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/src/lread.c	Fri Dec 14 14:25:04 2007 +0100
+++ b/src/lread.c	Mon Dec 17 08:44:14 2007 +0100
@@ -2029,7 +2029,7 @@
  overflow:
 #ifdef HAVE_BIGNUM
   {
-    bignum_set_string (scratch_bignum, (const char *) buf, 0);
+    bignum_set_string (scratch_bignum, (const char *) buf, base);
     return make_bignum_bg (scratch_bignum);
   }
 #else