright (C) 1991, 1993 Free Software Foundation, Inc */
+
+#define SECS_PER_HOUR 3600L
+#define SECS_PER_DAY 86400L
+
+#include <time.h>
+
+static const unsigned short int __mon_lengths[2][12] =
+ {
+ /* Normal years. */
+ { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 },
+ /* Leap years. */
+ { 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }
+ };
+
+
+void
+__tm_conv(tmbuf, t, offset)
+struct tm *tmbuf;
+time_t *t;
+time_t offset;
+{
+ long days, rem;
+ register int y;
+ register unsigned short int *ip;
+
+ days = *t / SECS_PER_DAY;
+ rem = *t % SECS_PER_DAY;
+ rem += offset;
+ while (rem < 0)
+ {
+ rem += SECS_PER_DAY;
+ --days;
+ }
+ while (rem >= SECS_PER_DAY)
+ {
+ rem -= SECS_PER_DAY;
+ ++days;
+ }
+ tmbuf->tm_hour = rem / SECS_PER_HOUR;
+ rem %= SECS_PER_HOUR;
+ tmbuf->tm_min = rem / 60;
+ tmbuf->tm_sec = rem % 60;
+ /* January 1, 1970 was a Thursday. */
+ tmbuf->tm_wday = (4 + days) % 7;
+ if (tmbuf->tm_wday < 0)
+ tmbuf->tm_wday += 7;
+ y = 1970;
+ while (days >= (rem = __isleap(y) ? 366 : 365))
+ {
+ ++y;
+ days -= rem;
+ }
+ while (days < 0)
+ {
+ --y;
+ days += __isleap(y) ? 366 : 365;
+ }
+ tmbuf->tm_year = y - 1900;
+ tmbuf->tm_yday = days;
+ ip = __mon_lengths[__isleap(y)];
+ for (y = 0; days >= ip[y]; ++y)
+ days -= ip[y];
+ tmbuf->tm_mon = y;
+ tmbuf->tm_mday = days + 1;
+ tmbuf->tm_isdst = -1;
+}
+
+#endif