CLENQUEUEUNMAPMEMOBJ(3clc)

💅 CLENQUEUEUNMAPMEMOBJ — the 3clc glow-up ✨

okay bestie, so this is clEnqueueUnmapMemObject from the OpenCL Manual (3clc), and it's literally the "ok we're done here, put it back" command. no cap.

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✨ NAME ✨

clEnqueueUnmapMemObject — enqueues a command to unmap a previously mapped region of a memory object. 🎀

cl_int 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);

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🌸 PARAMETERS 🌸

here's the tea on every single one of them, no skipping:

• command_queue — must be a valid command-queue. like, a real one. not a vibe.
• memobj — a valid memory object. and the OpenCL context chillin' with command_queue and memobj has to be the same context. they gotta be in the same group chat, fr fr. 👯
• mapped_ptr — the host address that a previous call to clEnqueueMapBuffer(3clc) or clEnqueueMapImage(3clc) handed back for memobj. the receipt, basically. 🧾
• event_wait_list, num_events_in_wait_list — these two are the "wait your turn" girlies. they specify events that need to complete before clEnqueueUnmapMemObject can even be executed. so:
  • 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 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. (recycle era ♻️)
• event — returns an event object that identifies this particular copy command, and you can use it 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. and if that's your situation, clEnqueueBarrierWithWaitList(3clc) can be used instead. so you're not stranded, bestie. 🫶

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📝 NOTES 📝

• Reads or writes from the host using the pointer returned by clEnqueueMapBuffer(3clc) or clEnqueueMapImage(3clc) are considered to be complete. done. finished. ate. 💅
• clEnqueueMapBuffer(3clc) and clEnqueueMapImage(3clc) increment the mapped count of the memory object. the initial mapped count value of a memory object is zero. multiple calls to clEnqueueMapBuffer(3clc) or clEnqueueMapImage(3clc) on the same memory object will increment this mapped count by the appropriate number of calls. and then clEnqueueUnmapMemObject decrements the mapped count of the memory object. it's giving loyalty-card stamp math, and honestly? iconic. 🎟️
• clEnqueueMapBuffer(3clc) and clEnqueueMapImage(3clc) act as synchronization points for a region of the buffer object being mapped. ✨

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💀 ERRORS 💀

clEnqueueUnmapMemObject returns CL_SUCCESS if the function is executed successfully. otherwise, it returns one of these, and we're gonna read them all:

• 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(3clc) or clEnqueueMapImage(3clc) for memobj.
• 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_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_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.

okay real talk, the context-mismatch ones are the ones that get everybody. if your stuff isn't from the same context, it's not gonna work, periodt. 🫠

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📚 SPECIFICATION 📚

OpenCL Specification[1] — that's the source, she's citable, she's canon. 👑

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👀 SEE ALSO 👀

clEnqueueMapBuffer(3clc), clEnqueueMapImage(3clc)

(its little sibling mapping functions, go read them too 🦋)

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🫶 AUTHORS 🫶

The Khronos Group

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⚖️ 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.

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🔖 NOTES 🔖

1. OpenCL Specification — page 120, section 5.4.2 - Unmapping Mapped Memory Objects 📖

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and that's the whole page, bestie!! 💖 this one's from The Khronos Group, the OpenCL Manual, dated 01/14/2021, and the page is CLENQUEUEUNMAPMEMOBJ(3clc). go unmap responsibly, mwah 💋✨