On Thu, Feb 20, 2025 at 04:39:23PM +0000, Aditya Garg wrote:
> From: Hector Martin <marcan@xxxxxxxxx>
>
> %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).
...
> orig = get_unaligned(fourcc);
> - val = orig & ~BIT(31);
> + switch (fmt[2]) {
> + case 'h':
> + val = orig;
> + break;
> + case 'r':
> + orig = swab32(orig);
> + val = orig;
> + break;
> + case 'l':
> + orig = le32_to_cpu(orig);
> + val = orig;
> + break;
> + case 'b':
> + orig = be32_to_cpu(orig);
I do not see that orig is a union of different types. Have you run sparse?
It will definitely complain on this code.
> + val = orig;
> + break;
> + case 'c':
> + /* Pixel formats are printed LSB-first */
> + val = swab32(orig & ~BIT(31));
> + pixel_fmt = true;
> + break;
> + default:
> + return error_string(buf, end, "(%p4?)", spec);
> + }
...
> - *p++ = ' ';
> - strcpy(p, orig & BIT(31) ? "big-endian" : "little-endian");
> - p += strlen(p);
> + if (pixel_fmt) {
Technically we can avoid a boolean by checking fmt[2] again here, but I'm okay
with a temporary holder.
> + *p++ = ' ';
> + strcpy(p, orig & BIT(31) ? "big-endian" : "little-endian");
> + p += strlen(p);
> + }
--
With Best Regards,
Andy Shevchenko
