Virtio-loopback-adapter Beta version for review:

- Beta version of the code to be discussed during the review planned on the 09/11/2022
- Before being merged into master, this code might be changed with fixes and optimization

Signed-off-by: Timos Ampelikiotis <t.ampelikiotis@virtualopensystems.com>

1 files changed, 142 insertions, 0 deletions

diff --git a/queue.h b/queue.h
new file mode 100644
index 0000000..a2505e2
--- /dev/null
+++ b/queue.h
@@ -0,0 +1,142 @@
+/*      $NetBSD: queue.h,v 1.52 2009/04/20 09:56:08 mschuett Exp $ */
+
+/*
+ * QEMU version: Copy from netbsd, removed debug code, removed some of
+ * the implementations.  Left in singly-linked lists, lists, simple
+ * queues, and tail queues.
+ */
+
+/*
+ * Based on queue.h of QEMU project
+ *
+ *   Copyright (c) 1991, 1993
+ *    The Regents of the University of California.  All rights reserved.
+ *
+ * Copyright (c) 2022 Virtual Open Systems SAS.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ *      @(#)queue.h     8.5 (Berkeley) 8/20/94
+ */
+
+#ifndef QEMU_SYS_QUEUE_H
+#define QEMU_SYS_QUEUE_H
+
+/*
+ * This file defines four types of data structures: singly-linked lists,
+ * lists, simple queues, and tail queues.
+ *
+ * A singly-linked list is headed by a single forward pointer. The
+ * elements are singly linked for minimum space and pointer manipulation
+ * overhead at the expense of O(n) removal for arbitrary elements. New
+ * elements can be added to the list after an existing element or at the
+ * head of the list.  Elements being removed from the head of the list
+ * should use the explicit macro for this purpose for optimum
+ * efficiency. A singly-linked list may only be traversed in the forward
+ * direction.  Singly-linked lists are ideal for applications with large
+ * datasets and few or no removals or for implementing a LIFO queue.
+ *
+ * A list is headed by a single forward pointer (or an array of forward
+ * pointers for a hash table header). The elements are doubly linked
+ * so that an arbitrary element can be removed without a need to
+ * traverse the list. New elements can be added to the list before
+ * or after an existing element or at the head of the list. A list
+ * may only be traversed in the forward direction.
+ *
+ * A simple queue is headed by a pair of pointers, one the head of the
+ * list and the other to the tail of the list. The elements are singly
+ * linked to save space, so elements can only be removed from the
+ * head of the list. New elements can be added to the list after
+ * an existing element, at the head of the list, or at the end of the
+ * list. A simple queue may only be traversed in the forward direction.
+ *
+ * A tail queue is headed by a pair of pointers, one to the head of the
+ * list and the other to the tail of the list. The elements are doubly
+ * linked so that an arbitrary element can be removed without a need to
+ * traverse the list. New elements can be added to the list before or
+ * after an existing element, at the head of the list, or at the end of
+ * the list. A tail queue may be traversed in either direction.
+ *
+ * For details on the use of these macros, see the queue(3) manual page.
+ */
+
+
+typedef struct QTailQLink {
+    void *tql_next;
+    struct QTailQLink *tql_prev;
+} QTailQLink;
+
+/*
+ * Tail queue definitions.  The union acts as a poor man template, as if
+ * it were QTailQLink<type>.
+ */
+#define QTAILQ_HEAD(name, type)                                     \
+union name {                                                        \
+    struct type *tqh_first;                                         \
+    QTailQLink tqh_circ;                                            \
+}
+
+#define QTAILQ_HEAD_INITIALIZER(head)                               \
+    { .tqh_circ = { NULL, &(head).tqh_circ } }
+
+#define QTAILQ_ENTRY(type)                                          \
+union {                                                             \
+    struct type *tqe_next;                                          \
+    QTailQLink tqe_circ;                                            \
+}
+
+/*
+ * Tail queue functions.
+ */
+#define QTAILQ_INIT(head) do {                                      \
+    (head)->tqh_first = NULL;                                       \
+    (head)->tqh_circ.tql_prev = &(head)->tqh_circ;                  \
+} while (0)
+
+#define QTAILQ_INSERT_TAIL(head, elm, field) do {                   \
+    (elm)->field.tqe_next = NULL;                                   \
+    (elm)->field.tqe_circ.tql_prev = (head)->tqh_circ.tql_prev;     \
+    (head)->tqh_circ.tql_prev->tql_next = (elm);                    \
+    (head)->tqh_circ.tql_prev = &(elm)->field.tqe_circ;             \
+} while (0)
+
+
+#define QTAILQ_FOREACH(var, head, field)                            \
+    for ((var) = ((head)->tqh_first);                               \
+            (var);                                                  \
+            (var) = ((var)->field.tqe_next))
+
+/*
+ * Tail queue access methods.
+ */
+#define QTAILQ_EMPTY(head)               ((head)->tqh_first == NULL)
+#define QTAILQ_FIRST(head)               ((head)->tqh_first)
+#define QTAILQ_NEXT(elm, field)          ((elm)->field.tqe_next)
+
+#define field_at_offset(base, offset, type)                                \
+    ((type *) (((char *) (base)) + (offset)))
+
+
+#endif /* QEMU_SYS_QUEUE_H */