printf.9: Support more than 32 bits in %b

This will be usable after clang has been extended to accept length
modifiers for %b when compiling kernel code.
But we need FreeBSD to support it first...

Reviewed by:		markj, Timo Völker
MFC after:		1 week
Differential Revision:	https://reviews.freebsd.org/D54286

share/man/man9/printf.9

@@ -24,7 +24,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd December 18, 2025
+.Dd December 19, 2025
 .Dt PRINTF 9
 .Os
 .Sh NAME
@@ -95,14 +95,15 @@ arguments.
 The base value is the output base (radix) expressed as an octal value;
 for example, \e10 gives octal and \e20 gives hexadecimal.
 The arguments are made up of a sequence of bit identifiers.
-Each bit identifier begins with an
-.Em octal
-value which is the number of the bit (starting from 1) this identifier
-describes.
+Each bit identifier begins with a character specifying the number of the bit
+(starting from 1) this identifier describes.
+The characters from \e01 to \e40 can be used to specify bit numbers in the
+range from 1 to 32 and characters from \e200 to \e377 to specify bit numbers
+in the range from 1 to 128.
 The rest of the identifier is a string of characters containing the name of
 the bit.
-The string is terminated by either the bit number at the start of the next
-bit identifier or
+The identifier is terminated by either the bit number at the start of the next
+bit identifier or by
 .Dv NUL
 for the last bit identifier.
 .Pp
@@ -173,6 +174,16 @@ reg=3<BITTWO,BITONE>
 out: 41:41:5a:5a
 .Ed
 .Pp
+The same output will be generated by the following function:
+.Bd -literal -offset indent
+void
+printf_test(void)
+{
+	printf("reg=%b\en", 3, "\e10\e201BITTWO\e200BITONE");
+	printf("out: %4D\en", "AAZZ", ":");
+}
+.Ed
+.Pp
 The call
 .Bd -literal -offset indent
 log(LOG_DEBUG, "%s%d: been there.\en", sc->sc_name, sc->sc_unit);