feat: further kernel power and power optimizations

kernel/src/ACPI/CpuIdle.hpp

@@ -0,0 +1,33 @@
+/*
+    * CpuIdle.hpp
+    * ACPI-guided CPU idle-state selection
+    * Copyright (c) 2026 Daniel Hammer
+*/
+
+#pragma once
+#include <cstdint>
+#include <ACPI/ACPI.hpp>
+
+namespace Hal {
+    namespace CpuIdle {
+
+        // Initialize ACPI idle-state policy from the AML namespace and FADT.
+        void Initialize(ACPI::CommonSDTHeader* xsdt);
+
+        // Enter an idle state chosen for the predicted idle duration.
+        // Falls back to MWAIT/HLT when ACPI data is unavailable.
+        void Wait(uint32_t predictedIdleMs, bool hasMwait,
+                  volatile uint64_t* monitorAddr = nullptr);
+
+        // Same as Wait(), but called with interrupts disabled and returns with
+        // interrupts disabled. Used by tickless idle paths that need atomic
+        // STI+HLT/MWAIT semantics.
+        void WaitWithInterruptsDisabled(uint32_t predictedIdleMs, bool hasMwait,
+                                        volatile uint64_t* monitorAddr = nullptr);
+
+        // Shallow atomic idle for latency-sensitive interactive bursts.
+        void WaitShallowWithInterruptsDisabled(bool hasMwait,
+                                               volatile uint64_t* monitorAddr = nullptr);
+
+    };
+};