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/* -------------------------------------------
Copyright (C) 2024-2025, Amlal El Mahrouss, licensed under the Apache 2.0 license.
------------------------------------------- */
#pragma once
/// @author Amlal El Mahrouss
/// @file Semaphore.h
/// @brief Semaphore structure and functions for synchronization in the kernel.
#include <CompilerKit/CompilerKit.h>
#include <KernelKit/Timer.h>
#include <NeKit/Defines.h>
#define kSemaphoreOwnerIndex (0U)
#define kSemaphoreCountIndex (1U)
#define kSemaphoreCount (2U)
#define kSemaphoreIncrementOwner(sem) (sem[kSemaphoreOwnerIndex]++)
#define kSemaphoreDecrementOwner(sem) (sem[kSemaphoreOwnerIndex]--)
namespace Kernel {
/// @brief Semaphore structure used for synchronization.
typedef UInt64 SemaphoreArr[kSemaphoreCount];
/// @brief Checks if the semaphore is valid.
inline BOOL rtl_sem_is_valid(const SemaphoreArr& sem, UInt64 owner = 0) {
return sem[kSemaphoreOwnerIndex] == owner && sem[kSemaphoreCountIndex] > 0;
}
/// @brief Releases the semaphore, resetting its owner and count.
/// @param sem
/// @return
inline BOOL rtl_sem_release(SemaphoreArr& sem) {
sem[kSemaphoreOwnerIndex] = 0;
sem[kSemaphoreCountIndex] = 0;
return TRUE;
}
/// @brief Initializes the semaphore with an owner and a count of zero.
/// @param sem the semaphore array to use.
/// @param owner the owner to set, could be anything identifitable.
/// @return
inline BOOL rtl_sem_acquire(SemaphoreArr& sem, UInt64 owner) {
if (!owner) {
err_global_get() = kErrorInvalidData;
return FALSE; // Invalid owner
}
sem[kSemaphoreOwnerIndex] = owner;
sem[kSemaphoreCountIndex] = 0;
return TRUE;
}
/// @brief Waits for the semaphore to be available, blocking until it is.
/// @param sem
/// @param timeout
/// @param condition condition pointer.
/// @return
inline BOOL rtl_sem_wait(SemaphoreArr& sem, UInt64 owner, UInt64 timeout,
BOOL* condition = nullptr) {
if (!rtl_sem_is_valid(sem, owner)) {
return FALSE;
}
if (timeout <= 0) {
err_global_get() = kErrorTimeout;
return FALSE;
}
if (!condition || *condition) {
if (sem[kSemaphoreCountIndex] == 0) {
err_global_get() = kErrorUnavailable;
return FALSE;
}
err_global_get() = kErrorSuccess;
sem[kSemaphoreCountIndex]--;
return TRUE;
}
HardwareTimer timer(timeout);
BOOL ret = timer.Wait();
if (ret) {
if (!condition || *condition) {
if (sem[kSemaphoreCountIndex] == 0) {
err_global_get() = kErrorUnavailable;
return FALSE;
}
err_global_get() = kErrorSuccess;
sem[kSemaphoreCountIndex]--;
return TRUE;
}
}
err_global_get() = kErrorTimeout;
return FALSE; // Failed to acquire semaphore
}
} // namespace Kernel
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