Allow identification of the type of memory (ram or mmio) backing a specific page

src/mem.rs

@@ -30,6 +30,15 @@ impl MemConfig {
         None
     }
 
+    pub fn memory_mapping_type(&self, page: PageNum) -> Option<MemoryMappingType> {
+        if page_in_range(page, self.ram_start, self.ram.pages) {
+            Some(MemoryMappingType::RAM)
+        } else {
+            self.find_device_by_page(page)
+                .map(|_x| MemoryMappingType::MMIO)
+        }
+    }
+
     pub fn read_dword(&self, page: PageNum, offset: u16) -> Result<DWord, MemAccessFault> {
         if page_in_range(page, self.ram_start, self.ram.pages) {
             self.ram.read_dword(page - self.ram_start, offset)
@@ -168,6 +177,12 @@ fn page_in_range(page: PageNum, start: PageNum, pages: PageNum) -> bool {
     page >= start && page - start < pages
 }
 
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum MemoryMappingType {
+    MMIO,
+    RAM,
+}
+
 pub struct Ram {
     buf: MmapMut,
     pages: PageNum,