sphore.h

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/* (c) Magnus Auvinen. See licence.txt in the root of the distribution for more information. */
/* If you are missing that file, acquire a complete release at teeworlds.com.                */
 
#ifndef BASE_SPHORE_H
#define BASE_SPHORE_H
 
#include "detect.h"
 
#include <atomic>

 
#if defined(CONF_FAMILY_WINDOWS)
typedef void *SEMAPHORE;
#elif defined(CONF_PLATFORM_MACOS)
#include <semaphore.h>
typedef sem_t *SEMAPHORE;
#elif defined(CONF_FAMILY_UNIX)
#include <semaphore.h>
typedef sem_t SEMAPHORE;
#else
#error not implemented on this platform
#endif

void sphore_init(SEMAPHORE *sem);

void sphore_wait(SEMAPHORE *sem);

void sphore_signal(SEMAPHORE *sem);

void sphore_destroy(SEMAPHORE *sem);
 
class CSemaphore
{
    SEMAPHORE m_Sem;
    // implement the counter separately, because the `sem_getvalue`-API is
    // deprecated on macOS: https://stackoverflow.com/a/16655541
    std::atomic_int m_Count{0};
 
public:
    CSemaphore() { sphore_init(&m_Sem); }
    ~CSemaphore() { sphore_destroy(&m_Sem); }
    CSemaphore(const CSemaphore &) = delete;
    int GetApproximateValue() { return m_Count.load(); }
    void Wait()
    {
        sphore_wait(&m_Sem);
        m_Count.fetch_sub(1);
    }
    void Signal()
    {
        m_Count.fetch_add(1);
        sphore_signal(&m_Sem);
    }
};
 
#endif