From 770af27d75e080edd6f15e3c943a599618058d61 Mon Sep 17 00:00:00 2001
From: Philipp Oppermann <dev@phil-opp.com>
Date: Wed, 13 Mar 2019 14:31:45 +0100
Subject: [PATCH] Create a new mapping and write through it to the screen

---
 src/main.rs | 26 +++++++++-----------------
 1 file changed, 9 insertions(+), 17 deletions(-)

diff --git a/src/main.rs b/src/main.rs
index 6a1fea0f..f883906b 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -12,7 +12,7 @@ entry_point!(kernel_main);
 fn kernel_main(boot_info: &'static BootInfo) -> ! {
     use blog_os::interrupts::PICS;
     use blog_os::memory;
-    use x86_64::{structures::paging::MapperAllSizes, VirtAddr};
+    use x86_64::{structures::paging::Page, VirtAddr};
 
     println!("Hello World{}", "!");
 
@@ -21,24 +21,16 @@ fn kernel_main(boot_info: &'static BootInfo) -> ! {
     unsafe { PICS.lock().initialize() };
     x86_64::instructions::interrupts::enable();
 
-    let mapper = unsafe { memory::init(boot_info.physical_memory_offset) };
+    let mut mapper = unsafe { memory::init(boot_info.physical_memory_offset) };
+    let mut frame_allocator = memory::EmptyFrameAllocator;
 
-    let addresses = [
-        // the identity-mapped vga buffer page
-        0xb8000,
-        // some code page
-        0x20010a,
-        // some stack page
-        0x57ac_001f_fe48,
-        // virtual address mapped to physical address 0
-        boot_info.physical_memory_offset,
-    ];
+    // map a previously unmapped page
+    let page = Page::containing_address(VirtAddr::new(0x1000));
+    memory::create_example_mapping(page, &mut mapper, &mut frame_allocator);
 
-    for &address in &addresses {
-        let virt = VirtAddr::new(address);
-        let phys = mapper.translate_addr(virt);
-        println!("{:?} -> {:?}", virt, phys);
-    }
+    // write the string `New!` to the screen through the new mapping
+    let page_ptr: *mut u64 = page.start_address().as_mut_ptr();
+    unsafe { page_ptr.offset(400).write_volatile(0x_f021_f077_f065_f04e) };
 
     println!("It did not crash!");
     blog_os::hlt_loop();