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bignum.c: ee should be signed

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In C, signed + unsigned of the same size results in unsigned (cf:
ISO/IEC 9899:1990 section 6.2.1.5). However `num` is signed here.
Which means the addition must be done in signed.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@65734 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
This commit is contained in:
shyouhei 2018-11-15 05:10:40 +00:00
parent 42d797d8e9
commit 2212c1dc16
1 changed files with 4 additions and 3 deletions
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7
bignum.c
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@ -1511,15 +1511,16 @@ bigdivrem_mulsub(BDIGIT *zds, size_t zn, BDIGIT x, const BDIGIT *yds, size_t yn)
i = 0; i = 0;
do { do {
BDIGIT_DBL ee; BDIGIT_DBL_SIGNED ee;
t2 += (BDIGIT_DBL)yds[i] * x; t2 += (BDIGIT_DBL)yds[i] * x;
ee = num - BIGLO(t2); ee = num - BIGLO(t2);
num = (BDIGIT_DBL)zds[i] + ee; num = (BDIGIT_DBL_SIGNED)zds[i] + ee;
if (ee) zds[i] = BIGLO(num); if (ee) zds[i] = BIGLO(num);
num = BIGDN(num); num = BIGDN(num);
t2 = BIGDN(t2); t2 = BIGDN(t2);
} while (++i < yn); } while (++i < yn);
num += zds[i] - t2; /* borrow from high digit; don't update */ num -= (BDIGIT_DBL_SIGNED)t2;
num += (BDIGIT_DBL_SIGNED)zds[yn]; /* borrow from high digit; don't update */
return num; return num;
} }