fix: fix ACPI hardware-ID endianness bug

2026-08-15 16:34:57 +02:00
parent c917af0629
commit af7d096969
1 changed files with 15 additions and 0 deletions
@@ -22,7 +22,22 @@ namespace Hal {

        // ============================================================================
        // ACPI encodes PNP IDs as compressed 32-bit EISAIDs.
+        static constexpr uint32_t ByteSwap32(uint32_t value) {
+            return ((value & 0x000000FFu) << 24) |
+                   ((value & 0x0000FF00u) <<  8) |
+                   ((value & 0x00FF0000u) >>  8) |
+                   ((value & 0xFF000000u) >> 24);
+        }
+
+        static_assert(ByteSwap32(0x0301D041u) == 0x41D00103u); // PNP0103
+        static_assert(ByteSwap32(0x090CD041u) == 0x41D00C09u); // PNP0C09
+
        static void DecodeEisaId(uint32_t id, char* out) {
+            // AML exposes the EISAID integer in little-endian byte order, while
+            // the compressed manufacturer and product fields are defined in
+            // display order. Convert it before extracting either field.
+            id = ByteSwap32(id);
+
            // EISA ID encoding:
            // Bits 31-16: 3 compressed letters (5 bits each, '@' based)
            // Bits 15-0:  4 hex digits (product number)