Init commit, initial version of c heap-sort for generic types

c/data_structures/heap.c

@@ -0,0 +1,54 @@
+#include "heap.h"
+
+// TODO: remove the extra checks for heap_size if i don't need them based on calling
+static int parent(int i) {
+    return (i > 0) ? (i - 1) / 2 : -1;
+}
+
+static int left_child(int i) {
+    return i * 2 + 1;
+}
+
+static int right_child(int i) {
+    return i * 2 + 2;
+}
+
+static int left_sibling(int i) {
+    return (i % 2 == 0) ? i - 1 : -1;
+}
+
+static int right_sibling(int i) {
+    return (i % 2 == 1) ? i + 1 : -1;
+}
+
+void dlos_node_swap(dlos_ComparableNode *arr, int a, int b) {
+    dlos_ComparableNode temp = arr[a];
+    arr[a] = arr[b];
+    arr[b] = temp;
+}
+
+static int index_of_larger_child(int i, dlos_Heap *h) {
+    int larger = left_child(i);
+    if (larger >= h->size) {
+        return -1;
+    }
+    if (larger + 1 < h->size && h->compare(&h->arr[larger], &h->arr[larger + 1]) > 0) {
+        larger = larger + 1;
+    }
+    return larger;
+}
+
+void dlos_sift_down(int i, dlos_Heap *h) {
+    int target = index_of_larger_child(i, h);
+    while (target > 0 && h->compare(&h->arr[i], &h->arr[target]) > 0) {
+        dlos_node_swap(h->arr, i, target);
+        i = target;
+        target = index_of_larger_child(i, h);
+    }
+}
+
+void dlos_max_heap(dlos_Heap *h) {
+    for (int i = parent(h->size - 1); i >= 0; i--) {
+        dlos_sift_down(i, h);
+    }
+}