feat: add PID allocator implementation with bitmap-based allocation

1 files changed, 29 insertions, 0 deletions

diff --git a/na/include/lume/pid.h b/na/include/lume/pid.h
new file mode 100644
index 0000000..8503750
--- /dev/null
+++ b/na/include/lume/pid.h
@@ -0,0 +1,29 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/* Copyright (C) 2026 Richard Qin */
+
+#pragma once
+
+/*
+ * PID Allocator — Bitmap-based O(1) block search
+ * Reference: docs/specs/task.md §3.2
+ */
+
+#include <lume/types.h>
+#include <kernel/sync/spinlock.h>
+
+inline constexpr int32 kMaxPid = 32768;
+
+class PidAllocator {
+public:
+    void init();
+    int32 alloc();
+    void free(int32 pid);
+
+private:
+    static constexpr int32 kBitmapWords = kMaxPid / 64;
+    Spinlock lock_;
+    uint64 bitmap_[kBitmapWords];
+    int32 next_hint_ = 2;
+};
+
+extern PidAllocator g_pid_alloc;