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//! 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");
}