fix KBSR/KBDR mem-map registers

dummy me did not realize the ready bit was bit 15

src/vm/instruction.rs

@@ -312,6 +312,6 @@ fn trap_puts(vm: &mut VM) {
 }
 
 fn trap_getc(vm: &mut VM) {
-    while vm.mem.get_mem(0xFE00) & 1 == 0 {}
+    while vm.mem.get_mem(0xFE00) & (1 << 15) == 0 {}
     vm.registers.r0 = vm.mem.get_mem(0xFE02) & 0xFF;
 }

src/vm/memory.rs

@@ -30,7 +30,13 @@ impl Memory<'_> {
     pub fn get_mem(&mut self, addr: u16) -> u16 {
         if addr >= 0xFE00 {
             return match addr {
-                0xFE00 => self.io.check_key() as u16,
+                0xFE00 => {
+                    if self.io.check_key() {
+                        1 << 15
+                    } else {
+                        0
+                    }
+                }
                 0xFE02 => {
                     let key = match self.io.get_key() {
                         Some(key) => key as u16,

src/vm/terminal_io.rs

@@ -29,6 +29,7 @@ pub trait KeyboardIO {
 
 pub struct TerminalIO {
     stdin_channel: Receiver<u8>,
+    char: Option<u8>,
 }
 
 impl TerminalIO {
@@ -36,6 +37,7 @@ impl TerminalIO {
         setup_termios();
         TerminalIO {
             stdin_channel: Self::spawn_stdin_channel(),
+            char: None,
         }
     }
 
@@ -59,17 +61,14 @@ impl Drop for TerminalIO {
 
 impl KeyboardIO for TerminalIO {
     fn get_key(&mut self) -> Option<u8> {
-        match self.stdin_channel.try_recv() {
-            Ok(key) => Some(key),
-            Err(mpsc::TryRecvError::Empty) => None,
-            Err(mpsc::TryRecvError::Disconnected) => panic!("terminal keyboard stream broke"),
-        }
+        self.char
     }
 
     fn check_key(&mut self) -> bool {
-        match self.stdin_channel.try_iter().peekable().peek() {
-            Some(data) => true,
-            None => false,
+        match self.stdin_channel.try_recv() {
+            Ok(key) => { self.char = Some(key); true },
+            Err(mpsc::TryRecvError::Empty) => false,
+            Err(mpsc::TryRecvError::Disconnected) => panic!("terminal keyboard stream broke"),
         }
     }
 }