translator_delta_range_constraint_relation_impl.hpp

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// === AUDIT STATUS ===
// internal:    { status: Planned, auditors: [], commit: }
// external_1:  { status: not started, auditors: [], commit: }
// external_2:  { status: not started, auditors: [], commit: }
// =====================
 
#pragma once
#include "barretenberg/relations/translator_vm/translator_delta_range_constraint_relation.hpp"
 
namespace bb {
 
template <typename FF>
template <typename ContainerOverSubrelations, typename AllEntities, typename Parameters>
void TranslatorDeltaRangeConstraintRelationImpl<FF>::accumulate(ContainerOverSubrelations& accumulators,
                                                                const AllEntities& in,
                                                                const Parameters& /*unused*/,
                                                                const FF& scaling_factor)
{
    static const FF minus_one = FF(-1);
    static const FF minus_two = FF(-2);
    static const FF minus_three = FF(-3);
    static const size_t micro_limb_bits = 14;
    static const auto maximum_sort_value = -FF((1 << micro_limb_bits) - 1);
 
    [&]() {
        using Accumulator = std::tuple_element_t<0, ContainerOverSubrelations>;
        using View = typename Accumulator::View;
        auto ordered_range_constraints_0 = View(in.ordered_range_constraints_0);
        auto ordered_range_constraints_1 = View(in.ordered_range_constraints_1);
        auto ordered_range_constraints_2 = View(in.ordered_range_constraints_2);
        auto ordered_range_constraints_3 = View(in.ordered_range_constraints_3);
        auto ordered_range_constraints_4 = View(in.ordered_range_constraints_4);
        auto ordered_range_constraints_0_shift = View(in.ordered_range_constraints_0_shift);
        auto ordered_range_constraints_1_shift = View(in.ordered_range_constraints_1_shift);
        auto ordered_range_constraints_2_shift = View(in.ordered_range_constraints_2_shift);
        auto ordered_range_constraints_3_shift = View(in.ordered_range_constraints_3_shift);
        auto ordered_range_constraints_4_shift = View(in.ordered_range_constraints_4_shift);
 
        // Represents the position of the final non-masked witness index
        const auto lagrange_real_last = View(in.lagrange_real_last);
        const auto lagrange_masking = View(in.lagrange_masking);
 
        // This selector is 0 at the real_last row and in masking rows (where delta checks are skipped),
        // and -1 at all other rows (where delta checks are enforced). The naming reflects that it is
        // NOT at the last row or masking region when non-zero.
        const auto not_last_or_masking = (lagrange_real_last + lagrange_masking + minus_one);
 
        // Compute wire differences
        auto delta_1 = ordered_range_constraints_0_shift - ordered_range_constraints_0;
        auto delta_2 = ordered_range_constraints_1_shift - ordered_range_constraints_1;
        auto delta_3 = ordered_range_constraints_2_shift - ordered_range_constraints_2;
        auto delta_4 = ordered_range_constraints_3_shift - ordered_range_constraints_3;
        auto delta_5 = ordered_range_constraints_4_shift - ordered_range_constraints_4;
 
        // Contribution (1) (contributions 1-5 ensure that the sequential values have a difference of {0,1,2,3})
        auto tmp_1 = delta_1;
        tmp_1 *= (delta_1 + minus_one);
        tmp_1 *= (delta_1 + minus_two);
        tmp_1 *= (delta_1 + minus_three);
        tmp_1 *= not_last_or_masking;
        tmp_1 *= scaling_factor;
        std::get<0>(accumulators) += tmp_1;
 
        // Contribution (2)
        auto tmp_2 = delta_2;
        tmp_2 *= (delta_2 + minus_one);
        tmp_2 *= (delta_2 + minus_two);
        tmp_2 *= (delta_2 + minus_three);
        tmp_2 *= not_last_or_masking;
        tmp_2 *= scaling_factor;
 
        std::get<1>(accumulators) += tmp_2;
 
        // Contribution (3)
        auto tmp_3 = delta_3;
        tmp_3 *= (delta_3 + minus_one);
        tmp_3 *= (delta_3 + minus_two);
        tmp_3 *= (delta_3 + minus_three);
        tmp_3 *= not_last_or_masking;
        tmp_3 *= scaling_factor;
        std::get<2>(accumulators) += tmp_3;
 
        // Contribution (4)
        auto tmp_4 = delta_4;
        tmp_4 *= (delta_4 + minus_one);
        tmp_4 *= (delta_4 + minus_two);
        tmp_4 *= (delta_4 + minus_three);
        tmp_4 *= not_last_or_masking;
        tmp_4 *= scaling_factor;
        std::get<3>(accumulators) += tmp_4;
 
        // Contribution (5)
        auto tmp_5 = delta_5;
        tmp_5 *= (delta_5 + minus_one);
        tmp_5 *= (delta_5 + minus_two);
        tmp_5 *= (delta_5 + minus_three);
        tmp_5 *= not_last_or_masking;
        tmp_5 *= scaling_factor;
        std::get<4>(accumulators) += tmp_5;
    }();
 
    [&]() {
        using Accumulator = std::tuple_element_t<5, ContainerOverSubrelations>;
        using View = typename Accumulator::View;
        auto ordered_range_constraints_0 = View(in.ordered_range_constraints_0);
        auto ordered_range_constraints_1 = View(in.ordered_range_constraints_1);
        auto ordered_range_constraints_2 = View(in.ordered_range_constraints_2);
        auto ordered_range_constraints_3 = View(in.ordered_range_constraints_3);
        auto ordered_range_constraints_4 = View(in.ordered_range_constraints_4);
        const auto lagrange_real_last = View(in.lagrange_real_last);
 
        // Contribution (6) (Contributions 6-10 ensure that the last value is the designated maximum value. We don't
        // need to constrain the first value to be 0, because the shift mechanic does this for us)
        std::get<5>(accumulators) +=
            lagrange_real_last * (ordered_range_constraints_0 + maximum_sort_value) * scaling_factor;
        // Contribution (7)
        std::get<6>(accumulators) +=
            lagrange_real_last * (ordered_range_constraints_1 + maximum_sort_value) * scaling_factor;
        // Contribution (8)
        std::get<7>(accumulators) +=
            lagrange_real_last * (ordered_range_constraints_2 + maximum_sort_value) * scaling_factor;
        // Contribution (9)
        std::get<8>(accumulators) +=
            lagrange_real_last * (ordered_range_constraints_3 + maximum_sort_value) * scaling_factor;
        // Contribution (10)
        std::get<9>(accumulators) +=
            lagrange_real_last * (ordered_range_constraints_4 + maximum_sort_value) * scaling_factor;
    }();
};
} // namespace bb