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libmp: with mpmod() m = 2^a - c ensure that digits(c) < digits(m)

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This commit is contained in:
cinap_lenrek 2015-12-01 11:13:52 +01:00
parent fbd825890e
commit ffdfc17cee
1 changed files with 8 additions and 4 deletions
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12
sys/src/libmp/port/mpmod.c
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@ -13,7 +13,7 @@ mpmod(mpint *x, mpint *n, mpint *r)
sign = x->sign; sign = x->sign;
assert(n->flags & MPnorm); assert(n->flags & MPnorm);
if(n->top < 2 || n->top > nelem(q) || (x->top-n->top) > nelem(q)) if(n->top <= 2 || n->top > nelem(q) || (x->top-n->top) > nelem(q))
goto hard; goto hard;
/* /*
@ -42,11 +42,15 @@ mpmod(mpint *x, mpint *n, mpint *r)
c = mpnew(0); c = mpnew(0);
p = mpnew(0); p = mpnew(0);
} }
mpassign(n, p); mpleft(p, s, m);
mpleft(n, s, m);
mpleft(mpone, k*Dbits, c); mpleft(mpone, k*Dbits, c);
mpsub(c, m, c); mpsub(c, m, c);
if(c->top >= k){
mpassign(mpzero, p);
busy = 0;
goto hard;
}
mpassign(n, p);
} }
mpleft(x, s, r); mpleft(x, s, r);