1 files changed, 103 insertions, 0 deletions
diff --git a/circuitpython/extmod/moduheapq.c b/circuitpython/extmod/moduheapq.c
new file mode 100644
index 0000000..34867a5
--- /dev/null
+++ b/circuitpython/extmod/moduheapq.c
@@ -0,0 +1,103 @@
+// SPDX-FileCopyrightText: 2014 MicroPython & CircuitPython contributors (https://github.com/adafruit/circuitpython/graphs/contributors)
+// SPDX-FileCopyrightText: Copyright (c) 2014 Damien P. George
+//
+// SPDX-License-Identifier: MIT
+
+#include "py/objlist.h"
+#include "py/runtime.h"
+
+#include "supervisor/shared/translate.h"
+
+#if MICROPY_PY_UHEAPQ
+
+// the algorithm here is modelled on CPython's heapq.py
+
+STATIC mp_obj_list_t *uheapq_get_heap(mp_obj_t heap_in) {
+    if (!mp_obj_is_type(heap_in, &mp_type_list)) {
+        mp_raise_TypeError(MP_ERROR_TEXT("heap must be a list"));
+    }
+    return MP_OBJ_TO_PTR(heap_in);
+}
+
+STATIC void uheapq_heap_siftdown(mp_obj_list_t *heap, mp_uint_t start_pos, mp_uint_t pos) {
+    mp_obj_t item = heap->items[pos];
+    while (pos > start_pos) {
+        mp_uint_t parent_pos = (pos - 1) >> 1;
+        mp_obj_t parent = heap->items[parent_pos];
+        if (mp_binary_op(MP_BINARY_OP_LESS, item, parent) == mp_const_true) {
+            heap->items[pos] = parent;
+            pos = parent_pos;
+        } else {
+            break;
+        }
+    }
+    heap->items[pos] = item;
+}
+
+STATIC void uheapq_heap_siftup(mp_obj_list_t *heap, mp_uint_t pos) {
+    mp_uint_t start_pos = pos;
+    mp_uint_t end_pos = heap->len;
+    mp_obj_t item = heap->items[pos];
+    for (mp_uint_t child_pos = 2 * pos + 1; child_pos < end_pos; child_pos = 2 * pos + 1) {
+        // choose right child if it's <= left child
+        if (child_pos + 1 < end_pos && mp_binary_op(MP_BINARY_OP_LESS, heap->items[child_pos], heap->items[child_pos + 1]) == mp_const_false) {
+            child_pos += 1;
+        }
+        // bubble up the smaller child
+        heap->items[pos] = heap->items[child_pos];
+        pos = child_pos;
+    }
+    heap->items[pos] = item;
+    uheapq_heap_siftdown(heap, start_pos, pos);
+}
+
+STATIC mp_obj_t mod_uheapq_heappush(mp_obj_t heap_in, mp_obj_t item) {
+    mp_obj_list_t *heap = uheapq_get_heap(heap_in);
+    mp_obj_list_append(heap_in, item);
+    uheapq_heap_siftdown(heap, 0, heap->len - 1);
+    return mp_const_none;
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_2(mod_uheapq_heappush_obj, mod_uheapq_heappush);
+
+STATIC mp_obj_t mod_uheapq_heappop(mp_obj_t heap_in) {
+    mp_obj_list_t *heap = uheapq_get_heap(heap_in);
+    if (heap->len == 0) {
+        mp_raise_msg(&mp_type_IndexError, MP_ERROR_TEXT("empty heap"));
+    }
+    mp_obj_t item = heap->items[0];
+    heap->len -= 1;
+    heap->items[0] = heap->items[heap->len];
+    heap->items[heap->len] = MP_OBJ_NULL; // so we don't retain a pointer
+    if (heap->len) {
+        uheapq_heap_siftup(heap, 0);
+    }
+    return item;
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_1(mod_uheapq_heappop_obj, mod_uheapq_heappop);
+
+STATIC mp_obj_t mod_uheapq_heapify(mp_obj_t heap_in) {
+    mp_obj_list_t *heap = uheapq_get_heap(heap_in);
+    for (mp_uint_t i = heap->len / 2; i > 0;) {
+        uheapq_heap_siftup(heap, --i);
+    }
+    return mp_const_none;
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_1(mod_uheapq_heapify_obj, mod_uheapq_heapify);
+
+#if !MICROPY_ENABLE_DYNRUNTIME
+STATIC const mp_rom_map_elem_t mp_module_uheapq_globals_table[] = {
+    { MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_uheapq) },
+    { MP_ROM_QSTR(MP_QSTR_heappush), MP_ROM_PTR(&mod_uheapq_heappush_obj) },
+    { MP_ROM_QSTR(MP_QSTR_heappop), MP_ROM_PTR(&mod_uheapq_heappop_obj) },
+    { MP_ROM_QSTR(MP_QSTR_heapify), MP_ROM_PTR(&mod_uheapq_heapify_obj) },
+};
+
+STATIC MP_DEFINE_CONST_DICT(mp_module_uheapq_globals, mp_module_uheapq_globals_table);
+
+const mp_obj_module_t mp_module_uheapq = {
+    .base = { &mp_type_module },
+    .globals = (mp_obj_dict_t *)&mp_module_uheapq_globals,
+};
+#endif
+
+#endif // MICROPY_PY_UHEAPQ