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-rw-r--r--src/common/uint128.h20
-rw-r--r--src/common/wall_clock.cpp15
2 files changed, 28 insertions, 7 deletions
diff --git a/src/common/uint128.h b/src/common/uint128.h
index 83560a9ce..4780b2f9d 100644
--- a/src/common/uint128.h
+++ b/src/common/uint128.h
@@ -98,4 +98,24 @@ namespace Common {
#endif
}
+// This function divides a u128 by a u32 value and produces two u64 values:
+// the result of division and the remainder
+[[nodiscard]] static inline std::pair<u64, u64> Divide128On32(u128 dividend, u32 divisor) {
+ u64 remainder = dividend[0] % divisor;
+ u64 accum = dividend[0] / divisor;
+ if (dividend[1] == 0)
+ return {accum, remainder};
+ // We ignore dividend[1] / divisor as that overflows
+ const u64 first_segment = (dividend[1] % divisor) << 32;
+ accum += (first_segment / divisor) << 32;
+ const u64 second_segment = (first_segment % divisor) << 32;
+ accum += (second_segment / divisor);
+ remainder += second_segment % divisor;
+ if (remainder >= divisor) {
+ accum++;
+ remainder -= divisor;
+ }
+ return {accum, remainder};
+}
+
} // namespace Common
diff --git a/src/common/wall_clock.cpp b/src/common/wall_clock.cpp
index 1545993bd..49830b8ab 100644
--- a/src/common/wall_clock.cpp
+++ b/src/common/wall_clock.cpp
@@ -20,9 +20,7 @@ using base_time_point = std::chrono::time_point<base_timer>;
class StandardWallClock final : public WallClock {
public:
explicit StandardWallClock(u64 emulated_cpu_frequency_, u64 emulated_clock_frequency_)
- : WallClock(emulated_cpu_frequency_, emulated_clock_frequency_, false),
- emulated_clock_factor{GetFixedPoint64Factor(emulated_clock_frequency, 1000000000)},
- emulated_cpu_factor{GetFixedPoint64Factor(emulated_cpu_frequency, 1000000000)} {
+ : WallClock(emulated_cpu_frequency_, emulated_clock_frequency_, false) {
start_time = base_timer::now();
}
@@ -45,11 +43,16 @@ public:
}
u64 GetClockCycles() override {
- return MultiplyHigh(GetTimeNS().count(), emulated_clock_factor);
+ std::chrono::nanoseconds time_now = GetTimeNS();
+ const u128 temporary =
+ Common::Multiply64Into128(time_now.count(), emulated_clock_frequency);
+ return Common::Divide128On32(temporary, 1000000000).first;
}
u64 GetCPUCycles() override {
- return MultiplyHigh(GetTimeNS().count(), emulated_cpu_factor);
+ std::chrono::nanoseconds time_now = GetTimeNS();
+ const u128 temporary = Common::Multiply64Into128(time_now.count(), emulated_cpu_frequency);
+ return Common::Divide128On32(temporary, 1000000000).first;
}
void Pause([[maybe_unused]] bool is_paused) override {
@@ -58,8 +61,6 @@ public:
private:
base_time_point start_time;
- const u64 emulated_clock_factor;
- const u64 emulated_cpu_factor;
};
#ifdef ARCHITECTURE_x86_64