NAME¶
clEnqueueReadBufferRect - Enqueue commands to read from a
rectangular region from a buffer object to host memory.
cl_int
clEnqueueReadBufferRect(cl_command_queue command_queue,
cl_mem buffer,
cl_bool blocking_read,
const size_t * buffer_origin,
const size_t * host_origin,
const size_t * region,
size_t buffer_row_pitch,
size_t buffer_slice_pitch,
size_t host_row_pitch,
size_t host_slice_pitch,
void *ptr,
cl_uint num_events_in_wait_list,
const cl_event *event_wait_list,
cl_event *event);
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_list
event_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.
NOTES¶
Calling clEnqueueReadBufferRect to read a region of the
buffer object with the ptr argument value set to host_ptr and
host_origin, buffer_origin values are the same, where
host_ptr is a pointer to the memory region specified when the buffer
object being read is created with CL_MEM_USE_HOST_PTR, must meet the
same requirements given for clEnqueueReadBuffer(3clc).
Calling clEnqueueWriteBufferRect to update the latest bits
in a region of the buffer object with the ptr argument value set to
host_ptr and host_origin, buffer_origin values are the
same, where host_ptr is a pointer to the memory region specified when
the buffer object being written is created with CL_MEM_USE_HOST_PTR,
must meet the following requirements in order to avoid undefined
behavior:
• The host memory region given by
(buffer_originregion) contains the latest bits when the enqueued
write command begins execution.
• The buffer object or memory objects created from
this buffer object are not mapped.
• The buffer object or memory objects created from
this buffer object are not used by any command-queue until the write command
has finished execution.
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.
SPECIFICATION¶
OpenCL Specification[1]
SEE ALSO¶
clEnqueueCopyBuffer(3clc),
clEnqueueCopyBufferRect(3clc), clEnqueueWriteBuffer(3clc),
clEnqueueWriteBufferRect(3clc), clEnqueueReadBuffer(3clc)
AUTHORS¶
The Khronos Group
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.
NOTES¶
- 1.
- OpenCL Specification
page 74, section 5.2.2 - Reading, Writing and Copying
Buffer Objects
