1. First steps in Reaktor Core - Native Instruments

There’s also another difference: in the analog world the tape is moving. If we
want to move our digital tape we would need to copy all array elements to
their neighbor positions at each audio clock, which is quite CPU intensive.
Instead, we will move the heads.
From the preceding, we can conclude that we will need the following:
array – to simulate our digital tape loop
write index – this is our record head
read index – this is our playback head
The write and the read indices will be moving through the array sample by
sample. When either of them reaches the end of the array, it needs to be
reset to the beginning of the array (that corresponds to connecting the open
ends of the tape into a loop). The difference between the write and the read
position corresponds to the delay time measured in samples.
This technique is quite common in programming and is called “circular
buffer” or “ring buffer”.
We start by programming the record head. It operates similarly to the sawtooth
oscillator we programmed earlier, except that the computations are done in
integer mode. The value increment is one per audio tick and the output value
range is from 0 to N-1, where N is the size of the array. Let’s put the circuitry
for computing the write index into a RecordPos macro:
The N input should receive the number of elements in the array and the Pos
output will carry the current writing position (index). Here is how this macro can
be implemented (compare this to the sawtooth oscillator implementation):
Note that the comparison module is set to >=. That was unimportant for the
sawtooth oscillator, we could use >= or > there, but in integer computations
the difference is in most cases critical. Using >= condition ensures that the
write index will never reach a value of N (which would be out of range).
On the top-level, we create an array module and connect it to the RecordPos
through the Size [] module (available in Built-In Module > Memory > Size []),
which reports the size of the array:
130 – REAKTOR CORE