Enqueues a command to unmap a previously mapped region of a memory object.

void * clEnqueueUnmapMemObject ( cl_command_queue command_queue,
  cl_mem memobj,
  void *mapped_ptr,
  cl_uint num_events_in_wait_list,
  const cl_event *event_wait_list,
  cl_event *event)



Must be a valid command-queue.


A valid memory object. The OpenCL context associated with command_queue and memobj must be the same.


The host address returned by a previous call to clEnqueueMapBuffer or clEnqueueMapImage for memobj.

event_wait_list , num_events_in_wait_list

Specify events that need to complete before clEnqueueUnmapMemObject can be executed. If event_wait_list is NULL, then clEnqueueUnmapMemObject 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.


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. clEnqueueBarrier can be used instead.


Reads or writes from the host using the pointer returned by clEnqueueMapBuffer or clEnqueueMapImage are considered to be complete.

clEnqueueMapBuffer and clEnqueueMapImage increments 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 memory object being mapped.


clEnqueueUnmapMemObject 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_MEM_OBJECT if memobj is not a valid memory object.
  • CL_INVALID_VALUE if mapped_ptr is not a valid pointer returned by clEnqueueMapBuffer or clEnqueueMapImage for memobj.
  • 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_OUT_OF_HOST_MEMORY if there is a failure to allocate resources required by the OpenCL implementation on the host.
  • CL_INVALID_CONTEXT if the context associated with command_queue and memobj are not the same or if the context associated with command_queue and events in event_wait_list are not the same.


OpenCL Specification

Also see

clEnqueueMapBuffer, clEnqueueMapImage

Copyright © 2007-2009 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.