ptos/amd64: Add global descriptor table defs

Signed-off-by: Chloe M <chloe@mensia.org>
2026-07-10 21:10:30 -04:00
parent abad8f8cfe
commit 8c0a1da9a8
1 changed files with 40 additions and 0 deletions
@@ -0,0 +1,40 @@
+/*
+ * Copyright (c) 2026, Chloe M.
+ * Provided under the BSD-3 clause.
+ *
+ * Description: Global descriptor table
+ * Author:      Chloe M.
+ */
+
+#ifndef _MACHINE_GDT_H_
+#define _MACHINE_GDT_H_ 1
+
+#include <ptdef.h>
+
+/* Number of GDT entries */
+#define GDT_ENTRY_COUNT 7
+
+/* Kernel code/data */
+#define GDT_KCODE  0x08
+#define GDT_KDATA  0x10
+
+/* User code/data */
+#define GDT_UCODE  0x18
+#define GDT_UDATA  0x20
+
+/* Task state segment */
+#define GDT_TSS    0x28
+#define GDT_TSS_INDEX 0x05
+
+/*
+ * Global descriptor table entry
+ */
+typedef struct PACKED {
+    USHORT Limit;
+    USHORT BaseLow;
+    UCHAR BaseMid;
+    USHORT Attributes;
+    UCHAR BaseHigh;
+} GDT_ENTRY;
+
+#endif  /* !_MACHINE_GDT_H_ */