extmod/moduheapq: Adhoc changes to support ordering by utime.ticks_ms().

As required for further elaboration of uasyncio, like supporting baremetal
systems with wraparound timesources. This is not intended to be public
interface, and likely will be further refactored in the future.

1 files changed, 50 insertions, 14 deletions

diff --git a/extmod/moduheapq.c b/extmod/moduheapq.c
index 567ee83da..94e1faa51 100644
--- a/extmod/moduheapq.c
+++ b/extmod/moduheapq.c
@@ -28,9 +28,12 @@
 #include "py/objlist.h"
 #include "py/runtime0.h"
 #include "py/runtime.h"
+#include "py/smallint.h"
 
 #if MICROPY_PY_UHEAPQ
 
+#define MODULO MICROPY_PY_UTIME_TICKS_PERIOD
+
 // the algorithm here is modelled on CPython's heapq.py
 
 STATIC mp_obj_list_t *get_heap(mp_obj_t heap_in) {
@@ -40,12 +43,33 @@ STATIC mp_obj_list_t *get_heap(mp_obj_t heap_in) {
     return MP_OBJ_TO_PTR(heap_in);
 }
 
-STATIC void heap_siftdown(mp_obj_list_t *heap, mp_uint_t start_pos, mp_uint_t pos) {
+STATIC bool time_less_than(mp_obj_t item, mp_obj_t parent) {
+    if (!MP_OBJ_IS_TYPE(item, &mp_type_tuple) || !MP_OBJ_IS_TYPE(parent, &mp_type_tuple)) {
+        mp_raise_TypeError("");
+    }
+    mp_obj_tuple_t *item_p = MP_OBJ_TO_PTR(item);
+    mp_obj_tuple_t *parent_p = MP_OBJ_TO_PTR(parent);
+    mp_uint_t item_tm = MP_OBJ_SMALL_INT_VALUE(item_p->items[0]);
+    mp_uint_t parent_tm = MP_OBJ_SMALL_INT_VALUE(parent_p->items[0]);
+    mp_uint_t res = parent_tm - item_tm;
+    if ((mp_int_t)res < 0) {
+        res += MODULO;
+    }
+    return res < (MODULO / 2);
+}
+
+STATIC void heap_siftdown(mp_obj_list_t *heap, mp_uint_t start_pos, mp_uint_t pos, bool timecmp) {
     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) {
+        bool lessthan;
+        if (MP_UNLIKELY(timecmp)) {
+            lessthan = time_less_than(item, parent);
+        } else {
+            lessthan = (mp_binary_op(MP_BINARY_OP_LESS, item, parent) == mp_const_true);
+        }
+        if (lessthan) {
             heap->items[pos] = parent;
             pos = parent_pos;
         } else {
@@ -55,32 +79,43 @@ STATIC void heap_siftdown(mp_obj_list_t *heap, mp_uint_t start_pos, mp_uint_t po
     heap->items[pos] = item;
 }
 
-STATIC void heap_siftup(mp_obj_list_t *heap, mp_uint_t pos) {
+STATIC void heap_siftup(mp_obj_list_t *heap, mp_uint_t pos, bool timecmp) {
     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;
+        if (child_pos + 1 < end_pos) {
+            bool lessthan;
+            if (MP_UNLIKELY(timecmp)) {
+                lessthan = time_less_than(heap->items[child_pos], heap->items[child_pos + 1]);
+            } else {
+                lessthan = (mp_binary_op(MP_BINARY_OP_LESS, heap->items[child_pos], heap->items[child_pos + 1]) == mp_const_true);
+            }
+            if (!lessthan) {
+                child_pos += 1;
+            }
         }
         // bubble up the smaller child
         heap->items[pos] = heap->items[child_pos];
         pos = child_pos;
     }
     heap->items[pos] = item;
-    heap_siftdown(heap, start_pos, pos);
+    heap_siftdown(heap, start_pos, pos, timecmp);
 }
 
-STATIC mp_obj_t mod_uheapq_heappush(mp_obj_t heap_in, mp_obj_t item) {
+STATIC mp_obj_t mod_uheapq_heappush(size_t n_args, const mp_obj_t *args) {
+    mp_obj_t heap_in = args[0];
     mp_obj_list_t *heap = get_heap(heap_in);
-    mp_obj_list_append(heap_in, item);
-    heap_siftdown(heap, 0, heap->len - 1);
+    mp_obj_list_append(heap_in, args[1]);
+    bool is_timeq = (n_args > 2 && args[2] == mp_const_true);
+    heap_siftdown(heap, 0, heap->len - 1, is_timeq);
     return mp_const_none;
 }
-STATIC MP_DEFINE_CONST_FUN_OBJ_2(mod_uheapq_heappush_obj, mod_uheapq_heappush);
+STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mod_uheapq_heappush_obj, 2, 3, mod_uheapq_heappush);
 
-STATIC mp_obj_t mod_uheapq_heappop(mp_obj_t heap_in) {
+STATIC mp_obj_t mod_uheapq_heappop(size_t n_args, const mp_obj_t *args) {
+    mp_obj_t heap_in = args[0];
     mp_obj_list_t *heap = get_heap(heap_in);
     if (heap->len == 0) {
         nlr_raise(mp_obj_new_exception_msg(&mp_type_IndexError, "empty heap"));
@@ -90,16 +125,17 @@ STATIC mp_obj_t mod_uheapq_heappop(mp_obj_t heap_in) {
     heap->items[0] = heap->items[heap->len];
     heap->items[heap->len] = MP_OBJ_NULL; // so we don't retain a pointer
     if (heap->len) {
-        heap_siftup(heap, 0);
+        bool is_timeq = (n_args > 1 && args[1] == mp_const_true);
+        heap_siftup(heap, 0, is_timeq);
     }
     return item;
 }
-STATIC MP_DEFINE_CONST_FUN_OBJ_1(mod_uheapq_heappop_obj, mod_uheapq_heappop);
+STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mod_uheapq_heappop_obj, 1, 2, mod_uheapq_heappop);
 
 STATIC mp_obj_t mod_uheapq_heapify(mp_obj_t heap_in) {
     mp_obj_list_t *heap = get_heap(heap_in);
     for (mp_uint_t i = heap->len / 2; i > 0;) {
-        heap_siftup(heap, --i);
+        heap_siftup(heap, --i, false);
     }
     return mp_const_none;
 }