TWI ISR swtich statement

TWI_switch.c

ISR(TWI_vect) {
  switch(TW_STATUS) {
    // NOTE: SLA+W = SLave Address + Write bit
    //       SLA+R = SLave Address + Read bit

    // All
    case TW_NO_INFO:    // No state information available
    case TW_BUS_ERROR:  // Bus error; Illegal START or STOP condition

    // All Master
    case TW_START:      // Start condition transmitted
    case TW_REP_START:  // Repeated start condition transmitted

    // Master Transmitter
    case TW_MT_SLA_ACK:    // SLA+W transmitted, ACK received = Slave receiver ACKed address
    case TW_MT_SLA_NACK:   // SLA+W transmitted, NACK received = Slave receiver with transmitted address doesn't exists?
    case TW_MT_DATA_ACK:   // Data transmitted, ACK received = Slave receiver ACKed data
    case TW_MT_DATA_NACK:  // Data transmitted, NACK received
    case TW_MT_ARB_LOST:   // Arbitration lost in SLA+W or data

    // Master Receiver
    case TW_MR_SLA_ACK:    // SLA+R transmitted, ACK received = Slave transmitter ACKed address
    case TW_MR_SLA_NACK:   // SLA+R transmitted, NACK received = Slave transmitter with transmitted address doesn't exists?
    case TW_MR_DATA_ACK:   // Data received, ACK returned
    case TW_MR_DATA_NACK:  // Data received, NACK returned
    case TW_MR_ARB_LOST:   // Arbitration lost in SLA+R or NACK

    // Slave Receiver
    case TW_SR_SLA_ACK:            // SLA+W received, ACK returned = Addressed, returned ACK
    case TW_SR_GCALL_ACK:          // General call received, ACK returned = Addressed generally, returned ACK
    case TW_SR_ARB_LOST_SLA_ACK:   // Arbitration lost in SLA+RW, SLA+W received, ACK returned
    case TW_SR_ARB_LOST_GCALL_ACK: // Arbitration lost in SLA+RW, general call received, ACK returned
    case TW_SR_DATA_ACK:           // Data received, ACK returned
    case TW_SR_DATA_NACK:          // Data received, NACK returned
    case TW_SR_GCALL_DATA_ACK:     // General call data received, ACK returned
    case TW_SR_GCALL_DATA_NACK:    // General call data received, NACK returned
    case TW_SR_STOP:               // Stop or repeated start condition received while selected

    // Slave Transmitter
    case TW_ST_SLA_ACK:           // SLA+R received, ACK returned = Addressed, returned ACK
    case TW_ST_ARB_LOST_SLA_ACK:  // Arbitration lost in SLA+RW, SLA+R received, ACK returned
    case TW_ST_DATA_ACK:          // Data transmitted, ACK received
    case TW_ST_DATA_NACK:         // Data transmitted, NACK received = Received NACK, so we are done
    case TW_ST_LAST_DATA:         // Last data byte transmitted, ACK received = Received ACK, but we are done already!
  }
}