4 files changed, 29 insertions, 37 deletions

diff --git a/src/common/page_table.h b/src/common/page_table.h
index fec8378f3..e653d52ad 100644
--- a/src/common/page_table.h
+++ b/src/common/page_table.h
@@ -51,7 +51,7 @@ struct PageTable {
     class PageInfo {
     public:
         /// Returns the page pointer
-        [[nodiscard]] u8* Pointer() const noexcept {
+        [[nodiscard]] uintptr_t Pointer() const noexcept {
             return ExtractPointer(raw.load(std::memory_order_relaxed));
         }
 
@@ -61,7 +61,7 @@ struct PageTable {
         }
 
         /// Returns the page pointer and attribute pair, extracted from the same atomic read
-        [[nodiscard]] std::pair<u8*, PageType> PointerType() const noexcept {
+        [[nodiscard]] std::pair<uintptr_t, PageType> PointerType() const noexcept {
             const uintptr_t non_atomic_raw = raw.load(std::memory_order_relaxed);
             return {ExtractPointer(non_atomic_raw), ExtractType(non_atomic_raw)};
         }
@@ -73,13 +73,13 @@ struct PageTable {
         }
 
         /// Write a page pointer and type pair atomically
-        void Store(u8* pointer, PageType type) noexcept {
-            raw.store(reinterpret_cast<uintptr_t>(pointer) | static_cast<uintptr_t>(type));
+        void Store(uintptr_t pointer, PageType type) noexcept {
+            raw.store(pointer | static_cast<uintptr_t>(type));
         }
 
         /// Unpack a pointer from a page info raw representation
-        [[nodiscard]] static u8* ExtractPointer(uintptr_t raw) noexcept {
-            return reinterpret_cast<u8*>(raw & (~uintptr_t{0} << ATTRIBUTE_BITS));
+        [[nodiscard]] static uintptr_t ExtractPointer(uintptr_t raw) noexcept {
+            return raw & (~uintptr_t{0} << ATTRIBUTE_BITS);
         }
 
         /// Unpack a page type from a page info raw representation
diff --git a/src/common/settings.cpp b/src/common/settings.cpp
index 491adc30e..15fd2e222 100644
--- a/src/common/settings.cpp
+++ b/src/common/settings.cpp
@@ -72,7 +72,8 @@ std::string GetTimeZoneString(TimeZone time_zone) {
 
     std::string location_name;
     if (time_zone_index == 0) { // Auto
-#if __cpp_lib_chrono >= 201907L
+#if __cpp_lib_chrono >= 201907L && !defined(MINGW)
+        // Disabled for MinGW -- tzdb always returns Etc/UTC
         try {
             const struct std::chrono::tzdb& time_zone_data = std::chrono::get_tzdb();
             const std::chrono::time_zone* current_zone = time_zone_data.current_zone();
diff --git a/src/common/time_zone.cpp b/src/common/time_zone.cpp
index d8d7896c6..69e728a9d 100644
--- a/src/common/time_zone.cpp
+++ b/src/common/time_zone.cpp
@@ -4,13 +4,13 @@
 #include <chrono>
 #include <exception>
 #include <iomanip>
+#include <map>
 #include <sstream>
 #include <stdexcept>
 #include <fmt/chrono.h>
 #include <fmt/core.h>
 
 #include "common/logging/log.h"
-#include "common/settings.h"
 #include "common/time_zone.h"
 
 namespace Common::TimeZone {
@@ -33,32 +33,29 @@ std::string GetDefaultTimeZone() {
     return "GMT";
 }
 
-static std::string GetOsTimeZoneOffset() {
-    const std::time_t t{std::time(nullptr)};
-    const std::tm tm{*std::localtime(&t)};
-
-    return fmt::format("{:%z}", tm);
-}
-
-static int ConvertOsTimeZoneOffsetToInt(const std::string& timezone) {
-    try {
-        return std::stoi(timezone);
-    } catch (const std::invalid_argument&) {
-        LOG_CRITICAL(Common, "invalid_argument with {}!", timezone);
-        return 0;
-    } catch (const std::out_of_range&) {
-        LOG_CRITICAL(Common, "out_of_range with {}!", timezone);
-        return 0;
-    }
+// Results are not comparable to seconds since Epoch
+static std::time_t TmSpecToSeconds(const struct std::tm& spec) {
+    const int year = spec.tm_year - 1; // Years up to now
+    const int leap_years = year / 4 - year / 100;
+    std::time_t cumulative = spec.tm_year;
+    cumulative = cumulative * 365 + leap_years + spec.tm_yday; // Years to days
+    cumulative = cumulative * 24 + spec.tm_hour;               // Days to hours
+    cumulative = cumulative * 60 + spec.tm_min;                // Hours to minutes
+    cumulative = cumulative * 60 + spec.tm_sec;                // Minutes to seconds
+    return cumulative;
 }
 
 std::chrono::seconds GetCurrentOffsetSeconds() {
-    const int offset{ConvertOsTimeZoneOffsetToInt(GetOsTimeZoneOffset())};
+    const std::time_t t{std::time(nullptr)};
+    const std::tm local{*std::localtime(&t)};
+    const std::tm gmt{*std::gmtime(&t)};
 
-    int seconds{(offset / 100) * 60 * 60}; // Convert hour component to seconds
-    seconds += (offset % 100) * 60;        // Convert minute component to seconds
+    // gmt_seconds is a different offset than time(nullptr)
+    const auto gmt_seconds = TmSpecToSeconds(gmt);
+    const auto local_seconds = TmSpecToSeconds(local);
+    const auto seconds_offset = local_seconds - gmt_seconds;
 
-    return std::chrono::seconds{seconds};
+    return std::chrono::seconds{seconds_offset};
 }
 
 // Key is [Hours * 100 + Minutes], multiplied by 100 if DST
@@ -71,11 +68,6 @@ const static std::map<s64, const char*> off_timezones = {
 };
 
 std::string FindSystemTimeZone() {
-#if defined(MINGW)
-    // MinGW has broken strftime -- https://sourceforge.net/p/mingw-w64/bugs/793/
-    // e.g. fmt::format("{:%z}") -- returns "Eastern Daylight Time" when it should be "-0400"
-    return timezones[0];
-#else
     const s64 seconds = static_cast<s64>(GetCurrentOffsetSeconds().count());
 
     const s64 minutes = seconds / 60;
@@ -97,7 +89,6 @@ std::string FindSystemTimeZone() {
         }
     }
     return fmt::format("Etc/GMT{:s}{:d}", hours > 0 ? "-" : "+", std::abs(hours));
-#endif
 }
 
 } // namespace Common::TimeZone
diff --git a/src/common/wall_clock.cpp b/src/common/wall_clock.cpp
index dc0dcbd68..71e15ab4c 100644
--- a/src/common/wall_clock.cpp
+++ b/src/common/wall_clock.cpp
@@ -56,12 +56,12 @@ std::unique_ptr<WallClock> CreateOptimalClock() {
 #ifdef ARCHITECTURE_x86_64
     const auto& caps = GetCPUCaps();
 
-    if (caps.invariant_tsc && caps.tsc_frequency >= WallClock::GPUTickFreq) {
+    if (caps.invariant_tsc && caps.tsc_frequency >= std::nano::den) {
         return std::make_unique<X64::NativeClock>(caps.tsc_frequency);
     } else {
         // Fallback to StandardWallClock if the hardware TSC
         // - Is not invariant
-        // - Is not more precise than GPUTickFreq
+        // - Is not more precise than 1 GHz (1ns resolution)
         return std::make_unique<StandardWallClock>();
     }
 #else