chips/avr: Clear DDR and PORT registers during 'reset' operation

This chip doesn't reboot at reset time so that USB stays active, this
means we need to carefully reset all of the GPIO registers. We
probably need to do more careful resetting of the timer registers too,
but there isn't ROM space available today.

Signed-off-by: Keith Packard <keithp@keithp.com>

chips/avr/ao-snek-avr.c

@@ -78,6 +78,9 @@ static uint8_t timer0_fract = 0;
 #define FIRST_ADC	14
 
 static uint8_t	power[NUM_PIN];
+static uint8_t	power_pin;
+static uint8_t	dir_pin;
+static uint8_t	on_pins[NUM_PIN];
 
 ISR(TIMER0_OVF_vect)
 {
@@ -159,6 +162,16 @@ port_init(void)
 	OCR4C = 0xff;
 
 	memset(power, 0xff, NUM_PIN);
+	DDRB = 0;
+	DDRC = 0;
+	DDRD = 0;
+	DDRE = 0;
+	DDRF = 0;
+	PORTB = 0;
+	PORTC = 0;
+	PORTD = 0;
+	PORTE = 0;
+	PORTF = 0;
 }
 
 #include <avr/wdt.h>
@@ -181,10 +194,6 @@ main (void)
 		snek_parse();
 }
 
-static uint8_t	power_pin;
-static uint8_t	dir_pin;
-static uint8_t	on_pins[NUM_PIN];
-
 static const PROGMEM uint8_t _pin_map[NUM_PIN] = PIN_MAP;
 static const PROGMEM uint8_t _adc_map[NUM_ADC] = ADC_MAP;
 static uint8_t const PROGMEM ocr_reg_addrs[NUM_PIN] = OCR_REG_ADDRS;