AP_Common: move implemenation of ap_mktime (NFC)

libraries/AP_Common/time.cpp

@@ -0,0 +1,44 @@
+#include "time.h"
+
+/*
+  mktime replacement from Samba
+ */
+time_t ap_mktime(const struct tm *t)
+{
+    time_t epoch = 0;
+    int n;
+    int mon [] = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }, y, m, i;
+    const unsigned MINUTE = 60;
+    const unsigned HOUR = 60*MINUTE;
+    const unsigned DAY = 24*HOUR;
+    const unsigned YEAR = 365*DAY;
+
+    if (t->tm_year < 70) {
+        return (time_t)-1;
+    }
+
+    n = t->tm_year + 1900 - 1;
+    epoch = (t->tm_year - 70) * YEAR +
+            ((n / 4 - n / 100 + n / 400) - (1969 / 4 - 1969 / 100 + 1969 / 400)) * DAY;
+
+    y = t->tm_year + 1900;
+    m = 0;
+
+    for (i = 0; i < t->tm_mon; i++) {
+        epoch += mon [m] * DAY;
+        if (m == 1 && y % 4 == 0 && (y % 100 != 0 || y % 400 == 0)) {
+            epoch += DAY;
+        }
+
+        if (++m > 11) {
+            m = 0;
+            y++;
+        }
+    }
+
+    epoch += (t->tm_mday - 1) * DAY;
+    epoch += t->tm_hour * HOUR + t->tm_min * MINUTE + t->tm_sec;
+
+    return epoch;
+}
+