--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/avriotools.c	Sat Feb 21 15:49:59 2009 +0800
@@ -0,0 +1,76 @@
+#include "avriotools.h"
+#include <avr/io.h>
+
+typedef struct _port_regs {
+    volatile uint8_t *port, *ddr, *pin;
+} port_regs_t;
+
+static port_regs_t regs[] = {
+    { &PORTB, &DDRB, &PINB },
+    { &PORTD, &DDRD, &PIND }
+};
+#define NPORTS (sizeof(regs) / sizeof(*regs))
+
+#define ERR -1
+#define OK 0
+
+int pin_mode(volatile uint8_t * port, int pin, pin_mode_t mode) {
+    port_regs_t *preg;
+    int i;
+
+    for(i = 0; i < NPORTS; i++) {
+	preg = regs + i;
+	if(preg->port == port)
+	    break;
+    }
+    if(i == NPORTS)
+	return ERR;
+
+    switch(mode) {
+    case PM_INPUT:
+	*preg->ddr &= ~_BV(pin);
+	*preg->port |= _BV(pin);
+	break;
+	
+    case PM_OUTPUT:
+	*preg->ddr |=  _BV(pin);
+	break;
+	
+    default:
+	return ERR;
+    }
+
+    return OK;
+}
+
+/* To make setbaud.h no more complaint */
+#define BAUD 9600
+#include <util/setbaud.h>
+
+int uart_init(uint32_t baud) {
+    unsigned long ubrr_v;
+    long err;
+
+    if(baud > (F_CPU / 8))
+	return ERR;
+
+#define F_CPUx2 (F_CPU * 2UL)
+
+    ubrr_v = (F_CPU + baud * 8UL) / (baud * 16UL) - 1UL;
+    /* Allow bias of baud rate in 2%, or use U2X clock.
+     * ATmega168 divides baud rate generator clock by 2, 8, or 16.
+     * Setting U2X bit makes the clock divided by 8 instead of 16.
+     * It makes more accurately output and higher max baud rate.
+     */
+    err = 16L * 100L * (ubrr_v + 1) * baud - F_CPU * 100L;
+    if(err > F_CPUx2 || err < -F_CPUx2 || ubrr_v < 2) {
+	ubrr_v = (F_CPU + baud * 4UL) / (baud * 8UL) - 1UL;
+	UCSRA |= (1 << U2X);
+    } else {
+	UCSRA &= ~(1 << U2X);
+    }
+    
+    UBRRH = ubrr_v >> 8;
+    UBRRL = ubrr_v & 0xff;
+    return OK;
+}