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author | comex <comexk@gmail.com> | 2023-07-02 00:01:11 +0200 |
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committer | comex <comexk@gmail.com> | 2023-07-02 00:01:11 +0200 |
commit | 98685d48e3cb9f25f6919f004ec62cadf33afad2 (patch) | |
tree | 9df2ce7f57370641589bfae7196c77b090bcbe0f /src/common/x64/rdtsc.cpp | |
parent | PR feedback + constification (diff) | |
parent | Update translations (2023-07-01) (#10972) (diff) | |
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Diffstat (limited to '')
-rw-r--r-- | src/common/x64/rdtsc.cpp | 39 |
1 files changed, 39 insertions, 0 deletions
diff --git a/src/common/x64/rdtsc.cpp b/src/common/x64/rdtsc.cpp new file mode 100644 index 000000000..9273274a3 --- /dev/null +++ b/src/common/x64/rdtsc.cpp @@ -0,0 +1,39 @@ +// SPDX-FileCopyrightText: Copyright 2023 yuzu Emulator Project +// SPDX-License-Identifier: GPL-2.0-or-later + +#include <thread> + +#include "common/steady_clock.h" +#include "common/uint128.h" +#include "common/x64/rdtsc.h" + +namespace Common::X64 { + +template <u64 Nearest> +static u64 RoundToNearest(u64 value) { + const auto mod = value % Nearest; + return mod >= (Nearest / 2) ? (value - mod + Nearest) : (value - mod); +} + +u64 EstimateRDTSCFrequency() { + // Discard the first result measuring the rdtsc. + FencedRDTSC(); + std::this_thread::sleep_for(std::chrono::milliseconds{1}); + FencedRDTSC(); + + // Get the current time. + const auto start_time = RealTimeClock::Now(); + const u64 tsc_start = FencedRDTSC(); + // Wait for 100 milliseconds. + std::this_thread::sleep_for(std::chrono::milliseconds{100}); + const auto end_time = RealTimeClock::Now(); + const u64 tsc_end = FencedRDTSC(); + // Calculate differences. + const u64 timer_diff = static_cast<u64>( + std::chrono::duration_cast<std::chrono::nanoseconds>(end_time - start_time).count()); + const u64 tsc_diff = tsc_end - tsc_start; + const u64 tsc_freq = MultiplyAndDivide64(tsc_diff, 1000000000ULL, timer_diff); + return RoundToNearest<100'000>(tsc_freq); +} + +} // namespace Common::X64 |