1 /* GStreamer
2 * Copyright (C) 2012 Wim Taymans <wim.taymans@gmail.be>
3 *
4 * This library is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU Library General Public
6 * License as published by the Free Software Foundation; either
7 * version 2 of the License, or (at your option) any later version.
8 *
9 * This library is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * Library General Public License for more details.
13 *
14 * You should have received a copy of the GNU Library General Public
15 * License along with this library; if not, write to the
16 * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
17 * Boston, MA 02110-1301, USA.
18 */
19
20 #include "my-memory.h"
21
22 typedef struct
23 {
24 GstMemory mem;
25
26 gpointer data;
27
28 } MyMemory;
29
30
31 static GstMemory *
_my_alloc(GstAllocator * allocator,gsize size,GstAllocationParams * params)32 _my_alloc (GstAllocator * allocator, gsize size, GstAllocationParams * params)
33 {
34 MyMemory *mem;
35 gsize maxsize = size + params->prefix + params->padding;
36
37 GST_DEBUG ("alloc from allocator %p", allocator);
38
39 mem = g_slice_new (MyMemory);
40
41 gst_memory_init (GST_MEMORY_CAST (mem), params->flags, allocator, NULL,
42 maxsize, params->align, params->prefix, size);
43
44 mem->data = NULL;
45
46 return (GstMemory *) mem;
47 }
48
49 static void
_my_free(GstAllocator * allocator,GstMemory * mem)50 _my_free (GstAllocator * allocator, GstMemory * mem)
51 {
52 MyMemory *mmem = (MyMemory *) mem;
53
54 g_free (mmem->data);
55 g_slice_free (MyMemory, mmem);
56 GST_DEBUG ("%p: freed", mmem);
57 }
58
59 static gpointer
_my_mem_map(MyMemory * mem,gsize maxsize,GstMapFlags flags)60 _my_mem_map (MyMemory * mem, gsize maxsize, GstMapFlags flags)
61 {
62 gpointer res;
63
64 while (TRUE) {
65 if ((res = g_atomic_pointer_get (&mem->data)) != NULL)
66 break;
67
68 res = g_malloc (maxsize);
69
70 if (g_atomic_pointer_compare_and_exchange (&mem->data, NULL, res))
71 break;
72
73 g_free (res);
74 }
75
76 GST_DEBUG ("%p: mapped %p", mem, res);
77
78 return res;
79 }
80
81 static gboolean
_my_mem_unmap(MyMemory * mem)82 _my_mem_unmap (MyMemory * mem)
83 {
84 GST_DEBUG ("%p: unmapped", mem);
85 return TRUE;
86 }
87
88 static MyMemory *
_my_mem_share(MyMemory * mem,gssize offset,gsize size)89 _my_mem_share (MyMemory * mem, gssize offset, gsize size)
90 {
91 MyMemory *sub;
92 GstMemory *parent;
93
94 GST_DEBUG ("%p: share %" G_GSSIZE_FORMAT " %" G_GSIZE_FORMAT, mem, offset,
95 size);
96
97 /* find the real parent */
98 if ((parent = mem->mem.parent) == NULL)
99 parent = (GstMemory *) mem;
100
101 if (size == -1)
102 size = mem->mem.size - offset;
103
104 sub = g_slice_new (MyMemory);
105 /* the shared memory is always readonly */
106 gst_memory_init (GST_MEMORY_CAST (sub), GST_MINI_OBJECT_FLAGS (parent) |
107 GST_MINI_OBJECT_FLAG_LOCK_READONLY, mem->mem.allocator, parent,
108 mem->mem.maxsize, mem->mem.align, mem->mem.offset + offset, size);
109
110 /* install pointer */
111 sub->data = _my_mem_map (mem, mem->mem.maxsize, GST_MAP_READ);
112
113 return sub;
114 }
115
116 typedef struct
117 {
118 GstAllocator parent;
119 } MyMemoryAllocator;
120
121 typedef struct
122 {
123 GstAllocatorClass parent_class;
124 } MyMemoryAllocatorClass;
125
126 GType my_memory_allocator_get_type (void);
127 G_DEFINE_TYPE (MyMemoryAllocator, my_memory_allocator, GST_TYPE_ALLOCATOR);
128
129 static void
my_memory_allocator_class_init(MyMemoryAllocatorClass * klass)130 my_memory_allocator_class_init (MyMemoryAllocatorClass * klass)
131 {
132 GstAllocatorClass *allocator_class;
133
134 allocator_class = (GstAllocatorClass *) klass;
135
136 allocator_class->alloc = _my_alloc;
137 allocator_class->free = _my_free;
138 }
139
140 static void
my_memory_allocator_init(MyMemoryAllocator * allocator)141 my_memory_allocator_init (MyMemoryAllocator * allocator)
142 {
143 GstAllocator *alloc = GST_ALLOCATOR_CAST (allocator);
144
145 alloc->mem_type = "MyMemory";
146 alloc->mem_map = (GstMemoryMapFunction) _my_mem_map;
147 alloc->mem_unmap = (GstMemoryUnmapFunction) _my_mem_unmap;
148 alloc->mem_share = (GstMemoryShareFunction) _my_mem_share;
149 }
150
151 void
my_memory_init(void)152 my_memory_init (void)
153 {
154 GstAllocator *allocator;
155
156 allocator = g_object_new (my_memory_allocator_get_type (), NULL);
157
158 gst_allocator_register ("MyMemory", allocator);
159 }
160