libboard_zynq: wrap eth Buffer for alignment

libboard_zynq/src/eth/mod.rs

@@ -1,3 +1,4 @@
+use core::ops::{Deref, DerefMut};
 use libregister::*;
 use crate::println;
 use super::slcr;
@@ -18,6 +19,29 @@ const TX_100: u32 = 25_000_000;
 /// Clock for GbE
 const TX_1000: u32 = 125_000_000;
 
+#[derive(Clone)]
+#[repr(C, align(0x08))]
+pub struct Buffer(pub [u8; MTU]);
+
+impl Buffer {
+    pub fn new() -> Self {
+        Buffer([0; MTU])
+    }
+}
+
+impl Deref for Buffer {
+    type Target = [u8];
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+impl DerefMut for Buffer {
+    fn deref_mut(&mut self) -> &mut <Self as Deref>::Target {
+        &mut self.0
+    }
+}
+
 pub struct Eth<'r, RX, TX> {
     rx: RX,
     tx: TX,
@@ -239,7 +263,7 @@ impl<'r, RX, TX> Eth<'r, RX, TX> {
         });
     }
 
-    pub fn start_rx<'rx>(self, rx_list: &'rx mut [rx::DescEntry], rx_buffers: &'rx mut [[u8; MTU]]) -> Eth<'r, rx::DescList<'rx>, TX> {
+    pub fn start_rx<'rx>(self, rx_list: &'rx mut [rx::DescEntry], rx_buffers: &'rx mut [Buffer]) -> Eth<'r, rx::DescList<'rx>, TX> {
         let new_self = Eth {
             rx: rx::DescList::new(rx_list, rx_buffers),
             tx: self.tx,
@@ -258,7 +282,7 @@ impl<'r, RX, TX> Eth<'r, RX, TX> {
         new_self
     }
 
-    pub fn start_tx<'tx>(self, tx_list: &'tx mut [tx::DescEntry], tx_buffers: &'tx mut [[u8; MTU]]) -> Eth<'r, RX, tx::DescList<'tx>> {
+    pub fn start_tx<'tx>(self, tx_list: &'tx mut [tx::DescEntry], tx_buffers: &'tx mut [Buffer]) -> Eth<'r, RX, tx::DescList<'tx>> {
         let new_self = Eth {
             rx: self.rx,
             tx: tx::DescList::new(tx_list, tx_buffers),

libboard_zynq/src/eth/rx.rs

@@ -1,6 +1,6 @@
 use core::ops::Deref;
 use libregister::*;
-use super::MTU;
+use super::Buffer;
 
 #[derive(Debug)]
 pub enum Error {
@@ -55,16 +55,16 @@ register_bit!(desc_word1, global_broadcast, 31);
 #[repr(C)]
 pub struct DescList<'a> {
     list: &'a mut [DescEntry],
-    buffers: &'a mut [[u8; MTU]],
+    buffers: &'a mut [Buffer],
     next: usize,
 }
 
 impl<'a> DescList<'a> {
-    pub fn new(list: &'a mut [DescEntry], buffers: &'a mut [[u8; MTU]]) -> Self {
+    pub fn new(list: &'a mut [DescEntry], buffers: &'a mut [Buffer]) -> Self {
         let last = list.len().min(buffers.len()) - 1;
         for (i, (entry, buffer)) in list.iter_mut().zip(buffers.iter_mut()).enumerate() {
             let is_last = i == last;
-            let buffer_addr = &mut buffer[0] as *mut _ as u32;
+            let buffer_addr = &mut buffer.0[0] as *mut _ as u32;
             assert!(buffer_addr & 0b11 == 0);
             entry.word0.write(
                 DescWord0::zeroed()

libboard_zynq/src/eth/tx.rs

@@ -1,6 +1,6 @@
 use core::ops::{Deref, DerefMut};
 use libregister::*;
-use super::{MTU, regs};
+use super::{Buffer, regs};
 
 /// Descriptor entry
 #[repr(C, align(0x08))]
@@ -42,12 +42,12 @@ pub const DESCS: usize = 8;
 #[repr(C)]
 pub struct DescList<'a> {
     list: &'a mut [DescEntry],
-    buffers: &'a mut [[u8; MTU]],
+    buffers: &'a mut [Buffer],
     next: usize,
 }
 
 impl<'a> DescList<'a> {
-    pub fn new(list: &'a mut [DescEntry], buffers: &'a mut [[u8; MTU]]) -> Self {
+    pub fn new(list: &'a mut [DescEntry], buffers: &'a mut [Buffer]) -> Self {
         let last = list.len().min(buffers.len()) - 1;
         // Sending seems to not work properly with only one packet
         // buffer (two duplicates get send with every packet), so
@@ -57,7 +57,7 @@ impl<'a> DescList<'a> {
 
         for (i, (entry, buffer)) in list.iter_mut().zip(buffers.iter_mut()).enumerate() {
             let is_last = i == last;
-            let buffer_addr = &mut buffer[0] as *mut _ as u32;
+            let buffer_addr = &mut buffer.0[0] as *mut _ as u32;
             assert!(buffer_addr & 0b11 == 0);
             entry.word0.write(
                 DescWord0::zeroed()