memory: add more examples

Add an example of a custom allocator with a custom API.

tests/examples/memory/Makefile.am

@@ -1,5 +1,5 @@
 noinst_PROGRAMS = memory_test
 
-memory_test_SOURCES = memory_test.c my-memory.c my-memory.h
+memory_test_SOURCES = memory_test.c my-memory.c my-memory.h my-vidmem.c my-vidmem.h
 memory_test_LDADD = $(GST_OBJ_LIBS)
 memory_test_CFLAGS = $(GST_OBJ_CFLAGS)

tests/examples/memory/memory_test.c

@@ -6,6 +6,7 @@
 #include <gst/gst.h>
 
 #include "my-memory.h"
+#include "my-vidmem.h"
 
 int
 main (int argc, char **argv)
@@ -14,9 +15,11 @@ main (int argc, char **argv)
   GstMemory *mem;
   GstAllocationParams params;
   GstMapInfo info;
+  guint f, w, h;
 
   gst_init (&argc, &argv);
 
+  /* memory using the default API */
   my_memory_init ();
 
   alloc = gst_allocator_find ("MyMemory");
@@ -28,6 +31,29 @@ main (int argc, char **argv)
   gst_memory_unmap (mem, &info);
 
   gst_memory_unref (mem);
+  gst_allocator_unref (alloc);
+
+  /* allocator with custom alloc API */
+  my_vidmem_init ();
+
+  /* we can get the allocator but we can only make objects from it when we know
+   * the API */
+  alloc = gst_allocator_find ("MyVidmem");
+
+  /* use custom api to alloc */
+  mem = my_vidmem_alloc (0, 640, 480);
+  g_assert (my_is_vidmem (mem));
+
+  my_vidmem_get_format (mem, &f, &w, &h);
+  g_assert (f == 0);
+  g_assert (w == 640);
+  g_assert (h == 480);
+
+  gst_memory_map (mem, &info, GST_MAP_READ);
+  gst_memory_unmap (mem, &info);
+
+  gst_memory_unref (mem);
+  gst_allocator_unref (alloc);
 
   return 0;
 }

tests/examples/memory/my-memory.h

@@ -19,5 +19,7 @@
 
 #include <gst/gst.h>
 
+/* example of an allocator that delays allocation of the memory
+ * until the memory is mapped */
 void my_memory_init (void);
 

tests/examples/memory/my-vidmem.c

@@ -0,0 +1,167 @@
+/* GStreamer
+ * Copyright (C) 2012 Wim Taymans <wim.taymans@gmail.be>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#include "my-vidmem.h"
+
+static GstAllocator *_my_allocator;
+
+typedef struct
+{
+  GstMemory mem;
+
+  guint format;
+  guint width;
+  guint height;
+  gpointer data;
+
+} MyVidmem;
+
+
+static GstMemory *
+_my_alloc_alloc (GstAllocator * allocator, gsize size,
+    GstAllocationParams * params, gpointer user_data)
+{
+  g_warning ("Use my_vidmem_alloc() to allocate from this allocator");
+
+  return NULL;
+}
+
+static gpointer
+_my_vidmem_map (MyVidmem * mem, gsize maxsize, GstMapFlags flags)
+{
+  gpointer res;
+
+  while (TRUE) {
+    if ((res = g_atomic_pointer_get (&mem->data)) != NULL)
+      break;
+
+    res = g_malloc (maxsize);
+
+    if (g_atomic_pointer_compare_and_exchange (&mem->data, NULL, res))
+      break;
+
+    g_free (res);
+  }
+
+  GST_DEBUG ("%p: mapped %p", mem, res);
+
+  return res;
+}
+
+static gboolean
+_my_vidmem_unmap (MyVidmem * mem)
+{
+  GST_DEBUG ("%p: unmapped", mem);
+  return TRUE;
+}
+
+static void
+_my_vidmem_free (MyVidmem * mem)
+{
+  g_free (mem->data);
+  g_slice_free (MyVidmem, mem);
+  GST_DEBUG ("%p: freed", mem);
+}
+
+static MyVidmem *
+_my_vidmem_share (MyVidmem * mem, gssize offset, gsize size)
+{
+  MyVidmem *sub;
+  GstMemory *parent;
+
+  GST_DEBUG ("%p: share %" G_GSSIZE_FORMAT, G_GSIZE_FORMAT, mem, offset, size);
+
+  /* find the real parent */
+  if ((parent = mem->mem.parent) == NULL)
+    parent = (GstMemory *) mem;
+
+  if (size == -1)
+    size = mem->mem.size - offset;
+
+  sub = g_slice_new (MyVidmem);
+  /* the shared memory is always readonly */
+  gst_memory_init (GST_MEMORY_CAST (sub), GST_MINI_OBJECT_FLAGS (parent) |
+      GST_MINI_OBJECT_FLAG_LOCK_READONLY, mem->mem.allocator, parent,
+      mem->mem.maxsize, mem->mem.align, mem->mem.offset + offset, size);
+
+  /* install pointer */
+  sub->data = _my_vidmem_map (mem, mem->mem.maxsize, GST_MAP_READ);
+
+  return sub;
+}
+
+void
+my_vidmem_init (void)
+{
+  static const GstMemoryInfo info = {
+    "MyVidmem",
+    (GstAllocatorAllocFunction) _my_alloc_alloc,
+    (GstMemoryMapFunction) _my_vidmem_map,
+    (GstMemoryUnmapFunction) _my_vidmem_unmap,
+    (GstMemoryFreeFunction) _my_vidmem_free,
+    (GstMemoryCopyFunction) NULL,
+    (GstMemoryShareFunction) _my_vidmem_share,
+    (GstMemoryIsSpanFunction) NULL,
+  };
+
+  _my_allocator = gst_allocator_new (&info, NULL, NULL);
+
+  gst_allocator_register ("MyVidmem", gst_allocator_ref (_my_allocator));
+}
+
+
+GstMemory *
+my_vidmem_alloc (guint format, guint width, guint height)
+{
+  MyVidmem *mem;
+  gsize maxsize;
+
+  GST_DEBUG ("alloc frame format %u %ux%u", format, width, height);
+
+  maxsize = (GST_ROUND_UP_4 (width) * height);
+
+  mem = g_slice_new (MyVidmem);
+
+  gst_memory_init (GST_MEMORY_CAST (mem), 0, _my_allocator, NULL,
+      maxsize, 31, 0, maxsize);
+
+  mem->format = format;
+  mem->width = width;
+  mem->height = height;
+  mem->data = NULL;
+
+  return (GstMemory *) mem;
+}
+
+gboolean
+my_is_vidmem (GstMemory * mem)
+{
+  return mem->allocator == _my_allocator;
+}
+
+void
+my_vidmem_get_format (GstMemory * mem, guint * format, guint * width,
+    guint * height)
+{
+  MyVidmem *vmem = (MyVidmem *) mem;
+
+  *format = vmem->format;
+  *width = vmem->width;
+  *height = vmem->height;
+}

tests/examples/memory/my-vidmem.h

@@ -0,0 +1,31 @@
+/* GStreamer
+ * Copyright (C) 2012 Wim Taymans <wim.taymans@gmail.be>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#include <gst/gst.h>
+
+/* example of an allocator that needs a custom alloc function */
+void my_vidmem_init (void);
+
+GstMemory * my_vidmem_alloc             (guint format, guint width, guint height);
+
+gboolean    my_is_vidmem                (GstMemory *mem);
+
+void        my_vidmem_get_format        (GstMemory *mem, guint *format,
+                                         guint *width, guint *height);
+