Implement reading from real memory

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