2 files changed, 60 insertions, 2 deletions

diff --git a/src/core/hle/shared_page.cpp b/src/core/hle/shared_page.cpp
index 2a1caeaac..4d9272923 100644
--- a/src/core/hle/shared_page.cpp
+++ b/src/core/hle/shared_page.cpp
@@ -2,8 +2,11 @@
 // Licensed under GPLv2 or any later version
 // Refer to the license.txt file included.
 
+#include <chrono>
 #include <cstring>
+#include <ctime>
 
+#include "core/core_timing.h"
 #include "core/hle/shared_page.h"
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
@@ -12,6 +15,57 @@ namespace SharedPage {
 
 SharedPageDef shared_page;
 
+static int update_time_event;
+
+/// Gets system time in 3DS format. The epoch is Jan 1900, and the unit is millisecond.
+static u64 GetSystemTime() {
+    auto now = std::chrono::system_clock::now();
+
+    // 3DS system does't allow user to set a time before Jan 1 2000,
+    // so we use it as an auxiliary epoch to calculate the console time.
+    std::tm epoch_tm;
+    epoch_tm.tm_sec = 0;
+    epoch_tm.tm_min = 0;
+    epoch_tm.tm_hour = 0;
+    epoch_tm.tm_mday = 1;
+    epoch_tm.tm_mon = 0;
+    epoch_tm.tm_year = 100;
+    epoch_tm.tm_isdst = 0;
+    auto epoch = std::chrono::system_clock::from_time_t(std::mktime(&epoch_tm));
+
+    // 3DS console time uses Jan 1 1900 as internal epoch,
+    // so we use the milliseconds between 1900 and 2000 as base console time
+    u64 console_time = 3155673600000ULL;
+
+    // Only when system time is after 2000, we set it as 3DS system time
+    if (now > epoch) {
+        console_time += std::chrono::duration_cast<std::chrono::milliseconds>(now - epoch).count();
+    }
+
+    // If the system time is in daylight saving, we give an additional hour to console time
+    std::time_t now_time_t = std::chrono::system_clock::to_time_t(now);
+    std::tm* now_tm = std::localtime(&now_time_t);
+    if (now_tm && now_tm->tm_isdst > 0)
+        console_time += 60 * 60 * 1000;
+
+    return console_time;
+}
+
+static void UpdateTimeCallback(u64 userdata, int cycles_late) {
+    DateTime& date_time = shared_page.date_time_counter % 2 ?
+        shared_page.date_time_0 : shared_page.date_time_1;
+
+    date_time.date_time = GetSystemTime();
+    date_time.update_tick = CoreTiming::GetTicks();
+    date_time.tick_to_second_coefficient = g_clock_rate_arm11;
+    date_time.tick_offset = 0;
+
+    ++shared_page.date_time_counter;
+
+    // system time is updated hourly
+    CoreTiming::ScheduleEvent(msToCycles(60 * 60 * 1000) - cycles_late, update_time_event);
+}
+
 void Init() {
     std::memset(&shared_page, 0, sizeof(shared_page));
 
@@ -19,6 +73,9 @@ void Init() {
 
     // Some games wait until this value becomes 0x1, before asking running_hw
     shared_page.unknown_value = 0x1;
+
+    update_time_event = CoreTiming::RegisterEvent("SharedPage::UpdateTimeCallback", UpdateTimeCallback);
+    CoreTiming::ScheduleEvent(0, update_time_event);
 }
 
 } // namespace
diff --git a/src/core/hle/shared_page.h b/src/core/hle/shared_page.h
index 35a07c685..cd9246726 100644
--- a/src/core/hle/shared_page.h
+++ b/src/core/hle/shared_page.h
@@ -25,13 +25,14 @@ namespace SharedPage {
 struct DateTime {
     u64_le date_time;                  // 0
     u64_le update_tick;                // 8
-    INSERT_PADDING_BYTES(0x20 - 0x10); // 10
+    u64_le tick_to_second_coefficient; // 10
+    u64_le tick_offset;                // 18
 };
 static_assert(sizeof(DateTime) == 0x20, "Datetime size is wrong");
 
 struct SharedPageDef {
     // Most of these names are taken from the 3dbrew page linked above.
-    u32_le   date_time_selector;         // 0
+    u32_le   date_time_counter;          // 0
     u8       running_hw;                 // 4
     /// "Microcontroller hardware info"
     u8       mcu_hw_info;                // 5