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Remove a division from the Montgomery setup by calculating
[u/mdw/catacomb]
/
mpmont.c
diff --git
a/mpmont.c
b/mpmont.c
index
66b7657
..
35bffc2
100644
(file)
--- a/
mpmont.c
+++ b/
mpmont.c
@@
-1,6
+1,6
@@
/* -*-c-*-
*
/* -*-c-*-
*
- * $Id: mpmont.c,v 1.
3 1999/11/21 11:35:10
mdw Exp $
+ * $Id: mpmont.c,v 1.
4 1999/11/21 12:27:06
mdw Exp $
*
* Montgomery reduction
*
*
* Montgomery reduction
*
@@
-30,6
+30,11
@@
/*----- Revision history --------------------------------------------------*
*
* $Log: mpmont.c,v $
/*----- Revision history --------------------------------------------------*
*
* $Log: mpmont.c,v $
+ * Revision 1.4 1999/11/21 12:27:06 mdw
+ * Remove a division from the Montgomery setup by calculating
+ * %$R^2 \bmod m$% first and then %$R \bmod m$% by Montgomery reduction of
+ * %$R^2$%.
+ *
* Revision 1.3 1999/11/21 11:35:10 mdw
* Performance improvement: use @mp_sqr@ and @mpmont_reduce@ instead of
* @mpmont_mul@ for squaring in exponentiation.
* Revision 1.3 1999/11/21 11:35:10 mdw
* Performance improvement: use @mp_sqr@ and @mpmont_reduce@ instead of
* @mpmont_mul@ for squaring in exponentiation.
@@
-92,15
+97,14
@@
void mpmont_create(mpmont *mm, mp *m)
{
size_t l = MP_LEN(m);
{
size_t l = MP_LEN(m);
- mp *r = mp_create(l + 1);
+ mp *r = mp_create(
2 *
l + 1);
mm->shift = l * MPW_BITS;
MPX_ZERO(r->v, r->vl - 1);
r->vl[-1] = 1;
mm->shift = l * MPW_BITS;
MPX_ZERO(r->v, r->vl - 1);
r->vl[-1] = 1;
- mm->r = mm->r2 = MP_NEW;
- mp_div(0, &mm->r, r, m);
- r = mp_sqr(r, mm->r);
+ mm->r2 = MP_NEW;
mp_div(0, &mm->r2, r, m);
mp_div(0, &mm->r2, r, m);
+ mm->r = mpmont_reduce(mm, MP_NEW, mm->r2);
MP_DROP(r);
}
}
MP_DROP(r);
}
}