On Fri, Aug 27, 2021 at 01:08:10AM -0700, Joe Perches wrote: > On Fri, 2021-08-27 at 10:48 +0300, Andy Shevchenko wrote: > > On Thu, Aug 26, 2021 at 11:43:01AM -0700, Joe Perches wrote: > > > A few sysfs output uses of hex arrays are uppercase and are nominally ABI. > > > > > > Add a mechanism to the existing vsprintf %*ph hex output extension to > > > support upper case hex output. > > > > ... > > > > > + The preferred output is lowercase > > > %*ph 00 01 02 ... 3f > > > %*phC 00:01:02: ... :3f > > > %*phD 00-01-02- ... -3f > > > %*phN 000102 ... 3f > > > + Formats with X are uppercase, used for backwards compatibility > > > + %*phX 00 01 02 ... 3F > > > + %*phCX 00:01:02: ... :3F > > > + %*phDX 00-01-02- ... -3F > > > + %*phNX 000102 ... 3F > > > > Why not using %*pH...? > > I find X more intelligible. > > > > + char locase = 0x20; /* ASCII OR'd for lower case see: number() */ > > > > If you use h vs H, you may derive this from (fmt[...] & SMALL). > > It's not necessary to use any more of the rather limited vsprintf > extension namespace. I understand your concern, but %*ph is quite widely used (I guess top 1 or 2 among all %p extensions), its performance degradation with your code may affect a lot of other users and hence a kernel as a whole. So, that's why my proposal stays. Of course you may provide a benchmark (btw, where are the test cases for this?) for yours and mine variant and we will see if it makes sense to optimize. -- With Best Regards, Andy Shevchenko
