From 9dcc7bde8bb05dbc62fa196bcbe1484762e66917 Mon Sep 17 00:00:00 2001
From: Morph <39850852+Morph1984@users.noreply.github.com>
Date: Sun, 23 Apr 2023 00:09:49 -0400
Subject: [PATCH] time: Use compile time division for TimeSpanType conversion

---
 src/core/hle/service/time/clock_types.h             | 13 ++++++++-----
 .../hle/service/time/standard_steady_clock_core.cpp |  2 +-
 .../service/time/tick_based_steady_clock_core.cpp   |  2 +-
 src/core/hle/service/time/time.cpp                  |  4 ++--
 src/core/hle/service/time/time_sharedmemory.cpp     |  5 +++--
 5 files changed, 15 insertions(+), 11 deletions(-)

diff --git a/src/core/hle/service/time/clock_types.h b/src/core/hle/service/time/clock_types.h
index e6293ffb9..9fc01ea90 100644
--- a/src/core/hle/service/time/clock_types.h
+++ b/src/core/hle/service/time/clock_types.h
@@ -3,6 +3,8 @@
 
 #pragma once
 
+#include <ratio>
+
 #include "common/common_funcs.h"
 #include "common/common_types.h"
 #include "common/uuid.h"
@@ -74,18 +76,19 @@ static_assert(std::is_trivially_copyable_v<ContinuousAdjustmentTimePoint>,
 /// https://switchbrew.org/wiki/Glue_services#TimeSpanType
 struct TimeSpanType {
     s64 nanoseconds{};
-    static constexpr s64 ns_per_second{1000000000ULL};
 
     s64 ToSeconds() const {
-        return nanoseconds / ns_per_second;
+        return nanoseconds / std::nano::den;
     }
 
     static TimeSpanType FromSeconds(s64 seconds) {
-        return {seconds * ns_per_second};
+        return {seconds * std::nano::den};
     }
 
-    static TimeSpanType FromTicks(u64 ticks, u64 frequency) {
-        return FromSeconds(static_cast<s64>(ticks) / static_cast<s64>(frequency));
+    template <u64 Frequency>
+    static TimeSpanType FromTicks(u64 ticks) {
+        using TicksToNSRatio = std::ratio<std::nano::den, Frequency>;
+        return {static_cast<s64>(ticks * TicksToNSRatio::num / TicksToNSRatio::den)};
     }
 };
 static_assert(sizeof(TimeSpanType) == 8, "TimeSpanType is incorrect size");
diff --git a/src/core/hle/service/time/standard_steady_clock_core.cpp b/src/core/hle/service/time/standard_steady_clock_core.cpp
index 3dbbb9850..5627b7003 100644
--- a/src/core/hle/service/time/standard_steady_clock_core.cpp
+++ b/src/core/hle/service/time/standard_steady_clock_core.cpp
@@ -10,7 +10,7 @@ namespace Service::Time::Clock {
 
 TimeSpanType StandardSteadyClockCore::GetCurrentRawTimePoint(Core::System& system) {
     const TimeSpanType ticks_time_span{
-        TimeSpanType::FromTicks(system.CoreTiming().GetClockTicks(), Core::Hardware::CNTFREQ)};
+        TimeSpanType::FromTicks<Core::Hardware::CNTFREQ>(system.CoreTiming().GetClockTicks())};
     TimeSpanType raw_time_point{setup_value.nanoseconds + ticks_time_span.nanoseconds};
 
     if (raw_time_point.nanoseconds < cached_raw_time_point.nanoseconds) {
diff --git a/src/core/hle/service/time/tick_based_steady_clock_core.cpp b/src/core/hle/service/time/tick_based_steady_clock_core.cpp
index 27600413e..0d9fb3143 100644
--- a/src/core/hle/service/time/tick_based_steady_clock_core.cpp
+++ b/src/core/hle/service/time/tick_based_steady_clock_core.cpp
@@ -10,7 +10,7 @@ namespace Service::Time::Clock {
 
 SteadyClockTimePoint TickBasedSteadyClockCore::GetTimePoint(Core::System& system) {
     const TimeSpanType ticks_time_span{
-        TimeSpanType::FromTicks(system.CoreTiming().GetClockTicks(), Core::Hardware::CNTFREQ)};
+        TimeSpanType::FromTicks<Core::Hardware::CNTFREQ>(system.CoreTiming().GetClockTicks())};
 
     return {ticks_time_span.ToSeconds(), GetClockSourceId()};
 }
diff --git a/src/core/hle/service/time/time.cpp b/src/core/hle/service/time/time.cpp
index 868be60c5..7197ca30f 100644
--- a/src/core/hle/service/time/time.cpp
+++ b/src/core/hle/service/time/time.cpp
@@ -240,8 +240,8 @@ void Module::Interface::CalculateMonotonicSystemClockBaseTimePoint(HLERequestCon
     const auto current_time_point{steady_clock_core.GetCurrentTimePoint(system)};
 
     if (current_time_point.clock_source_id == context.steady_time_point.clock_source_id) {
-        const auto ticks{Clock::TimeSpanType::FromTicks(system.CoreTiming().GetClockTicks(),
-                                                        Core::Hardware::CNTFREQ)};
+        const auto ticks{Clock::TimeSpanType::FromTicks<Core::Hardware::CNTFREQ>(
+            system.CoreTiming().GetClockTicks())};
         const s64 base_time_point{context.offset + current_time_point.time_point -
                                   ticks.ToSeconds()};
         IPC::ResponseBuilder rb{ctx, (sizeof(s64) / 4) + 2};
diff --git a/src/core/hle/service/time/time_sharedmemory.cpp b/src/core/hle/service/time/time_sharedmemory.cpp
index ce1c85bcc..a00676669 100644
--- a/src/core/hle/service/time/time_sharedmemory.cpp
+++ b/src/core/hle/service/time/time_sharedmemory.cpp
@@ -21,8 +21,9 @@ SharedMemory::~SharedMemory() = default;
 
 void SharedMemory::SetupStandardSteadyClock(const Common::UUID& clock_source_id,
                                             Clock::TimeSpanType current_time_point) {
-    const Clock::TimeSpanType ticks_time_span{Clock::TimeSpanType::FromTicks(
-        system.CoreTiming().GetClockTicks(), Core::Hardware::CNTFREQ)};
+    const Clock::TimeSpanType ticks_time_span{
+        Clock::TimeSpanType::FromTicks<Core::Hardware::CNTFREQ>(
+            system.CoreTiming().GetClockTicks())};
     const Clock::SteadyClockContext context{
         static_cast<u64>(current_time_point.nanoseconds - ticks_time_span.nanoseconds),
         clock_source_id};