Provide %b in #'format; use it for converting between ints and bit vectors. lisp/ChangeLog addition: 2007-12-17 Aidan Kehoe <kehoea@parhasard.net> * subr.el (integer-to-bit-vector): New. * subr.el (bit-vector-to-integer): New. Provide naive implementations using the Lisp reader for these. src/ChangeLog addition: 2007-12-17 Aidan Kehoe <kehoea@parhasard.net> * doprnt.c (emacs_doprnt_1): Add support for formatted printing of both longs and bignums as base 2. * editfns.c (Fformat): Document the new %b escape for #'format. * lisp.h: Make ulong_to_bit_string available beside long_to_string. * lread.c: Fix a bug where the integer base was being ignored in certain contexts; thank you Sebastian Freundt. This is necessary for correct behaviour of #'integer-to-bit-vector and #'bit-vector-to-integer, just added to subr.el * print.c (ulong_to_bit_string): New. Analagous to long_to_string, but used all the time when %b is encountered, since we can't pass that to sprintf. man/ChangeLog addition: 2007-12-17 Aidan Kehoe <kehoea@parhasard.net> * lispref/strings.texi (Formatting Strings): Document %b for binary output.

--- a/man/lispref/strings.texi	Fri Dec 14 14:25:04 2007 +0100
+++ b/man/lispref/strings.texi	Mon Dec 17 08:44:14 2007 +0100
@@ -715,6 +715,11 @@
 Replace the specification with the base-sixteen representation of an
 integer, using uppercase letters.
 
+@item %b
+@cindex integer to binary
+Replace the specification with the base-two representation of an
+integer.
+
 @item %c
 Replace the specification with the character which is the value given.