# SND_SetupChannelNoise

## Syntax

      #include <nitro/snd.h>

      void SND_SetupChannelNoise(
              int chNo,
              int volume,
              SNDChannelDataShift shift,
              int timer,
              int pan );

## Arguments

`chNo` | The channel number. Takes a value between 14 and 15.
`volume` | The volume. Takes a value between 0 and 127.
`shift` | Data shift specification.
`timer` | The timer. Takes a value between 0x10 and 0xffff.
`pan` | The pan. Takes values in the range of 0 (left) to 64 (center) to 127 (right).

## Return Values

None.

## Description

This function sets up a channel for playing white noise.

The function sets the parameters for the channel specified by `chNo`. The channel must first be locked by the `SND_LockChannel` function. Once the parameters have been set, call the `SND_StartTimer` function to begin actual playback.

Choose from among these values for the data shift setting `shift`:

Table. SNDChannelDataShift

Label | Description
--- | ---
SND_CHANNEL_DATASHIFT_NONE | Do not perform a data shift.
SND_CHANNEL_DATASHIFT_1BIT | Shift data 1 bit right.
SND_CHANNEL_DATASHIFT_2BIT | Shift data 2 bits right.
SND_CHANNEL_DATASHIFT_4BIT | Shift data 4 bits right.

timer specifies 8 cycles of white noise by clock count. The number of ticks per second is approximately 16.757 MHz with `SND_TIMER_CLOCK`. For example, the following calculation will play a pitch that has a frequency freq Hz.

    timer = SND_TIMER_CLOCK / ( 8 * freq )

### Note

This function is an ARM7 reserved function. After this function is called, its processing will occur only after the command is issued with the `SND_FlushCommand` function.

If program execution must be synchronized with process completion, first use the `SND_GetCurrentCommandTag` function to obtain the command tag immediately after calling this function. Then, after the command is issued, use the command tag and call either the `SND_IsFinishedCommandTag` or `SND_WaitForCommandProc` function to confirm that processing has finished or to wait for it to complete.

## See Also

`SND_LockChannel, SND_StartTimer, SND_FlushCommand, SND_GetCurrentCommandTag, SND_IsFinishedCommandTag, SND_WaitForCommandProc`

## Revision History

2005/02/17 Added a note about ARM7 command processing.
2004/08/10 Initial version.

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