Implement reading from real memory

src/emulator.rs

@@ -3,6 +3,7 @@ use std::{
     fmt::Display,
     fs::{self, File},
     io::{Read, Seek, SeekFrom, Write},
+    ops::Range,
     path::{Path, PathBuf},
     sync::{
         atomic::{AtomicBool, AtomicUsize, Ordering},
@@ -397,6 +398,13 @@ impl Emulator {
                 let value = sim.read_register(register);
                 let _ = done.send(value);
             }
+            EmulatorCommand::ReadMemory(sim_id, addresses, mut buffer, done) => {
+                let Some(sim) = self.sims.get_mut(sim_id.to_index()) else {
+                    return;
+                };
+                sim.read_memory(addresses, &mut buffer);
+                let _ = done.send(buffer);
+            }
             EmulatorCommand::SetAudioEnabled(p1, p2) => {
                 self.audio_on[SimId::Player1.to_index()].store(p1, Ordering::Release);
                 self.audio_on[SimId::Player2.to_index()].store(p2, Ordering::Release);
@@ -455,6 +463,7 @@ pub enum EmulatorCommand {
     Pause,
     Resume,
     ReadRegister(SimId, VBRegister, oneshot::Sender<u32>),
+    ReadMemory(SimId, Range<u32>, Vec<u8>, oneshot::Sender<Vec<u8>>),
     SetAudioEnabled(bool, bool),
     Link,
     Unlink,

src/emulator/shrooms_vb_core.rs

@@ -1,4 +1,4 @@
-use std::{ffi::c_void, ptr, slice};
+use std::{ffi::c_void, ops::Range, ptr, slice};
 
 use anyhow::{anyhow, Result};
 use bitflags::bitflags;
@@ -101,6 +101,8 @@ extern "C" {
     fn vb_get_user_data(sim: *mut VB) -> *mut c_void;
     #[link_name = "vbInit"]
     fn vb_init(sim: *mut VB) -> *mut VB;
+    #[link_name = "vbRead"]
+    fn vb_read(sim: *mut VB, address: u32, typ_: VBDataType) -> i32;
     #[link_name = "vbReset"]
     fn vb_reset(sim: *mut VB);
     #[link_name = "vbSetCartRAM"]
@@ -314,6 +316,13 @@ impl Sim {
             VBRegister::PC => unsafe { vb_get_program_counter(self.sim) },
         }
     }
+
+    pub fn read_memory(&mut self, addresses: Range<u32>, into: &mut Vec<u8>) {
+        for address in addresses {
+            let byte = unsafe { vb_read(self.sim, address, VBDataType::U8) };
+            into.push(byte as u8);
+        }
+    }
 }
 
 impl Drop for Sim {

src/gdbserver.rs

@@ -135,6 +135,7 @@ struct GdbConnection {
     ack_messages: bool,
     request_buf: Vec<u8>,
     response_buf: Option<Vec<u8>>,
+    memory_buf: Option<Vec<u8>>,
 }
 
 impl GdbConnection {
@@ -148,6 +149,7 @@ impl GdbConnection {
             ack_messages: true,
             request_buf: vec![],
             response_buf: None,
+            memory_buf: None,
         }
     }
     async fn run(mut self) -> Result<()> {
@@ -155,7 +157,7 @@ impl GdbConnection {
         self.client.send_command(EmulatorCommand::Pause);
         loop {
             let mut req = Request::read(&mut self.stream_in, &mut self.request_buf).await?;
-            println!("received {:?}", req);
+            println!("received {:02x?}", req);
 
             if req.kind == RequestKind::Signal {
                 self.client.send_command(EmulatorCommand::Pause);
@@ -173,7 +175,7 @@ impl GdbConnection {
             } else if req.match_str("qSupported:") {
                 let res = self
                     .response()
-                    .write_str("multiprocess+;swbreak+;vContSupported+");
+                    .write_str("multiprocess+;swbreak+;vContSupported+;PacketSize=10000");
                 self.send(res).await?;
             } else if req.match_str("QThreadSuffixSupported")
                 || req.match_str("QListThreadsInStopReply")
@@ -199,8 +201,7 @@ impl GdbConnection {
                     REGISTERS.get(register)
                 };
                 let Some(reg_info) = get_reg_info() else {
-                    let res = self.response();
-                    self.send(res).await?;
+                    self.send_empty().await?;
                     continue;
                 };
                 let res = self.response().write_str(&reg_info.to_description());
@@ -239,37 +240,81 @@ impl GdbConnection {
                     rx.recv().ok()
                 };
                 let Some(value) = read_register() else {
-                    let res = self.response();
-                    self.send(res).await?;
+                    self.send_empty().await?;
                     continue;
                 };
                 let res = self.response().write_hex(value);
                 self.send(res).await?;
             } else if req.match_str("m") {
-                let mut read_params = || {
+                let mut read_memory = || {
                     let start = req.match_hex::<u32>()?;
                     if !req.match_str(",") {
                         return None;
                     };
                     let size = req.match_hex::<u32>()?;
-                    Some((start, size))
+                    let mut buf = self.memory_buf.take().unwrap_or_default();
+                    buf.clear();
+                    let (tx, rx) = ::oneshot::channel();
+                    self.client.send_command(EmulatorCommand::ReadMemory(
+                        self.sim_id,
+                        start..(start + size),
+                        buf,
+                        tx,
+                    ));
+                    rx.recv().ok()
                 };
-                let Some((start, size)) = read_params() else {
-                    let res = self.response();
-                    self.send(res).await?;
+                let Some(memory) = read_memory() else {
+                    self.send_empty().await?;
                     continue;
                 };
                 let mut res = self.response();
-                for i in 0..size {
-                    res = res.write_hex((start + i) as u8);
+                for byte in &memory {
+                    res = res.write_hex(*byte);
                 }
+                self.memory_buf = Some(memory);
+                self.send(res).await?;
+            } else if req.match_str("x") {
+                let mut read_memory = || {
+                    let start = req.match_hex::<u32>()?;
+                    if !req.match_str(",") {
+                        return None;
+                    };
+                    let size = req.match_hex::<u32>()?;
+                    let mut buf = self.memory_buf.take().unwrap_or_default();
+                    buf.clear();
+                    let (tx, rx) = ::oneshot::channel();
+                    self.client.send_command(EmulatorCommand::ReadMemory(
+                        self.sim_id,
+                        start..(start + size),
+                        buf,
+                        tx,
+                    ));
+                    rx.recv().ok()
+                };
+                let Some(memory) = read_memory() else {
+                    self.send_empty().await?;
+                    continue;
+                };
+                let mut res = self.response();
+                if memory.is_empty() {
+                    res = res.write_str("OK");
+                } else {
+                    for byte in &memory {
+                        res = res.write_byte(*byte);
+                    }
+                }
+                self.memory_buf = Some(memory);
                 self.send(res).await?;
             } else {
                 // unrecognized command
+                self.send_empty().await?;
+            }
+        }
+    }
+
+    async fn send_empty(&mut self) -> std::io::Result<()> {
         let res = self.response();
-                self.send(res).await?;
-            }
-        }
+        self.send(res).await
     }
 
     fn response(&mut self) -> Response {
@@ -281,7 +326,10 @@ impl GdbConnection {
 
     async fn send(&mut self, res: Response) -> std::io::Result<()> {
         let buffer = res.finish();
-        println!("{:?}", std::str::from_utf8(&buffer));
+        match std::str::from_utf8(&buffer) {
+            Ok(text) => println!("response: {text}"),
+            Err(_) => println!("response: {buffer:02x?}"),
+        }
         self.stream_out.write_all(&buffer).await?;
         self.response_buf = Some(buffer);
         self.stream_out.flush().await

src/gdbserver/response.rs

@@ -18,16 +18,30 @@ impl Response {
         }
     }
 
-    pub fn write_str(mut self, str: &str) -> Self {
+    pub fn write_str(self, str: &str) -> Self {
+        let mut me = self;
         for byte in str.as_bytes() {
-            self.buffer.push(*byte);
-            self.checksum = self.checksum.wrapping_add(*byte);
+            me = me.write_byte(*byte);
+        }
+        me
+    }
+
+    pub fn write_byte(mut self, byte: u8) -> Self {
+        if byte == b'}' || byte == b'#' || byte == b'$' || byte == b'*' {
+            self.buffer.push(b'}');
+            self.checksum = self.checksum.wrapping_add(b'}');
+            let escaped = byte ^ 0x20;
+            self.buffer.push(escaped);
+            self.checksum = self.checksum.wrapping_add(escaped);
+        } else {
+            self.buffer.push(byte);
+            self.checksum = self.checksum.wrapping_add(byte);
         }
         self
     }
 
     pub fn write_hex<T: ToBytes>(mut self, value: T) -> Self {
-        for byte in value.to_be_bytes().as_ref() {
+        for byte in value.to_le_bytes().as_ref() {
             for digit in [(byte >> 4), (byte & 0xf)] {
                 let char = if digit > 9 {
                     b'a' + digit - 10