feat: add kernel ACPI support for querying battery percentage, add battery indicator to desktop, move log state to 0:/state directory

kernel/src/ACPI/AcpiDevices.cpp

@@ -319,6 +319,58 @@ namespace Hal {
 
         // EnumerateAll
 
+        // ============================================================================
+        // Fill one DeviceInfo from a namespace node.
+        static void DescribeDevice(AML::Namespace& ns, int32_t idx, DeviceInfo& dev) {
+            dev.NodeIndex = idx;
+            ns.GetNodePath(idx, dev.Path, 128);
+
+            dev.Status = EvaluateSta(idx);
+            dev.IsPresent = (dev.Status & STA_PRESENT) && (dev.Status & STA_FUNCTIONAL);
+
+            if (!EvaluateHid(idx, dev.HardwareId, 16))
+                dev.HardwareId[0] = '\0';
+            if (!EvaluateUid(idx, dev.UniqueId, 16))
+                dev.UniqueId[0] = '\0';
+
+            dev.Address = EvaluateAdr(idx);
+        }
+
+        // ============================================================================
+
+        // FindDeviceByHid
+
+        // ============================================================================
+        bool FindDeviceByHid(const char* hid, DeviceInfo& out) {
+            auto& interp = AML::GetInterpreter();
+            if (!interp.IsInitialized()) return false;
+
+            auto& ns = interp.GetNamespace();
+            int32_t found = -1;
+
+            // Only _HID is evaluated per candidate; the full description is
+            // built once, for the match. WalkDescendants has no early exit, so
+            // the first match wins and later ones are ignored.
+            ns.WalkDescendants(ns.RootIndex(), AML::ObjectType::Device,
+                [&](int32_t idx, [[maybe_unused]] const AML::NamespaceNode* node) {
+                    if (found >= 0) return;
+
+                    char candidate[16];
+                    if (!EvaluateHid(idx, candidate, 16)) return;
+                    if (StrEqual(candidate, hid)) found = idx;
+                });
+
+            if (found < 0) return false;
+
+            out = DeviceInfo{};
+            DescribeDevice(ns, found, out);
+            return true;
+        }
+
+        // ============================================================================
+
+        // EnumerateAll
+
         // ============================================================================
         void EnumerateAll(DeviceList& result) {
             auto& interp = AML::GetInterpreter();
@@ -326,39 +378,32 @@ namespace Hal {
 
             auto& ns = interp.GetNamespace();
             result.Count = 0;
+            result.Truncated = false;
 
             // Walk all namespace nodes looking for Device objects
             ns.WalkDescendants(ns.RootIndex(), AML::ObjectType::Device,
                 [&](int32_t idx, [[maybe_unused]] const AML::NamespaceNode* node) {
-                    if (result.Count >= MaxDevices) return;
-
-                    auto& dev = result.Devices[result.Count];
-                    dev.NodeIndex = idx;
-
-                    // Get the path
-                    ns.GetNodePath(idx, dev.Path, 128);
-
-                    // Evaluate _STA
-                    dev.Status = EvaluateSta(idx);
-                    dev.IsPresent = (dev.Status & STA_PRESENT) && (dev.Status & STA_FUNCTIONAL);
-
-                    // Evaluate _HID
-                    if (!EvaluateHid(idx, dev.HardwareId, 16))
-                        dev.HardwareId[0] = '\0';
-
-                    // Evaluate _UID
-                    if (!EvaluateUid(idx, dev.UniqueId, 16))
-                        dev.UniqueId[0] = '\0';
-
-                    // Evaluate _ADR
-                    dev.Address = EvaluateAdr(idx);
+                    if (result.Count >= MaxDevices) {
+                        result.Truncated = true;
+                        return;
+                    }
 
+                    DescribeDevice(ns, idx, result.Devices[result.Count]);
                     result.Count++;
                 });
 
             KernelLogStream(OK, "ACPI") << "Enumerated " << base::dec
                 << (uint64_t)result.Count << " ACPI devices";
 
+            // The list is a fixed-size stack object, so a large namespace runs
+            // past it. Say so: a device missing from the log below may simply
+            // be one that did not fit, and looking it up by HID still works.
+            if (result.Truncated) {
+                KernelLogStream(WARNING, "ACPI") << "Device list truncated at "
+                    << base::dec << (uint64_t)MaxDevices
+                    << "; use FindDeviceByHid to reach the rest";
+            }
+
             // Log discovered devices
             for (int i = 0; i < result.Count; i++) {
                 auto& dev = result.Devices[i];