On Tue 2022-11-08 16:33:22, Russell King 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). > > Signed-off-by: Hector Martin <marcan@xxxxxxxxx> > Signed-off-by: Russell King (Oracle) <rmk+kernel@xxxxxxxxxxxxxxx> Reviewed-by: Petr Mladek <pmladek@xxxxxxxx> See one nit below. > --- a/lib/vsprintf.c > +++ b/lib/vsprintf.c > @@ -1762,27 +1762,50 @@ char *fourcc_string(char *buf, char *end, const u32 *fourcc, > char output[sizeof("0123 little-endian (0x01234567)")]; > char *p = output; > unsigned int i; > + bool pixel_fmt = false; > u32 orig, val; > > - if (fmt[1] != 'c' || fmt[2] != 'c') > + if (fmt[1] != 'c') > return error_string(buf, end, "(%p4?)", spec); > > if (check_pointer(&buf, end, fourcc, spec)) > return buf; > > orig = get_unaligned(fourcc); > - val = orig & ~BIT(31); > + switch (fmt[2]) { > + case 'h': > + val = orig; > + break; > + case 'r': > + val = orig = swab32(orig); I do not like much these multi assignments. I think that the result was not even defined in some older C standards. Though, I can't find it now. And even make W=3 does not warn about it. > + break; > + case 'l': > + val = orig = le32_to_cpu(orig); > + break; > + case 'b': > + val = orig = be32_to_cpu(orig); > + break; Best Regards, Petr