first draft

1 files changed, 68 insertions, 2 deletions

diff --git a/src/time/mktime.c b/src/time/mktime.c
index 9e58d4eb..d19ad8d6 100644
--- a/src/time/mktime.c
+++ b/src/time/mktime.c
@@ -1,11 +1,77 @@
 #include <time.h>
+#include "_time.h"
+#include "_assert.h"
 
 /** convert time structure to arithmetic type **/
 
 time_t mktime(struct tm * timeptr)
 {
-	(void)timeptr;
-	return (time_t)-1;
+	int i;
+
+	ASSERT_NONNULL(timeptr);
+
+	while (timeptr->tm_sec < 0) {
+		timeptr->tm_min--;
+		timeptr->tm_sec += SEC_PER_MIN;
+	}
+
+	if (timeptr->tm_sec >= SEC_PER_MIN) {
+		timeptr->tm_min += timeptr->tm_sec / SEC_PER_MIN;
+		timeptr->tm_sec %= SEC_PER_MIN;
+	}
+
+	while (timeptr->tm_min < 0) {
+		timeptr->tm_hour--;
+		timeptr->tm_min += MIN_PER_HR;
+	}
+
+	if (timeptr->tm_min >= MIN_PER_HR) {
+		timeptr->tm_hour += timeptr->tm_min / MIN_PER_HR;
+		timeptr->tm_sec %= MIN_PER_HR;
+	}
+
+	while (timeptr->tm_hour < 0) {
+		timeptr->tm_mday--;
+		timeptr->tm_hour += HR_PER_DAY;
+	}
+
+	if (timeptr->tm_hour >= HR_PER_DAY) {
+		timeptr->tm_mday += timeptr->tm_hour / HR_PER_DAY;
+		timeptr->tm_hour %= HR_PER_DAY;
+	}
+
+	/* tm_mday is 1 based */
+	while (timeptr->tm_mday < 1) {
+		timeptr->tm_mon--;
+		timeptr->tm_mday += DAYS_IN(timeptr->tm_year, timeptr->tm_mon);
+	}
+
+	while (timeptr->tm_mday > DAYS_IN(timeptr->tm_year, timeptr->tm_mon)) {
+		timeptr->tm_mday -= DAYS_IN(timeptr->tm_year, timeptr->tm_mon);
+		timeptr->tm_mon++;
+	}
+
+	/* negative years are OK, it just means before 1900 */
+
+	if (timeptr->tm_mon >= MON_PER_YEAR) {
+		timeptr->tm_year += timeptr->tm_mon / MON_PER_YEAR;
+		timeptr->tm_mon %= MON_PER_YEAR;
+	}
+
+	timeptr->tm_yday = 0;
+	for (i = 1; i < timeptr->tm_mon; i++) {
+		timeptr->tm_yday += DAYS_IN(timeptr->tm_year, timeptr->tm_mon);
+	}
+	timeptr->tm_yday += timeptr->tm_mday;
+
+	/* TODO: timeptr->tm_wday */
+	/* TODO: timeptr->tm_isdst */
+
+	return ((timeptr->tm_year - EPOCH_YEAR) * SEC_PER_YEAR)
+		+ (timeptr->tm_yday * SEC_PER_DAY)
+		+ (timeptr->tm_hour * SEC_PER_HR)
+		+ (timeptr->tm_min * SEC_PER_MIN)
+		+ timeptr->tm_sec;
 }
 
 /***