8 files changed, 120 insertions, 39 deletions

diff --git a/src/core/core.cpp b/src/core/core.cpp
index 715172771..31c590866 100644
--- a/src/core/core.cpp
+++ b/src/core/core.cpp
@@ -30,6 +30,7 @@
 #include "core/hle/service/sm/sm.h"
 #include "core/loader/loader.h"
 #include "core/perf_stats.h"
+#include "core/settings.h"
 #include "core/telemetry_session.h"
 #include "frontend/applets/profile_select.h"
 #include "frontend/applets/software_keyboard.h"
@@ -96,6 +97,11 @@ struct System::Impl {
         CoreTiming::Init();
         kernel.Initialize();
 
+        const auto current_time = std::chrono::duration_cast<std::chrono::seconds>(
+            std::chrono::system_clock::now().time_since_epoch());
+        Settings::values.custom_rtc_differential =
+            Settings::values.custom_rtc.value_or(current_time) - current_time;
+
         // Create a default fs if one doesn't already exist.
         if (virtual_filesystem == nullptr)
             virtual_filesystem = std::make_shared<FileSys::RealVfsFilesystem>();
diff --git a/src/core/hle/service/time/time.cpp b/src/core/hle/service/time/time.cpp
index 16564de24..c13640ad8 100644
--- a/src/core/hle/service/time/time.cpp
+++ b/src/core/hle/service/time/time.cpp
@@ -12,9 +12,16 @@
 #include "core/hle/kernel/client_session.h"
 #include "core/hle/service/time/interface.h"
 #include "core/hle/service/time/time.h"
+#include "core/settings.h"
 
 namespace Service::Time {
 
+static std::chrono::seconds GetSecondsSinceEpoch() {
+    return std::chrono::duration_cast<std::chrono::seconds>(
+               std::chrono::system_clock::now().time_since_epoch()) +
+           Settings::values.custom_rtc_differential;
+}
+
 static void PosixToCalendar(u64 posix_time, CalendarTime& calendar_time,
                             CalendarAdditionalInfo& additional_info,
                             [[maybe_unused]] const TimeZoneRule& /*rule*/) {
@@ -68,9 +75,7 @@ public:
 
 private:
     void GetCurrentTime(Kernel::HLERequestContext& ctx) {
-        const s64 time_since_epoch{std::chrono::duration_cast<std::chrono::seconds>(
-                                       std::chrono::system_clock::now().time_since_epoch())
-                                       .count()};
+        const s64 time_since_epoch{GetSecondsSinceEpoch().count()};
         LOG_DEBUG(Service_Time, "called");
 
         IPC::ResponseBuilder rb{ctx, 4};
@@ -266,10 +271,7 @@ void Module::Interface::GetClockSnapshot(Kernel::HLERequestContext& ctx) {
     IPC::RequestParser rp{ctx};
     const auto initial_type = rp.PopRaw<u8>();
 
-    const s64 time_since_epoch{std::chrono::duration_cast<std::chrono::seconds>(
-                                   std::chrono::system_clock::now().time_since_epoch())
-                                   .count()};
-
+    const s64 time_since_epoch{GetSecondsSinceEpoch().count()};
     const std::time_t time(time_since_epoch);
     const std::tm* tm = std::localtime(&time);
     if (tm == nullptr) {
diff --git a/src/core/settings.h b/src/core/settings.h
index de01b05c0..29ce98983 100644
--- a/src/core/settings.h
+++ b/src/core/settings.h
@@ -6,6 +6,7 @@
 
 #include <array>
 #include <atomic>
+#include <chrono>
 #include <map>
 #include <optional>
 #include <string>
@@ -350,6 +351,11 @@ struct Values {
     bool use_docked_mode;
     bool enable_nfc;
     std::optional<u32> rng_seed;
+    // Measured in seconds since epoch
+    std::optional<std::chrono::seconds> custom_rtc;
+    // Set on game boot, reset on stop. Seconds difference between current time and `custom_rtc`
+    std::chrono::seconds custom_rtc_differential;
+
     s32 current_user;
     s32 language_index;
 
diff --git a/src/yuzu/configuration/config.cpp b/src/yuzu/configuration/config.cpp
index 165d70e9c..ddf4cf552 100644
--- a/src/yuzu/configuration/config.cpp
+++ b/src/yuzu/configuration/config.cpp
@@ -419,13 +419,21 @@ void Config::ReadValues() {
 
     Settings::values.language_index = qt_config->value("language_index", 1).toInt();
 
-    const auto enabled = qt_config->value("rng_seed_enabled", false).toBool();
-    if (enabled) {
+    const auto rng_seed_enabled = qt_config->value("rng_seed_enabled", false).toBool();
+    if (rng_seed_enabled) {
         Settings::values.rng_seed = qt_config->value("rng_seed", 0).toULongLong();
     } else {
         Settings::values.rng_seed = std::nullopt;
     }
 
+    const auto custom_rtc_enabled = qt_config->value("custom_rtc_enabled", false).toBool();
+    if (custom_rtc_enabled) {
+        Settings::values.custom_rtc =
+            std::chrono::seconds(qt_config->value("custom_rtc", 0).toULongLong());
+    } else {
+        Settings::values.custom_rtc = std::nullopt;
+    }
+
     qt_config->endGroup();
 
     qt_config->beginGroup("Miscellaneous");
@@ -653,6 +661,11 @@ void Config::SaveValues() {
     qt_config->setValue("rng_seed_enabled", Settings::values.rng_seed.has_value());
     qt_config->setValue("rng_seed", Settings::values.rng_seed.value_or(0));
 
+    qt_config->setValue("custom_rtc_enabled", Settings::values.custom_rtc.has_value());
+    qt_config->setValue("custom_rtc",
+                        QVariant::fromValue<long long>(
+                            Settings::values.custom_rtc.value_or(std::chrono::seconds{}).count()));
+
     qt_config->endGroup();
 
     qt_config->beginGroup("Miscellaneous");
diff --git a/src/yuzu/configuration/configure_system.cpp b/src/yuzu/configuration/configure_system.cpp
index 445d01ca0..94e27349d 100644
--- a/src/yuzu/configuration/configure_system.cpp
+++ b/src/yuzu/configuration/configure_system.cpp
@@ -51,6 +51,12 @@ ConfigureSystem::ConfigureSystem(QWidget* parent) : QWidget(parent), ui(new Ui::
             ui->rng_seed_edit->setText(QStringLiteral("00000000"));
     });
 
+    connect(ui->custom_rtc_checkbox, &QCheckBox::stateChanged, this, [this](bool checked) {
+        ui->custom_rtc_edit->setEnabled(checked);
+        if (!checked)
+            ui->custom_rtc_edit->setDateTime(QDateTime::currentDateTime());
+    });
+
     this->setConfiguration();
 }
 
@@ -67,6 +73,13 @@ void ConfigureSystem::setConfiguration() {
     const auto rng_seed =
         QString("%1").arg(Settings::values.rng_seed.value_or(0), 8, 16, QLatin1Char{'0'}).toUpper();
     ui->rng_seed_edit->setText(rng_seed);
+
+    ui->custom_rtc_checkbox->setChecked(Settings::values.custom_rtc.has_value());
+    ui->custom_rtc_edit->setEnabled(Settings::values.custom_rtc.has_value());
+
+    const auto rtc_time = Settings::values.custom_rtc.value_or(
+        std::chrono::seconds(QDateTime::currentSecsSinceEpoch()));
+    ui->custom_rtc_edit->setDateTime(QDateTime::fromSecsSinceEpoch(rtc_time.count()));
 }
 
 void ConfigureSystem::ReadSystemSettings() {}
@@ -82,6 +95,12 @@ void ConfigureSystem::applyConfiguration() {
     else
         Settings::values.rng_seed = std::nullopt;
 
+    if (ui->custom_rtc_checkbox->isChecked())
+        Settings::values.custom_rtc =
+            std::chrono::seconds(ui->custom_rtc_edit->dateTime().toSecsSinceEpoch());
+    else
+        Settings::values.custom_rtc = std::nullopt;
+
     Settings::Apply();
 }
 
diff --git a/src/yuzu/configuration/configure_system.ui b/src/yuzu/configuration/configure_system.ui
index 74e800c2a..073327298 100644
--- a/src/yuzu/configuration/configure_system.ui
+++ b/src/yuzu/configuration/configure_system.ui
@@ -22,6 +22,13 @@
         <string>System Settings</string>
        </property>
        <layout class="QGridLayout" name="gridLayout">
+        <item row="2" column="0">
+         <widget class="QLabel" name="label_sound">
+          <property name="text">
+           <string>Sound output mode</string>
+          </property>
+         </widget>
+        </item>
         <item row="1" column="1">
          <widget class="QComboBox" name="combo_language">
           <property name="toolTip">
@@ -114,27 +121,6 @@
           </item>
          </widget>
         </item>
-        <item row="3" column="0">
-         <widget class="QLabel" name="label_console_id">
-          <property name="text">
-           <string>Console ID:</string>
-          </property>
-         </widget>
-        </item>
-        <item row="2" column="0">
-         <widget class="QLabel" name="label_sound">
-          <property name="text">
-           <string>Sound output mode</string>
-          </property>
-         </widget>
-        </item>
-        <item row="0" column="0">
-         <widget class="QLabel" name="label_birthday">
-          <property name="text">
-           <string>Birthday</string>
-          </property>
-         </widget>
-        </item>
         <item row="0" column="1">
          <layout class="QHBoxLayout" name="horizontalLayout_birthday2">
           <item>
@@ -206,6 +192,20 @@
           </item>
          </layout>
         </item>
+        <item row="3" column="0">
+         <widget class="QLabel" name="label_console_id">
+          <property name="text">
+           <string>Console ID:</string>
+          </property>
+         </widget>
+        </item>
+        <item row="0" column="0">
+         <widget class="QLabel" name="label_birthday">
+          <property name="text">
+           <string>Birthday</string>
+          </property>
+         </widget>
+        </item>
         <item row="3" column="1">
          <widget class="QPushButton" name="button_regenerate_console_id">
           <property name="sizePolicy">
@@ -241,21 +241,21 @@
           </item>
          </widget>
         </item>
-        <item row="1" column="0">
-         <widget class="QLabel" name="label_language">
+        <item row="5" column="0">
+         <widget class="QCheckBox" name="rng_seed_checkbox">
           <property name="text">
-           <string>Language</string>
+           <string>RNG Seed</string>
           </property>
          </widget>
         </item>
-        <item row="4" column="0">
-         <widget class="QCheckBox" name="rng_seed_checkbox">
+        <item row="1" column="0">
+         <widget class="QLabel" name="label_language">
           <property name="text">
-           <string>RNG Seed</string>
+           <string>Language</string>
           </property>
          </widget>
         </item>
-        <item row="4" column="1">
+        <item row="5" column="1">
          <widget class="QLineEdit" name="rng_seed_edit">
           <property name="sizePolicy">
            <sizepolicy hsizetype="Minimum" vsizetype="Fixed">
@@ -276,6 +276,27 @@
           </property>
          </widget>
         </item>
+        <item row="4" column="0">
+         <widget class="QCheckBox" name="custom_rtc_checkbox">
+          <property name="text">
+           <string>Custom RTC</string>
+          </property>
+         </widget>
+        </item>
+        <item row="4" column="1">
+         <widget class="QDateTimeEdit" name="custom_rtc_edit">
+          <property name="minimumDate">
+           <date>
+            <year>1970</year>
+            <month>1</month>
+            <day>1</day>
+           </date>
+          </property>
+          <property name="displayFormat">
+           <string>d MMM yyyy h:mm:ss AP</string>
+          </property>
+         </widget>
+        </item>
        </layout>
       </widget>
      </item>
diff --git a/src/yuzu_cmd/config.cpp b/src/yuzu_cmd/config.cpp
index fe0d1eebf..7a77f76e8 100644
--- a/src/yuzu_cmd/config.cpp
+++ b/src/yuzu_cmd/config.cpp
@@ -325,13 +325,21 @@ void Config::ReadValues() {
     Settings::values.current_user = std::clamp<int>(
         sdl2_config->GetInteger("System", "current_user", 0), 0, Service::Account::MAX_USERS - 1);
 
-    const auto enabled = sdl2_config->GetBoolean("System", "rng_seed_enabled", false);
-    if (enabled) {
+    const auto rng_seed_enabled = sdl2_config->GetBoolean("System", "rng_seed_enabled", false);
+    if (rng_seed_enabled) {
         Settings::values.rng_seed = sdl2_config->GetInteger("System", "rng_seed", 0);
     } else {
         Settings::values.rng_seed = std::nullopt;
     }
 
+    const auto custom_rtc_enabled = sdl2_config->GetBoolean("System", "custom_rtc_enabled", false);
+    if (custom_rtc_enabled) {
+        Settings::values.custom_rtc =
+            std::chrono::seconds(sdl2_config->GetInteger("System", "custom_rtc", 0));
+    } else {
+        Settings::values.custom_rtc = std::nullopt;
+    }
+
     // Core
     Settings::values.use_cpu_jit = sdl2_config->GetBoolean("Core", "use_cpu_jit", true);
     Settings::values.use_multi_core = sdl2_config->GetBoolean("Core", "use_multi_core", false);
diff --git a/src/yuzu_cmd/default_ini.h b/src/yuzu_cmd/default_ini.h
index 0f3f8da50..ba51a4a51 100644
--- a/src/yuzu_cmd/default_ini.h
+++ b/src/yuzu_cmd/default_ini.h
@@ -183,6 +183,12 @@ enable_nfc =
 rng_seed_enabled =
 rng_seed =
 
+# Sets the current time (in seconds since 12:00 AM Jan 1, 1970) that will be used by the time service
+# This will auto-increment, with the time set being the time the game is started
+# This override will only occur if custom_rtc_enabled is true, otherwise the current time is used
+custom_rtc_enabled =
+custom_rtc =
+
 # Sets the account username, max length is 32 characters
 # yuzu (default)
 username = yuzu