C Specification

To enqueue a command to copy a buffer object identified by src_buffer to another buffer object identified by dst_buffer, call the function

// Provided by CL_VERSION_1_0
cl_int clEnqueueCopyBuffer(
    cl_command_queue command_queue,
    cl_mem src_buffer,
    cl_mem dst_buffer,
    size_t src_offset,
    size_t dst_offset,
    size_t size,
    cl_uint num_events_in_wait_list,
    const cl_event* event_wait_list,
    cl_event* event);

Parameters

  • command_queue refers to a host command-queue in which the copy command will be queued. The OpenCL context associated with command_queue, src_buffer and dst_buffer must be the same.

  • src_offset refers to the offset where to begin copying data from src_buffer.

  • dst_offset refers to the offset where to begin copying data into dst_buffer.

  • size refers to the size in bytes to copy.

  • 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 copy command and can be used to query or queue a wait for this command to complete. If event is NULL or the enqueue is unsuccessful, no event will be created and therefore it will not be possible to query the status of this command or to wait for this command to complete. If event_wait_list and event are not NULL, event must not refer to an element of the event_wait_list array.

Description

The usage information which indicates whether the memory object can be read or written by a kernel and/or the host and is given by the cl_mem_flags argument value specified when src_buffer or _dst_buffer is created is ignored by clEnqueueCopyBuffer.

clEnqueueCopyBuffer 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 host command-queue.

  • CL_INVALID_CONTEXT if the context associated with command_queue, src_buffer and dst_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 src_buffer and dst_buffer are not valid buffer objects.

  • CL_INVALID_VALUE if src_offset, dst_offset, size, src_offset + size or dst_offset + size require accessing elements outside the src_buffer and dst_buffer buffer objects respectively.

  • 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 src_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. This error code is missing before version 1.1.

  • CL_MISALIGNED_SUB_BUFFER_OFFSET if dst_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. This error code is missing before version 1.1.

  • CL_MEM_COPY_OVERLAP if src_buffer and dst_buffer are the same buffer or sub-buffer object and the source and destination regions overlap or if src_buffer and dst_buffer are different sub-buffers of the same associated buffer object and they overlap. The regions overlap if src_offset ≤ dst_offset ≤ src_offset + size - 1 or if dst_offset ≤ src_offset ≤ dst_offset + size - 1.

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

  • 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 dst_buffer was created with CL_MEM_IMMUTABLE_EXT.

See Also

CL_VERSION_1_0, cl_command_queue, cl_event, cl_mem, cl_uint

Document Notes

For more information, see the OpenCL Specification

This page is extracted from the OpenCL Specification. Fixes and changes should be made to the Specification, not directly.

Copyright

Copyright 2014-2025 The Khronos Group Inc.

SPDX-License-Identifier: CC-BY-4.0