clEnqueueReadBufferRect - Enqueue commands to read from a rectangular region from a buffer object to host

Authors

TheKhronosGroup

Copyright

       Copyright © 2007-2011 The Khronos Group Inc.
       Permission is hereby granted, free of charge, to any person obtaining a copy of this software and/or
       associated documentation files (the "Materials"), to deal in the Materials without restriction, including
       without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
       copies of the Materials, and to permit persons to whom the Materials are furnished to do so, subject to
       the condition that this copyright notice and permission notice shall be included in all copies or
       substantial portions of the Materials.

Errors

clEnqueueReadBufferRect returns CL_SUCCESS if the function is executed successfully. Otherwise, it
       returns one of the following errors:

       •   CL_INVALID_COMMAND_QUEUE if command_queue is not a valid command-queue.

       •   CL_INVALID_CONTEXT if the context associated with command_queue and buffer are not the same or if the
           context associated with command_queue and events in event_wait_list are not the same.

       •   CL_INVALID_MEM_OBJECT if buffer is not a valid buffer object.

       •   CL_INVALID_VALUE if the region being read specified by (buffer_origin, region, buffer_row_pitch,
           buffer_slice_pitch) is out of bounds.

       •   CL_INVALID_VALUE if ptr is a NULL value.

       •   CL_INVALID_VALUE if any region array element is 0.

       •   CL_INVALID_VALUE if buffer_row_pitch is not 0 and is less than region[0].

       •   CL_INVALID_VALUE if host_row_pitch is not 0 and is less than region[0].

       •   CL_INVALID_VALUE if buffer_slice_pitch is not 0 and is less than region[1] * buffer_row_pitch and not
           a multiple of buffer_row_pitch.

       •   CL_INVALID_VALUE if host_slice_pitch is not 0 and is less than region[1] * host_row_pitch and not a
           multiple of host_row_pitch.

       •   CL_INVALID_EVENT_WAIT_LIST if event_wait_list is NULL and num_events_in_wait_list > 0, or
           event_wait_list is not NULL and num_events_in_wait_list is 0, or if event objects in event_wait_list
           are not valid events.

       •   CL_MISALIGNED_SUB_BUFFER_OFFSET if buffer is a sub-buffer object and offset specified when the
           sub-buffer object is created is not aligned to CL_DEVICE_MEM_BASE_ADDR_ALIGN value for device
           associated with queue.

       •   CL_EXEC_STATUS_ERROR_FOR_EVENTS_IN_WAIT_LIST if the read and write operations are blocking and the
           execution status of any of the events in event_wait_list is a negative integer value.

       •   CL_MEM_OBJECT_ALLOCATION_FAILURE if there is a failure to allocate memory for data store associated
           with buffer.

       •   CL_INVALID_OPERATION if clEnqueueReadBufferRect is called on buffer which has been created with
           CL_MEM_HOST_WRITE_ONLY or CL_MEM_HOST_NO_ACCESS.

       •   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.

Name

       clEnqueueReadBufferRect - Enqueue commands to read from a rectangular region from a buffer object to host
       memory.

       cl_intclEnqueueReadBufferRect(cl_command_queuecommand_queue,cl_membuffer,cl_boolblocking_read,constsize_t*buffer_origin,constsize_t*host_origin,constsize_t*region,size_tbuffer_row_pitch,size_tbuffer_slice_pitch,size_thost_row_pitch,size_thost_slice_pitch,void*ptr,cl_uintnum_events_in_wait_list,constcl_event*event_wait_list,cl_event*event);

Notes

        1. OpenCL Specification
           page 74, section 5.2.2 - Reading, Writing and Copying Buffer Objects

The Khronos Group                                  11/18/2024                         CLENQUEUEREADBUFFERR(3clc)

Parameters

command_queue
Refers to the command-queue in which the read command will be queued. command_queue and buffer must
be created with the same OpenCL context.

buffer
Refers to a valid buffer object.

blocking_read
Indicates if the read operations are blocking or non-blocking.

If blocking_read is CL_TRUE i.e. the read command is blocking, clEnqueueReadBufferRect does not
return until the buffer data has been read and copied into memory pointed to by ptr.

If blocking_read is CL_FALSE i.e. the read command is non-blocking, clEnqueueReadBufferRect queues a
non-blocking read command and returns. The contents of the buffer that ptr points to cannot be used
until the read command has completed. The event argument argument returns an event object which can
be used to query the execution status of the read command. When the read command has completed, the
contents of the buffer that ptr points to can be used by the application.

buffer_origin
The (x,y,z) offset in the memory region associated with buffer. For a 2D rectangle region, the z
value given by buffer_origin[2] should be 0. The offset in bytes is computed as buffer_origin[2] *
buffer_slice_pitch + buffer_origin[1] * buffer_row_pitch + buffer_origin[0].

host_origin
The (x,y,z) offset in the memory region pointed to by ptr. For a 2D rectangle region, the z value
given by host_origin[2] should be 0. The offset in bytes is computed as host_origin[2] *
host_slice_pitch + host_origin[1] * host_row_pitch + host_origin[0].

region
The (width,height,depth) in bytes of the 2D or 3D rectangle being read or written. For a 2D
rectangle copy, the depth value given by region[2] should be 1.

buffer_row_pitch
The length of each row in bytes to be used for the memory region associated with buffer. If
buffer_row_pitch is 0, buffer_row_pitch is computed as region[0].

buffer_slice_pitch
The length of each 2D slice in bytes to be used for the memory region associated with buffer. If
buffer_slice_pitch is 0, buffer_slice_pitch is computed as region[1] * buffer_row_pitch.

host_row_pitch
The length of each row in bytes to be used for the memory region pointed to by ptr. If host_row_pitch
is 0, host_row_pitch is computed as region[0].

host_slice_pitch
The length of each 2D slice in bytes to be used for the memory region pointed to by ptr. If
host_slice_pitch is 0, host_slice_pitch is computed as region[1] * host_row_pitch.

ptr
The pointer to buffer in host memory where data is to be read into.

event_wait_list , num_events_in_wait_listevent_wait_list and num_events_in_wait_list specify events that need to complete before this
particular command can be executed. If event_wait_list is NULL, then this particular command does not
wait on any event to complete. If event_wait_list is NULL, num_events_in_wait_list must be 0. If
event_wait_list is not NULL, the list of events pointed to by event_wait_list must be valid and
num_events_in_wait_list must be greater than 0. The events specified in event_wait_list act as
synchronization points. The context associated with events in event_wait_list and command_queue must
be the same. The memory associated with event_wait_list can be reused or freed after the function
returns.

event
Returns an event object that identifies this particular read 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 the event_wait_list and the event arguments are not NULL, the event argument should not
refer to an element of the event_wait_list array.