const char StateZero = 0;
const char StateA = 1;
const char StateB = 2;
const char StateAB = StateA | StateB;

char entry = StateZero;
char prev = StateZero;

void pollEncoder( void ) {
    char cur = 0;
    if( !pinA )
        cur = StateA;
    if( !pinB )
        cur |= StateB;

    if( cur == prev )
        return;

    if( cur != StateAB ) {
        if( prev == StateAB && cur != entry ) {
            if( entry == StateA || cur == StateB )
                up();
            else if( entry == StateB || cur == StateA )
                down();
            entry = cur;
        } else if( cur != StateZero ) {
            entry = cur;
        }
    }
    
    prev = cur;
}