From: Leo Liu <sdl.web@gmail.com>
To: 17556@debbugs.gnu.org
Subject: bug#17556: 24.4.50; fix math-bignum
Date: Fri, 23 May 2014 12:46:05 +0800 [thread overview]
Message-ID: <m3a9a9gl0y.fsf@gmail.com> (raw)
Due to integer overflow (math-bignum most-negative-fixnum) is incorrect.
Any objection if I fix it like in this patch:
=== modified file 'lisp/calc/calc.el'
--- lisp/calc/calc.el 2014-01-01 07:43:34 +0000
+++ lisp/calc/calc.el 2014-05-23 04:42:18 +0000
@@ -2773,9 +2773,15 @@
;; Coerce integer A to be a bignum. [B S]
(defun math-bignum (a)
- (if (>= a 0)
- (cons 'bigpos (math-bignum-big a))
- (cons 'bigneg (math-bignum-big (- a)))))
+ (cond
+ ((>= a 0)
+ (cons 'bigpos (math-bignum-big a)))
+ ((= a most-negative-fixnum)
+ ;; Note: (- most-negative-fixnum) is most-negative-fixnum
+ (math-sub (cons 'bigneg (math-bignum-big (- (1+ a))))
+ 1))
+ (t
+ (cons 'bigneg (math-bignum-big (- a))))))
(defun math-bignum-big (a) ; [L s]
(if (= a 0)
next reply other threads:[~2014-05-23 4:46 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-23 4:46 Leo Liu [this message]
2014-05-23 7:33 ` bug#17556: 24.4.50; fix math-bignum Andreas Schwab
2014-05-23 8:23 ` martin rudalics
2014-05-23 9:44 ` Leo Liu
2014-05-24 15:19 ` Leo Liu
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
List information: https://www.gnu.org/software/emacs/
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=m3a9a9gl0y.fsf@gmail.com \
--to=sdl.web@gmail.com \
--cc=17556@debbugs.gnu.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
Code repositories for project(s) associated with this public inbox
https://git.savannah.gnu.org/cgit/emacs.git
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).