scalar_multiplication.test.cpp

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#include "scalar_multiplication.hpp"
#include "barretenberg/api/file_io.hpp"
#include "barretenberg/common/thread.hpp"
#include "barretenberg/ecc/curves/bn254/bn254.hpp"
#include "barretenberg/ecc/curves/grumpkin/grumpkin.hpp"
#include "barretenberg/ecc/curves/types.hpp"
#include "barretenberg/numeric/random/engine.hpp"
#include "barretenberg/polynomials/polynomial.hpp"
#include "barretenberg/srs/factories/mem_bn254_crs_factory.hpp"
#include <filesystem>
#include <gtest/gtest.h>
 
using namespace bb;
 
namespace {
auto& engine = numeric::get_randomness();
} // namespace
 
template <class Curve> class ScalarMultiplicationTest : public ::testing::Test {
  public:
    using Group = typename Curve::Group;
    using Element = typename Curve::Element;
    using AffineElement = typename Curve::AffineElement;
    using ScalarField = typename Curve::ScalarField;
 
    static constexpr size_t num_points = 31013;
 
    // Bounds used by test_batch_multi_scalar_mul. Kept small so num_points (and therefore
    // SetUpTestSuite, which builds num_points random EC points) stays cheap — especially under wasm,
    // where the fixture build previously dominated the whole ecc_tests run.
    static constexpr size_t kMaxBatchMSMs = 32;
    static constexpr size_t kMaxBatchPointsPerMSM = 400;
 
    // Used by test_consume_point_batch{,_and_accumulate}, which read generators[0..kMaxBucketTestPoints).
    static constexpr size_t kMaxBucketTestPoints = 30071;
 
    // Pinning invariants: these tests walk generators[]/scalars[] without bounds checks beyond an
    // occasional runtime ASSERT_LT. Pin the relationships at compile time so changing any one of
    // these constants in isolation cannot regress into an out-of-bounds walk.
    static_assert(kMaxBatchMSMs * kMaxBatchPointsPerMSM < num_points,
                  "test_batch_multi_scalar_mul can exceed num_points; "
                  "raise num_points or lower kMaxBatchMSMs / kMaxBatchPointsPerMSM");
    static_assert(kMaxBucketTestPoints <= num_points,
                  "test_consume_point_batch* reads past end of generators; "
                  "raise num_points or lower kMaxBucketTestPoints");
 
    static inline std::vector<AffineElement> generators{};
    static inline std::vector<ScalarField> scalars{};
 
    static AffineElement naive_msm(std::span<ScalarField> input_scalars, std::span<const AffineElement> input_points)
    {
        size_t total_points = input_scalars.size();
        size_t num_threads = get_num_cpus();
        std::vector<Element> expected_accs(num_threads);
        size_t range_per_thread = (total_points + num_threads - 1) / num_threads;
        parallel_for(num_threads, [&](size_t thread_idx) {
            Element expected_thread_acc;
            expected_thread_acc.self_set_infinity();
            size_t start = thread_idx * range_per_thread;
            size_t end = ((thread_idx + 1) * range_per_thread > total_points) ? total_points
                                                                              : (thread_idx + 1) * range_per_thread;
            bool skip = start >= total_points;
            if (!skip) {
                for (size_t i = start; i < end; ++i) {
                    expected_thread_acc += input_points[i] * input_scalars[i];
                }
            }
            expected_accs[thread_idx] = expected_thread_acc;
        });
 
        Element expected_acc = Element();
        expected_acc.self_set_infinity();
        for (auto& acc : expected_accs) {
            expected_acc += acc;
        }
        return AffineElement(expected_acc);
    }
 
    static void SetUpTestSuite()
    {
        generators.resize(num_points);
        scalars.resize(num_points);
        parallel_for_range(num_points, [&](size_t start, size_t end) {
            for (size_t i = start; i < end; ++i) {
                generators[i] = Group::one * Curve::ScalarField::random_element(&engine);
                scalars[i] = Curve::ScalarField::random_element(&engine);
            }
        });
        for (size_t i = 0; i < num_points - 1; ++i) {
            ASSERT_EQ(generators[i].x == generators[i + 1].x, false);
        }
    };
 
    // ======================= Test Methods =======================
 
    void test_get_scalar_slice()
    {
        constexpr uint32_t fr_size = 254;
        constexpr uint32_t slice_bits = 7;
        constexpr uint32_t num_slices = (fr_size + 6) / 7;
        constexpr uint32_t last_slice_bits = fr_size - ((num_slices - 1) * slice_bits);
 
        for (size_t x = 0; x < 100; ++x) {
            uint256_t input_u256 = engine.get_random_uint256();
            input_u256.data[3] = input_u256.data[3] & 0x3FFFFFFFFFFFFFFF; // 254 bits
            while (input_u256 > ScalarField::modulus) {
                input_u256 -= ScalarField::modulus;
            }
            std::vector<uint32_t> slices(num_slices);
 
            uint256_t acc = input_u256;
            for (uint32_t i = 0; i < num_slices; ++i) {
                uint32_t mask = ((1U << slice_bits) - 1U);
                uint32_t shift = slice_bits;
                if (i == 0) {
                    mask = ((1U << last_slice_bits) - 1U);
                    shift = last_slice_bits;
                }
                slices[num_slices - 1 - i] = static_cast<uint32_t>((acc & mask).data[0]);
                acc = acc >> shift;
            }
 
            ScalarField input(input_u256);
            input.self_from_montgomery_form_reduced();
 
            ASSERT_EQ(input.data[0], input_u256.data[0]);
            ASSERT_EQ(input.data[1], input_u256.data[1]);
            ASSERT_EQ(input.data[2], input_u256.data[2]);
            ASSERT_EQ(input.data[3], input_u256.data[3]);
 
            for (uint32_t i = 0; i < num_slices; ++i) {
                uint32_t result = scalar_multiplication::MSM<Curve>::get_scalar_slice(input, i, slice_bits);
                EXPECT_EQ(result, slices[i]);
            }
        }
    }
 
    void test_consume_point_batch()
    {
        const size_t total_points = kMaxBucketTestPoints;
        const size_t num_buckets = 128;
 
        std::vector<uint64_t> input_point_schedule;
        for (size_t i = 0; i < total_points; ++i) {
            uint64_t bucket = static_cast<uint64_t>(engine.get_random_uint8()) & 0x7f;
            uint64_t schedule = static_cast<uint64_t>(bucket) + (static_cast<uint64_t>(i) << 32);
            input_point_schedule.push_back(schedule);
        }
        typename scalar_multiplication::MSM<Curve>::AffineAdditionData affine_data;
        typename scalar_multiplication::MSM<Curve>::BucketAccumulators bucket_data(num_buckets);
        scalar_multiplication::MSM<Curve>::batch_accumulate_points_into_buckets(
            input_point_schedule, generators, affine_data, bucket_data);
 
        std::vector<Element> expected_buckets(num_buckets);
        for (auto& e : expected_buckets) {
            e.self_set_infinity();
        }
        for (size_t i = 0; i < total_points; ++i) {
            uint64_t bucket = input_point_schedule[i] & 0xFFFFFFFF;
            EXPECT_LT(static_cast<size_t>(bucket), num_buckets);
            expected_buckets[static_cast<size_t>(bucket)] += generators[i];
        }
        for (size_t i = 0; i < num_buckets; ++i) {
            if (!expected_buckets[i].is_point_at_infinity()) {
                AffineElement expected(expected_buckets[i]);
                EXPECT_EQ(expected, bucket_data.buckets[i]);
            } else {
                EXPECT_FALSE(bucket_data.bucket_exists.get(i));
            }
        }
    }
 
    void test_consume_point_batch_and_accumulate()
    {
        const size_t total_points = kMaxBucketTestPoints;
        const size_t num_buckets = 128;
 
        std::vector<uint64_t> input_point_schedule;
        for (size_t i = 0; i < total_points; ++i) {
            uint64_t bucket = static_cast<uint64_t>(engine.get_random_uint8()) & 0x7f;
            uint64_t schedule = static_cast<uint64_t>(bucket) + (static_cast<uint64_t>(i) << 32);
            input_point_schedule.push_back(schedule);
        }
        typename scalar_multiplication::MSM<Curve>::AffineAdditionData affine_data;
        typename scalar_multiplication::MSM<Curve>::BucketAccumulators bucket_data(num_buckets);
        scalar_multiplication::MSM<Curve>::batch_accumulate_points_into_buckets(
            input_point_schedule, generators, affine_data, bucket_data);
 
        Element result = scalar_multiplication::MSM<Curve>::accumulate_buckets(bucket_data);
 
        Element expected_acc;
        expected_acc.self_set_infinity();
        size_t num_threads = get_num_cpus();
        std::vector<Element> expected_accs(num_threads);
        size_t range_per_thread = (total_points + num_threads - 1) / num_threads;
        parallel_for(num_threads, [&](size_t thread_idx) {
            Element expected_thread_acc;
            expected_thread_acc.self_set_infinity();
            size_t start = thread_idx * range_per_thread;
            size_t end = (thread_idx == num_threads - 1) ? total_points : (thread_idx + 1) * range_per_thread;
            bool skip = start >= total_points;
            if (!skip) {
                for (size_t i = start; i < end; ++i) {
                    ScalarField scalar = input_point_schedule[i] & 0xFFFFFFFF;
                    expected_thread_acc += generators[i] * scalar;
                }
            }
            expected_accs[thread_idx] = expected_thread_acc;
        });
 
        for (size_t i = 0; i < num_threads; ++i) {
            expected_acc += expected_accs[i];
        }
        AffineElement expected(expected_acc);
        EXPECT_EQ(AffineElement(result), expected);
    }
 
    void test_radix_sort_count_zero_entries()
    {
        const size_t total_points = 30071;
 
        std::vector<uint64_t> input_point_schedule;
        for (size_t i = 0; i < total_points; ++i) {
            uint64_t bucket = static_cast<uint64_t>(engine.get_random_uint8()) & 0x7f;
            uint64_t schedule = static_cast<uint64_t>(bucket) + (static_cast<uint64_t>(i) << 32);
            input_point_schedule.push_back(schedule);
        }
 
        size_t result = scalar_multiplication::sort_point_schedule_and_count_zero_buckets(
            &input_point_schedule[0], input_point_schedule.size(), 7);
 
        // Verify zero entry count is correct
        size_t expected = 0;
        for (size_t i = 0; i < total_points; ++i) {
            expected += static_cast<size_t>((input_point_schedule[i] & 0xFFFFFFFF) == 0);
        }
        EXPECT_EQ(result, expected);
 
        // Verify the array is sorted by bucket index (lower 32 bits)
        for (size_t i = 1; i < total_points; ++i) {
            uint32_t prev_bucket = static_cast<uint32_t>(input_point_schedule[i - 1]);
            uint32_t curr_bucket = static_cast<uint32_t>(input_point_schedule[i]);
            EXPECT_LE(prev_bucket, curr_bucket) << "Array not sorted at index " << i;
        }
    }
 
    // Regression test: radix sort zero-counting bug for bucket_index_bits > 16 (3+ recursion levels).
    // The recursive call passes `keys` instead of `top_level_keys`, causing num_zero_entries to be
    // overwritten by non-zero-bucket counts when the MSD radix sort recurses 3+ levels deep.
    void test_radix_sort_count_zero_entries_wide_buckets()
    {
        // Use bucket_index_bits = 17, which pads to 24 bits → 3 recursion levels (shift: 16→8→0).
        // At the 3rd level, the top_level_keys bug causes zero-counting to fire for every
        // level-0 bucket's sub-bucket-0, not just the bucket-0 chain.
        constexpr uint32_t bucket_index_bits = 17;
        constexpr size_t num_entries = 1000;
 
        std::vector<uint64_t> schedule(num_entries);
 
        // Place some entries with bucket_index = 0 (true zero-bucket entries)
        const size_t num_true_zeros = 10;
        for (size_t i = 0; i < num_true_zeros; ++i) {
            schedule[i] = static_cast<uint64_t>(i) << 32; // point_index=i, bucket_index=0
        }
 
        // Place entries with bucket_index = 65536 (= 1 << 16). These have bits [0:16) all zero,
        // so the buggy code counts them as zero-bucket entries after the final recursion level
        // overwrites num_zero_entries from the level-0 bucket 1 path.
        const size_t num_false_zeros = 20;
        for (size_t i = 0; i < num_false_zeros; ++i) {
            size_t idx = num_true_zeros + i;
            schedule[idx] = (static_cast<uint64_t>(idx) << 32) | 65536ULL;
        }
 
        // Fill remaining entries with random non-zero bucket indices that won't confuse the count
        for (size_t i = num_true_zeros + num_false_zeros; i < num_entries; ++i) {
            uint32_t bucket = (engine.get_random_uint32() % ((1U << bucket_index_bits) - 1)) + 1;
            // Avoid bucket_index values with all lower 16 bits zero (i.e., multiples of 65536)
            if ((bucket & 0xFFFF) == 0) {
                bucket |= 1;
            }
            schedule[i] = (static_cast<uint64_t>(i) << 32) | static_cast<uint64_t>(bucket);
        }
 
        size_t result = scalar_multiplication::sort_point_schedule_and_count_zero_buckets(
            schedule.data(), num_entries, bucket_index_bits);
 
        // Count actual zero-bucket entries after sort
        size_t expected = 0;
        for (size_t i = 0; i < num_entries; ++i) {
            if ((schedule[i] & scalar_multiplication::BUCKET_INDEX_MASK) == 0) {
                expected++;
            }
        }
 
        EXPECT_EQ(result, expected) << "Zero-bucket count is wrong for bucket_index_bits=" << bucket_index_bits
                                    << ". Got " << result << ", expected " << expected
                                    << " (likely overwritten by count from a non-zero bucket)";
 
        // Also verify the array is sorted
        for (size_t i = 1; i < num_entries; ++i) {
            uint32_t prev = static_cast<uint32_t>(schedule[i - 1]);
            uint32_t curr = static_cast<uint32_t>(schedule[i]);
            EXPECT_LE(prev, curr) << "Array not sorted at index " << i;
        }
    }
 
    void test_pippenger_low_memory()
    {
        std::span<ScalarField> test_scalars(&scalars[0], num_points);
        AffineElement result =
            scalar_multiplication::MSM<Curve>::msm(generators, PolynomialSpan<ScalarField>(0, test_scalars));
        AffineElement expected = naive_msm(test_scalars, generators);
        EXPECT_EQ(result, expected);
    }
 
    void test_batch_multi_scalar_mul()
    {
        BB_BENCH_NAME("BatchMultiScalarMul");
 
        const size_t num_msms = static_cast<size_t>(engine.get_random_uint8()) % kMaxBatchMSMs;
        std::vector<AffineElement> expected(num_msms);
 
        std::vector<std::vector<ScalarField>> batch_scalars_copies(num_msms);
        std::vector<std::span<const AffineElement>> batch_points_span;
        std::vector<std::span<ScalarField>> batch_scalars_spans;
 
        size_t vector_offset = 0;
        for (size_t k = 0; k < num_msms; ++k) {
            const size_t num_pts = static_cast<size_t>(engine.get_random_uint16()) % kMaxBatchPointsPerMSM;
 
            ASSERT_LT(vector_offset + num_pts, num_points);
            std::span<const AffineElement> batch_points(&generators[vector_offset], num_pts);
 
            batch_scalars_copies[k].resize(num_pts);
            for (size_t i = 0; i < num_pts; ++i) {
                batch_scalars_copies[k][i] = scalars[vector_offset + i];
            }
 
            vector_offset += num_pts;
            batch_points_span.push_back(batch_points);
            batch_scalars_spans.push_back(batch_scalars_copies[k]);
 
            expected[k] = naive_msm(batch_scalars_spans[k], batch_points_span[k]);
        }
 
        std::vector<AffineElement> result =
            scalar_multiplication::MSM<Curve>::batch_multi_scalar_mul(batch_points_span, batch_scalars_spans);
 
        EXPECT_EQ(result, expected);
    }
 
    void test_batch_multi_scalar_mul_sparse()
    {
        const size_t num_msms = 10;
        std::vector<AffineElement> expected(num_msms);
 
        std::vector<std::vector<ScalarField>> batch_scalars(num_msms);
        std::vector<std::span<const AffineElement>> batch_points_span;
        std::vector<std::span<ScalarField>> batch_scalars_spans;
 
        for (size_t k = 0; k < num_msms; ++k) {
            const size_t num_pts = 33;
            auto& test_scalars = batch_scalars[k];
 
            test_scalars.resize(num_pts);
 
            size_t fixture_offset = k * num_pts;
 
            std::span<AffineElement> batch_points(&generators[fixture_offset], num_pts);
            for (size_t i = 0; i < 13; ++i) {
                test_scalars[i] = 0;
            }
            for (size_t i = 13; i < 23; ++i) {
                test_scalars[i] = scalars[fixture_offset + i + 13];
            }
            for (size_t i = 23; i < num_pts; ++i) {
                test_scalars[i] = 0;
            }
            batch_points_span.push_back(batch_points);
            batch_scalars_spans.push_back(batch_scalars[k]);
 
            expected[k] = naive_msm(batch_scalars[k], batch_points);
        }
 
        std::vector<AffineElement> result =
            scalar_multiplication::MSM<Curve>::batch_multi_scalar_mul(batch_points_span, batch_scalars_spans);
 
        EXPECT_EQ(result, expected);
    }
 
    void test_msm()
    {
        const size_t start_index = 1234;
        const size_t num_pts = num_points - start_index;
 
        PolynomialSpan<ScalarField> scalar_span =
            PolynomialSpan<ScalarField>(start_index, std::span<ScalarField>(&scalars[0], num_pts));
        AffineElement result = scalar_multiplication::MSM<Curve>::msm(generators, scalar_span);
 
        std::span<AffineElement> points(&generators[start_index], num_pts);
        AffineElement expected = naive_msm(scalar_span.span, points);
        EXPECT_EQ(result, expected);
    }
 
    void test_msm_all_zeroes()
    {
        const size_t start_index = 1234;
        const size_t num_pts = num_points - start_index;
        std::vector<ScalarField> test_scalars(num_pts, ScalarField::zero());
 
        PolynomialSpan<ScalarField> scalar_span = PolynomialSpan<ScalarField>(start_index, test_scalars);
        AffineElement result = scalar_multiplication::MSM<Curve>::msm(generators, scalar_span);
 
        EXPECT_EQ(result, Group::affine_point_at_infinity);
    }
 
    void test_msm_empty_polynomial()
    {
        std::vector<ScalarField> test_scalars;
        std::vector<AffineElement> input_points;
        PolynomialSpan<ScalarField> scalar_span = PolynomialSpan<ScalarField>(0, test_scalars);
        AffineElement result = scalar_multiplication::MSM<Curve>::msm(input_points, scalar_span);
 
        EXPECT_EQ(result, Group::affine_point_at_infinity);
    }
 
    void test_scalars_unchanged_after_msm()
    {
        const size_t num_pts = 100;
        std::vector<ScalarField> test_scalars(num_pts);
        std::vector<ScalarField> scalars_copy(num_pts);
 
        for (size_t i = 0; i < num_pts; ++i) {
            test_scalars[i] = scalars[i];
            scalars_copy[i] = test_scalars[i];
        }
 
        std::span<const AffineElement> points(&generators[0], num_pts);
        PolynomialSpan<ScalarField> scalar_span(0, test_scalars);
 
        scalar_multiplication::MSM<Curve>::msm(points, scalar_span);
 
        for (size_t i = 0; i < num_pts; ++i) {
            EXPECT_EQ(test_scalars[i], scalars_copy[i]) << "Scalar at index " << i << " was modified";
        }
    }
 
    void test_scalars_unchanged_after_batch_multi_scalar_mul()
    {
        const size_t num_msms = 3;
        const size_t num_pts = 100;
 
        std::vector<std::vector<ScalarField>> batch_scalars(num_msms);
        std::vector<std::vector<ScalarField>> scalars_copies(num_msms);
        std::vector<std::span<const AffineElement>> batch_points;
        std::vector<std::span<ScalarField>> batch_scalar_spans;
 
        for (size_t k = 0; k < num_msms; ++k) {
            batch_scalars[k].resize(num_pts);
            scalars_copies[k].resize(num_pts);
 
            for (size_t i = 0; i < num_pts; ++i) {
                batch_scalars[k][i] = scalars[k * num_pts + i];
                scalars_copies[k][i] = batch_scalars[k][i];
            }
 
            batch_points.push_back(std::span<const AffineElement>(&generators[k * num_pts], num_pts));
            batch_scalar_spans.push_back(batch_scalars[k]);
        }
 
        scalar_multiplication::MSM<Curve>::batch_multi_scalar_mul(batch_points, batch_scalar_spans);
 
        for (size_t k = 0; k < num_msms; ++k) {
            for (size_t i = 0; i < num_pts; ++i) {
                EXPECT_EQ(batch_scalars[k][i], scalars_copies[k][i])
                    << "Scalar at MSM " << k << ", index " << i << " was modified";
            }
        }
    }
 
    void test_scalar_one()
    {
        const size_t num_pts = 5;
        std::vector<ScalarField> test_scalars(num_pts, ScalarField::one());
        std::span<const AffineElement> points(&generators[0], num_pts);
 
        PolynomialSpan<ScalarField> scalar_span(0, test_scalars);
        AffineElement result = scalar_multiplication::MSM<Curve>::msm(points, scalar_span);
 
        Element expected;
        expected.self_set_infinity();
        for (size_t i = 0; i < num_pts; ++i) {
            expected += points[i];
        }
 
        EXPECT_EQ(result, AffineElement(expected));
    }
 
    void test_scalar_minus_one()
    {
        const size_t num_pts = 5;
        std::vector<ScalarField> test_scalars(num_pts, -ScalarField::one());
        std::span<const AffineElement> points(&generators[0], num_pts);
 
        PolynomialSpan<ScalarField> scalar_span(0, test_scalars);
        AffineElement result = scalar_multiplication::MSM<Curve>::msm(points, scalar_span);
 
        Element expected;
        expected.self_set_infinity();
        for (size_t i = 0; i < num_pts; ++i) {
            expected -= points[i];
        }
 
        EXPECT_EQ(result, AffineElement(expected));
    }
 
    void test_single_point()
    {
        std::vector<ScalarField> test_scalars = { scalars[0] };
        std::span<const AffineElement> points(&generators[0], 1);
 
        PolynomialSpan<ScalarField> scalar_span(0, test_scalars);
        AffineElement result = scalar_multiplication::MSM<Curve>::msm(points, scalar_span);
 
        AffineElement expected(points[0] * test_scalars[0]);
        EXPECT_EQ(result, expected);
    }
 
    void test_size_thresholds()
    {
        std::vector<size_t> test_sizes = { 1, 2, 15, 16, 17, 50, 127, 128, 129, 256, 512 };
 
        for (size_t num_pts : test_sizes) {
            ASSERT_LE(num_pts, num_points);
 
            std::vector<ScalarField> test_scalars(num_pts);
            for (size_t i = 0; i < num_pts; ++i) {
                test_scalars[i] = scalars[i];
            }
 
            std::span<const AffineElement> points(&generators[0], num_pts);
            PolynomialSpan<ScalarField> scalar_span(0, test_scalars);
 
            AffineElement result = scalar_multiplication::MSM<Curve>::msm(points, scalar_span);
            AffineElement expected = naive_msm(test_scalars, points);
 
            EXPECT_EQ(result, expected) << "Failed for size " << num_pts;
        }
    }
 
    void test_duplicate_points()
    {
        // Use enough points to trigger Pippenger (> PIPPENGER_THRESHOLD = 16)
        const size_t num_pts = 32;
        AffineElement base_point = generators[0];
 
        std::vector<AffineElement> points(num_pts, base_point);
        std::vector<ScalarField> test_scalars(num_pts);
        ScalarField scalar_sum = ScalarField::zero();
 
        for (size_t i = 0; i < num_pts; ++i) {
            test_scalars[i] = scalars[i];
            scalar_sum += test_scalars[i];
        }
 
        PolynomialSpan<ScalarField> scalar_span(0, test_scalars);
        // Duplicate points are an edge case (P + P requires doubling, not addition).
        // Must use handle_edge_cases=true for correctness with Pippenger.
        AffineElement result = scalar_multiplication::MSM<Curve>::msm(points, scalar_span, /*handle_edge_cases=*/true);
 
        AffineElement expected(base_point * scalar_sum);
        EXPECT_EQ(result, expected);
    }
 
    void test_mixed_zero_scalars()
    {
        const size_t num_pts = 100;
        std::vector<ScalarField> test_scalars(num_pts);
        Element expected;
        expected.self_set_infinity();
 
        for (size_t i = 0; i < num_pts; ++i) {
            if (i % 2 == 0) {
                test_scalars[i] = ScalarField::zero();
            } else {
                test_scalars[i] = scalars[i];
                expected += generators[i] * test_scalars[i];
            }
        }
 
        std::span<const AffineElement> points(&generators[0], num_pts);
        PolynomialSpan<ScalarField> scalar_span(0, test_scalars);
 
        AffineElement result = scalar_multiplication::MSM<Curve>::msm(points, scalar_span);
        EXPECT_EQ(result, AffineElement(expected));
    }
 
    void test_pippenger_free_function()
    {
        const size_t num_pts = 200;
        std::vector<ScalarField> test_scalars(num_pts);
        for (size_t i = 0; i < num_pts; ++i) {
            test_scalars[i] = scalars[i];
        }
 
        std::span<const AffineElement> points(&generators[0], num_pts);
        PolynomialSpan<ScalarField> scalar_span(0, test_scalars);
 
        auto result = scalar_multiplication::pippenger<Curve>(scalar_span, points);
 
        AffineElement expected = naive_msm(test_scalars, points);
        EXPECT_EQ(AffineElement(result), expected);
    }
 
    void test_pippenger_unsafe_free_function()
    {
        const size_t num_pts = 200;
        std::vector<ScalarField> test_scalars(num_pts);
        for (size_t i = 0; i < num_pts; ++i) {
            test_scalars[i] = scalars[i];
        }
 
        std::span<const AffineElement> points(&generators[0], num_pts);
        PolynomialSpan<ScalarField> scalar_span(0, test_scalars);
 
        auto result = scalar_multiplication::pippenger_unsafe<Curve>(scalar_span, points);
 
        AffineElement expected = naive_msm(test_scalars, points);
        EXPECT_EQ(AffineElement(result), expected);
    }
};
 
using CurveTypes = ::testing::Types<bb::curve::BN254, bb::curve::Grumpkin>;
TYPED_TEST_SUITE(ScalarMultiplicationTest, CurveTypes);
 
// ======================= Test Wrappers =======================
 
TYPED_TEST(ScalarMultiplicationTest, GetScalarSlice)
{
    this->test_get_scalar_slice();
}
TYPED_TEST(ScalarMultiplicationTest, ConsumePointBatch)
{
    this->test_consume_point_batch();
}
TYPED_TEST(ScalarMultiplicationTest, ConsumePointBatchAndAccumulate)
{
    this->test_consume_point_batch_and_accumulate();
}
TYPED_TEST(ScalarMultiplicationTest, RadixSortCountZeroEntries)
{
    this->test_radix_sort_count_zero_entries();
}
TYPED_TEST(ScalarMultiplicationTest, RadixSortCountZeroEntriesWideBuckets)
{
    this->test_radix_sort_count_zero_entries_wide_buckets();
}
TYPED_TEST(ScalarMultiplicationTest, PippengerLowMemory)
{
    this->test_pippenger_low_memory();
}
TYPED_TEST(ScalarMultiplicationTest, BatchMultiScalarMul)
{
    this->test_batch_multi_scalar_mul();
}
TYPED_TEST(ScalarMultiplicationTest, BatchMultiScalarMulSparse)
{
    this->test_batch_multi_scalar_mul_sparse();
}
TYPED_TEST(ScalarMultiplicationTest, MSM)
{
    this->test_msm();
}
TYPED_TEST(ScalarMultiplicationTest, MSMAllZeroes)
{
    this->test_msm_all_zeroes();
}
TYPED_TEST(ScalarMultiplicationTest, MSMEmptyPolynomial)
{
    this->test_msm_empty_polynomial();
}
TYPED_TEST(ScalarMultiplicationTest, ScalarsUnchangedAfterMSM)
{
    this->test_scalars_unchanged_after_msm();
}
TYPED_TEST(ScalarMultiplicationTest, ScalarsUnchangedAfterBatchMultiScalarMul)
{
    this->test_scalars_unchanged_after_batch_multi_scalar_mul();
}
TYPED_TEST(ScalarMultiplicationTest, ScalarOne)
{
    this->test_scalar_one();
}
TYPED_TEST(ScalarMultiplicationTest, ScalarMinusOne)
{
    this->test_scalar_minus_one();
}
TYPED_TEST(ScalarMultiplicationTest, SinglePoint)
{
    this->test_single_point();
}
TYPED_TEST(ScalarMultiplicationTest, SizeThresholds)
{
    this->test_size_thresholds();
}
TYPED_TEST(ScalarMultiplicationTest, DuplicatePoints)
{
    this->test_duplicate_points();
}
TYPED_TEST(ScalarMultiplicationTest, MixedZeroScalars)
{
    this->test_mixed_zero_scalars();
}
TYPED_TEST(ScalarMultiplicationTest, PippengerFreeFunction)
{
    this->test_pippenger_free_function();
}
TYPED_TEST(ScalarMultiplicationTest, PippengerUnsafeFreeFunction)
{
    this->test_pippenger_unsafe_free_function();
}
 
// Curve-independent unit tests for the work-unit partitioner.
// partition_by_weight is the load-bearing balancing logic in get_work_units; pinning its
// behavior with synthetic weights makes regressions in the partition algorithm visible
// without needing a full MSM run.
namespace {
 
using PartitionMSM = scalar_multiplication::MSM<curve::BN254>;
using WorkUnit = PartitionMSM::MSMWorkUnit;
 
// Total weight assigned to a thread (sum of WorkUnit sizes weighted by the input vector).
size_t thread_weight(const std::vector<WorkUnit>& units, const std::vector<std::vector<uint16_t>>& weights)
{
    size_t total = 0;
    for (const auto& u : units) {
        for (size_t k = 0; k < u.size; ++k) {
            total += weights[u.batch_msm_index][u.start_index + k];
        }
    }
    return total;
}
 
} // namespace
 
TEST(PartitionByWeight, NoMsmsReturnsEmptyThreads)
{
    auto units = PartitionMSM::partition_by_weight({}, 8);
    ASSERT_EQ(units.size(), 8U);
    for (const auto& t : units) {
        EXPECT_TRUE(t.empty());
    }
}
 
TEST(PartitionByWeight, AllEmptyMsmsReturnsEmptyThreads)
{
    std::vector<std::vector<uint16_t>> weights{ {}, {}, {} };
    auto units = PartitionMSM::partition_by_weight(weights, 4);
    ASSERT_EQ(units.size(), 4U);
    for (const auto& t : units) {
        EXPECT_TRUE(t.empty());
    }
}
 
TEST(PartitionByWeight, SingleThreadGetsEverything)
{
    std::vector<std::vector<uint16_t>> weights{ { 5, 5, 5, 5, 5 } };
    auto units = PartitionMSM::partition_by_weight(weights, 1);
    ASSERT_EQ(units.size(), 1U);
    ASSERT_EQ(units[0].size(), 1U);
    EXPECT_EQ(units[0][0].batch_msm_index, 0U);
    EXPECT_EQ(units[0][0].start_index, 0U);
    EXPECT_EQ(units[0][0].size, 5U);
}
 
TEST(PartitionByWeight, EvenSplitAcrossThreads)
{
    // 8 weights of 5 => total 40, target 10 per thread (4 threads), so 2 weights per thread.
    std::vector<std::vector<uint16_t>> weights{ { 5, 5, 5, 5, 5, 5, 5, 5 } };
    auto units = PartitionMSM::partition_by_weight(weights, 4);
    ASSERT_EQ(units.size(), 4U);
    for (size_t t = 0; t < 4; ++t) {
        ASSERT_EQ(units[t].size(), 1U) << "thread " << t;
        EXPECT_EQ(units[t][0].size, 2U) << "thread " << t;
        EXPECT_EQ(thread_weight(units[t], weights), 10U) << "thread " << t;
    }
}
 
TEST(PartitionByWeight, HeavyFirstWeightClosesFirstThreadEarly)
{
    // First weight alone exceeds the per-thread target; remainder is evenly split.
    std::vector<std::vector<uint16_t>> weights{ { 100, 5, 5, 5, 5 } };
    auto units = PartitionMSM::partition_by_weight(weights, 4);
    ASSERT_EQ(units.size(), 4U);
    // Thread 0 should close after the heavy weight.
    ASSERT_FALSE(units[0].empty());
    EXPECT_EQ(units[0][0].start_index, 0U);
    EXPECT_EQ(units[0][0].size, 1U);
    // Total assigned across all threads must equal n.
    size_t total_assigned = 0;
    for (const auto& t : units) {
        for (const auto& u : t) {
            total_assigned += u.size;
        }
    }
    EXPECT_EQ(total_assigned, 5U);
}
 
TEST(PartitionByWeight, BoundaryStraddlesMsm)
{
    // Two MSMs of 4 weights of 5 each => total 40, 4 threads, target 10.
    // Boundary should land mid-MSM if weights cross between MSMs.
    std::vector<std::vector<uint16_t>> weights{ { 5, 5, 5, 5 }, { 5, 5, 5, 5 } };
    auto units = PartitionMSM::partition_by_weight(weights, 4);
    ASSERT_EQ(units.size(), 4U);
    size_t total_assigned = 0;
    for (const auto& t : units) {
        for (const auto& u : t) {
            total_assigned += u.size;
        }
    }
    EXPECT_EQ(total_assigned, 8U);
    // Each thread should carry exactly weight 10.
    for (size_t t = 0; t < 4; ++t) {
        EXPECT_EQ(thread_weight(units[t], weights), 10U) << "thread " << t;
    }
}
 
TEST(PartitionByWeight, LastThreadAbsorbsRemainder)
{
    // weights {7,7,1}, num_threads=3 => total 15, target = ceil(15/3) = 5.
    // Walk: T0 closes after weight 7, T1 closes after weight 7, then weight 1 trails.
    // Without the "current_thread_idx < num_threads - 1" guard the partitioner would
    // refuse to close T2 (running weight 1 < target 5) and the trailing weight would
    // be lost. The guard makes T2 absorb it via the post-loop push.
    std::vector<std::vector<uint16_t>> weights{ { 7, 7, 1 } };
    auto units = PartitionMSM::partition_by_weight(weights, 3);
    ASSERT_EQ(units.size(), 3U);
    size_t total_assigned = 0;
    for (const auto& t : units) {
        for (const auto& u : t) {
            total_assigned += u.size;
        }
    }
    EXPECT_EQ(total_assigned, 3U);
    ASSERT_EQ(units[2].size(), 1U);
    EXPECT_EQ(units[2][0].start_index, 2U);
    EXPECT_EQ(units[2][0].size, 1U);
    EXPECT_EQ(thread_weight(units[2], weights), 1U);
}
 
TEST(PartitionByWeight, MoreThreadsThanScalars)
{
    // 3 weights of 5 => total 15, 8 threads, target ceil(15/8)=2.
    // Each weight (5) immediately crosses target => first 3 threads each get one scalar.
    std::vector<std::vector<uint16_t>> weights{ { 5, 5, 5 } };
    auto units = PartitionMSM::partition_by_weight(weights, 8);
    ASSERT_EQ(units.size(), 8U);
    for (size_t t = 0; t < 3; ++t) {
        ASSERT_EQ(units[t].size(), 1U) << "thread " << t;
        EXPECT_EQ(units[t][0].size, 1U);
    }
    for (size_t t = 3; t < 8; ++t) {
        EXPECT_TRUE(units[t].empty()) << "thread " << t;
    }
}
 
// Non-templated test for explicit small inputs
TEST(ScalarMultiplication, SmallInputsExplicit)
{
    uint256_t x0(0x68df84429941826a, 0xeb08934ed806781c, 0xc14b6a2e4f796a73, 0x08dc1a9a11a3c8db);
    uint256_t y0(0x8ae5c31aa997f141, 0xe85f20c504f2c11b, 0x81a94193f3b1ce2b, 0x26f2c37372adb5b7);
    uint256_t x1(0x80f5a592d919d32f, 0x1362652b984e51ca, 0xa0b26666f770c2a1, 0x142c6e1964e5c3c5);
    uint256_t y1(0xb6c322ebb5ae4bc5, 0xf9fef6c7909c00f8, 0xb37ca1cc9af3b421, 0x1e331c7fa73d6a59);
    uint256_t s0(0xe48bf12a24272e08, 0xf8dd0182577f3567, 0xec8fd222b8a6becb, 0x102d76b945612c9b);
    uint256_t s1(0x098ae8d69f1e4e9e, 0xb5c8313c0f6040ed, 0xf78041e30cc46c44, 0x1d1e6e0c21892e13);
 
    std::vector<grumpkin::fr> scalars{ s0, s1 };
 
    std::vector<grumpkin::g1::affine_element> points{ grumpkin::g1::affine_element(x0, y0),
                                                      grumpkin::g1::affine_element(x1, y1) };
 
    PolynomialSpan<grumpkin::fr> scalar_span = PolynomialSpan<grumpkin::fr>(0, scalars);
 
    auto result = scalar_multiplication::MSM<curve::Grumpkin>::msm(points, scalar_span);
 
    grumpkin::g1::element expected = (points[0] * scalars[0]) + (points[1] * scalars[1]);
 
    EXPECT_EQ(result, grumpkin::g1::affine_element(expected));
}