+/*
+ * Any merge of blames happens on lists of blames that arrived via
+ * different parents in a single suspect. In this case, we want to
+ * sort according to the suspect line numbers as opposed to the final
+ * image line numbers. The function body is somewhat longish because
+ * it avoids unnecessary writes.
+ */
+
+static struct blame_entry *blame_merge(struct blame_entry *list1,
+ struct blame_entry *list2)
+{
+ struct blame_entry *p1 = list1, *p2 = list2,
+ **tail = &list1;
+
+ if (!p1)
+ return p2;
+ if (!p2)
+ return p1;
+
+ if (p1->s_lno <= p2->s_lno) {
+ do {
+ tail = &p1->next;
+ if ((p1 = *tail) == NULL) {
+ *tail = p2;
+ return list1;
+ }
+ } while (p1->s_lno <= p2->s_lno);
+ }
+ for (;;) {
+ *tail = p2;
+ do {
+ tail = &p2->next;
+ if ((p2 = *tail) == NULL) {
+ *tail = p1;
+ return list1;
+ }
+ } while (p1->s_lno > p2->s_lno);
+ *tail = p1;
+ do {
+ tail = &p1->next;
+ if ((p1 = *tail) == NULL) {
+ *tail = p2;
+ return list1;
+ }
+ } while (p1->s_lno <= p2->s_lno);
+ }
+}
+
+static void *get_next_blame(const void *p)
+{
+ return ((struct blame_entry *)p)->next;
+}
+
+static void set_next_blame(void *p1, void *p2)
+{
+ ((struct blame_entry *)p1)->next = p2;
+}
+
+/*
+ * Final image line numbers are all different, so we don't need a
+ * three-way comparison here.
+ */
+
+static int compare_blame_final(const void *p1, const void *p2)
+{
+ return ((struct blame_entry *)p1)->lno > ((struct blame_entry *)p2)->lno
+ ? 1 : -1;
+}
+
+static int compare_blame_suspect(const void *p1, const void *p2)
+{
+ const struct blame_entry *s1 = p1, *s2 = p2;
+ /*
+ * to allow for collating suspects, we sort according to the
+ * respective pointer value as the primary sorting criterion.
+ * The actual relation is pretty unimportant as long as it
+ * establishes a total order. Comparing as integers gives us
+ * that.
+ */
+ if (s1->suspect != s2->suspect)
+ return (intptr_t)s1->suspect > (intptr_t)s2->suspect ? 1 : -1;
+ if (s1->s_lno == s2->s_lno)
+ return 0;
+ return s1->s_lno > s2->s_lno ? 1 : -1;
+}
+
+static struct blame_entry *blame_sort(struct blame_entry *head,
+ int (*compare_fn)(const void *, const void *))
+{
+ return llist_mergesort (head, get_next_blame, set_next_blame, compare_fn);
+}
+
+static int compare_commits_by_reverse_commit_date(const void *a,
+ const void *b,
+ void *c)
+{
+ return -compare_commits_by_commit_date(a, b, c);
+}
+