1 files changed, 78 insertions, 0 deletions
diff --git a/uart.c b/uart.c
new file mode 100644
index 0000000..df3243f
--- /dev/null
+++ b/uart.c
@@ -0,0 +1,78 @@
+static char txbuf[64];
+static uint8_t txput = 0, txsend = 0;
+
+ISR(USART_RX_vect)
+{
+	uint8_t data = UDR0;
+}
+
+ISR(USART_UDRE_vect)
+{
+	if (txsend != txput) {
+		UDR0 = txbuf[txsend];
+		txsend++;
+		txsend &= 63;
+		UCSR0B = (1 << RXCIE0) | (1 << UDRIE0) | (1 << RXEN0) | (1 << TXEN0);
+	} else {
+		UCSR0B = (1 << RXCIE0) | (1 << RXEN0) | (1 << TXEN0);
+	}
+}
+
+static void _uart_putch(const char ch)
+{
+	txbuf[txput] = ch;
+	txput++;
+	txput &= 63;
+}
+
+static void uart_putpgm(PGM_P str)
+{
+	char c;
+	uint8_t sreg = SREG;
+	cli();
+
+	do {
+		c = pgm_read_byte(str);
+		if (!c)
+			break;
+		_uart_putch(c);
+		str++;
+	} while (1);
+	if (UCSR0A & (1 << UDRE0))
+		__vector_19();
+	
+	SREG = sreg;
+}
+#define uart_puts(str) do { \
+	static const char _mystr[] PROGMEM = str; \
+	uart_putpgm(_mystr); } while (0)
+
+#define hexdigit(x) ((x) + '0' + ((x) > 9 ? ('a' - '0' - 10) : 0))
+static void uart_puthex(uint8_t val)
+{
+	uint8_t tmp, sreg = SREG;
+	cli();
+
+	tmp = val >> 4;
+	tmp += '0';
+	if (tmp > '9')
+		tmp += 'a' - '0' - 10;
+	_uart_putch(tmp);
+	tmp = val & 0xf;
+	tmp += '0';
+	if (tmp > '9')
+		tmp += 'a' - '0' - 10;
+	_uart_putch(tmp);
+	if (UCSR0A & (1 << UDRE0))
+		__vector_19();
+
+	SREG = sreg;
+}
+
+static void uart_init(void)
+{
+	UBRR0 = 12;	/* 38461 ~ 38400 */
+	UCSR0C = (1 << UCSZ01) | (1 << UCSZ00);
+	UCSR0B = (1 << RXCIE0) | (1 << RXEN0) | (1 << TXEN0);
+}
+