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

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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.

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

return nibble_map;
}
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