Function radixsort0

numpy/core/src/npysort/radixsort.cpp:50–95

template <class T, class UT>
static UT *
radixsort0(UT *start, UT *aux, npy_intp num)
{
    npy_intp cnt[sizeof(UT)][1 << 8] = {{0}};
    UT key0 = KEY_OF<T>(start[0]);

    for (npy_intp i = 0; i < num; i++) {
        UT k = KEY_OF<T>(start[i]);

        for (size_t l = 0; l < sizeof(UT); l++) {
            cnt[l][nth_byte(k, l)]++;
        }
    }

    size_t ncols = 0;
    npy_ubyte cols[sizeof(UT)];
    for (size_t l = 0; l < sizeof(UT); l++) {
        if (cnt[l][nth_byte(key0, l)] != num) {
            cols[ncols++] = l;
        }
    }

    for (size_t l = 0; l < ncols; l++) {
        npy_intp a = 0;
        for (npy_intp i = 0; i < 256; i++) {
            npy_intp b = cnt[cols[l]][i];
            cnt[cols[l]][i] = a;
            a += b;
        }
    }

    for (size_t l = 0; l < ncols; l++) {
        UT *temp;
        for (npy_intp i = 0; i < num; i++) {
            UT k = KEY_OF<T>(start[i]);
            npy_intp dst = cnt[cols[l]][nth_byte(k, cols[l])]++;
            aux[dst] = start[i];
        }

        temp = aux;
        aux = start;
        start = temp;
    }

    return start;
}

template <class T, class UT>
static int