NAME¶
clEnqueueWriteBuffer - Enqueue commands to write to a buffer object from host
memory.
cl_int
clEnqueueWriteBuffer(cl_command_queue command_queue,
cl_mem buffer,
cl_bool blocking_write,
size_t offset, size_t size,
const 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 write command
will be queued. command_queue and buffer must be created with
the same OpenCL context.
buffer
Refers to a valid buffer object.
blocking_write
Indicates if the write operations are
blocking or
nonblocking.
If blocking_write is CL_TRUE, the OpenCL
implementation copies the data referred to by ptr and enqueues the
write operation in the command-queue. The memory pointed to by ptr
can be reused by the application after the clEnqueueWriteBuffer call
returns.
If blocking_write is CL_FALSE, the OpenCL
implementation will use ptr to perform a nonblocking write. As the
write is non-blocking the implementation can return immediately. The memory
pointed to by ptr cannot be reused by the application after the call
returns. The event argument returns an event object which can be used
to query the execution status of the write command. When the write command
has completed, the memory pointed to by ptr can then be reused by the
application.
offset
The offset in bytes in the buffer object to write
to.
size
The size in bytes of data being written.
ptr
The pointer to buffer in host memory where data is to be
written from.
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
write 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.
NOTES¶
Calling clEnqueueWriteBuffer to update the latest bits in a region of the
buffer object with the ptr argument value set to host_ptr +
offset, 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 (host_ptr +
offset, cb) 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 read command
has finished execution.
ERRORS¶
clEnqueueWriteBuffer 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 written
specified by (offset, size) is out of bounds or if ptr is
a NULL value or if size is 0.
•CL_INVALID_EVENT_WAIT_LIST if
event_wait_list is NULL and num_events_in_wait_list greater than
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
clEnqueueWriteBuffer(3clc) is called on buffer which has been
created with CL_MEM_HOST_READ_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), clEnqueueReadBuffer(3clc),
clEnqueueReadBufferRect(3clc), clEnqueueWriteBufferRect(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 72, section 5.2.2 - Reading, Writing, Copying Buffer
Objects