Create linked list interface.

src/llist.h

@@ -0,0 +1,57 @@
+/*
+ * Copyright (C) 2019  Ortega Froysa, Nicolás <nicolas@ortegas.org>
+ * Author: Ortega Froysa, Nicolás <nicolas@ortegas.org>
+ *
+ * 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, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include <gmp.h>
+
+struct llist_item {
+	mpz_t n; // the number stored
+	struct llist_item *next; // the next element in the list
+	struct llist_item *prev; // the previous element in the list
+};
+
+struct llist {
+	struct llist_item *first; // first element of the list
+	struct llist_item *last; // last element of the list
+	size_t size; // number of elements in the list
+};
+
+/*
+ * initialize an empty linked list where `first` and `last` are
+ * equal to NULL and `size` is 0.
+ */
+void llist_init(struct llist *list);
+
+/*
+ * free all space allocated to the list.
+ */
+void llist_deinit(struct llist *list);
+
+/*
+ * insert an item at the end of the linked list with value `n`.
+ *
+ * returns 1 on success, 0 on failure.
+ */
+int llist_insert(struct llist *list, mpz_t n);
+/*
+ * insert an item in the linked list in a sorted position.
+ *
+ * returns 1 on success, 0 on failure.
+ */
+int llist_sorted_insert(struct llist *list, mpz_t n);