From aabff7a1d387da57090b1f27878256a85853af42 Mon Sep 17 00:00:00 2001
From: apio <blobs.trading@gmail.com>
Date: Sun, 30 Oct 2022 20:46:25 +0100
Subject: [PATCH] libc: Add mktime()

---
 libs/libc/include/time.h |  3 +++
 libs/libc/src/time.cpp   | 11 +++++++++++
 2 files changed, 14 insertions(+)

diff --git a/libs/libc/include/time.h b/libs/libc/include/time.h
index 02db35f0..3921b6ff 100644
--- a/libs/libc/include/time.h
+++ b/libs/libc/include/time.h
@@ -71,6 +71,9 @@ extern "C"
     /* Fills buf with a string representation of time. Thread-safe. */
     char* ctime_r(const time_t* time, char buf[26]);
 
+    /* Returns the UNIX timestamp representation of the broken-down time in the time structure. */
+    time_t mktime(struct tm* time);
+
     /* Fills str with a formatted string representation of time according to the format string. */
     size_t strftime(char* str, size_t max, const char* format, const struct tm* time);
 
diff --git a/libs/libc/src/time.cpp b/libs/libc/src/time.cpp
index 8face2c3..4643eec5 100644
--- a/libs/libc/src/time.cpp
+++ b/libs/libc/src/time.cpp
@@ -30,6 +30,12 @@ static int day_of_week(int year, int mon, int day)
     return (year + year / 4 - year / 100 + year / 400 + t[mon - 1] + day) % 7;
 }
 
+static time_t broken_down_to_unix(time_t year, time_t yday, time_t hour, time_t min, time_t sec)
+{
+    return sec + min * 60 + hour * 3600 + yday * 86400 + (year - 70) * 31536000 + ((year - 69) / 4) * 86400 -
+           ((year - 1) / 100) * 86400 + ((year + 299) / 400) * 86400;
+}
+
 static void time_to_struct_tm(time_t time, struct tm* result)
 {
     result->tm_isdst = 0; // No DST/timezone support for now.
@@ -164,4 +170,9 @@ extern "C"
     {
         return asctime(localtime(time));
     }
+
+    time_t mktime(struct tm* time)
+    {
+        return broken_down_to_unix(time->tm_year, time->tm_yday, time->tm_hour, time->tm_min, time->tm_sec);
+    }
 }
\ No newline at end of file