File content as of revision 1:52fba054be6c:

/*
name:                encoder.h
date:                04-june-2011
header description:  contains functions and external variables to interface quadrature encoder
compiler-library:    the mbed library interface is used on the whole..
compatability:       can also be compatable with generalised code with diffrerent hardware and software
hardware dependency: works on rover 5 model platform interfaced with mbed controller

indentation:         <mbed default intendation - 4 spaces>
resources:          http://www.sparkfun.com/products/10336
                    http://letsmakerobots.com/node/24031
                    http://www.sparkfun.com/datasheets/Robotics/Rover%205%20Introduction.pdf
            */
#include "mbed.h"
#include "quadratureEncoder.h"
//gets a bit position by shifting 1
#define Abit   0
#define Bbit   1

#define _BV(x) (1 << x)

// sbi sets a particular bit and cbi clears the bit (target byte-word, bit position)
#define sbi(y,x) y|=_BV(x)
#define cbi(y,x) y&=~_BV(x)

quadratureEncoder::quadratureEncoder(PinName pinA, PinName pinB):
_pinA(pinA), _pinB(pinB){
    _pinA.rise(this, &quadratureEncoder::ARise);
    _pinA.fall(this, &quadratureEncoder::AFall);
    _pinB.rise(this, &quadratureEncoder::BRise);
    _pinB.fall(this, &quadratureEncoder::BFall);
    
    _oldState = 0x00;
    _nowState = 0x00;
    _moved = 0;
    _count = 0;
}

////////////////////////////////////////////////////////////////////////////////////////
int quadratureEncoder::getCount() {
    return _count;
}

void quadratureEncoder::resetCount() {
    _count = 0;
}

void quadratureEncoder::setCount(int setCounter) {
    _count = setCounter;
}



////////////////////////////////////////////////////////////////////////////////////////
void quadratureEncoder::resetMoved() {
    _moved = 0;
}

void quadratureEncoder::setMoved(int setMover) {
    _moved = setMover;
}

int quadratureEncoder::getMoved() {
    return _moved;
}

////////////////////////////////////////////////////////////////////////////////////////
char quadratureEncoder::saveState(char nowS) {
    return nowS;
}

char quadratureEncoder::getBit(char bitP, char targB) {
    targB = targB & _BV(bitP);
    if (targB == 0)
        return 0;
    else
        return 1;
}


/*
function:   the following 8 functions are ISR called by rise and fall of 4 pins
input:      none (interupt called)
output:     none
functioning:interrupts are called when the pin change occours
            sets or clears the respective bit
            checks the previous state and increments respective direction
            restores new state value into old state
            increments a count value for processing    */
void quadratureEncoder::ARise() {
    sbi(_nowState,Abit);
    if (getBit(Bbit,_oldState)==0 && getBit(Abit,_oldState)==0)
        _moved++;
    else if (getBit(Bbit,_oldState)==0 && getBit(Abit,_oldState)==1)
        _moved--;
    _oldState = saveState(_nowState);
    _count++;
}

void quadratureEncoder::AFall() {
    cbi(_nowState, Abit);
    if (getBit(Bbit,_oldState)==1 && getBit(Abit,_oldState)==1)
        _moved++;
    else if (getBit(Bbit,_oldState)==1 && getBit(Abit,_oldState)==0)
        _moved--;
    _oldState = saveState(_nowState);
    _count++;
}

void quadratureEncoder::BRise() {
    sbi(_nowState,Bbit);
    if (getBit(Bbit,_oldState)==1 && getBit(Abit,_oldState)==0)
        _moved++;
    else if (getBit(Bbit,_oldState)==0 && getBit(Abit,_oldState)==0)
        _moved--;
    _oldState = saveState(_nowState);
    _count++;
}

void quadratureEncoder::BFall() {
    cbi(_nowState, Bbit);
    if (getBit(Bbit,_oldState)==0 && getBit(Abit,_oldState)==1)
        _moved++;
    else if (getBit(Bbit,_oldState)==1 && getBit(Abit,_oldState)==1)
        _moved--;
    _oldState = saveState(_nowState);
    _count++;
}