[Pixman] [PATCH v2 1/8] Add doubly linked lists
Søren Sandmann
sandmann at cs.au.dk
Sat Jun 2 06:23:50 PDT 2012
From: Søren Sandmann Pedersen <ssp at redhat.com>
This commit adds some new inline functions to maintain a doubly linked
list.
The way to use them is to embed a pixman_link_t into the structures
that should be linked, and use a pixman_list_t as the head of the
list.
The new functions are
pixman_list_init (pixman_list_t *list);
pixman_list_prepend (pixman_list_t *list, pixman_link_t *link);
pixman_list_move_to_front (pixman_list_t *list, pixman_link_t *link);
There are also a new macro:
CONTAINER_OF(type, member, data);
that can be used to get from a pointer to a member to the containing
structure.
V2: Use the C89 macro offsetof() instead of rolling our own -
suggested by Alan Coopersmith.
---
pixman/pixman-compiler.h | 4 ++++
pixman/pixman-private.h | 45 +++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 49 insertions(+)
diff --git a/pixman/pixman-compiler.h b/pixman/pixman-compiler.h
index ffd5172..a978acc 100644
--- a/pixman/pixman-compiler.h
+++ b/pixman/pixman-compiler.h
@@ -89,6 +89,10 @@
# define PIXMAN_EXPORT
#endif
+/* member offsets */
+#define CONTAINER_OF(type, member, data) \
+ ((type *)(((uint8_t *)data) - offsetof (type, member)))
+
/* TLS */
#if defined(PIXMAN_NO_TLS)
diff --git a/pixman/pixman-private.h b/pixman/pixman-private.h
index f4ca632..76d65e2 100644
--- a/pixman/pixman-private.h
+++ b/pixman/pixman-private.h
@@ -13,6 +13,7 @@
#include <assert.h>
#include <stdio.h>
#include <string.h>
+#include <stddef.h>
#include "pixman-compiler.h"
@@ -736,6 +737,50 @@ pixman_bool_t
pixman_region16_copy_from_region32 (pixman_region16_t *dst,
pixman_region32_t *src);
+/* Doubly linked lists */
+typedef struct pixman_link_t pixman_link_t;
+struct pixman_link_t
+{
+ pixman_link_t *next;
+ pixman_link_t *prev;
+};
+
+typedef struct pixman_list_t pixman_list_t;
+struct pixman_list_t
+{
+ pixman_link_t *head;
+ pixman_link_t *tail;
+};
+
+static force_inline void
+pixman_list_init (pixman_list_t *list)
+{
+ list->head = (pixman_link_t *)list;
+ list->tail = (pixman_link_t *)list;
+}
+
+static force_inline void
+pixman_list_prepend (pixman_list_t *list, pixman_link_t *link)
+{
+ link->next = list->head;
+ link->prev = (pixman_link_t *)list;
+ list->head->prev = link;
+ list->head = link;
+}
+
+static force_inline void
+pixman_list_unlink (pixman_link_t *link)
+{
+ link->prev->next = link->next;
+ link->next->prev = link->prev;
+}
+
+static force_inline void
+pixman_list_move_to_front (pixman_list_t *list, pixman_link_t *link)
+{
+ pixman_list_unlink (link);
+ pixman_list_prepend (list, link);
+}
/* Misc macros */
--
1.7.10.2
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