Add DmaBuf for DMA-capable memory areas

framework/aster-frame/src/vm/dma/dma_stream.rs

@@ -38,7 +38,7 @@ struct DmaStreamInner {
 
 /// `DmaDirection` limits the data flow direction of `DmaStream` and
 /// prevents users from reading and writing to `DmaStream` unexpectedly.
-#[derive(Debug, PartialEq, Clone)]
+#[derive(Debug, PartialEq, Clone, Copy)]
 pub enum DmaDirection {
     ToDevice,
     FromDevice,
@@ -108,6 +108,10 @@ impl DmaStream {
         &self.inner.vm_segment
     }
 
+    pub fn nframes(&self) -> usize {
+        self.inner.vm_segment.nframes()
+    }
+
     pub fn nbytes(&self) -> usize {
         self.inner.vm_segment.nbytes()
     }

framework/aster-frame/src/vm/frame.rs

@@ -595,6 +595,21 @@ impl<'a> VmReader<'a> {
         }
         copy_len
     }
+
+    /// Read a value of `Pod` type.
+    ///
+    /// # Panic
+    ///
+    /// If the length of the `Pod` type exceeds `self.remain()`, then this method will panic.
+    pub fn read_val<T: Pod>(&mut self) -> T {
+        assert!(self.remain() >= core::mem::size_of::<T>());
+
+        let mut val = T::new_uninit();
+        let mut writer = VmWriter::from(val.as_bytes_mut());
+        let read_len = self.read(&mut writer);
+
+        val
+    }
 }
 
 impl<'a> From<&'a [u8]> for VmReader<'a> {

framework/aster-frame/src/vm/mod.rs

@@ -25,7 +25,7 @@ use core::ops::Range;
 use spin::Once;
 
 pub use self::{
-    dma::{DmaCoherent, DmaDirection, DmaStream, HasDaddr},
+    dma::{Daddr, DmaCoherent, DmaDirection, DmaStream, HasDaddr},
     frame::{VmFrame, VmFrameVec, VmFrameVecIter, VmReader, VmSegment, VmWriter},
     io::VmIo,
     memory_set::{MapArea, MemorySet},