IntGroup.cpp

/*
 * This file is part of the BTCCollider distribution (https://github.com/JeanLucPons/BTCCollider).
 * Copyright (c) 2020 Jean Luc PONS.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, version 3.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
*/

#include "IntGroup.h"

using namespace std;

IntGroup::IntGroup(int size) {
  this->size = size;
  subp = (Int *)malloc(size * sizeof(Int));
}

IntGroup::~IntGroup() {
  free(subp);
}

void IntGroup::Set(Int *pts) {
  ints = pts;
}

// Compute modular inversion of the whole group
void IntGroup::ModInv() {

  Int newValue;
  Int inverse;

  subp[0].Set(&ints[0]);
  for (int i = 1; i < size; i++) {
    subp[i].ModMulK1(&subp[i - 1], &ints[i]);
  }

  // Do the inversion
  inverse.Set(&subp[size - 1]);
  inverse.ModInv();

  for (int i = size - 1; i > 0; i--) {
    newValue.ModMulK1(&subp[i - 1], &inverse);
    inverse.ModMulK1(&ints[i]);
    ints[i].Set(&newValue);
  }

  ints[0].Set(&inverse);

}