# SNDEXIirFilterParam

## Definition

  `#include <twl/snd.h>`

      typedef struct _SNDEXIirFilterParam
      {
          u16 n0;
          u16 n1;
          u16 n2;
          u16 d1;
          u16 d2;
      } SNDEXIirFilterParam;

## Elements

n0, n1, n2, d1, d2 | Coefficients that compose an IIR filter (0 – 65,535).

## Description

A structure that is a collection of parameters used to set IIR filters.

You can use the parameters (Hex-type values) calculated with the IIR_FilterBuilder unchanged. (However, when using Values-type values, you must type-cast them to `u16`.)

The initial values for these parameters, for each filter that can be specified by the `SNDEXIirFilterTarget` structure, are as follows.

    n0 = 0x7FFF(32767), n1 = n2 = d1 = d2 = 0

Even if you have configured parameters for the various filters, resetting them to the values above will restore the initial filter state.

## See Also

`SNDEX_SetIirFilter, SNDEX_SetIirFilterAsync`

## Revision History

2008/09/10 Added a link to IIR_FilterBuilder.
2008/07/08 Initial version.

CONFIDENTIAL