mirror of
https://git.eden-emu.dev/eden-emu/eden
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49 lines
1.4 KiB
C++
49 lines
1.4 KiB
C++
// SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
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// SPDX-License-Identifier: GPL-3.0-or-later
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#include <thread>
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#ifdef _MSC_VER
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#include <intrin.h>
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#else
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#include <x86intrin.h>
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#endif
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#include "common/x64/cpu_detect.h"
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#include "common/x64/cpu_wait.h"
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#include "common/x64/rdtsc.h"
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namespace Common::X64 {
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#ifdef __clang__
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__attribute__((target("waitpkg,mwaitx")))
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#elif defined(__GNUC__)
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#pragma GCC target("waitpkg")
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#pragma GCC target("mwaitx")
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#endif
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void MicroSleep(u64 rem) {
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// 100,000 cycles is a reasonable amount of time to wait to save on CPU resources.
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// For reference:
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// At 1 GHz, 100K cycles is 100us
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// At 2 GHz, 100K cycles is 50us
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// At 4 GHz, 100K cycles is 25us
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auto& caps = GetCPUCaps();
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u32 cycles = caps.invariant_tsc
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? rem * (caps.tsc_frequency / 1000000ULL)
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: 1'000'000ULL;
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if (caps.waitpkg) {
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constexpr auto RequestC02State = 0U;
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_tpause(RequestC02State, FencedRDTSC() + cycles);
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} else if (caps.monitorx) {
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constexpr auto EnableWaitTimeFlag = 1U << 1;
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constexpr auto RequestC1State = 0U;
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// monitor_var should be aligned to a cache line.
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alignas(64) static const u64 monitor_var{};
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_mm_monitorx(const_cast<u64*>(std::addressof(monitor_var)), 0, 0);
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_mm_mwaitx(EnableWaitTimeFlag, RequestC1State, cycles);
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} else {
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std::this_thread::yield();
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}
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}
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} // namespace Common::X64
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