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use crate::segmentation::SegmentSelector;
use core::fmt;
use core::mem::size_of;
#[repr(C, packed)]
pub struct DescriptorTablePointer<Entry> {
pub limit: u16,
pub base: *const Entry,
}
impl<T> Default for DescriptorTablePointer<T> {
fn default() -> DescriptorTablePointer<T> {
DescriptorTablePointer {
limit: 0,
base: core::ptr::null(),
}
}
}
impl<T> DescriptorTablePointer<T> {
pub fn new(tbl: &T) -> Self {
let len = size_of::<T>() - 1;
assert!(len < 0x10000);
DescriptorTablePointer {
base: tbl as *const T,
limit: len as u16,
}
}
pub fn new_from_slice(slice: &[T]) -> Self {
let len = slice.len() * size_of::<T>() - 1;
assert!(len < 0x10000);
DescriptorTablePointer {
base: slice.as_ptr(),
limit: len as u16,
}
}
}
impl<T> fmt::Debug for DescriptorTablePointer<T> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
unsafe { write!(f, "DescriptorTablePointer ({} {:?})", self.limit, self.base) }
}
}
pub unsafe fn lgdt<T>(gdt: &DescriptorTablePointer<T>) {
llvm_asm!("lgdt ($0)" :: "r" (gdt) : "memory");
}
pub unsafe fn sgdt<T>(idt: &mut DescriptorTablePointer<T>) {
llvm_asm!("sgdt ($0)" : "=r" (idt as *mut DescriptorTablePointer<T>) :: "memory");
}
pub unsafe fn load_ldtr(selector: SegmentSelector) {
llvm_asm!("lldt $0" :: "r" (selector.bits()) : "memory");
}
pub unsafe fn ldtr() -> SegmentSelector {
let selector: u16;
llvm_asm!("sldt $0" : "=r"(selector));
SegmentSelector::from_raw(selector)
}
pub unsafe fn lidt<T>(idt: &DescriptorTablePointer<T>) {
llvm_asm!("lidt ($0)" :: "r" (idt) : "memory");
}
pub unsafe fn sidt<T>(idt: &mut DescriptorTablePointer<T>) {
llvm_asm!("sidt ($0)" : "=r" (idt as *mut DescriptorTablePointer<T>) :: "memory");
}