A memory includes a sequence of memory locations storing a corresponding sequence of state codes that specifying the shape of a waveform. The sequence of state codes is read from the memory and decoded by a long and toggle decoder circuit. The decoding operation generates a sequence of signal codes. When the state code is a long code, the sequence of signal codes includes same signal codes corresponding to a signal level of the waveform. When the state code is a toggle code, the sequence of signal codes includes a first signal code corresponding to one signal level of the waveform and a second signal code corresponding to another signal level of the waveform. A signal decode circuit then decodes the signal codes in the sequence of signal codes to generate the waveform for output which includes the signal levels corresponding to the decoded signal codes.