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audio: copier: avoid shift by 32 in ALH nibble channel map #11256

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Merged
kv2019i merged 1 commit into from
Oct 6, 2026
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audio: copier: avoid shift by 32 in ALH nibble channel map #11256

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9 changes: 7 additions & 2 deletions src/audio/copier/copier_dai.c
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Original file line number Diff line number Diff line change
Expand Up @@ -27,8 +27,13 @@ static uint32_t bitmask_to_nibble_channel_map(uint8_t bitmask)
channel_count++;
}

/* absent channel is represented as 0xf nibble */
nibble_map |= 0xFFFFFFFF << (channel_count * 4);
/* Absent channel is represented as 0xf nibble. With all 8 channels present the shift count
* would be 32, which is undefined behavior for 32-bit types.
* On Xtensa and x86 architectures this would result in returning 0xffffffff, marking all

@abonislawski abonislawski Oct 2, 2026

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this should be shortened

@tmleman tmleman Oct 5, 2026

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Is it about the line length or is the comment too extensive in general?

@softwarecki softwarecki Oct 5, 2026

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For me this is okay. Not everyone may know why this behavior occurs or why this if statement is important.

@abonislawski abonislawski Oct 6, 2026

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@tmleman in general, we are adding way too long comments everywhere. For example here the first 2 lines are all what we need.

@tmleman tmleman Oct 6, 2026

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@abonislawski I would even agree with you if it weren't for the fact that a push will trigger a re-run in CI.

@abonislawski abonislawski Oct 6, 2026

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fair enough 😃

@wjablon1 wjablon1 Oct 6, 2026 •
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IMO It is maybe too verbose but still acceptable. But since we are on this topic, I would avoid describing entire flows and referencing other function names if that's possible (especially inside lower-level functions while checking preconditions). Such descriptions could easily become obsolete after refactoring or re-design. So generally I agree with @abonislawski

* channels absent.
*/
if (channel_count < 8)
nibble_map |= 0xFFFFFFFF << (channel_count * 4);

return nibble_map;
}
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