bn_utils.tcc

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/** @file
 *****************************************************************************
 * @author     This file is part of libff, developed by SCIPR Lab
 *             and contributors (see AUTHORS).
 * @copyright  MIT license (see LICENSE file)
 *****************************************************************************/
 
#ifndef BN_UTILS_TCC_
#define BN_UTILS_TCC_
 
namespace libff
{
 
template<typename FieldT> void bn_batch_invert(std::vector<FieldT> &vec)
{
    std::vector<FieldT> prod;
    prod.reserve(vec.size());
 
    FieldT acc = 1;
 
    for (auto el : vec) {
        assert(!el.isZero());
        prod.emplace_back(acc);
        FieldT::mul(acc, acc, el);
    }
 
    FieldT acc_inverse = acc;
    acc_inverse.inverse();
 
    for (long i = vec.size() - 1; i >= 0; --i) {
        const FieldT old_el = vec[i];
        FieldT::mul(vec[i], acc_inverse, prod[i]);
        FieldT::mul(acc_inverse, acc_inverse, old_el);
    }
}
 
} // namespace libff
#endif // FIELD_UTILS_TCC_