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/**
 * @file drv_mixer.h
 *
 * Mixer ioctl interface.
 *
 * This interface can/should be exported by any device that supports
 * control -> actuator mixing.
 */

#ifndef _DRV_MIXER_H
#define _DRV_MIXER_H

#include <stdint.h>
#include <sys/ioctl.h>

#include <systemlib/mixer.h>

/**
 * Structure used for receiving mixers.
 *
 * Note that the mixers array is not actually an array of mixers; it
 * simply represents the first mixer in the buffer.
 */
struct MixInfo {
	unsigned	num_controls;
	struct mixer_s	mixer;
};

/**
 * Handy macro for determining the allocation size of a MixInfo structure.
 */
#define MIXINFO_SIZE(_num_controls)	(sizeof(struct MixInfo) + ((_num_controls) * sizeof(struct scaler_s)))

/*
 * ioctl() definitions
 */

#define _MIXERIOCBASE		(0x2400)
#define _MIXERIOC(_n)		(_IOC(_MIXERIOCBASE, _n))

/** get the number of actuators that require mixers in *(unsigned)arg */
#define MIXERIOCGETMIXERCOUNT	_MIXERIOC(0)

/**
 * Copy a mixer from the device into *(struct MixInfo *)arg.
 *
 * The num_controls field indicates the number of controls for which space
 * is allocated following the MixInfo structure.  If the allocation
 * is too small, no mixer data is retured.  The control_count field in
 * the MixInfo.mixer structure is always updated.
 *
 * If no mixer is assigned for the given index, the ioctl returns ENOENT.
 */
#define MIXERIOCGETMIXER(_mixer)	_MIXERIOC(0x20 + _mixer)

/**
 * Copy a mixer from *(struct mixer_s *)arg to the device.
 *
 * If arg is zero, the mixer is deleted.
 */
#define MIXERIOCSETMIXER(_mixer)	_MIXERIOC(0x40 + _mixer)

#endif /* _DRV_ACCEL_H */