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 VX_API_CALL	vxAccessLUT (vx_lut lut, void **ptr, vx_enum usage)
	Grants access to a LUT table and increments the object reference count in case of success. More...
vx_status VX_API_CALL	vxCommitLUT (vx_lut lut, const void *ptr)
	Commits the Lookup Table and decrements the object reference count in case of success. More...
vx_lut VX_API_CALL	vxCreateLUT (vx_context context, vx_enum data_type, vx_size count)
	Creates LUT object of a given type. More...
vx_status VX_API_CALL	vxQueryLUT (vx_lut lut, vx_enum attribute, void *ptr, vx_size size)
	Queries attributes from a LUT. More...
vx_status VX_API_CALL	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 842 of file vx_types.h.

Function Documentation

vx_lut VX_API_CALL 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

An LUT reference vx_lut. Any possible errors preventing a successful creation should be checked using vxGetStatus.

vx_status VX_API_CALL 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 lut is not a vx_lut.

vx_status VX_API_CALL 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 in bytes of the container to which ptr points.

Returns

A vx_status_e enumeration.

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

Grants access to a LUT table and increments the object reference count in case of success.

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	ptr The user-supplied address to a pointer, via which the requested contents are returned. If ptr is NULL, an error occurs. If ptr is not NULL and (*ptr) is NULL, (*ptr) will be set to the address of a memory area managed by the OpenVX framework containing the requested data. If both ptr and (*ptr) are not NULL, requested data will be copied to (*ptr) (optionally in case of write-only access).
[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 VX_API_CALL vxCommitLUT	(	vx_lut	lut,
		const void *	ptr
	)

Commits the Lookup Table and decrements the object reference count in case of success.

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 provided or returned by vxAccessLUT. This cannot be NULL.

  Returns

  A vx_status_e enumeration.

  Precondition

  vxAccessLUT.