Function _buffer_format_string

numpy/core/src/multiarray/buffer.c:190–436

* Fill in str with an appropriate PEP 3118 format string, based on * descr. For structured dtypes, calls itself recursively. Each call extends * str at offset then updates offset, and uses descr->byteorder, (and * possibly the byte order in obj) to determine the byte-order char. * * Returns 0 for success, -1 for failure */

 * Returns 0 for success, -1 for failure
 */
static int
_buffer_format_string(PyArray_Descr *descr, _tmp_string_t *str,
                      PyObject* obj, Py_ssize_t *offset,
                      char *active_byteorder)
{
    int k;
    char _active_byteorder = '@';
    Py_ssize_t _offset = 0;

    if (active_byteorder == NULL) {
        active_byteorder = &_active_byteorder;
    }
    if (offset == NULL) {
        offset = &_offset;
    }

    if (descr->subarray) {
        PyObject *item, *subarray_tuple;
        Py_ssize_t total_count = 1;
        Py_ssize_t dim_size;
        Py_ssize_t old_offset;
        char buf[128];
        int ret;

        if (PyTuple_Check(descr->subarray->shape)) {
            subarray_tuple = descr->subarray->shape;
            Py_INCREF(subarray_tuple);
        }
        else {
            subarray_tuple = Py_BuildValue("(O)", descr->subarray->shape);
        }

        if (_append_char(str, '(') < 0) {
            ret = -1;
            goto subarray_fail;
        }
        for (k = 0; k < PyTuple_GET_SIZE(subarray_tuple); ++k) {
            if (k > 0) {
                if (_append_char(str, ',') < 0) {
                    ret = -1;
                    goto subarray_fail;
                }
            }
            item = PyTuple_GET_ITEM(subarray_tuple, k);
            dim_size = PyNumber_AsSsize_t(item, NULL);

            PyOS_snprintf(buf, sizeof(buf), "%ld", (long)dim_size);
            if (_append_str(str, buf) < 0) {
                ret = -1;
                goto subarray_fail;
            }
            total_count *= dim_size;
        }
        if (_append_char(str, ')') < 0) {
            ret = -1;
            goto subarray_fail;
        }