mirror of https://github.com/RPCS3/rpcs3.git
104 lines
1.6 KiB
C++
104 lines
1.6 KiB
C++
#include "sema.h"
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#include "sync.h"
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void semaphore_base::imp_wait()
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{
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for (int i = 0; i < 10; i++)
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{
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busy_wait();
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const s32 value = m_value.load();
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if (value > 0 && m_value.compare_and_swap_test(value, value - 1))
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{
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return;
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}
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}
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#ifdef _WIN32
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const s32 value = m_value.fetch_sub(1);
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if (value <= 0)
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{
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NtWaitForKeyedEvent(nullptr, &m_value, false, nullptr);
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}
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#else
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while (true)
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{
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// Try hard way
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const s32 value = m_value.op_fetch([](s32& value)
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{
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// Use sign bit to acknowledge waiter presence
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if (value && value > INT32_MIN)
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{
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value--;
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if (value < 0)
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{
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// Remove sign bit
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value -= INT32_MIN;
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}
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}
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else
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{
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// Set sign bit
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value = INT32_MIN;
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}
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});
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if (value >= 0)
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{
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// Signal other waiter to wake up or to restore sign bit
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futex(&m_value.raw(), FUTEX_WAKE_PRIVATE, 1, nullptr, nullptr, 0);
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return;
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}
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futex(&m_value.raw(), FUTEX_WAIT_PRIVATE, value, nullptr, nullptr, 0);
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}
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#endif
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}
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void semaphore_base::imp_post(s32 _old)
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{
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verify("semaphore_base: overflow" HERE), _old < 0;
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#ifdef _WIN32
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NtReleaseKeyedEvent(nullptr, &m_value, false, nullptr);
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#else
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futex(&m_value.raw(), FUTEX_WAKE_PRIVATE, 1, nullptr, nullptr, 0);
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#endif
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}
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bool semaphore_base::try_wait()
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{
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// Conditional decrement
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const s32 value = m_value.fetch_op([](s32& value)
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{
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if (value > 0)
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{
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value -= 1;
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}
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});
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return value > 0;
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}
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bool semaphore_base::try_post(s32 _max)
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{
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// Conditional increment
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const s32 value = m_value.fetch_op([&](s32& value)
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{
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if (value < _max)
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{
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value += 1;
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}
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});
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if (value < 0)
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{
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imp_post(value);
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}
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return value < _max;
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}
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