Add eli

1 files changed, 84 insertions, 0 deletions

diff --git a/src/eli.h b/src/eli.h
new file mode 100644
index 0000000..8cd75a6
--- /dev/null
+++ b/src/eli.h
@@ -0,0 +1,84 @@
+/*
+Copyright (C) 2017 Paweł Redman
+
+This program is free software; you can redistribute it and/or
+modify it under the terms of the GNU General Public License
+as published by the Free Software Foundation; either version 3
+of the License, or (at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program; if not, write to the Free Software Foundation,
+Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301  USA
+*/
+
+#include <stddef.h> // size_t
+
+#define eli_rebase(x, xm, y) \
+((void*)((char*)(y) + ((char*)(xm) - (char*)(x))))
+
+typedef struct {
+	void *prev, *next;
+} eli_header;
+
+// Link an element to the end of a list.
+static inline void eli_append_real(void **head, void *entry,
+                                   eli_header *head_h, eli_header *entry_h)
+{
+	eli_header *last_h;
+
+	// Empty list.
+	if (__builtin_expect(!*head, 0)) {
+		*head = entry;
+		entry_h->prev = entry;
+		entry_h->next = NULL;
+		return;
+	}
+
+	entry_h->prev = head_h->prev;
+	entry_h->next = NULL;
+
+	last_h = eli_rebase(entry, entry_h, head_h->prev);
+	last_h->next = entry;
+
+	head_h->prev = entry;
+}
+
+#define eli_append(pphead, entry, member) \
+eli_append_real((void**)(pphead), (entry), &((*(pphead))->member), &((entry)->member))
+
+// Unlink an element (from anywhere in a list).
+static inline void eli_unlink_real(void **head, void *entry,
+                                   eli_header *head_h, eli_header *entry_h)
+{
+	if (entry_h->prev && *head != entry) {
+		eli_header *prev_h;
+
+		prev_h = eli_rebase(entry, entry_h, head_h->prev);
+		prev_h->next = entry_h->next;
+	}
+
+	if (entry_h->next) {
+		eli_header *next_h;
+
+		next_h = eli_rebase(entry, entry_h, head_h->next);
+		next_h->prev = entry_h->prev;
+	} else {
+		head_h->prev = entry_h->prev;
+	}
+
+	if (*head == entry)
+		*head = entry_h->next;
+
+}
+
+#define eli_unlink(pphead, entry, member) \
+eli_unlink_real((void**)(pphead), (entry), &((*(pphead))->member), &((entry)->member))
+
+// Loop over a list
+#define eli_for(i, head, member) \
+for ((i) = (head); (i); (i) = (i)->member.next)