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mpdiv: fix sign bug

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This commit is contained in:
aiju 2018-05-04 21:18:46 +00:00
parent 454d26a0e4
commit 8dc43a951c
1 changed files with 8 additions and 4 deletions
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12
sys/src/libmp/port/mpdiv.c
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@ -9,7 +9,7 @@
void
mpdiv(mpint *dividend, mpint *divisor, mpint *quotient, mpint *remainder)
{
int j, s, vn, sign;
int j, s, vn, sign, qsign, rsign;
mpdigit qd, *up, *vp, *qp;
mpint *u, *v, *t;
@ -49,6 +49,13 @@ mpdiv(mpint *dividend, mpint *divisor, mpint *quotient, mpint *remainder)
mpassign(mpzero, quotient);
return;
}
qsign = divisor->sign * dividend->sign;
rsign = dividend->sign;
if(quotient != nil)
quotient->sign = qsign;
if(remainder != nil)
remainder->sign = rsign;
// D1: shift until divisor, v, has hi bit set (needed to make trial
// divisor accurate)
@ -121,14 +128,11 @@ mpdiv(mpint *dividend, mpint *divisor, mpint *quotient, mpint *remainder)
if(qp != nil){
assert((quotient->flags & MPtimesafe) == 0);
mpnorm(quotient);
if(dividend->sign != divisor->sign)
quotient->sign = -1;
}
if(remainder != nil){
assert((remainder->flags & MPtimesafe) == 0);
mpright(u, s, remainder); // u is the remainder shifted
remainder->sign = dividend->sign;
}
mpfree(t);