mango-hal 0.2.1

Hardware Abstraction Layer for the mango operationg system.
Documentation 
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use lazy_static::lazy_static;
use x86_64::structures::gdt::{Descriptor, GlobalDescriptorTable, SegmentSelector};
use x86_64::structures::tss::TaskStateSegment;
use x86_64::VirtAddr;

pub const DOUBLE_FAULT_IST_INDEX: u16 = 0;

lazy_static! {
  static ref TSS: TaskStateSegment = {
    let mut tss = TaskStateSegment::new();
    tss.interrupt_stack_table[DOUBLE_FAULT_IST_INDEX as usize] = {
      const STACK_SIZE: usize = 4096 * 5;
      static mut STACK: [u8; STACK_SIZE] = [0; STACK_SIZE];

      #[allow(unused_unsafe)] // Rust wrongly think next line does not need unsafe
      let stack_start = VirtAddr::from_ptr(unsafe { core::ptr::addr_of!(STACK) });
      let stack_end = stack_start + (STACK_SIZE as u64);
      stack_end
    };
    tss
  };
}

lazy_static! {
  static ref GDT: (GlobalDescriptorTable, Selectors) = {
    let mut gdt = GlobalDescriptorTable::new();
    let code_selector = gdt.append(Descriptor::kernel_code_segment());
    let tss_selector = gdt.append(Descriptor::tss_segment(&TSS));
    (
      gdt,
      Selectors {
        code_selector,
        tss_selector,
      },
    )
  };
}

struct Selectors
{
  code_selector: SegmentSelector,
  tss_selector: SegmentSelector,
}

pub fn init()
{
  use x86_64::instructions::segmentation::{Segment, CS};
  use x86_64::instructions::tables::load_tss;

  GDT.0.load();
  unsafe {
    CS::set_reg(GDT.1.code_selector);
    load_tss(GDT.1.tss_selector);
  }
}