mango-hal 0.2.1

Hardware Abstraction Layer for the mango operationg system.
Documentation 
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use alloc::alloc::{ GlobalAlloc, Layout };
use core::ptr::null_mut;
use linked_list_allocator::LockedHeap;
use x86_64::{
  structures::paging::{
    mapper::MapToError,
    FrameAllocator,
    Mapper,
    Page,
    PageTableFlags,
    Size4KiB,
  },
  VirtAddr,
};

pub const HEAP_START: usize = 0x_4444_4444_0000;
pub const HEAP_SIZE: usize = 100 * 1024; // 100 KiB

#[global_allocator]
static ALLOCATOR: LockedHeap = LockedHeap::empty();

pub fn init_heap(
  mapper: &mut impl Mapper<Size4KiB>,
  frame_allocator: &mut impl FrameAllocator<Size4KiB>
) -> Result<(), MapToError<Size4KiB>> {
  let page_range = {
    let heap_start = VirtAddr::new(HEAP_START as u64);
    let heap_end = heap_start + (HEAP_SIZE as u64) - 1u64;
    let heap_start_page = Page::containing_address(heap_start);
    let heap_end_page = Page::containing_address(heap_end);
    Page::range_inclusive(heap_start_page, heap_end_page)
  };

  for page in page_range {
    let frame = frame_allocator.allocate_frame().ok_or(MapToError::FrameAllocationFailed)?;
    let flags = PageTableFlags::PRESENT | PageTableFlags::WRITABLE;
    unsafe {
      mapper.map_to(page, frame, flags, frame_allocator)?.flush();
    }
  }

  unsafe {
    ALLOCATOR.lock().init(HEAP_START as *mut u8, HEAP_SIZE);
  }

  Ok(())
}

pub struct Dummy;

unsafe impl GlobalAlloc for Dummy {
  unsafe fn alloc(&self, _layout: Layout) -> *mut u8 {
    null_mut()
  }

  unsafe fn dealloc(&self, _ptr: *mut u8, _layout: Layout) {
    panic!("dealloc should be never called")
  }
}