ptos: sched: Add thread enqueue/dequeue helpers

Signed-off-by: Chloe M <chloe@mensia.org>

service/ptos/head/ke/sched.h

@@ -10,6 +10,7 @@
 #define _KE_SCHED_H_ 1
 
 #include <ps/thread.h>
+#include <ke/spinlock.h>
 #include <ptdef.h>
 #include <queue.h>
 
@@ -19,15 +20,33 @@
  *
  * @ThreadQueue:  Represents the actual queue that holds threads
  * @QueueEntries: Represents the number of entries in the queue
+ * @Lock:         Lock protecting this queue
  */
 typedef struct {
     TAILQ_HEAD(, _THREAD) ThreadQueue;
     USIZE QueueEntries;
+    SPINLOCK Lock;
 } SCHED_QUEUE;
 
 /* Macro used to initialize the scheduler queue */
 #define SCHED_QUEUE_INIT(SQ_P)          \
     TAILQ_INIT(&(SQ_P)->ThreadQueue);   \
-    (SQ_P)->QueueEntries = 0;
+    (SQ_P)->QueueEntries = 0;           \
+    KeSpinLockInit(&(SQ_P)->Lock, "sched");
+
+/*
+ * Enqueue a thread to a scheduler queue
+ *
+ * @Queue:      Scheduler queue to add to
+ * @Thread:     Thread to enqueue
+ */
+VOID KeSchedEnqueue(SCHED_QUEUE *Queue, THREAD *Thread);
+
+/*
+ * Dequeue a thread from a scheduler queue
+ *
+ * @Queue:  Scheduler queue to dequeue from
+ */
+THREAD *KeSchedDequeue(SCHED_QUEUE *Queue);
 
 #endif  /* !_KE_SCHED_H_ */

service/ptos/ke/sched.c

@@ -0,0 +1,38 @@
+/*
+ * Copyright (c) 2026, Chloe M.
+ * Provided under the BSD-3 clause.
+ *
+ * Description: Scheduler management
+ * Author:      Chloe M.
+ */
+
+#include <ke/sched.h>
+
+VOID
+KeSchedEnqueue(SCHED_QUEUE *Queue, THREAD *Thread)
+{
+    if (Queue == NULL || Thread == NULL) {
+        return;
+    }
+
+    KeSpinLockAcquire(&Queue->Lock, true);
+    TAILQ_INSERT_TAIL(&Queue->ThreadQueue, Thread, ThreadLink);
+    KeSpinLockRelease(&Queue->Lock);
+}
+
+THREAD *
+KeSchedDequeue(SCHED_QUEUE *Queue)
+{
+    THREAD *Thread;
+
+    KeSpinLockAcquire(&Queue->Lock, true);
+    if (TAILQ_EMPTY(&Queue->ThreadQueue)) {
+        KeSpinLockRelease(&Queue->Lock);
+        return NULL;
+    }
+
+    Thread = TAILQ_FIRST(&Queue->ThreadQueue);
+    TAILQ_REMOVE(&Queue->ThreadQueue, Thread, ThreadLink);
+    KeSpinLockRelease(&Queue->Lock);
+    return Thread;
+}