Universal Control

A universal control is a control type that supports abstract mechanisms for accessing data, thereby making it capable of representing any controllable parameter. More...

Functions
hpi_err_t	HPI_Universal_Info (const hpi_hsubsys_t *phSubSys, hpi_handle_t hC, struct hpi_entity **info)
	Retrieve information associated with an universal control. More...
hpi_err_t	HPI_Universal_Get (const hpi_hsubsys_t *phSubSys, hpi_handle_t hC, struct hpi_entity **value)
	Returns the current value of an universal control as an entity. More...
hpi_err_t	HPI_Universal_Set (const hpi_hsubsys_t *phSubSys, hpi_handle_t hC, struct hpi_entity *value)
	Set the current value of an universal control. More...

Detailed Description

A universal control is a control type that supports abstract mechanisms for accessing data, thereby making it capable of representing any controllable parameter.

Multiple related universal controls are created in sequence to form a block. For example, a tuner block might use 2 universal controls to represent the band and the frequency of the tuner. Carrying this description further, the band and frequency would be referred to as parameters of the tuner block.

A header universal control is used to name the block and specify the number and location of parameters that follow. The universal control list for the above tuner example looks like:

Index	Name	Description
n	Tuner	Block header, count = 2
n+1	Band	Parameter for the band
n+2	Frequency	Parameter for the frequency

A call to HPI_MixerGetControl() will return only the first control of type HPI_CONTROL_UNIVERSAL.

Need to add stuff about how to unpack the remaining parameter controls...

Function Documentation

HPI_Universal_Info()

hpi_err_t HPI_Universal_Info	(	const hpi_hsubsys_t *	phSubSys,
		hpi_handle_t	hC,
		struct hpi_entity **	info
	)

Retrieve information associated with an universal control.

Parameters

phSubSys	Vestigial subsys handle (unused), may be set to NULL
hC	Control handle.
info	Location where a pointer to the newly allocated buffer is returned. Info must always be freed by the caller because it may be allocated and contain a (partial) result even if the function returns an error.

See also

HPI_Entity_Free()

Returns

0 on success, or one of the HPI_ERROR_CODES.

HPI_Universal_Get()

hpi_err_t HPI_Universal_Get	(	const hpi_hsubsys_t *	phSubSys,
		hpi_handle_t	hC,
		struct hpi_entity **	value
	)

Returns the current value of an universal control as an entity.

Parameters

phSubSys	Vestigial subsys handle (unused), may be set to NULL
hC	Control handle.
value	Location where a pointer to the newly allocated buffer is returned. value must always be freed by the caller because it may be allocated and contain a (partial) result even if the function returns an error.

See also

HPI_Entity_Free()

Returns

0 on success, or one of the HPI_ERROR_CODES.

HPI_Universal_Set()

hpi_err_t HPI_Universal_Set	(	const hpi_hsubsys_t *	phSubSys,
		hpi_handle_t	hC,
		struct hpi_entity *	value
	)

Set the current value of an universal control.

Parameters

phSubSys	Vestigial subsys handle (unused), may be set to NULL
hC	Control handle.
value	Pointer to the entity containing the new value for the universal control.

Returns

0 on success, or one of the HPI_ERROR_CODES.