--- /dev/null
+/* Copyright (c) 2004-2017. The SimGrid Team.
+ * All rights reserved. */
+
+/* This program is free software; you can redistribute it and/or modify it
+ * under the terms of the license (GNU LGPL) which comes with this package. */
+
+/* Warning, this module is done to be efficient and performs tons of
+ cast and dirty things. So avoid using it unless you really know
+ what you are doing. */
+
+/* This type should be added to a type that is to be used in such a swag */
+
+#include "swag.h"
+#include "xbt/asserts.h"
+
+#define xbt_swag_getPrev(obj, offset) (((xbt_swag_hookup_t)(((char*)(obj)) + (offset)))->prev)
+#define xbt_swag_getNext(obj, offset) (((xbt_swag_hookup_t)(((char*)(obj)) + (offset)))->next)
+#define xbt_swag_belongs(obj, swag) (xbt_swag_getNext((obj), (swag)->offset) || (swag)->tail == (obj))
+
+static inline void *xbt_swag_getFirst(const_xbt_swag_t swag)
+{
+ return (swag->head);
+}
+
+/*
+ * \brief Offset computation
+ * \arg var a variable of type <tt>struct</tt> something
+ * \arg field a field of <tt>struct</tt> something
+ * \return the offset of \a field in <tt>struct</tt> something.
+ * @hideinitializer
+ *
+ * It is very similar to offsetof except that is done at runtime and that you have to declare a variable. Why defining
+ * such a macro then ? Because it is portable...
+ */
+#define xbt_swag_offset(var, field) ((char*)&((var).field) - (char*)&(var))
+/* @} */
+
+/* Creates a new swag.
+ * \param swag the swag to initialize
+ * \param offset where the hookup is located in the structure
+ * \see xbt_swag_offset
+ *
+ * Usage : xbt_swag_init(swag,&obj.setA-&obj);
+ */
+static inline void xbt_swag_init(xbt_swag_t swag, size_t offset)
+{
+ swag->tail = NULL;
+ swag->head = NULL;
+ swag->offset = offset;
+ swag->count = 0;
+}
+
+/*
+ * \param obj the objet to insert in the swag
+ * \param swag a swag
+ *
+ * insert (at the tail... you probably had a very good reason to do that, I hope you know what you're doing) \a obj in
+ * \a swag
+ */
+static inline void xbt_swag_insert(void *obj, xbt_swag_t swag)
+{
+ xbt_assert(!xbt_swag_belongs(obj, swag) || swag->tail,
+ "This object belongs to an empty swag! Did you correctly initialize the object's hookup?");
+
+ if (!swag->head) {
+ xbt_assert(!(swag->tail), "Inconsistent swag.");
+ swag->head = obj;
+ swag->tail = obj;
+ swag->count++;
+ } else if (obj != swag->tail && !xbt_swag_getNext(obj, swag->offset)) {
+ xbt_swag_getPrev(obj, swag->offset) = swag->tail;
+ xbt_swag_getNext(swag->tail, swag->offset) = obj;
+ swag->tail = obj;
+ swag->count++;
+ }
+}
+
+/*
+ * \param obj the objet to remove from the swag
+ * \param swag a swag
+ * \return \a obj if it was in the \a swag and NULL otherwise
+ *
+ * removes \a obj from \a swag
+ */
+static inline void *xbt_swag_remove(void *obj, xbt_swag_t swag)
+{
+ if (!obj)
+ return NULL;
+
+ size_t offset = swag->offset;
+ void* prev = xbt_swag_getPrev(obj, offset);
+ void* next = xbt_swag_getNext(obj, offset);
+
+ if (prev) {
+ xbt_swag_getNext(prev, offset) = next;
+ xbt_swag_getPrev(obj, offset) = NULL;
+ if (next) {
+ xbt_swag_getPrev(next, offset) = prev;
+ xbt_swag_getNext(obj, offset) = NULL;
+ } else {
+ swag->tail = prev;
+ }
+ swag->count--;
+ } else if (next) {
+ xbt_swag_getPrev(next, offset) = NULL;
+ xbt_swag_getNext(obj, offset) = NULL;
+ swag->head = next;
+ swag->count--;
+ } else if (obj == swag->head) {
+ swag->head = swag->tail = NULL;
+ swag->count--;
+ }
+
+ return obj;
+}
+
+/*
+ * \param swag a swag
+ * \return the number of objects in \a swag
+ */
+static inline int xbt_swag_size(const_xbt_swag_t swag)
+{
+ return (swag->count);
+}
