This code is violently stupid, but SOON I will be able to handle incoming packet data

avr/main.c

@@ -4,6 +4,7 @@
 #include <avr/sleep.h>
 
 #include <tabby/clock.h>
+#include <tabby/avr/uart.h>
 
 static volatile uint8_t bits      = 0;
 static volatile uint8_t value_in  = 0x00; /* Data coming in from Game Boy */
@@ -38,9 +39,9 @@ ISR(TIM0_COMPB_vect) {
     value_out <<= 1;
 
     if (--bits == 0) {
-        putchar(value_in);
+        uart_putchar(value_in, NULL);
 
-        value_out = getchar();
+        value_out = uart_getchar(NULL);
 
         bits = 8;
     }
@@ -100,6 +101,11 @@ static void snooze() {
 }
 
 int main() {
+    /*
+     * Best turn on the serial UART!
+     */
+    uart_init();
+
     /*
      * By default, the Game Boy link port is configured to monitor for external
      * clock pulses, so we'll go ahead and do that in this case.

avr/uart.c

@@ -0,0 +1,34 @@
+#include <stdio.h>
+
+#include <tabby/avr/uart.h>
+
+#define F_CPU 16000000UL
+#define BAUD  TABBY_AVR_UART_BAUD
+
+#include <util/setbaud.h>
+
+void uart_init() {
+    UBRR0H = UBRRH_VALUE;
+    UBRR0L = UBRRL_VALUE;
+
+#if USE_2X
+    UCSR0A |= _BV(U2X0);
+#else
+    UCSR0A &= ~(_BV(U2X0));
+#endif
+
+    UCSR0C = _BV(UCSZ01) | _BV(UCSZ00);
+    UCSR0B = _BV(RXEN0)  | _BV(TXEN0);
+}
+
+void uart_putchar(char c, FILE *fh) {
+    loop_until_bit_is_set(UCSR0A, UDRE0);
+
+    UDR0 = c;
+}
+
+char uart_getchar(FILE *fh) {
+    loop_until_bit_is_set(UCSR0A, RXC0);
+
+    return UDR0;
+}

include/tabby/avr.h

@@ -1,6 +0,0 @@
-#ifndef _TABBY_AVR_H
-#define _TABBY_AVR_H
-
-#define TABBY_AVR_SERIAL_BAUD 115200
-
-#endif /* _TABBY_AVR_H */

include/tabby/avr/uart.h

@@ -0,0 +1,12 @@
+#ifndef _TABBY_AVR_UART_H
+#define _TABBY_AVR_UART_H
+
+#define TABBY_AVR_UART_BAUD 115200
+
+void uart_init();
+
+void uart_putchar(char c, FILE *fh);
+
+char uart_getchar(FILE *fh);
+
+#endif /* _TABBY_AVR_UART_H */