case USCI_I2C_UCSTPIFG:                 // Vector 8: STPIFG
        if (i2cSlaveCtx.i2c_mode == I2C_RX_MODE) {          // Recieve
            ReceiveIndex = 0;
        } else if (i2cSlaveCtx.i2c_mode == I2C_TX_MODE) {   // Transmit
            TransmitIndex = 0;
        } 
        // else {
            // TODO: throw an error. 
        // }

        // Done 
        i2cSlaveCtx.i2c_mode = I2C_IDLE_MODE;
        break;