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Backport fix for http://debbugs.gnu.org/17556 from trunk

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* lisp/calc/calc.el (math-bignum): Handle most-negative-fixnum.
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Leo Liu 2014-06-27 12:10:04 +08:00
parent 340d54a195
commit 708dc66d7b
2 changed files with 16 additions and 3 deletions
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4
lisp/ChangeLog
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@ -1,3 +1,7 @@
2014-06-27 Leo Liu <sdl.web@gmail.com>
* calc/calc.el (math-bignum): Handle most-negative-fixnum. (Bug#17556)
2014-06-27 Glenn Morris <rgm@gnu.org>
* net/eww.el (eww-mode) <eww-current-title>: Make local. (Bug#17860)

15
lisp/calc/calc.el
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@ -2773,9 +2773,18 @@ largest Emacs integer.")
;; 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: cannot get the negation directly because
;; (- most-negative-fixnum) is most-negative-fixnum.
;;
;; most-negative-fixnum := -most-positive-fixnum - 1
(math-sub (cons 'bigneg (math-bignum-big most-positive-fixnum))
1))
(t
(cons 'bigneg (math-bignum-big (- a))))))
(defun math-bignum-big (a) ; [L s]
(if (= a 0)