Fix panic in ReadOnlyTextBuffer

Previously when reading from a ReadOnlyTextBuffer the pointer would
fall off the end and crash the emulator.

This commit also makes the ReadOnlyTextBuffer Unicode-compatible,
rather than the previous behaviour of clamping every character into
the ASCII range.

1 files changed, 3 insertions, 3 deletions

diff --git a/src/devices/system/read_only_text_buffer.rs b/src/devices/system/read_only_text_buffer.rs
index 7c59025..dae1024 100644
--- a/src/devices/system/read_only_text_buffer.rs
+++ b/src/devices/system/read_only_text_buffer.rs
@@ -6,15 +6,15 @@ pub struct ReadOnlyTextBuffer {
 impl ReadOnlyTextBuffer {
     pub fn from_text(text: &str) -> Self {
         Self {
-            chars: text.chars().map(|c| c as u32 as u8).collect(),
+            chars: text.bytes().collect(),
             pointer: 0,
         }
     }
 
     pub fn read_byte(&mut self) -> u8 {
-        let byte = self.chars[self.pointer];
+        let option = self.chars.get(self.pointer);
         self.pointer += 1;
-        return byte;
+        *option.unwrap_or(&0)
     }
 
     pub fn reset_pointer(&mut self) {