Add DMA support to storage card

src/backplane.rs

@@ -1,5 +1,6 @@
 use std::fmt::Debug;
 use std::fmt::Display;
+use std::marker::PhantomData;
 
 use anyhow::anyhow;
 use itertools::Itertools;
@@ -14,23 +15,41 @@ use crate::{
 };
 
 pub trait DMAHandler: Debug {
-    fn handle<'a>(&mut self, backplane: &'a Backplane, card_accessor: DMACardAccessor<'a>);
+    fn handle<'a>(&mut self, backplane: &'a Backplane, card_accessor: DMACardAccessorBuilder<'a>);
 }
 
 #[derive(Copy, Clone, Debug)]
 #[allow(dead_code)]
-pub struct DMACardAccessor<'a> {
+pub struct DMACardAccessorBuilder<'a> {
     backplane: &'a Backplane,
     card_no: usize,
 }
 
-impl DMACardAccessor<'_> {
+impl<'a> DMACardAccessorBuilder<'a> {
     #[allow(dead_code)]
-    pub fn get<T: Card>(&self) -> Option<MappedMutexGuard<T>> {
-        MutexGuard::try_map(self.backplane.cards.lock(), |cards| {
-            cards[self.card_no].downcast_mut::<T>()
+    pub fn build<T: Card>(self) -> DMACardAccessor<'a, T> {
+        DMACardAccessor {
+            backplane: self.backplane,
+            card_no: self.card_no,
+            card_type: PhantomData,
+        }
+    }
+}
+
+#[derive(Copy, Clone, Debug)]
+#[allow(dead_code)]
+pub struct DMACardAccessor<'a, T> {
+    backplane: &'a Backplane,
+    card_no: usize,
+    card_type: PhantomData<T>,
+}
+
+impl<T: Card> DMACardAccessor<'_, T> {
+    #[allow(dead_code)]
+    pub fn get(&self) -> MappedMutexGuard<T> {
+        MutexGuard::map(self.backplane.cards.lock(), |cards| {
+            cards[self.card_no].downcast_mut::<T>().unwrap()
         })
-        .ok()
     }
 }
 
@@ -176,7 +195,7 @@ impl Backplane {
         for handler in self.dma_handlers.lock().iter_mut() {
             handler.1.handle(
                 self,
-                DMACardAccessor {
+                DMACardAccessorBuilder {
                     backplane: self,
                     card_no: handler.0,
                 },

src/storage.rs

@@ -1,5 +1,5 @@
 use crate::{
-    backplane::DMAHandler,
+    backplane::{Backplane, DMACardAccessorBuilder, DMAHandler},
     card::{u16_get_be_byte, u32_get_be_byte, u32_set_be_byte, Card},
     m68k::BusError,
     register,
@@ -34,10 +34,12 @@ bitflags! {
 #[derive(Debug)]
 pub struct Storage {
     file: Option<(File, String)>,
-    read_data: VecDeque<u8>,
+    transfer: bool,
     sector: u32,
     count: u32,
     status: Status,
+    read_data: VecDeque<u8>,
+    start_addresss: u32,
 }
 
 // Registers
@@ -45,6 +47,7 @@ pub struct Storage {
 // 0x4-0x8: Sector count
 // 0x8-0xA: Command (W) / Status(R)
 // 0xA-0xC: Data
+// 0xC-0x11: Start address for DMA
 
 impl Card for Storage {
     fn new(data: Value) -> anyhow::Result<(Self, Option<Box<dyn DMAHandler>>)> {
@@ -60,12 +63,14 @@ impl Card for Storage {
         Ok((
             Self {
                 file: file.zip(file_name),
-                read_data: VecDeque::new(),
+                transfer: false,
                 sector: 0,
                 count: 0,
                 status: Status::empty(),
+                read_data: VecDeque::new(),
+                start_addresss: 0,
             },
-            None,
+            Some(Box::new(Dma)),
         ))
     }
 
@@ -80,6 +85,7 @@ impl Card for Storage {
                 }
                 NullableResult::Ok(self.read_data.pop_front().unwrap_or(0))
             }
+            0xC..=0x10 => NullableResult::Ok(u32_get_be_byte(self.start_addresss, address - 0xD)),
             0xFF => NullableResult::Ok(4),
             _ => NullableResult::Null,
         }
@@ -107,8 +113,23 @@ impl Card for Storage {
                         self.status.set(Status::DATA_READY, true);
                     }
                 }
+                0x1 => {
+                    if let Some((file, _)) = &mut self.file {
+                        file.seek(SeekFrom::Start(self.sector as u64 * SECTOR_SIZE))
+                            .unwrap();
+                        let mut buf = Vec::new();
+                        buf.resize(self.count as usize * SECTOR_SIZE as usize, 0);
+                        file.read_exact(&mut buf).unwrap();
+                        self.read_data.extend(buf);
+                        self.status.set(Status::BUSY, true);
+                        self.transfer = true;
+                    }
+                }
                 _ => (),
             },
+            0xC..=0x10 => {
+                self.start_addresss = u32_set_be_byte(self.start_addresss, address - 0xC, data);
+            }
             _ => (),
         }
         NullableResult::Ok(())
@@ -141,3 +162,23 @@ impl Display for Storage {
 }
 
 register!(Storage, "storage");
+
+#[derive(Debug)]
+struct Dma;
+
+impl DMAHandler for Dma {
+    fn handle<'a>(&mut self, backplane: &'a Backplane, card_accessor: DMACardAccessorBuilder<'a>) {
+        let card_accessor = card_accessor.build::<Storage>();
+        if card_accessor.get().transfer {
+            let mut address = card_accessor.get().start_addresss;
+            #[allow(clippy::redundant_closure_call)]
+            // Closure is used to drop the mutex guard between pop calls to prevent deadlock
+            while let Some(data) = (|| card_accessor.get().read_data.pop_front())() {
+                backplane.write_byte(address, data).unwrap();
+                address += 1;
+            }
+            card_accessor.get().transfer = false;
+            card_accessor.get().status.set(Status::BUSY, false);
+        }
+    }
+}