//#define CLAS_O_DEBUG

enum { UNKNOWN, T0, T1, T2, T3, OK, DONE };

static unsigned char clas_o_state = UNKNOWN;

unsigned long clas_o_x_data;
static unsigned int clas_o_x_numBits;

void clas_o_ResetDecoder () {
    clas_o_x_data = 0;
    clas_o_x_numBits = 0;
    clas_o_state = UNKNOWN;
}

static boolean clas_o_isDone() {
    return clas_o_state == DONE;
}

static void clas_o_done () {
    clas_o_state = DONE;
}

static void clas_o_gotBit (char value) {

    clas_o_x_numBits++;
    clas_o_x_data = (clas_o_x_data << 1) + (value & 0x01);

    clas_o_state = OK;
}

static int clas_o_decode (unsigned int width) {

    if( clas_o_state != UNKNOWN ) {
#ifdef CLAS_O_DEBUG
        Serial.print(width);
        Serial.print(" - ");
#endif
    }


    switch (clas_o_state) {
        case UNKNOWN: // Start of frame
            if ( 3500 <= width && width <= 4000 ) {
#ifdef CLAS_O_DEBUG
                Serial.print(width);
                Serial.print(" - ");
#endif
                clas_o_state = T0;
            }
            else {
                return -1;    // error, reset
            }
            break;

        case T0: // First half of pulse : HIGH around 230us

            if ( clas_o_x_numBits == 32 ) {   // end of frame
                clas_o_state = DONE;
                clas_o_x_data = (clas_o_x_data >> 8);    // Mask away some bits at the end
                return 1;
            }
            else if ( 340 <= width && width <= 540 ) {
                clas_o_state = T1;
            }
            else {
                if ( clas_o_x_numBits == 0 && 3400 <= width && width <= 3800 ) {
                    clas_o_state = T0;
                }
                else {
#ifdef CLAS_O_DEBUG
                    Serial.println(" X1X ");
#endif
                    return -1;  // error, reset
                }
            }
            break;

        case T1:
            if ( 800 <= width && width <= 1000) {
                clas_o_gotBit(0);
            } else if ( 1640 <= width && width <= 1940 ) {
                clas_o_gotBit(1);
            } else  {
#ifdef CLAS_O_DEBUG
                Serial.println(" X2X ");
#endif
                return -1;    // error, reset
            }
            clas_o_state = T0;
            break;
    }
    return 0;
}

boolean nextPulse_clas_o (unsigned int width) {

    if ( width > 0 ) {
        if (clas_o_state != DONE)

            switch (clas_o_decode(width)) {
                case -1:
                    clas_o_ResetDecoder();
                    break;
                case 1:  clas_o_done();  break;
            }
    }
    return clas_o_isDone();
}