Enqueues a command to map a region of an image object into the host address space and returns a pointer to this mapped region.
void * clEnqueueMapImage(cl_command_queue command_queue,
cl_mem image,
cl_bool blocking_map,
cl_map_flags map_flags,
const size_t * origin,
const size_t * region,
size_t *image_row_pitch,
size_t *image_slice_pitch,
cl_uint num_events_in_wait_list,
const cl_event *event_wait_list,
cl_event *event,
cl_int *errcode_ret)
command_queue
-
Must be a valid host command-queue.
image
-
A valid image object. The OpenCL context associated with
command_queue
andimage
must be the same. blocking_map
-
Indicates if the map operation is
blocking
ornon-blocking
.If
blocking_map
isCL_TRUE
,clEnqueueMapImage
does not return until the specified region inimage
is mapped into the host address space and the application can access the contents of the mapped region using the pointer returned byclEnqueueMapImage
.If
blocking_map
isCL_FALSE
i.e. map operation is non-blocking, the pointer to the mapped region returned byclEnqueueMapImage
cannot be used until the map command has completed. Theevent
argument returns an event object which can be used to query the execution status of the map command. When the map command is completed, the application can access the contents of the mapped region using the pointer returned byclEnqueueMapImage
. map_flags
-
A bit-bield with the following supported values.
origin
-
Defines the (
x, y, z
) offset in pixels in the 1D, 2D or 3D image, the (x, y
) offset and the image index in the 2D image array or the (x
) offset and the image index in the 1D image array. Ifimage
is a 2D image object,origin
[2] must be 0. Ifimage
is a 1D image or 1D image buffer object,origin
[1] andorigin
[2] must be 0. Ifimage
is a 1D image array object,origin
[2] must be 0. Ifimage
is a 1D image array object,origin
[1] describes the image index in the 1D image array. Ifimage
is a 2D image array object,origin
[2] describes the image index in the 2D image array. region
-
Defines the (
width
,height
,depth
) in pixels of the 1D, 2D or 3D rectangle, the (width
,height
) in pixels of the 2D rectangle and the number of images of a 2D image array or the (width
) in pixels of the 1D rectangle and the number of images of a 1D image array. Ifimage
is a 2D image object,region
[2] must be 1. Ifimage
is a 1D image or 1D image buffer object,region
[1] andregion
[2] must be 1. Ifimage
is a 1D image array object,region
[2] must be 1. The values inregion
cannot be 0. image_row_pitch
-
Returns the scan-line pitch in bytes for the mapped region. This must be a non-NULL value.
image_slice_pitch
-
Returns the size in bytes of each 2D slice of a 3D image or the size of each 1D or 2D image in a 1D or 2D image array for the mapped region. For a 1D and 2D image, zero is returned if this argument is not NULL. For a 3D image, 1D, and 2D image array,
image_slice_pitch
must be a non-NULL value. event_wait_list ,
num_events_in_wait_list
-
Specify events that need to complete before
clEnqueueMapImage
can be executed. Ifevent_wait_list
is NULL, thenclEnqueueMapImage
does not wait on any event to complete. Ifevent_wait_list
is NULL,num_events_in_wait_list
must be 0. Ifevent_wait_list
is not NULL, the list of events pointed to byevent_wait_list
must be valid andnum_events_in_wait_list
must be greater than 0. The events specified inevent_wait_list
act as synchronization points. The context associated with events inevent_wait_list
andcommand_queue
must be the same. The memory associated withevent_wait_list
can be reused or freed after the function returns. event
-
Returns an event object that identifies this particular copy command and can be used to query or queue a wait for this particular command to complete.
event
can be NULL in which case it will not be possible for the application to query the status of this command or queue a wait for this command to complete. If theevent_wait_list
and theevent
arguments are not NULL, theevent
argument should not refer to an element of theevent_wait_list
array. errcode_ret
-
Returns an appropriate error code. If
errcode_ret
is NULL, no error code is returned.
The pointer returned maps a 1D, 2D or 3D region starting at origin
and is at least region
[0] pixels in size for a 1D image, 1D image buffer or 1D image array, (image_row_pitch
* region
[1]) pixels in size for a 2D image or 2D image array, and (image_slice_pitch
* region
[2]) pixels in size for a 3D image.
The result of a memory access outside this region is undefined.
If the image object is created with CL_MEM_USE_HOST_PTR
set in mem_flags
, the following will be true:
-
The
host_ptr
specified inclCreateImage
is guaranteed to contain the latest bits in the region being mapped when theclEnqueueMapImage
command has completed. -
The pointer value returned by
clEnqueueMapImage
will be derived from thehost_ptr
specified when the image object is created.
Mapped image objects are unmapped using clEnqueueUnmapMemObject
.
clEnqueueMapBuffer
and clEnqueueMapImage
increment the mapped count of the memory object.
The initial mapped count value of a memory object is zero.
Multiple calls to clEnqueueMapBuffer
or clEnqueueMapImage
on the same memory object will increment this mapped count by appropriate number of calls.
clEnqueueUnmapMemObject
decrements the mapped count of the memory object.
clEnqueueMapBuffer
and clEnqueueMapImage
act as synchronization points for a region of the buffer object being mapped.
If the mipmap extensions are enabled with cl_khr_mipmap_image
, calls to clEnqueueReadImage
, clEnqueueWriteImage
and clEnqueueMapImage
can be used to read from or write to a specific mip-level of a mip-mapped image.
If image argument is a 1D image, origin
[1] specifies the mip-level to use.
If image argument is a 1D image array, origin
[2] specifies the mip-level to use.
If image argument is a 2D image, origin
[3] specifies the mip-level to use.
If image argument is a 2D image array or a 3D image, origin
[3] specifies the mip-level to use.
clEnqueueMapImage
will return a pointer to the mapped region.
The errcode_ret
is set to CL_SUCCESS
.
A NULL pointer is returned otherwise with one of the following error values returned in errcode_ret
:
-
CL_INVALID_COMMAND_QUEUE
ifcommand_queue
is not a valid host command-queue. -
CL_INVALID_CONTEXT
if the context associated withcommand_queue
andimage
are not the same or if the context associated withcommand_queue
and events inevent_wait_list
are not the same. -
CL_INVALID_MEM_OBJECT
ifimage
is not a valid image object. -
CL_INVALID_VALUE
if region being mapped given by (origin
,origin
+region
) is out of bounds or if values specified inmap_flags
are not valid. -
CL_INVALID_VALUE
if values inorigin
andregion
do not follow rules described in the argument description fororigin
andregion
. -
CL_INVALID_VALUE
ifimage_row_pitch
is NULL. -
CL_INVALID_VALUE
ifimage
is a 3D image, 1D or 2D image array object andimage_slice_pitch
is NULL. -
CL_INVALID_EVENT_WAIT_LIST
ifevent_wait_list
is NULL andnum_events_in_wait_list
> 0, orevent_wait_list
is not NULL andnum_events_in_wait_list
is 0, or if event objects inevent_wait_list
are not valid events. -
CL_INVALID_IMAGE_SIZE
if image dimensions (image width, height, specified or compute row and/or slice pitch) forimage
are not supported by device associated withqueue
. -
CL_IMAGE_FORMAT_NOT_SUPPORTED
if image format (image channel order and data type) forimage
are not supported by device associated withqueue
. -
CL_MAP_FAILURE
if there is a failure to map the requested region into the host address space. This error cannot occur for image objects created withCL_MEM_USE_HOST_PTR
orCL_MEM_ALLOC_HOST_PTR
. -
CL_EXEC_STATUS_ERROR_FOR_EVENTS_IN_WAIT_LIST
if the map operation is blocking and the execution status of any of the events inevent_wait_list
is a negative integer value. -
CL_MEM_OBJECT_ALLOCATION_FAILURE
if there is a failure to allocate memory for data store associated withimage
. -
CL_INVALID_OPERATION
if the device associated withcommand_queue
does not support images (i.e.CL_DEVICE_IMAGE_SUPPORT
specified in the table of OpenCL Device Queries forclGetDeviceInfo
isCL_FALSE
. -
CL_INVALID_OPERATION
ifimage
has been created withCL_MEM_HOST_WRITE_ONLY
orCL_MEM_HOST_NO_ACCESS
andCL_MAP_READ
is set inmap_flags
or ifimage
has been created withCL_MEM_HOST_READ_ONLY
orCL_MEM_HOST_NO_ACCESS
andCL_MAP_WRITE
orCL_MAP_WRITE_INVALIDATE_REGION
is set inmap_flags
. -
CL_OUT_OF_RESOURCES
if there is a failure to allocate resources required by the OpenCL implementation on the device. -
CL_OUT_OF_HOST_MEMORY
if there is a failure to allocate resources required by the OpenCL implementation on the host. -
CL_INVALID_OPERATION
if mapping would lead to overlapping regions being mapped for writing.