Refactor DeviceTree parsing.

1 files changed, 44 insertions, 0 deletions

diff --git a/kernel/src/util.rs b/kernel/src/util.rs
index 93c684d..29042c8 100644
--- a/kernel/src/util.rs
+++ b/kernel/src/util.rs
@@ -1,5 +1,7 @@
 //! Miscellaneous utilities.
 
+use core::mem::size_of;
+
 #[cold]
 #[inline(always)]
 fn cold() {}
@@ -48,3 +50,45 @@ macro_rules! dbg {
         ($($crate::dbg!($expr)),+,)
     };
 }
+
+/// A trait for types that can be converted to from big-endian or little-endian byte slices.
+pub trait FromEndianBytes {
+    /// Converts from a big-endian byte slice.
+    fn from_big_endian_bytes(bytes: &[u8]) -> Self;
+
+    /// Converts from a little-endian byte slice.
+    fn from_little_endian_bytes(bytes: &[u8]) -> Self;
+}
+
+macro_rules! impl_FromEndianBytes {
+    ($($ty:ty),* $(,)?) => {
+        $(impl FromEndianBytes for $ty {
+            fn from_big_endian_bytes(bytes: &[u8]) -> $ty {
+                let chunk = match bytes.last_chunk() {
+                    Some(chunk) => *chunk,
+                    None => {
+                        let mut chunk = [0; size_of::<$ty>()];
+                        chunk[size_of::<$ty>() - bytes.len()..]
+                            .copy_from_slice(bytes);
+                        chunk
+                    },
+                };
+                <$ty>::from_be_bytes(chunk)
+            }
+
+            fn from_little_endian_bytes(bytes: &[u8]) -> $ty {
+                let chunk = match bytes.first_chunk() {
+                    Some(chunk) => *chunk,
+                    None => {
+                        let mut chunk = [0; size_of::<$ty>()];
+                        chunk[.. bytes.len()].copy_from_slice(bytes);
+                        chunk
+                    },
+                };
+                <$ty>::from_le_bytes(chunk)
+            }
+        })*
+    };
+}
+
+impl_FromEndianBytes!(i8, i16, i32, i64, isize, u8, u16, u32, u64, usize);