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Linux input device mapping question resolved.

Linux input device mapping question resolved.

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AboooDy919
Member
207
10-27-2025, 10:54 PM
#1
I was examining input devices and noticed a section that lists available keys. I’m trying to understand how the hexadecimal value relates to those keys. It mentions a bit map storage, but I haven’t found a clear reference for the mapping details. The article you linked explains something similar, but it’s about a different topic. I searched online without success and didn’t manage to find official documentation or source code explanations. Since I’m not familiar with C or Linux internals, it’s possible I missed the right resources. Could someone help me decode this value or point me toward where the key values are stored? Thanks!
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AboooDy919
10-27-2025, 10:54 PM #1

I was examining input devices and noticed a section that lists available keys. I’m trying to understand how the hexadecimal value relates to those keys. It mentions a bit map storage, but I haven’t found a clear reference for the mapping details. The article you linked explains something similar, but it’s about a different topic. I searched online without success and didn’t manage to find official documentation or source code explanations. Since I’m not familiar with C or Linux internals, it’s possible I missed the right resources. Could someone help me decode this value or point me toward where the key values are stored? Thanks!

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OmqDace
Posting Freak
798
11-18-2025, 05:31 PM
#2
It seems unclear what you're aiming for, but you likely don't need to handle this yourself. Others have created input libraries and utilities to extract keys from devices. Use those resources instead. The linked post provides more insight and tools to bypass this issue.
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OmqDace
11-18-2025, 05:31 PM #2

It seems unclear what you're aiming for, but you likely don't need to handle this yourself. Others have created input libraries and utilities to extract keys from devices. Use those resources instead. The linked post provides more insight and tools to bypass this issue.

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GhostOfDay
Member
91
11-18-2025, 08:22 PM
#3
I've tackled similar tasks before using input libraries for events. The line you mentioned shows a bitmap in hex that supposedly lists all keys on the device, but I couldn't locate guidance on interpreting or decoding it myself... Still, thanks a lot! I remembered reading about it, though my mind was foggy and exhausted, so I probably overlooked how ioctl can decode device properties.
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GhostOfDay
11-18-2025, 08:22 PM #3

I've tackled similar tasks before using input libraries for events. The line you mentioned shows a bitmap in hex that supposedly lists all keys on the device, but I couldn't locate guidance on interpreting or decoding it myself... Still, thanks a lot! I remembered reading about it, though my mind was foggy and exhausted, so I probably overlooked how ioctl can decode device properties.

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Pickmaster12
Senior Member
710
11-26-2025, 11:42 AM
#4
The important data is a large bitmask representing the keys found in that file.
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Pickmaster12
11-26-2025, 11:42 AM #4

The important data is a large bitmask representing the keys found in that file.

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SushiCherry
Member
227
11-26-2025, 11:52 AM
#5
Thanks! That's really useful and matches exactly what I needed. I didn't notice they were in that file either.
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SushiCherry
11-26-2025, 11:52 AM #5

Thanks! That's really useful and matches exactly what I needed. I didn't notice they were in that file either.