upsamp converts a control signal to an audio signal. It does it by simple repetition of the kval. upsamp is a slightly more efficient form of the assignment, asig = ksig.
Examples
asrc buzz 10000,440,20, 1 ; band-limited pulse train
adif diff asrc ; emphasize the highs
anew balance adif, asrc ; but retain the power
agate reson asrc,0,440 ; use a lowpass of the original
asamp samphold anew, agate ; to gate the new audiosig
aout tone asamp,100 ; smooth out the rough edges