`dtables::*` is mode-portable

2 files changed, 28 insertions, 0 deletions

diff --git a/src/shared/dtables.rs b/src/shared/dtables.rs
new file mode 100644
index 0000000..d2e3413
--- /dev/null
+++ b/src/shared/dtables.rs
@@ -0,0 +1,27 @@
+//! Functions and data-structures to load descriptor tables.
+
+/// A struct describing a pointer to a descriptor table (GDT / IDT).
+/// This is in a format suitable for giving to 'lgdt' or 'lidt'.
+#[derive(Debug)]
+#[repr(C, packed)]
+pub struct DescriptorTablePointer {
+    /// Size of the DT.
+    pub limit: u16,
+    /// Pointer to the memory region containing the DT.
+    pub base: u64,
+}
+
+/// Load GDT table.
+pub unsafe fn lgdt(gdt: &DescriptorTablePointer) {
+    asm!("lgdt ($0)" :: "r" (gdt) : "memory");
+}
+
+/// Load LDT table.
+pub unsafe fn lldt(ldt: &DescriptorTablePointer) {
+    asm!("lldt ($0)" :: "r" (ldt) : "memory");
+}
+
+/// Load IDT table.
+pub unsafe fn lidt(idt: &DescriptorTablePointer) {
+    asm!("lidt ($0)" :: "r" (idt) : "memory");
+}
diff --git a/src/shared/mod.rs b/src/shared/mod.rs
index a461c08..977dcf4 100644
--- a/src/shared/mod.rs
+++ b/src/shared/mod.rs
@@ -2,6 +2,7 @@
 
 pub mod control_regs;
 pub mod descriptor;
+pub mod dtables;
 pub mod io;
 pub mod irq;
 pub mod paging;