From f3345e84ad3d1a771eec36d30de7717fcae7e63b Mon Sep 17 00:00:00 2001
From: bunnei <bunneidev@gmail.com>
Date: Mon, 15 Feb 2021 14:54:06 -0800
Subject: core: core_timing_util: Optimize core timing math.

- Avoids a lot of unnecessary 128-bit math for imperceptible accuracy.
---
 src/core/core_timing_util.h | 61 +++++++++++++++++++++++++++++++++++----------
 1 file changed, 48 insertions(+), 13 deletions(-)

(limited to 'src/core/core_timing_util.h')

diff --git a/src/core/core_timing_util.h b/src/core/core_timing_util.h
index e4a046bf9..14c36a485 100644
--- a/src/core/core_timing_util.h
+++ b/src/core/core_timing_util.h
@@ -1,24 +1,59 @@
-// Copyright 2008 Dolphin Emulator Project / 2017 Citra Emulator Project
-// Licensed under GPLv2+
+// Copyright 2020 yuzu Emulator Project
+// Licensed under GPLv2 or any later version
 // Refer to the license.txt file included.
 
 #pragma once
 
 #include <chrono>
+
 #include "common/common_types.h"
+#include "core/hardware_properties.h"
 
 namespace Core::Timing {
 
-s64 msToCycles(std::chrono::milliseconds ms);
-s64 usToCycles(std::chrono::microseconds us);
-s64 nsToCycles(std::chrono::nanoseconds ns);
-u64 msToClockCycles(std::chrono::milliseconds ns);
-u64 usToClockCycles(std::chrono::microseconds ns);
-u64 nsToClockCycles(std::chrono::nanoseconds ns);
-std::chrono::milliseconds CyclesToMs(s64 cycles);
-std::chrono::nanoseconds CyclesToNs(s64 cycles);
-std::chrono::microseconds CyclesToUs(s64 cycles);
-
-u64 CpuCyclesToClockCycles(u64 ticks);
+namespace detail {
+constexpr u64 CNTFREQ_ADJUSTED = Hardware::CNTFREQ / 1000;
+constexpr u64 BASE_CLOCK_RATE_ADJUSTED = Hardware::BASE_CLOCK_RATE / 1000;
+} // namespace detail
+
+[[nodiscard]] constexpr s64 msToCycles(std::chrono::milliseconds ms) {
+    return ms.count() * detail::BASE_CLOCK_RATE_ADJUSTED;
+}
+
+[[nodiscard]] constexpr s64 usToCycles(std::chrono::microseconds us) {
+    return us.count() * detail::BASE_CLOCK_RATE_ADJUSTED / 1000;
+}
+
+[[nodiscard]] constexpr s64 nsToCycles(std::chrono::nanoseconds ns) {
+    return ns.count() * detail::BASE_CLOCK_RATE_ADJUSTED / 1000000;
+}
+
+[[nodiscard]] constexpr u64 msToClockCycles(std::chrono::milliseconds ms) {
+    return static_cast<u64>(ms.count()) * detail::CNTFREQ_ADJUSTED;
+}
+
+[[nodiscard]] constexpr u64 usToClockCycles(std::chrono::microseconds us) {
+    return us.count() * detail::CNTFREQ_ADJUSTED / 1000;
+}
+
+[[nodiscard]] constexpr u64 nsToClockCycles(std::chrono::nanoseconds ns) {
+    return ns.count() * detail::CNTFREQ_ADJUSTED / 1000000;
+}
+
+[[nodiscard]] constexpr u64 CpuCyclesToClockCycles(u64 ticks) {
+    return ticks * detail::CNTFREQ_ADJUSTED / detail::BASE_CLOCK_RATE_ADJUSTED;
+}
+
+[[nodiscard]] constexpr std::chrono::milliseconds CyclesToMs(s64 cycles) {
+    return std::chrono::milliseconds(cycles / detail::BASE_CLOCK_RATE_ADJUSTED);
+}
+
+[[nodiscard]] constexpr std::chrono::nanoseconds CyclesToNs(s64 cycles) {
+    return std::chrono::nanoseconds(cycles * 1000000 / detail::BASE_CLOCK_RATE_ADJUSTED);
+}
+
+[[nodiscard]] constexpr std::chrono::microseconds CyclesToUs(s64 cycles) {
+    return std::chrono::microseconds(cycles * 1000 / detail::BASE_CLOCK_RATE_ADJUSTED);
+}
 
 } // namespace Core::Timing
-- 
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