More BumpAllocator APIs.

src/allocator/frame/bump.rs

@@ -12,21 +12,44 @@ use crate::{
 pub struct BumpAllocator<A> {
     areas: &'static [MemoryArea],
     offset: usize,
-    phantom: PhantomData<A>,
+    abs_offset: PhysicalAddress,
+    _marker: PhantomData<fn() -> A>,
 }
 
 impl<A: Arch> BumpAllocator<A> {
     pub fn new(areas: &'static [MemoryArea], offset: usize) -> Self {
         Self {
             areas,
-            offset,
-            phantom: PhantomData,
+            offset: 0,
+            abs_offset: areas[0].base,
+            _marker: PhantomData,
         }
     }
-
     pub fn areas(&self) -> &'static [MemoryArea] {
         self.areas
     }
+    /// Returns one semifree and the fully free areas. The offset is the number of bytes after
+    /// which the first area is free.
+    pub fn free_areas(&self) -> (&'static [MemoryArea], usize) {
+        let mut areas = self.areas;
+        let mut offset = self.offset;
+
+        loop {
+            let Some(area) = areas.first() else {
+                return (&[], 0);
+            };
+
+            if offset > area.size {
+                areas = &areas[1..];
+                offset -= area.size;
+            } else {
+                return (areas, offset);
+            }
+        }
+    }
+    pub fn abs_offset(&self) -> PhysicalAddress {
+        self.abs_offset
+    }
 
     pub fn offset(&self) -> usize {
         self.offset
@@ -38,7 +61,14 @@ impl<A: Arch> FrameAllocator for BumpAllocator<A> {
         let mut offset = self.offset;
         for area in self.areas.iter() {
             if offset < area.size {
-                if area.size - offset < count.data() {
+                if area.size - offset < count.data() * A::PAGE_SIZE {
+                    /*
+                    // The area may be too small for this alloc request. In that case, skip to the
+                    // next area.
+                    self.offset += area.size - offset;
+                    offset = 0;
+                    continue;
+                    */
                     return None;
                 }
 
@@ -46,6 +76,8 @@ impl<A: Arch> FrameAllocator for BumpAllocator<A> {
                 let page_virt = A::phys_to_virt(page_phys);
                 A::write_bytes(page_virt, 0, count.data() * A::PAGE_SIZE);
                 self.offset += count.data() * A::PAGE_SIZE;
+
+                self.abs_offset = page_phys;
                 return Some(page_phys);
             }
             offset -= area.size;