Add the implementation of list, used by semaphore.

2 files changed, 116 insertions, 0 deletions

diff --git a/libddekit/list.c b/libddekit/list.c
new file mode 100644
index 00000000..992ea9ad
--- /dev/null
+++ b/libddekit/list.c
@@ -0,0 +1,74 @@
+/* 
+   Copyright (C) 2009 Free Software Foundation, Inc.
+   Written by Zheng Da.
+
+   This file is part of the GNU Hurd.
+
+   The GNU Hurd 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 2, or (at your option)
+   any later version.
+
+   The GNU Hurd 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 the GNU Hurd; see the file COPYING.  If not, write to
+   the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */
+
+/* This file implements a double linked list. */
+
+#include "list.h"
+
+void entry_init (struct list *entry)
+{
+  entry->next = entry;
+  entry->prev = entry;
+}
+
+void add_entry_head (struct list *head, struct list *entry)
+{
+  entry->next = head->next;
+  head->next->prev = entry;
+  head->next = entry;
+  entry->prev = head;
+}
+
+void add_entry_end (struct list *head, struct list *entry)
+{
+  entry->next = head;
+  entry->prev = head->prev;
+  head->prev->next = entry;
+  head->prev = entry;
+}
+
+struct list *remove_entry_head (struct list *head)
+{
+  struct list *entry = head->next;
+
+  if (EMPTY_ENTRY (entry))
+    return NULL;
+  
+  remove_entry (entry);
+  return entry;
+}
+
+struct list *remove_entry_end (struct list *head)
+{
+  struct list *entry = head->prev;
+
+  if (EMPTY_ENTRY (entry))
+    return NULL;
+  
+  remove_entry (entry);
+  return entry;
+}
+
+void remove_entry (struct list *entry)
+{
+  entry->next->prev = entry->prev;
+  entry->prev->next = entry->next;
+}
+
diff --git a/libddekit/list.h b/libddekit/list.h
new file mode 100644
index 00000000..e6ee48bc
--- /dev/null
+++ b/libddekit/list.h
@@ -0,0 +1,42 @@
+/* 
+   Copyright (C) 2009 Free Software Foundation, Inc.
+   Written by Zheng Da.
+
+   This file is part of the GNU Hurd.
+
+   The GNU Hurd 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 2, or (at your option)
+   any later version.
+
+   The GNU Hurd 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 the GNU Hurd; see the file COPYING.  If not, write to
+   the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */
+
+#ifndef __LIST_H__
+#define __LIST_H__
+
+#include <stddef.h>
+
+struct list 
+{
+  struct list *next, *prev;
+};
+
+void entry_init (struct list *entry);
+void add_entry_head (struct list *head, struct list *entry);
+void add_entry_end (struct list *head, struct list *entry);
+struct list *remove_entry_head (struct list *head);
+struct list *remove_entry_end (struct list *head);
+void remove_entry (struct list *entry);
+
+#define LIST_HEADER(head) struct list head = {&head, &head}
+#define EMPTY_LIST(head) ((head)->next == (head))
+#define LIST_ENTRY(entry, type, field) ((type *) (((char *) entry) - offsetof (type, field)))
+
+#endif