static SoftFloat sbr_sum_square_c(int (*x)[2], int n)
{
    SoftFloat ret;
    uint64_t accu = 0, round;
    int i, nz;
    unsigned u;

    for (i = 0; i < n; i += 2) {
        // Larger values are inavlid and could cause overflows of accu.
        av_assert2(FFABS(x[i + 0][0]) >> 29 == 0);
        accu += (int64_t)x[i + 0][0] * x[i + 0][0];
        av_assert2(FFABS(x[i + 0][1]) >> 29 == 0);
        accu += (int64_t)x[i + 0][1] * x[i + 0][1];
        av_assert2(FFABS(x[i + 1][0]) >> 29 == 0);
        accu += (int64_t)x[i + 1][0] * x[i + 1][0];
        av_assert2(FFABS(x[i + 1][1]) >> 29 == 0);
        accu += (int64_t)x[i + 1][1] * x[i + 1][1];
    }

    u = accu >> 32;
    if (u == 0) {
        nz = 1;
    } else {
        nz = -1;
        while (u < 0x80000000U) {
            u <<= 1;
            nz++;
        }
        nz = 32 - nz;
    }

    round = 1ULL << (nz-1);
    u = ((accu + round) >> nz);
    u >>= 1;
    ret = av_int2sf(u, 15 - nz);

    return ret;
}