From a792a84840f9313f307061f0c54837257ccc101d Mon Sep 17 00:00:00 2001
From: Richard Qin <richard.qin.x@gmail.com>
Date: Wed, 13 May 2026 16:21:17 +0800
Subject: feat: implement O(1) Priority Bitmap Scheduling Class and Scheduler
 Core

---
 na/kernel/sched_class_o1.cc | 76 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 76 insertions(+)
 create mode 100644 na/kernel/sched_class_o1.cc

(limited to 'na/kernel/sched_class_o1.cc')

diff --git a/na/kernel/sched_class_o1.cc b/na/kernel/sched_class_o1.cc
new file mode 100644
index 0000000..a8ba5df
--- /dev/null
+++ b/na/kernel/sched_class_o1.cc
@@ -0,0 +1,76 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/* Copyright (C) 2026 Richard Qin */
+
+/*
+ * O(1) Priority Bitmap Scheduling Class
+ */
+
+#include <lume/sched.h>
+#include <lume/sched_class.h>
+#include <lume/task.h>
+#include <lume/bitops.h>
+#include <kernel/sched_internal.h>
+
+static void o1_init_rq(RunQueue* rq)
+{
+    rq->o1().init();
+}
+
+static void o1_enqueue_task(RunQueue* rq, TaskControlBlock* task)
+{
+    rq->o1().enqueue(task);
+    rq->inc_running();
+}
+
+static void o1_dequeue_task(RunQueue* rq, TaskControlBlock* task)
+{
+    rq->o1().dequeue(task);
+    rq->dec_running();
+}
+
+static TaskControlBlock* o1_pick_next_task(RunQueue* rq)
+{
+    return rq->o1().pick_next();
+}
+
+static void o1_put_prev_task(RunQueue* /*rq*/, TaskControlBlock* /*task*/) {}
+
+int32 priority_to_timeslice(uint8 priority)
+{
+    int32 ts = 20 - static_cast<int32>(priority) * 19 / 31;
+    if (ts < 1) ts = 1;
+    return ts;
+}
+
+static void o1_task_tick(RunQueue* rq, TaskControlBlock* curr)
+{
+    if (curr == rq->idle())
+        return;
+
+    curr->time_slice--;
+    if (curr->time_slice <= 0) {
+        curr->time_slice = priority_to_timeslice(curr->priority);
+        rq->set_need_resched(true);
+    }
+}
+
+static void o1_yield_task(RunQueue* rq, TaskControlBlock* curr)
+{
+    if (curr == rq->idle())
+        return;
+
+    curr->time_slice = 0;
+    rq->set_need_resched(true);
+}
+
+const SchedClass g_sched_class_o1 = {
+    .name = "o1",
+    .next = &g_sched_class_idle,
+    .init_rq = o1_init_rq,
+    .enqueue_task = o1_enqueue_task,
+    .dequeue_task = o1_dequeue_task,
+    .pick_next_task = o1_pick_next_task,
+    .put_prev_task = o1_put_prev_task,
+    .task_tick = o1_task_tick,
+    .yield_task = o1_yield_task,
+};
-- 
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