Connexions module: m36654 1
Circular Buffers
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David Waldo
This work is produced by The Connexions Project and licensed under the
Creative Commons Attribution License
†
Abstract
Circular buers are used for rst-in-rst-out (FIFO) buers.
1 Introduction
When performing DSP algorithms data needs to be stored as it is being input. Only a certain amount of
data is kept. New data is saved and the old data is removed. This is a rst-in-rst-out (FIFO) buer. There
are two ways to implenent the FIFO buer. One is to shift the data and the other is to implement a circular
buer.
2 Shifted buer
There are two ways of implementing a FIFO buer. Both methods start with dening an array that is the
length of data needed to be stored. The rst method of implementing a FIFO buer is to add the new data
to the beginning of the buer and shifting the old data in the buer. The last value that is shifted out is
discarded or used before it is removed.
Figure 1
To implement the FIFO buer by shifting the following pseudo-code can be used.
N
- number of coecients
x(n)
- stored input data, n = 0...N-1
input_sample
- variable that contains the newest input sample
∗
Version 1.2: Feb 28, 2011 11:38 pm US/Central
†
http://creativecommons.org/licenses/by/3.0/
http://cnx.org/content/m36654/1.2/
