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:

quoted

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.

...

quoted

+	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.

quoted

+	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.