Add memory map tag

src/lib.rs

@@ -2,8 +2,10 @@
 #![no_std]
 
 pub use elf_sections::{ElfSectionsTag, ElfSection, ElfSectionIter, ElfSectionType, ElfSectionFlags};
+pub use memory_map::{MemoryMapTag, MemoryArea, MemoryAreaIter};
 
 mod elf_sections;
+mod memory_map;
 
 pub unsafe fn load(address: usize) -> &'static Multiboot {
     let multiboot = &*(address as *const Multiboot);
@@ -23,6 +25,10 @@ impl Multiboot {
         self.get_tag(9).map(|tag| unsafe{&*(tag as *const Tag as *const ElfSectionsTag)})
     }
 
+    pub fn memory_area_tag(&self) -> Option<&'static MemoryMapTag> {
+        self.get_tag(6).map(|tag| unsafe{&*(tag as *const Tag as *const MemoryMapTag)})
+    }
+
     fn has_valid_end_tag(&self) -> bool {
         const END_TAG: Tag = Tag{typ:0, size:8};
 

src/memory_map.rs

@@ -0,0 +1,52 @@
+#[repr(C)]
+pub struct MemoryMapTag {
+    typ: u32,
+    size: u32,
+    entry_size: u32,
+    entry_version: u32,
+    first_area: MemoryArea,
+}
+
+impl MemoryMapTag {
+    pub fn memory_areas(&self) -> MemoryAreaIter {
+        let self_ptr = self as *const MemoryMapTag;
+        let start_area = (&self.first_area) as *const MemoryArea;
+        MemoryAreaIter {
+            current_area: start_area,
+            last_area: ((self_ptr as u32) + self.size - self.entry_size) as *const MemoryArea,
+            entry_size: self.entry_size,
+        }
+    }
+}
+
+#[repr(C)]
+pub struct MemoryArea {
+    pub base_addr: u64,
+    pub length: u64,
+    typ: u32,
+    _reserved: u32,
+}
+
+#[allow(raw_pointer_derive)]
+#[derive(Clone)]
+pub struct MemoryAreaIter {
+    current_area: *const MemoryArea,
+    last_area: *const MemoryArea,
+    entry_size: u32,
+}
+
+impl Iterator for MemoryAreaIter {
+    type Item = &'static MemoryArea;
+    fn next(&mut self) -> Option<&'static MemoryArea> {
+        if self.current_area > self.last_area {
+            None
+        } else {
+            let area = unsafe{&*self.current_area};
+            self.current_area = ((self.current_area as u32) + self.entry_size)
+                as *const MemoryArea;
+            if area.typ == 1 {
+                Some(area)
+            } else {self.next()}
+        }
+    }
+}