void modg(giant d, giant n)
/* n becomes n%d. n is arbitrary, but the denominator d must be positive! */
{
if (cur_recip == NULL) {
cur_recip = newgiant(current_max_size);
cur_den = newgiant(current_max_size);
gtog(d, cur_den);
make_recip(d, cur_recip);
}
else if (gcompg(d, cur_den)) {
gtog(d, cur_den);
make_recip(d, cur_recip);
}
modg_via_recip(d, cur_recip, n);
}
/*
* This version is not normally used; it's for when the reciprocal of
* curveOrder is not known and won't be used again.
*/
void curveOrderJustify(giant g, giant curveOrder)
{
giant recip;
CKASSERT(!isZero(curveOrder));
recip = borrowGiant(2 * abs(g->sign));
make_recip(curveOrder, recip);
curveOrderJustifyWithRecip(g, curveOrder, recip);
returnGiant(recip);
}
/*
* Common code used by x1OrderPlusJustify() and x1OrderPlusMod() to generate
* reciprocal of x1OrderPlus.
* 8 Sep 1998 - also used by feeSigSign().
*/
void calcX1OrderPlusRecip(curveParams *cp)
{
if(isZero(cp->x1OrderPlusRecip)) {
if((cp->x1OrderPlus == lesserX1Order(cp)) &&
(!isZero(cp->lesserX1OrderRecip))) {
/*
* lesserX1Order happens to be x1OrderPlus, and we
* have a reciprocal for lesserX1Order. Copy it over.
*/
recipLog((
"lesserX1OrderRecip --> x1OrderPlusRecip\n"));
gtog(cp->lesserX1OrderRecip, cp->x1OrderPlusRecip);
}
else {
/* Calculate the reciprocal. */
recipLog(("calc x1OrderPlusRecip\n"));
make_recip(cp->x1OrderPlus, cp->x1OrderPlusRecip);
}
}
else {
recipLog(("using existing x1OrderPlusRecip\n"));
}
}
/*
* curveOrderJustify routines with specific orders, using (and possibly
* generating) associated reciprocals.
*/
void lesserX1OrderJustify(giant g, curveParams *cp)
{
/*
* Note this is a pointer to a giant in *cp, not a newly
* malloc'd giant!
*/
giant lesserX1Ord = lesserX1Order(cp);
if(isZero(lesserX1Ord)) {
return;
}
/*
* Calculate reciprocal if we don't have it
*/
if(isZero(cp->lesserX1OrderRecip)) {
if((lesserX1Ord == cp->x1OrderPlus) &&
(!isZero(cp->x1OrderPlusRecip))) {
/*
* lesserX1Ord happens to be x1OrderPlus, and we
* have a reciprocal for x1OrderPlus. Copy it over.
*/
recipLog((
"x1OrderPlusRecip --> lesserX1OrderRecip\n"));
gtog(cp->x1OrderPlusRecip, cp->lesserX1OrderRecip);
}
else {
/* Calculate the reciprocal. */
recipLog(("calc lesserX1OrderRecip\n"));
make_recip(lesserX1Ord, cp->lesserX1OrderRecip);
}
}
else {
recipLog(("using existing lesserX1OrderRecip\n"));
}
curveOrderJustifyWithRecip(g, lesserX1Ord, cp->lesserX1OrderRecip);
}
