[vlc-commits] codec: add a set of functions to use a plain FIFO

[Steve Lhomme]

vlc | branch: master | Steve Lhomme <robux4 at videolabs.io> | Mon Sep  4 13:59:25 2017 +0200| [fc2257b66b8f0b6ee4ca498cb8f53b1b6b4b3597] | committer: Steve Lhomme

codec: add a set of functions to use a plain FIFO

It's similar to the block FIFO but with no locking.

> http://git.videolan.org/gitweb.cgi/vlc.git/?a=commit;h=fc2257b66b8f0b6ee4ca498cb8f53b1b6b4b3597
---

 modules/codec/vlc_fifo_helper.h | 125 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 125 insertions(+)

diff --git a/modules/codec/vlc_fifo_helper.h b/modules/codec/vlc_fifo_helper.h
new file mode 100644
index 0000000000..49a99b454f
--- /dev/null
+++ b/modules/codec/vlc_fifo_helper.h
@@ -0,0 +1,125 @@
+/*****************************************************************************
+ * vlc_fifo_helper.h: Basic FIFO helper functions
+ *****************************************************************************
+ * Copyright (C) 2017 VLC authors and VideoLAN
+ *
+ * Authors: Steve Lhomme <robux4 at gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation; either version 2.1 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 Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
+ *****************************************************************************/
+
+#ifndef VLC_FIFO_HELPER_H
+#define VLC_FIFO_HELPER_H 1
+
+typedef struct FIFO_ITEM {
+    struct FIFO_ITEM  *p_next;
+} fifo_item_t;
+
+typedef struct
+{
+    fifo_item_t  *p_first;
+    fifo_item_t  **pp_last;
+    size_t     i_depth;
+} fifo_t;
+
+static inline void fifo_Init(fifo_t *p_fifo)
+{
+    p_fifo->p_first = NULL;
+    p_fifo->pp_last = &p_fifo->p_first;
+    p_fifo->i_depth = 0;
+}
+
+static inline void fifo_Release(fifo_t *fifo)
+{
+    assert(fifo->i_depth == 0); /* we should have poped all the items */
+}
+
+static inline size_t fifo_GetCount(fifo_t *fifo)
+{
+    return fifo->i_depth;
+}
+
+static inline fifo_item_t *fifo_Show(fifo_t *p_fifo)
+{
+    fifo_item_t *b;
+
+    assert(p_fifo->p_first != NULL);
+    b = p_fifo->p_first;
+
+    return b;
+}
+
+static inline fifo_item_t *fifo_Get(fifo_t *fifo)
+{
+    fifo_item_t *block = fifo->p_first;
+
+    if (block == NULL)
+        return NULL; /* Nothing to do */
+
+    fifo->p_first = block->p_next;
+    if (block->p_next == NULL)
+        fifo->pp_last = &fifo->p_first;
+    block->p_next = NULL;
+
+    assert(fifo->i_depth > 0);
+    fifo->i_depth--;
+
+    return block;
+}
+
+static inline void fifo_Put(fifo_t *fifo, fifo_item_t *p_item)
+{
+    *(fifo->pp_last) = p_item;
+
+    while (p_item != NULL)
+    {
+        fifo->pp_last = &p_item->p_next;
+        fifo->i_depth++;
+
+        p_item = p_item->p_next;
+    }
+}
+
+/* macro to get the proper item type in/out of the FIFO
+ * The item type must have a field fifo_item_t named fifo
+ */
+#define TYPED_FIFO(type, prefix)                                      \
+static inline void prefix ## _fifo_Init(fifo_t *p_fifo)               \
+{                                                                     \
+    fifo_Init(p_fifo);                                                \
+}                                                                     \
+static inline void prefix ## _fifo_Release(fifo_t *p_fifo)            \
+{                                                                     \
+    fifo_Release(p_fifo);                                             \
+}                                                                     \
+static inline void prefix ## _fifo_Put(fifo_t *p_fifo, type *p_item)  \
+{                                                                     \
+    fifo_Put(p_fifo, &p_item->fifo);                                  \
+}                                                                     \
+static inline type *prefix ## _fifo_Get(fifo_t *p_fifo)               \
+{                                                                     \
+    return (type*)fifo_Get(p_fifo);                                   \
+}                                                                     \
+static inline type *prefix ## _fifo_Show(fifo_t *p_fifo)              \
+{                                                                     \
+    return (type*)fifo_Show(p_fifo);                                  \
+}                                                                     \
+static inline size_t prefix ## _fifo_GetCount(fifo_t *fifo)           \
+{                                                                     \
+    return fifo->i_depth;                                             \
+}
+
+
+#endif /* VLC_FIFO_HELPER_H */