Reinitialization in Csound

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Re-initialization in Csound

• The Csound reinit opcode provides a means to
  re-initialize portions of an instrument program
  during performance.
• During a re-initialization pass, k-rate
  execution pauses temporarily and a new I-time
  pass is made through the range of statements
  specified.
• After the re-initialization pass, k-rate
  execution resumes normally.

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Re-initialization Opcodes
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Basic Coding Principles

• Re-initialization begins at the statement
  following the reinit label and continues until an
  endin or rireturn opcode is encountered.
• reinit is always used intermittently, often in a
  conditional context. I.e., if a specified
  condition is met, or if a certain amount of time
  has elapsed, then re-initialize the necessary
  part of the instrument.
• The Csound timout opcode is very useful in
  conjunction with reinit, and often paired with it
  when periodic re-initialization is needed
• Syntax timout istart, idur, label

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Conditional Re-initialization
gliss start reinit here kgliss line 1,
iglissdur,2 rireturn end reinit
here if (kgliss lt 2) kgoto continue reinit gli
ss restart gliss continue kgate linen iamp,iris
e,p3,idecay asig oscili iamp,icpskgliss,ifn ou
t asig endin
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Periodic Reinitialization

N.B., re-initialization will include the timout
opcode start timout 0, idur,
continue reinit start skipped for idur
secs continue kgate linen iamp,irise,idur,idec
ay asig oscili kgate,icps,ifn out
asig endin
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Re-initialization Notes

• Only i-type statements, expressions, and
  arguments will be changed during a
  re-initialization pass.
• To access the current value of a k-variable
  during re-initialization, use the Csound i()
  function, e.g.

kdur table kindex,ifunction start idur i(kdur
) kgate linen iamp,idur.1,idur,idur.5 timout
0, idur, continue reinit start start reinit
above continue rireturn end reinit here
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Reading Assignment

• Read Boulanger Chapter 17 RP Constrained
  Random Event Generation and Retriggering in
  Csound
• Read the Csound Manual about reinit, rigoto,
  rireturn, and timout.
• Experiment!