wiring_digital.c

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/*
 *  Copyright (c) 2005-2006 David A. Mellis
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU Lesser General Public License as published by
 *  the Free Software Foundation, either version 2.1 of the License, or
 *  (at your option) any later version.
   
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU Lesser General Public License for more details.
  
 *  You should have received a copy of the GNU Lesser General Public License
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
 
#include "wiring_private.h"
#include "pins_waspmote.h"

void pinMode(uint8_t pin, uint8_t mode)
{
        uint8_t bit = digitalPinToBitMask(pin);
        uint8_t port = digitalPinToPort(pin);
        volatile uint8_t *reg;

        if (port == NOT_A_PIN) return;

        // JWS: can I let the optimizer do this?
        reg = portModeRegister(port);

        if (mode == INPUT) *reg &= ~bit;
        else *reg |= bit;
}

// Forcing this inline keeps the callers from having to push their own stuff
// on the stack. It is a good performance win and only takes 1 more byte per
// user than calling. (It will take more bytes on the 168.)
//
// But shouldn't this be moved into pinMode? Seems silly to check and do on
// each digitalread or write.
//
static inline void turnOffPWM(uint8_t timer) __attribute__ ((always_inline));
static inline void turnOffPWM(uint8_t timer)
{
        if (timer == TIMER1A) cbi(TCCR1A, COM1A1);
        if (timer == TIMER1B) cbi(TCCR1A, COM1B1);

#if defined(__AVR_ATmega168__)
        if (timer == TIMER0A) cbi(TCCR0A, COM0A1);
        if (timer == TIMER0B) cbi(TCCR0A, COM0B1);
        if (timer == TIMER2A) cbi(TCCR2A, COM2A1);
        if (timer == TIMER2B) cbi(TCCR2A, COM2B1);
#elif defined(__AVR_ATmega1281__)
        if (timer == TIMER0A) cbi(TCCR0A, COM0A1);
        if (timer == TIMER0B) cbi(TCCR0A, COM0B1);
        if (timer == TIMER2A) cbi(TCCR2A, COM2A1);
        if (timer == TIMER2B) cbi(TCCR2A, COM2B1);
#else
        if (timer == TIMER2) cbi(TCCR2, COM21);
#endif
}

void digitalWrite(uint8_t pin, uint8_t val)
{
        uint8_t timer = digitalPinToTimer(pin);
        uint8_t bit = digitalPinToBitMask(pin);
        uint8_t port = digitalPinToPort(pin);
        volatile uint8_t *out;

        if (port == NOT_A_PIN) return;

        // If the pin that support PWM output, we need to turn it off
        // before doing a digital write.
        if (timer != NOT_ON_TIMER) turnOffPWM(timer);

        out = portOutputRegister(port);

        if (val == LOW) *out &= ~bit;
        else *out |= bit;
}

int digitalRead(uint8_t pin)
{
        uint8_t timer = digitalPinToTimer(pin);
        uint8_t bit = digitalPinToBitMask(pin);
        uint8_t port = digitalPinToPort(pin);

        if (port == NOT_A_PIN) return LOW;

        // If the pin that support PWM output, we need to turn it off
        // before getting a digital reading.
        if (timer != NOT_ON_TIMER) turnOffPWM(timer);

        if (*portInputRegister(port) & bit) return HIGH;
        return LOW;
}

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