plookup.cpp

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// === AUDIT STATUS ===
// internal:    { status: not started, auditors: [], date: YYYY-MM-DD }
// external_1:  { status: not started, auditors: [], date: YYYY-MM-DD }
// external_2:  { status: not started, auditors: [], date: YYYY-MM-DD }
// =====================
 
#include "./plookup.hpp"
#include "barretenberg/stdlib/primitives/circuit_builders/circuit_builders.hpp"
#include "barretenberg/stdlib_circuit_builders/plookup_tables/plookup_tables.hpp"
#include "barretenberg/stdlib_circuit_builders/plookup_tables/types.hpp"
 
namespace bb::stdlib {
 
using plookup::ColumnIdx;
using plookup::MultiTableId;
using namespace bb;
 
template <typename Builder>
plookup::ReadData<field_t<Builder>> plookup_read<Builder>::get_lookup_accumulators(const MultiTableId id,
                                                                                   const field_t<Builder>& key_a,
                                                                                   const field_t<Builder>& key_b,
                                                                                   const bool is_2_to_1_lookup)
{
    Builder* ctx = key_a.get_context() ? key_a.get_context() : key_b.get_context();
    const plookup::ReadData<bb::fr> lookup_data =
        plookup::get_lookup_accumulators(id, key_a.get_value(), key_b.get_value(), is_2_to_1_lookup);
 
    plookup::ReadData<field_t<Builder>> lookup;
 
    // If both keys are constant (or key_b unused), we can directly create constant field elements
    if (key_a.is_constant() && (key_b.is_constant() || !is_2_to_1_lookup)) {
        for (size_t i = 0; i < lookup_data[ColumnIdx::C1].size(); ++i) {
            lookup[ColumnIdx::C1].emplace_back(field_t<Builder>(ctx, lookup_data[ColumnIdx::C1][i]));
            lookup[ColumnIdx::C2].emplace_back(field_t<Builder>(ctx, lookup_data[ColumnIdx::C2][i]));
            lookup[ColumnIdx::C3].emplace_back(field_t<Builder>(ctx, lookup_data[ColumnIdx::C3][i]));
        }
    } else {
        // At least one key needs witness constraints, so create plookup gates
        uint32_t lhs_index = key_a.get_witness_index();
        uint32_t rhs_index = key_b.get_witness_index();
 
        if (key_a.is_constant()) {
            lhs_index = ctx->put_constant_variable(key_a.get_value());
        }
        if (key_b.is_constant() && is_2_to_1_lookup) {
            rhs_index = ctx->put_constant_variable(key_b.get_value());
        }
 
        auto key_b_witness = std::make_optional(rhs_index);
        if (rhs_index == stdlib::IS_CONSTANT) {
            key_b_witness = std::nullopt;
        }
 
        const auto accumulator_witnesses =
            ctx->create_gates_from_plookup_accumulators(id, lookup_data, lhs_index, key_b_witness);
 
        for (size_t i = 0; i < lookup_data[ColumnIdx::C1].size(); ++i) {
            lookup[ColumnIdx::C1].emplace_back(
                field_t<Builder>::from_witness_index(ctx, accumulator_witnesses[ColumnIdx::C1][i]));
            lookup[ColumnIdx::C2].emplace_back(
                field_t<Builder>::from_witness_index(ctx, accumulator_witnesses[ColumnIdx::C2][i]));
            lookup[ColumnIdx::C3].emplace_back(
                field_t<Builder>::from_witness_index(ctx, accumulator_witnesses[ColumnIdx::C3][i]));
        }
    }
    return lookup;
}
 
template <typename Builder>
std::pair<field_t<Builder>, field_t<Builder>> plookup_read<Builder>::read_pair_from_table(const MultiTableId id,
                                                                                          const field_t<Builder>& key)
{
    const auto lookup = get_lookup_accumulators(id, key);
 
    return { lookup[ColumnIdx::C2][0], lookup[ColumnIdx::C3][0] };
}
 
template <typename Builder>
field_t<Builder> plookup_read<Builder>::read_from_2_to_1_table(const MultiTableId id,
                                                               const field_t<Builder>& key_a,
                                                               const field_t<Builder>& key_b)
{
    const auto lookup = get_lookup_accumulators(id, key_a, key_b, /*is_2_to_1_lookup=*/true);
 
    return lookup[ColumnIdx::C3][0];
}
 
template <typename Builder>
field_t<Builder> plookup_read<Builder>::read_from_1_to_2_table(const MultiTableId id, const field_t<Builder>& key_a)
{
    const auto lookup = get_lookup_accumulators(id, key_a);
 
    return lookup[ColumnIdx::C2][0];
}
 
template class plookup_read<bb::UltraCircuitBuilder>;
template class plookup_read<bb::MegaCircuitBuilder>;
} // namespace bb::stdlib