Change API for getch to make it the caller's responsibility to poll for

input, allowing it to do other stuff if it wants to.

uart.h

@@ -1,11 +1,13 @@
 #ifndef __UART_H
 #define __UART_H
 
+#include "types.h"
+
 void init_uart(void);
 void putch(char c);
 void putstr(char *s);
 void putint(unsigned int n);
 void puthex(unsigned int n);
-char getch(void);
+bool getch(char *c);
 
 #endif /* __UART_H */