From 4e61e22c3da59b259741e57298725330791aed3e Mon Sep 17 00:00:00 2001
From: Amlal El Mahrouss <amlal@nekernel.org>
Date: Mon, 21 Jul 2025 08:51:41 +0100
Subject: feat: NeKernel Semaphore API.

includes:

	- New semaphore API for the kernel, we also make use of the HardwareTimer class here.
	- Defined header only for now.
	- New HAL HW Timer API in AMD64.

Signed-off-by: Amlal El Mahrouss <amlal@nekernel.org>
---
 dev/kernel/KernelKit/KPC.h       |  1 +
 dev/kernel/KernelKit/Semaphore.h | 79 +++++++++++++++++++++++++++++++++++++++-
 2 files changed, 79 insertions(+), 1 deletion(-)

(limited to 'dev/kernel/KernelKit')

diff --git a/dev/kernel/KernelKit/KPC.h b/dev/kernel/KernelKit/KPC.h
index a3b13de6..26d1b113 100644
--- a/dev/kernel/KernelKit/KPC.h
+++ b/dev/kernel/KernelKit/KPC.h
@@ -65,6 +65,7 @@ inline constexpr KPCError kErrorFileLocked         = 64;
 inline constexpr KPCError kErrorDiskIsTooTiny      = 65;
 inline constexpr KPCError kErrorDmaExhausted       = 66;
 inline constexpr KPCError kErrorOutOfBitMapMemory  = 67;
+inline constexpr KPCError kErrorNetworkTimeout     = 68;
 /// Generic errors.
 inline constexpr KPCError kErrorUnimplemented = -1;
 
diff --git a/dev/kernel/KernelKit/Semaphore.h b/dev/kernel/KernelKit/Semaphore.h
index a1b5ecad..7fa05008 100644
--- a/dev/kernel/KernelKit/Semaphore.h
+++ b/dev/kernel/KernelKit/Semaphore.h
@@ -6,10 +6,87 @@
 
 #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 (0)
+#define kSemaphoreCountIndex (1)
+
+#define kSemaphoreCount (2)
+
 namespace Kernel {
-typedef Int64 Semaphore;
+/// @brief Semaphore structure used for synchronization.
+typedef UInt64 Semaphore[kSemaphoreCount];
+
+/// @brief Checks if the semaphore is valid.
+inline BOOL rtl_sem_is_valid(const Semaphore& sem) {
+  return sem[kSemaphoreOwnerIndex] != 0 || sem[kSemaphoreCountIndex] > 0;
+}
+
+/// @brief Releases the semaphore, resetting its owner and count.
+/// @param sem
+/// @return
+inline BOOL rtl_sem_release(Semaphore& sem) {
+  sem[kSemaphoreOwnerIndex] = 0;
+  sem[kSemaphoreCountIndex] = 0;
+
+  return TRUE;
+}
+
+/// @brief Initializes the semaphore with an owner and a count of zero.
+/// @param sem
+/// @param owner
+/// @return
+inline BOOL rtl_sem_init(Semaphore& sem, Int64 owner) {
+  if (!owner || sem[kSemaphoreOwnerIndex] > 0) {
+    return FALSE;
+  }
+
+  sem[kSemaphoreOwnerIndex] = owner;
+  sem[kSemaphoreCountIndex] = 0;
+
+  return TRUE;
+}
+
+/// @brief Waits for the semaphore to be available, blocking until it is.
+/// @param sem
+/// @param timeout
+/// @return
+inline BOOL rtl_sem_wait(Semaphore& sem, Int64 timeout) {
+  if (!rtl_sem_is_valid(sem)) {
+    return FALSE;
+  }
+
+  if (timeout <= 0) {
+    err_global_get() = kErrorNetworkTimeout;
+
+    return FALSE;
+  }
+
+  if (sem[kSemaphoreCountIndex] > 0) {
+    err_global_get() = kErrorSuccess;
+    sem[kSemaphoreCountIndex]--;
+
+    return TRUE;
+  }
+
+  HardwareTimer timer(timeout);
+  timer.Wait();
+  
+  if (sem[kSemaphoreCountIndex] > 0) {
+    err_global_get() = kErrorSuccess;
+    sem[kSemaphoreCountIndex]--;
+
+    return TRUE;
+  }
+
+  err_global_get() = kErrorNetworkTimeout;
+
+  return FALSE;  // Failed to acquire semaphore
+}  // namespace Kernel
 }  // namespace Kernel
\ No newline at end of file
-- 
cgit v1.2.3