rpcs3/Utilities/sema.h
Nekotekina f63e89f9b4 Implement waitable atomics
Moved Atomic.h to util/atomic.hpp
List source files in CMakeLists.txt
2019-07-29 03:04:55 +03:00

118 lines
1.9 KiB
C++

#pragma once
#include <mutex>
#include "types.h"
#include "util/atomic.hpp"
// Lightweight semaphore helper class
class semaphore_base
{
// Semaphore value
atomic_t<s32> m_value;
void imp_wait();
void imp_post(s32 _old);
protected:
explicit constexpr semaphore_base(s32 value)
: m_value{value}
{
}
void wait()
{
// Load value
const s32 value = m_value.load();
// Conditional decrement
if (UNLIKELY(value <= 0 || !m_value.compare_and_swap_test(value, value - 1)))
{
imp_wait();
}
}
bool try_wait()
{
return m_value.try_dec(0);
}
void post(s32 _max)
{
// Unconditional increment
const s32 value = m_value.fetch_add(1);
if (UNLIKELY(value < 0 || value >= _max))
{
imp_post(value);
}
}
bool try_post(s32 _max);
public:
// Get current semaphore value
s32 get() const
{
// Load value
const s32 value = m_value;
// Return only positive value
return value < 0 ? 0 : value;
}
};
// Lightweight semaphore template (default arguments define binary semaphore and Def == Max)
template <s32 Max = 1, s32 Def = Max>
class semaphore final : public semaphore_base
{
static_assert(Max >= 0, "semaphore<>: Max is out of bounds");
static_assert(Def >= 0, "semaphore<>: Def is out of bounds");
static_assert(Def <= Max, "semaphore<>: Def is too big");
using base = semaphore_base;
public:
// Default constructor (recommended)
constexpr semaphore()
: base(Def)
{
}
// Explicit value constructor (not recommended)
explicit constexpr semaphore(s32 value)
: base(value)
{
}
// Obtain a semaphore
void lock()
{
return base::wait();
}
// Try to obtain a semaphore
bool try_lock()
{
return base::try_wait();
}
// Return a semaphore
void unlock()
{
return base::post(Max);
}
// Try to return a semaphore
bool try_unlock()
{
return base::try_post(Max);
}
// Get max semaphore value
static constexpr s32 size()
{
return Max;
}
};