Function npyiter_goto_iterindex

numpy/core/src/multiarray/nditer_api.c:1811–1889

* This sets the AXISDATA portion of the iterator to the specified * iterindex, updating the pointers as well. This function does * no error checking. */

 * no error checking.
 */
NPY_NO_EXPORT void
npyiter_goto_iterindex(NpyIter *iter, npy_intp iterindex)
{
    npy_uint32 itflags = NIT_ITFLAGS(iter);
    int idim, ndim = NIT_NDIM(iter);
    int nop = NIT_NOP(iter);

    char **dataptr;
    NpyIter_AxisData *axisdata;
    npy_intp sizeof_axisdata;
    npy_intp istrides, nstrides, i, shape;

    axisdata = NIT_AXISDATA(iter);
    sizeof_axisdata = NIT_AXISDATA_SIZEOF(itflags, ndim, nop);
    nstrides = NAD_NSTRIDES();

    NIT_ITERINDEX(iter) = iterindex;

    ndim = ndim ? ndim : 1;

    if (iterindex == 0) {
        dataptr = NIT_RESETDATAPTR(iter);

        for (idim = 0; idim < ndim; ++idim) {
            char **ptrs;
            NAD_INDEX(axisdata) = 0;
            ptrs = NAD_PTRS(axisdata);
            for (istrides = 0; istrides < nstrides; ++istrides) {
                ptrs[istrides] = dataptr[istrides];
            }

            NIT_ADVANCE_AXISDATA(axisdata, 1);
        }
    }
    else {
        /*
         * Set the multi-index, from the fastest-changing to the
         * slowest-changing.
         */
        axisdata = NIT_AXISDATA(iter);
        shape = NAD_SHAPE(axisdata);
        i = iterindex;
        iterindex /= shape;
        NAD_INDEX(axisdata) = i - iterindex * shape;
        for (idim = 0; idim < ndim-1; ++idim) {
            NIT_ADVANCE_AXISDATA(axisdata, 1);

            shape = NAD_SHAPE(axisdata);
            i = iterindex;
            iterindex /= shape;
            NAD_INDEX(axisdata) = i - iterindex * shape;
        }

        dataptr = NIT_RESETDATAPTR(iter);

        /*
         * Accumulate the successive pointers with their
         * offsets in the opposite order, starting from the