1/**************************************************************************
2 *
3 * Copyright 2005 VMware, Inc.
4 * All Rights Reserved.
5 *
6 * Permission is hereby granted, free of charge, to any person obtaining a
7 * copy of this software and associated documentation files (the
8 * "Software"), to deal in the Software without restriction, including
9 * without limitation the rights to use, copy, modify, merge, publish,
10 * distribute, sub license, and/or sell copies of the Software, and to
11 * permit persons to whom the Software is furnished to do so, subject to
12 * the following conditions:
13 *
14 * The above copyright notice and this permission notice (including the
15 * next paragraph) shall be included in all copies or substantial portions
16 * of the Software.
17 *
18 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
19 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
20 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
21 * IN NO EVENT SHALL VMWARE AND/OR ITS SUPPLIERS BE LIABLE FOR
22 * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
23 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
24 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
25 *
26 **************************************************************************/
27
28#ifndef ST_CB_BUFFEROBJECTS_H
29#define ST_CB_BUFFEROBJECTS_H
30
31#include "main/mtypes.h"
32
33struct dd_function_table;
34struct pipe_resource;
35struct pipe_screen;
36struct st_context;
37
38/**
39 * State_tracker vertex/pixel buffer object, derived from Mesa's
40 * gl_buffer_object.
41 */
42struct st_buffer_object
43{
44   struct gl_buffer_object Base;
45   struct pipe_resource *buffer;     /* GPU storage */
46
47   struct gl_context *ctx;  /* the context that owns private_refcount */
48
49   /* This mechanism allows passing buffer references to the driver without
50    * using atomics to increase the reference count.
51    *
52    * This private refcount can be decremented without atomics but only one
53    * context (ctx above) can use this counter to be thread-safe.
54    *
55    * This number is atomically added to buffer->reference.count at
56    * initialization. If it's never used, the same number is atomically
57    * subtracted from buffer->reference.count before destruction. If this
58    * number is decremented, we can pass that reference to the driver without
59    * touching reference.count. At buffer destruction we only subtract
60    * the number of references we did not return. This can possibly turn
61    * a million atomic increments into 1 add and 1 subtract atomic op.
62    */
63   int private_refcount;
64
65   struct pipe_transfer *transfer[MAP_COUNT];
66};
67
68
69/** cast wrapper */
70static inline struct st_buffer_object *
71st_buffer_object(struct gl_buffer_object *obj)
72{
73   return (struct st_buffer_object *) obj;
74}
75
76
77enum pipe_map_flags
78st_access_flags_to_transfer_flags(GLbitfield access, bool wholeBuffer);
79
80
81extern void
82st_init_bufferobject_functions(struct pipe_screen *screen,
83                               struct dd_function_table *functions);
84
85static inline struct pipe_resource *
86st_get_buffer_reference(struct gl_context *ctx, struct gl_buffer_object *obj)
87{
88   if (unlikely(!obj))
89      return NULL;
90
91   struct st_buffer_object *stobj = st_buffer_object(obj);
92   struct pipe_resource *buffer = stobj->buffer;
93
94   if (unlikely(!buffer))
95      return NULL;
96
97   /* Only one context is using the fast path. All other contexts must use
98    * the slow path.
99    */
100   if (unlikely(stobj->ctx != ctx)) {
101      p_atomic_inc(&buffer->reference.count);
102      return buffer;
103   }
104
105   if (unlikely(stobj->private_refcount <= 0)) {
106      assert(stobj->private_refcount == 0);
107
108      /* This is the number of atomic increments we will skip. */
109      stobj->private_refcount = 100000000;
110      p_atomic_add(&buffer->reference.count, stobj->private_refcount);
111   }
112
113   /* Return a buffer reference while decrementing the private refcount. */
114   stobj->private_refcount--;
115   return buffer;
116}
117
118#endif
119