add circuitpython code

1 files changed, 559 insertions, 0 deletions

diff --git a/circuitpython/py/objlist.c b/circuitpython/py/objlist.c
new file mode 100644
index 0000000..9d1949b
--- /dev/null
+++ b/circuitpython/py/objlist.c
@@ -0,0 +1,559 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * SPDX-FileCopyrightText: Copyright (c) 2013, 2014 Damien P. George
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include <string.h>
+#include <assert.h>
+
+#include "py/objlist.h"
+#include "py/runtime.h"
+#include "py/stackctrl.h"
+
+#include "supervisor/shared/translate.h"
+
+STATIC mp_obj_t mp_obj_new_list_iterator(mp_obj_t list, size_t cur, mp_obj_iter_buf_t *iter_buf);
+STATIC mp_obj_list_t *list_new(size_t n);
+STATIC mp_obj_t list_extend(mp_obj_t self_in, mp_obj_t arg_in);
+STATIC mp_obj_t list_pop(size_t n_args, const mp_obj_t *args);
+
+// TODO: Move to mpconfig.h
+#define LIST_MIN_ALLOC 4
+
+/******************************************************************************/
+/* list                                                                       */
+
+STATIC void list_print(const mp_print_t *print, mp_obj_t o_in, mp_print_kind_t kind) {
+    mp_obj_list_t *o = MP_OBJ_TO_PTR(o_in);
+    const char *item_separator = ", ";
+    if (!(MICROPY_PY_UJSON && kind == PRINT_JSON)) {
+        kind = PRINT_REPR;
+    } else {
+        #if MICROPY_PY_UJSON_SEPARATORS
+        item_separator = MP_PRINT_GET_EXT(print)->item_separator;
+        #endif
+    }
+    mp_print_str(print, "[");
+    for (size_t i = 0; i < o->len; i++) {
+        if (i > 0) {
+            mp_print_str(print, item_separator);
+        }
+        mp_obj_print_helper(print, o->items[i], kind);
+    }
+    mp_print_str(print, "]");
+}
+
+STATIC mp_obj_t list_extend_from_iter(mp_obj_t list, mp_obj_t iterable) {
+    mp_obj_t iter = mp_getiter(iterable, NULL);
+    mp_obj_t item;
+    while ((item = mp_iternext(iter)) != MP_OBJ_STOP_ITERATION) {
+        mp_obj_list_append(list, item);
+    }
+    return list;
+}
+
+mp_obj_t mp_obj_new_list_from_iter(mp_obj_t iterable) {
+    mp_obj_t list = mp_obj_new_list(0, NULL);
+    return list_extend_from_iter(list, iterable);
+}
+
+STATIC mp_obj_t list_make_new(const mp_obj_type_t *type_in, size_t n_args, size_t n_kw, const mp_obj_t *args) {
+    (void)type_in;
+    mp_arg_check_num(n_args, n_kw, 0, 1, false);
+
+    switch (n_args) {
+        case 0:
+            // return a new, empty list
+            return mp_obj_new_list(0, NULL);
+
+        case 1:
+        default: {
+            // make list from iterable
+            // TODO: optimize list/tuple
+            mp_obj_t list = mp_obj_new_list(0, NULL);
+            return list_extend_from_iter(list, args[0]);
+        }
+    }
+}
+
+STATIC mp_obj_list_t *native_list(mp_obj_t self_in) {
+    return MP_OBJ_TO_PTR(mp_obj_cast_to_native_base(self_in, MP_OBJ_FROM_PTR(&mp_type_list)));
+}
+
+STATIC mp_obj_t list_unary_op(mp_unary_op_t op, mp_obj_t self_in) {
+    mp_obj_list_t *self = native_list(self_in);
+    switch (op) {
+        case MP_UNARY_OP_BOOL:
+            return mp_obj_new_bool(self->len != 0);
+        case MP_UNARY_OP_LEN:
+            return MP_OBJ_NEW_SMALL_INT(self->len);
+        #if MICROPY_PY_SYS_GETSIZEOF
+        case MP_UNARY_OP_SIZEOF: {
+            size_t sz = sizeof(*self) + sizeof(mp_obj_t) * self->alloc;
+            return MP_OBJ_NEW_SMALL_INT(sz);
+        }
+        #endif
+        default:
+            return MP_OBJ_NULL;      // op not supported
+    }
+}
+
+STATIC mp_obj_t list_binary_op(mp_binary_op_t op, mp_obj_t lhs, mp_obj_t rhs) {
+    mp_obj_list_t *o = native_list(lhs);
+    switch (op) {
+        case MP_BINARY_OP_ADD: {
+            if (!mp_obj_is_type(rhs, &mp_type_list)) {
+                return MP_OBJ_NULL; // op not supported
+            }
+            mp_obj_list_t *p = MP_OBJ_TO_PTR(rhs);
+            mp_obj_list_t *s = list_new(o->len + p->len);
+            mp_seq_cat(s->items, o->items, o->len, p->items, p->len, mp_obj_t);
+            return MP_OBJ_FROM_PTR(s);
+        }
+        case MP_BINARY_OP_INPLACE_ADD: {
+            list_extend(lhs, rhs);
+            return lhs;
+        }
+        case MP_BINARY_OP_MULTIPLY: {
+            mp_int_t n;
+            if (!mp_obj_get_int_maybe(rhs, &n)) {
+                return MP_OBJ_NULL; // op not supported
+            }
+            if (n < 0) {
+                n = 0;
+            }
+            size_t new_len = mp_seq_multiply_len(o->len, n);
+            mp_obj_list_t *s = list_new(new_len);
+            mp_seq_multiply(o->items, sizeof(*o->items), o->len, n, s->items);
+            return MP_OBJ_FROM_PTR(s);
+        }
+        case MP_BINARY_OP_EQUAL:
+        case MP_BINARY_OP_LESS:
+        case MP_BINARY_OP_LESS_EQUAL:
+        case MP_BINARY_OP_MORE:
+        case MP_BINARY_OP_MORE_EQUAL: {
+            if (!mp_obj_is_type(rhs, &mp_type_list)) {
+                if (op == MP_BINARY_OP_EQUAL) {
+                    return mp_const_false;
+                }
+                return MP_OBJ_NULL; // op not supported
+            }
+
+            mp_obj_list_t *another = MP_OBJ_TO_PTR(rhs);
+            bool res = mp_seq_cmp_objs(op, o->items, o->len, another->items, another->len);
+            return mp_obj_new_bool(res);
+        }
+
+        default:
+            return MP_OBJ_NULL; // op not supported
+    }
+}
+
+STATIC mp_obj_t list_subscr(mp_obj_t self_in, mp_obj_t index, mp_obj_t value) {
+    mp_obj_list_t *self = native_list(self_in);
+    if (value == MP_OBJ_NULL) {
+        // delete
+        #if MICROPY_PY_BUILTINS_SLICE
+        if (mp_obj_is_type(index, &mp_type_slice)) {
+            mp_bound_slice_t slice;
+            if (!mp_seq_get_fast_slice_indexes(self->len, index, &slice)) {
+                mp_raise_NotImplementedError(NULL);
+            }
+
+            mp_int_t len_adj = slice.start - slice.stop;
+            assert(len_adj <= 0);
+            mp_seq_replace_slice_no_grow(self->items, self->len, slice.start, slice.stop, self->items /*NULL*/, 0, sizeof(*self->items));
+            // Clear "freed" elements at the end of list
+            mp_seq_clear(self->items, self->len + len_adj, self->len, sizeof(*self->items));
+            self->len += len_adj;
+            return mp_const_none;
+        }
+        #endif
+        mp_obj_t args[2] = {MP_OBJ_FROM_PTR(self), index};
+        list_pop(2, args);
+        return mp_const_none;
+    } else if (value == MP_OBJ_SENTINEL) {
+        // load
+        #if MICROPY_PY_BUILTINS_SLICE
+        if (mp_obj_is_type(index, &mp_type_slice)) {
+            mp_bound_slice_t slice;
+            if (!mp_seq_get_fast_slice_indexes(self->len, index, &slice)) {
+                return mp_seq_extract_slice(self->len, self->items, &slice);
+            }
+            mp_obj_list_t *res = list_new(slice.stop - slice.start);
+            mp_seq_copy(res->items, self->items + slice.start, res->len, mp_obj_t);
+            return MP_OBJ_FROM_PTR(res);
+        }
+        #endif
+        size_t index_val = mp_get_index(self->base.type, self->len, index, false);
+        return self->items[index_val];
+    } else {
+        #if MICROPY_PY_BUILTINS_SLICE
+        if (mp_obj_is_type(index, &mp_type_slice)) {
+            size_t value_len;
+            mp_obj_t *value_items;
+            mp_obj_get_array(value, &value_len, &value_items);
+            mp_bound_slice_t slice_out;
+            if (!mp_seq_get_fast_slice_indexes(self->len, index, &slice_out)) {
+                mp_raise_NotImplementedError(NULL);
+            }
+            mp_int_t len_adj = value_len - (slice_out.stop - slice_out.start);
+            if (len_adj > 0) {
+                if (self->len + len_adj > self->alloc) {
+                    // TODO: Might optimize memory copies here by checking if block can
+                    // be grown inplace or not
+                    self->items = m_renew(mp_obj_t, self->items, self->alloc, self->len + len_adj);
+                    self->alloc = self->len + len_adj;
+                }
+                mp_seq_replace_slice_grow_inplace(self->items, self->len,
+                    slice_out.start, slice_out.stop, value_items, value_len, len_adj, sizeof(*self->items));
+            } else {
+                mp_seq_replace_slice_no_grow(self->items, self->len,
+                    slice_out.start, slice_out.stop, value_items, value_len, sizeof(*self->items));
+                // Clear "freed" elements at the end of list
+                mp_seq_clear(self->items, self->len + len_adj, self->len, sizeof(*self->items));
+                // TODO: apply allocation policy re: alloc_size
+            }
+            self->len += len_adj;
+            return mp_const_none;
+        }
+        #endif
+        mp_obj_list_store(self_in, index, value);
+        return mp_const_none;
+    }
+}
+
+STATIC mp_obj_t list_getiter(mp_obj_t o_in, mp_obj_iter_buf_t *iter_buf) {
+    return mp_obj_new_list_iterator(o_in, 0, iter_buf);
+}
+
+mp_obj_t mp_obj_list_append(mp_obj_t self_in, mp_obj_t arg) {
+    mp_check_self(mp_obj_is_type(self_in, &mp_type_list));
+    mp_obj_list_t *self = native_list(self_in);
+    if (self->len >= self->alloc) {
+        self->items = m_renew(mp_obj_t, self->items, self->alloc, self->alloc * 2);
+        self->alloc *= 2;
+        mp_seq_clear(self->items, self->len + 1, self->alloc, sizeof(*self->items));
+    }
+    self->items[self->len++] = arg;
+    return mp_const_none; // return None, as per CPython
+}
+
+STATIC mp_obj_t list_extend(mp_obj_t self_in, mp_obj_t arg_in) {
+    mp_check_self(mp_obj_is_type(self_in, &mp_type_list));
+    if (mp_obj_is_type(arg_in, &mp_type_list)) {
+        mp_obj_list_t *self = native_list(self_in);
+        mp_obj_list_t *arg = native_list(arg_in);
+
+        if (self->len + arg->len > self->alloc) {
+            // TODO: use alloc policy for "4"
+            self->items = m_renew(mp_obj_t, self->items, self->alloc, self->len + arg->len + 4);
+            self->alloc = self->len + arg->len + 4;
+            mp_seq_clear(self->items, self->len + arg->len, self->alloc, sizeof(*self->items));
+        }
+
+        memcpy(self->items + self->len, arg->items, sizeof(mp_obj_t) * arg->len);
+        self->len += arg->len;
+    } else {
+        list_extend_from_iter(self_in, arg_in);
+    }
+    return mp_const_none; // return None, as per CPython
+}
+
+inline mp_obj_t mp_obj_list_pop(mp_obj_list_t *self, size_t index) {
+    if (self->len == 0) {
+        mp_raise_IndexError_varg(MP_ERROR_TEXT("pop from empty %q"), MP_QSTR_list);
+    }
+    mp_obj_t ret = self->items[index];
+    self->len -= 1;
+    memmove(self->items + index, self->items + index + 1, (self->len - index) * sizeof(mp_obj_t));
+    // Clear stale pointer from slot which just got freed to prevent GC issues
+    self->items[self->len] = MP_OBJ_NULL;
+    if (self->alloc > LIST_MIN_ALLOC && self->alloc > 2 * self->len) {
+        self->items = m_renew(mp_obj_t, self->items, self->alloc, self->alloc / 2);
+        self->alloc /= 2;
+    }
+    return ret;
+}
+
+STATIC mp_obj_t list_pop(size_t n_args, const mp_obj_t *args) {
+    mp_check_self(mp_obj_is_type(args[0], &mp_type_list));
+    mp_obj_list_t *self = native_list(args[0]);
+    size_t index = mp_get_index(self->base.type, self->len, n_args == 1 ? MP_OBJ_NEW_SMALL_INT(-1) : args[1], false);
+    return mp_obj_list_pop(self, index);
+}
+
+STATIC void mp_quicksort(mp_obj_t *head, mp_obj_t *tail, mp_obj_t key_fn, mp_obj_t binop_less_result) {
+    MP_STACK_CHECK();
+    while (head < tail) {
+        mp_obj_t *h = head - 1;
+        mp_obj_t *t = tail;
+        mp_obj_t v = key_fn == MP_OBJ_NULL ? tail[0] : mp_call_function_1(key_fn, tail[0]); // get pivot using key_fn
+        for (;;) {
+            do {++h;
+            } while (h < t && mp_binary_op(MP_BINARY_OP_LESS, key_fn == MP_OBJ_NULL ? h[0] : mp_call_function_1(key_fn, h[0]), v) == binop_less_result);
+            do {--t;
+            } while (h < t && mp_binary_op(MP_BINARY_OP_LESS, v, key_fn == MP_OBJ_NULL ? t[0] : mp_call_function_1(key_fn, t[0])) == binop_less_result);
+            if (h >= t) {
+                break;
+            }
+            mp_obj_t x = h[0];
+            h[0] = t[0];
+            t[0] = x;
+        }
+        mp_obj_t x = h[0];
+        h[0] = tail[0];
+        tail[0] = x;
+        // do the smaller recursive call first, to keep stack within O(log(N))
+        if (t - head < tail - h - 1) {
+            mp_quicksort(head, t, key_fn, binop_less_result);
+            head = h + 1;
+        } else {
+            mp_quicksort(h + 1, tail, key_fn, binop_less_result);
+            tail = t;
+        }
+    }
+}
+
+// TODO Python defines sort to be stable but ours is not
+mp_obj_t mp_obj_list_sort(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
+    static const mp_arg_t allowed_args[] = {
+        { MP_QSTR_key, MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_rom_obj = MP_ROM_NONE} },
+        { MP_QSTR_reverse, MP_ARG_KW_ONLY | MP_ARG_BOOL, {.u_bool = false} },
+    };
+
+    // parse args
+    struct {
+        mp_arg_val_t key, reverse;
+    } args;
+    mp_arg_parse_all(n_args - 1, pos_args + 1, kw_args,
+        MP_ARRAY_SIZE(allowed_args), allowed_args, (mp_arg_val_t *)&args);
+
+    mp_check_self(mp_obj_is_type(pos_args[0], &mp_type_list));
+    mp_obj_list_t *self = native_list(pos_args[0]);
+
+    if (self->len > 1) {
+        mp_quicksort(self->items, self->items + self->len - 1,
+            args.key.u_obj == mp_const_none ? MP_OBJ_NULL : args.key.u_obj,
+            args.reverse.u_bool ? mp_const_false : mp_const_true);
+    }
+
+    return mp_const_none;
+}
+
+mp_obj_t mp_obj_list_clear(mp_obj_t self_in) {
+    mp_check_self(mp_obj_is_type(self_in, &mp_type_list));
+    mp_obj_list_t *self = native_list(self_in);
+    self->len = 0;
+    self->items = m_renew(mp_obj_t, self->items, self->alloc, LIST_MIN_ALLOC);
+    self->alloc = LIST_MIN_ALLOC;
+    mp_seq_clear(self->items, 0, self->alloc, sizeof(*self->items));
+    return mp_const_none;
+}
+
+STATIC mp_obj_t list_copy(mp_obj_t self_in) {
+    mp_check_self(mp_obj_is_type(self_in, &mp_type_list));
+    mp_obj_list_t *self = native_list(self_in);
+    return mp_obj_new_list(self->len, self->items);
+}
+
+STATIC mp_obj_t list_count(mp_obj_t self_in, mp_obj_t value) {
+    mp_check_self(mp_obj_is_type(self_in, &mp_type_list));
+    mp_obj_list_t *self = native_list(self_in);
+    return mp_seq_count_obj(self->items, self->len, value);
+}
+
+STATIC mp_obj_t list_index(size_t n_args, const mp_obj_t *args) {
+    mp_check_self(mp_obj_is_type(args[0], &mp_type_list));
+    mp_obj_list_t *self = native_list(args[0]);
+    return mp_seq_index_obj(self->items, self->len, n_args, args);
+}
+
+inline void mp_obj_list_insert(mp_obj_list_t *self, size_t index, mp_obj_t obj) {
+    mp_obj_list_append(MP_OBJ_FROM_PTR(self), mp_const_none);
+
+    for (size_t i = self->len - 1; i > index; --i) {
+        self->items[i] = self->items[i - 1];
+    }
+    self->items[index] = obj;
+}
+
+STATIC mp_obj_t list_insert(mp_obj_t self_in, mp_obj_t idx, mp_obj_t obj) {
+    mp_check_self(mp_obj_is_type(self_in, &mp_type_list));
+    mp_obj_list_t *self = native_list(self_in);
+    // insert has its own strange index logic
+    mp_int_t index = MP_OBJ_SMALL_INT_VALUE(idx);
+    if (index < 0) {
+        index += self->len;
+    }
+    if (index < 0) {
+        index = 0;
+    }
+    if ((size_t)index > self->len) {
+        index = self->len;
+    }
+    mp_obj_list_insert(self, index, obj);
+    return mp_const_none;
+}
+
+mp_obj_t mp_obj_list_remove(mp_obj_t self_in, mp_obj_t value) {
+    mp_check_self(mp_obj_is_type(self_in, &mp_type_list));
+    mp_obj_t args[] = {self_in, value};
+    args[1] = list_index(2, args);
+    list_pop(2, args);
+
+    return mp_const_none;
+}
+
+STATIC mp_obj_t list_reverse(mp_obj_t self_in) {
+    mp_check_self(mp_obj_is_type(self_in, &mp_type_list));
+    mp_obj_list_t *self = native_list(self_in);
+
+    mp_int_t len = self->len;
+    for (mp_int_t i = 0; i < len / 2; i++) {
+        mp_obj_t a = self->items[i];
+        self->items[i] = self->items[len - i - 1];
+        self->items[len - i - 1] = a;
+    }
+
+    return mp_const_none;
+}
+
+STATIC MP_DEFINE_CONST_FUN_OBJ_2(list_append_obj, mp_obj_list_append);
+STATIC MP_DEFINE_CONST_FUN_OBJ_2(list_extend_obj, list_extend);
+STATIC MP_DEFINE_CONST_FUN_OBJ_1(list_clear_obj, mp_obj_list_clear);
+STATIC MP_DEFINE_CONST_FUN_OBJ_1(list_copy_obj, list_copy);
+STATIC MP_DEFINE_CONST_FUN_OBJ_2(list_count_obj, list_count);
+STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(list_index_obj, 2, 4, list_index);
+STATIC MP_DEFINE_CONST_FUN_OBJ_3(list_insert_obj, list_insert);
+STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(list_pop_obj, 1, 2, list_pop);
+STATIC MP_DEFINE_CONST_FUN_OBJ_2(list_remove_obj, mp_obj_list_remove);
+STATIC MP_DEFINE_CONST_FUN_OBJ_1(list_reverse_obj, list_reverse);
+STATIC MP_DEFINE_CONST_FUN_OBJ_KW(list_sort_obj, 1, mp_obj_list_sort);
+
+STATIC const mp_rom_map_elem_t list_locals_dict_table[] = {
+    { MP_ROM_QSTR(MP_QSTR_append), MP_ROM_PTR(&list_append_obj) },
+    { MP_ROM_QSTR(MP_QSTR_clear), MP_ROM_PTR(&list_clear_obj) },
+    { MP_ROM_QSTR(MP_QSTR_copy), MP_ROM_PTR(&list_copy_obj) },
+    { MP_ROM_QSTR(MP_QSTR_count), MP_ROM_PTR(&list_count_obj) },
+    { MP_ROM_QSTR(MP_QSTR_extend), MP_ROM_PTR(&list_extend_obj) },
+    { MP_ROM_QSTR(MP_QSTR_index), MP_ROM_PTR(&list_index_obj) },
+    { MP_ROM_QSTR(MP_QSTR_insert), MP_ROM_PTR(&list_insert_obj) },
+    { MP_ROM_QSTR(MP_QSTR_pop), MP_ROM_PTR(&list_pop_obj) },
+    { MP_ROM_QSTR(MP_QSTR_remove), MP_ROM_PTR(&list_remove_obj) },
+    { MP_ROM_QSTR(MP_QSTR_reverse), MP_ROM_PTR(&list_reverse_obj) },
+    { MP_ROM_QSTR(MP_QSTR_sort), MP_ROM_PTR(&list_sort_obj) },
+};
+
+STATIC MP_DEFINE_CONST_DICT(list_locals_dict, list_locals_dict_table);
+
+const mp_obj_type_t mp_type_list = {
+    { &mp_type_type },
+    .flags = MP_TYPE_FLAG_EXTENDED,
+    .name = MP_QSTR_list,
+    .print = list_print,
+    .make_new = list_make_new,
+    .locals_dict = (mp_obj_dict_t *)&list_locals_dict,
+    MP_TYPE_EXTENDED_FIELDS(
+        .unary_op = list_unary_op,
+        .binary_op = list_binary_op,
+        .subscr = list_subscr,
+        .getiter = list_getiter,
+        ),
+};
+
+void mp_obj_list_init(mp_obj_list_t *o, size_t n) {
+    o->base.type = &mp_type_list;
+    o->alloc = n < LIST_MIN_ALLOC ? LIST_MIN_ALLOC : n;
+    o->len = n;
+    o->items = m_new(mp_obj_t, o->alloc);
+    mp_seq_clear(o->items, n, o->alloc, sizeof(*o->items));
+}
+
+STATIC mp_obj_list_t *list_new(size_t n) {
+    mp_obj_list_t *o = m_new_obj(mp_obj_list_t);
+    mp_obj_list_init(o, n);
+    return o;
+}
+
+mp_obj_t mp_obj_new_list(size_t n, mp_obj_t *items) {
+    mp_obj_list_t *o = list_new(n);
+    if (items != NULL) {
+        for (size_t i = 0; i < n; i++) {
+            o->items[i] = items[i];
+        }
+    }
+    return MP_OBJ_FROM_PTR(o);
+}
+
+void mp_obj_list_get(mp_obj_t self_in, size_t *len, mp_obj_t **items) {
+    mp_obj_list_t *self = native_list(self_in);
+    *len = self->len;
+    *items = self->items;
+}
+
+void mp_obj_list_set_len(mp_obj_t self_in, size_t len) {
+    // trust that the caller knows what it's doing
+    // TODO realloc if len got much smaller than alloc
+    mp_obj_list_t *self = MP_OBJ_TO_PTR(self_in);
+    self->len = len;
+}
+
+void mp_obj_list_store(mp_obj_t self_in, mp_obj_t index, mp_obj_t value) {
+    mp_obj_list_t *self = native_list(self_in);
+    size_t i = mp_get_index(self->base.type, self->len, index, false);
+    self->items[i] = value;
+}
+
+/******************************************************************************/
+/* list iterator                                                              */
+
+typedef struct _mp_obj_list_it_t {
+    mp_obj_base_t base;
+    mp_fun_1_t iternext;
+    mp_obj_t list;
+    size_t cur;
+} mp_obj_list_it_t;
+
+STATIC mp_obj_t list_it_iternext(mp_obj_t self_in) {
+    mp_obj_list_it_t *self = MP_OBJ_TO_PTR(self_in);
+    mp_obj_list_t *list = MP_OBJ_TO_PTR(self->list);
+    if (self->cur < list->len) {
+        mp_obj_t o_out = list->items[self->cur];
+        self->cur += 1;
+        return o_out;
+    } else {
+        return MP_OBJ_STOP_ITERATION;
+    }
+}
+
+mp_obj_t mp_obj_new_list_iterator(mp_obj_t list, size_t cur, mp_obj_iter_buf_t *iter_buf) {
+    assert(sizeof(mp_obj_list_it_t) <= sizeof(mp_obj_iter_buf_t));
+    mp_obj_list_it_t *o = (mp_obj_list_it_t *)iter_buf;
+    o->base.type = &mp_type_polymorph_iter;
+    o->iternext = list_it_iternext;
+    o->list = list;
+    o->cur = cur;
+    return MP_OBJ_FROM_PTR(o);
+}