[PATCH v3 2/3] lib/vsprintf: Add support for generic FOURCCs by extending %p4cc

Rasmus Villemoes linux at rasmusvillemoes.dk
Fri Feb 21 11:54:57 UTC 2025


On Fri, 21 Feb 2025 at 12:37, Aditya Garg <gargaditya08 at live.com> wrote:
>
> From: Hector Martin <marcan at marcan.st>
>
> %p4cc is designed for DRM/V4L2 FOURCCs with their specific quirks, but
> it's useful to be able to print generic 4-character codes formatted as
> an integer. Extend it to add format specifiers for printing generic
> 32-bit FOURCCs with various endian semantics:
>
> %p4ch   Host-endian
> %p4cl   Little-endian
> %p4cb   Big-endian
> %p4cr   Reverse-endian
>
> The endianness determines how bytes are interpreted as a u32, and the
> FOURCC is then always printed MSByte-first (this is the opposite of
> V4L/DRM FOURCCs). This covers most practical cases, e.g. %p4cr would
> allow printing LSByte-first FOURCCs stored in host endian order
> (other than the hex form being in character order, not the integer
> value).
>
> Signed-off-by: Hector Martin <marcan at marcan.st>
> Signed-off-by: Aditya Garg <gargaditya08 at live.com>

Acked-by: Rasmus Villemoes <linux at rasmusvillemoes.dk>


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