From 6146ccba2d8049ae1c5215b67face37b21cab0ae Mon Sep 17 00:00:00 2001
From: Philipp Oppermann <dev@phil-opp.com>
Date: Wed, 13 Mar 2019 14:23:28 +0100
Subject: [PATCH] Add a `memory::create_example_mapping` function

---
 src/memory.rs | 22 ++++++++++++++++++++--
 1 file changed, 20 insertions(+), 2 deletions(-)

diff --git a/src/memory.rs b/src/memory.rs
index d356dc92..5f40ff97 100644
--- a/src/memory.rs
+++ b/src/memory.rs
@@ -1,6 +1,9 @@
 use x86_64::{
-    structures::paging::{MappedPageTable, MapperAllSizes, PageTable, PhysFrame},
-    VirtAddr,
+    structures::paging::{
+        FrameAllocator, MappedPageTable, Mapper, MapperAllSizes, Page, PageTable, PhysFrame,
+        Size4KiB,
+    },
+    PhysAddr, VirtAddr,
 };
 
 /// Initialize a new MappedPageTable.
@@ -36,3 +39,18 @@ unsafe fn active_level_4_table(physical_memory_offset: u64) -> &'static mut Page
 
     &mut *page_table_ptr // unsafe
 }
+
+/// Creates an example mapping for the given page to frame `0xb8000`.
+pub fn create_example_mapping(
+    page: Page,
+    mapper: &mut impl Mapper<Size4KiB>,
+    frame_allocator: &mut impl FrameAllocator<Size4KiB>,
+) {
+    use x86_64::structures::paging::PageTableFlags as Flags;
+
+    let frame = PhysFrame::containing_address(PhysAddr::new(0xb8000));
+    let flags = Flags::PRESENT | Flags::WRITABLE;
+
+    let map_to_result = unsafe { mapper.map_to(page, frame, flags, frame_allocator) };
+    map_to_result.expect("map_to failed").flush();
+}