Object: LUT

Detailed Description

Defines the Look-Up Table Interface.

A lookup table is an array that simplifies run-time computation by replacing computation with a simpler array indexing operation.

Typedefs
typedef struct _vx_lut *	vx_lut
	The Look-Up Table (LUT) Object.

Enumerations
enum	vx_lut_attribute_e {   VX_LUT_ATTRIBUTE_TYPE = ((( VX_ID_KHRONOS ) << 20) | ( VX_TYPE_LUT << 8)) + 0x0,   VX_LUT_ATTRIBUTE_COUNT = ((( VX_ID_KHRONOS ) << 20) | ( VX_TYPE_LUT << 8)) + 0x1,   VX_LUT_ATTRIBUTE_SIZE = ((( VX_ID_KHRONOS ) << 20) | ( VX_TYPE_LUT << 8)) + 0x2 }
	The Look-Up Table (LUT) attribute list. More...

Functions
vx_status	vxAccessLUT (vx_lut lut, void **ptr, vx_enum usage)
	Gets direct access to the LUT table data. More...
vx_status	vxCommitLUT (vx_lut lut, void *ptr)
	Commits the Lookup Table. More...
vx_lut	vxCreateLUT (vx_context context, vx_enum data_type, vx_size count)
	Creates LUT object of a given type. More...
vx_status	vxQueryLUT (vx_lut lut, vx_enum attribute, void *ptr, vx_size size)
	Queries attributes from a LUT. More...
vx_status	vxReleaseLUT (vx_lut *lut)
	Releases a reference to a LUT object. The object may not be garbage collected until its total reference count is zero. More...

Enumeration Type Documentation

enum vx_lut_attribute_e

The Look-Up Table (LUT) attribute list.

Enumerator
VX_LUT_ATTRIBUTE_TYPE	Indicates the value type of the LUT. Use a vx_enum.
VX_LUT_ATTRIBUTE_COUNT	Indicates the number of elements in the LUT. Use a vx_size.
VX_LUT_ATTRIBUTE_SIZE	Indicates the total size of the LUT in bytes. Uses a vx_size.

Definition at line 808 of file vx_types.h.

Function Documentation

vx_lut vxCreateLUT	(	vx_context	context,
		vx_enum	data_type,
		vx_size	count
	)

Creates LUT object of a given type.

Parameters

[in]	context	The reference to the context.
[in]	data_type	The type of data stored in the LUT.
[in]	count	The number of entries desired.

Note

For OpenVX 1.0, count must be equal to 256 and data_type can only be VX_TYPE_UINT8.

Returns

vx_lut

vx_status vxReleaseLUT

(

vx_lut *

lut

)

Releases a reference to a LUT object. The object may not be garbage collected until its total reference count is zero.

Parameters

[in]

lut

The pointer to the LUT to release.

Postcondition

After returning from this function the reference is zeroed.

Returns

A vx_status_e enumeration.

Return values

VX_SUCCESS	No errors.
VX_ERROR_INVALID_REFERENCE	If graph is not a vx_graph.

vx_status vxQueryLUT	(	vx_lut	lut,
		vx_enum	attribute,
		void *	ptr,
		vx_size	size
	)

Queries attributes from a LUT.

Parameters

[in]	lut	The LUT to query.
[in]	attribute	The attribute to query. Use a vx_lut_attribute_e enumeration.
[out]	ptr	The location at which to store the resulting value.
[in]	size	The size of the container to which ptr points.

Returns

A vx_status_e enumeration.

vx_status vxAccessLUT	(	vx_lut	lut,
		void **	ptr,
		vx_enum	usage
	)

Gets direct access to the LUT table data.

There are several variations of call methodology:

• If ptr is NULL (which means the current data of the LUT is not desired), the LUT reference count is incremented.
• If ptr is not NULL but (*ptr) is NULL, (*ptr) will contain the address of the LUT data when the function returns and the reference count will be incremented. Whether the (*ptr) address is mapped or allocated is undefined. (*ptr) must be returned to vxCommitLUT.
• If ptr is not NULL and (*ptr) is not NULL, the user is signalling the implementation to copy the LUT data into the location specified by (*ptr). Users must use vxQueryLUT with VX_LUT_ATTRIBUTE_SIZE to determine how much memory to allocate for the LUT data.

In any case, vxCommitLUT must be called after LUT access is complete.

Parameters

[in]	lut	The LUT from which to get the data.
[in,out]	ptr	The address of the location to store the pointer to the LUT memory.
[in]	usage	This declares the intended usage of the pointer using the * vx_accessor_e enumeration.

Returns

A vx_status_e enumeration.

Postcondition

vxCommitLUT

vx_status vxCommitLUT	(	vx_lut	lut,
		void *	ptr
	)

Commits the Lookup Table.

Commits the data back to the LUT object and decrements the reference count. There are several variations of call methodology:

• If a user should allocated their own memory for the LUT data copy, the user is obligated to free this memory.
• If ptr is not NULL and the (*ptr) for vxAccessLUT was NULL, it is undefined whether the implementation will unmap or copy and free the memory.

  Parameters

  [in]	lut	The LUT to modify.
  [in]	ptr	The pointer used with vxAccessLUT. This cannot be NULL.

  Returns

  A vx_status_e enumeration.

  Precondition

  vxAccessLUT.