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authorTakashi Iwai <tiwai@suse.de>2010-01-19 15:53:43 +0100
committerTakashi Iwai <tiwai@suse.de>2010-01-19 15:53:43 +0100
commit9e4c84967ef027fe50a03cf48dd6da9519c8e60c (patch)
tree21d6b8168670f22521f3bb703e3b9d1932566c1c /lib/list_sort.c
parentd2f2fcd2541bae004db7f4798ffd9d2cb75ae817 (diff)
parent3fb4a508b8e7957aa899f32cd6d9d462e102c7ca (diff)
Merge branch 'fix/hda' into topic/hda
Conflicts: sound/pci/hda/patch_realtek.c
Diffstat (limited to 'lib/list_sort.c')
-rw-r--r--lib/list_sort.c102
1 files changed, 102 insertions, 0 deletions
diff --git a/lib/list_sort.c b/lib/list_sort.c
new file mode 100644
index 000000000000..19d11e0bb958
--- /dev/null
+++ b/lib/list_sort.c
@@ -0,0 +1,102 @@
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/list_sort.h>
+#include <linux/slab.h>
+#include <linux/list.h>
+
+/**
+ * list_sort - sort a list.
+ * @priv: private data, passed to @cmp
+ * @head: the list to sort
+ * @cmp: the elements comparison function
+ *
+ * This function has been implemented by Mark J Roberts <mjr@znex.org>. It
+ * implements "merge sort" which has O(nlog(n)) complexity. The list is sorted
+ * in ascending order.
+ *
+ * The comparison function @cmp is supposed to return a negative value if @a is
+ * less than @b, and a positive value if @a is greater than @b. If @a and @b
+ * are equivalent, then it does not matter what this function returns.
+ */
+void list_sort(void *priv, struct list_head *head,
+ int (*cmp)(void *priv, struct list_head *a,
+ struct list_head *b))
+{
+ struct list_head *p, *q, *e, *list, *tail, *oldhead;
+ int insize, nmerges, psize, qsize, i;
+
+ if (list_empty(head))
+ return;
+
+ list = head->next;
+ list_del(head);
+ insize = 1;
+ for (;;) {
+ p = oldhead = list;
+ list = tail = NULL;
+ nmerges = 0;
+
+ while (p) {
+ nmerges++;
+ q = p;
+ psize = 0;
+ for (i = 0; i < insize; i++) {
+ psize++;
+ q = q->next == oldhead ? NULL : q->next;
+ if (!q)
+ break;
+ }
+
+ qsize = insize;
+ while (psize > 0 || (qsize > 0 && q)) {
+ if (!psize) {
+ e = q;
+ q = q->next;
+ qsize--;
+ if (q == oldhead)
+ q = NULL;
+ } else if (!qsize || !q) {
+ e = p;
+ p = p->next;
+ psize--;
+ if (p == oldhead)
+ p = NULL;
+ } else if (cmp(priv, p, q) <= 0) {
+ e = p;
+ p = p->next;
+ psize--;
+ if (p == oldhead)
+ p = NULL;
+ } else {
+ e = q;
+ q = q->next;
+ qsize--;
+ if (q == oldhead)
+ q = NULL;
+ }
+ if (tail)
+ tail->next = e;
+ else
+ list = e;
+ e->prev = tail;
+ tail = e;
+ }
+ p = q;
+ }
+
+ tail->next = list;
+ list->prev = tail;
+
+ if (nmerges <= 1)
+ break;
+
+ insize *= 2;
+ }
+
+ head->next = list;
+ head->prev = list->prev;
+ list->prev->next = head;
+ list->prev = head;
+}
+
+EXPORT_SYMBOL(list_sort);