glxcurrent.c revision 75be6b76eef00352195220a4beefbc7ca0b76453 
1/*
2 * SGI FREE SOFTWARE LICENSE B (Version 2.0, Sept. 18, 2008)
3 * Copyright (C) 1991-2000 Silicon Graphics, Inc. All Rights Reserved.
4 *
5 * Permission is hereby granted, free of charge, to any person obtaining a
6 * copy of this software and associated documentation files (the "Software"),
7 * to deal in the Software without restriction, including without limitation
8 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
9 * and/or sell copies of the Software, and to permit persons to whom the
10 * Software is furnished to do so, subject to the following conditions:
11 *
12 * The above copyright notice including the dates of first publication and
13 * either this permission notice or a reference to
14 * http://oss.sgi.com/projects/FreeB/
15 * shall be included in all copies or substantial portions of the Software.
16 *
17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
18 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
20 * SILICON GRAPHICS, INC. BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
21 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF
22 * OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
23 * SOFTWARE.
24 *
25 * Except as contained in this notice, the name of Silicon Graphics, Inc.
26 * shall not be used in advertising or otherwise to promote the sale, use or
27 * other dealings in this Software without prior written authorization from
28 * Silicon Graphics, Inc.
29 */
30
31/**
32 * \file glxcurrent.c
33 * Client-side GLX interface for current context management.
34 */
35
36#ifdef PTHREADS
37#include <pthread.h>
38#endif
39
40#include "glxclient.h"
41#ifdef GLX_USE_APPLEGL
42#include <stdlib.h>
43
44#include "apple_glx.h"
45#include "apple_glx_context.h"
46#endif
47
48#include "glapi.h"
49
50/*
51** We setup some dummy structures here so that the API can be used
52** even if no context is current.
53*/
54
55static GLubyte dummyBuffer[__GLX_BUFFER_LIMIT_SIZE];
56static struct glx_context_vtable dummyVtable;
57/*
58** Dummy context used by small commands when there is no current context.
59** All the
60** gl and glx entry points are designed to operate as nop's when using
61** the dummy context structure.
62*/
63struct glx_context dummyContext = {
64   &dummyBuffer[0],
65   &dummyBuffer[0],
66   &dummyBuffer[0],
67   &dummyBuffer[__GLX_BUFFER_LIMIT_SIZE],
68   sizeof(dummyBuffer),
69   &dummyVtable
70};
71
72/*
73 * Current context management and locking
74 */
75
76#if defined( PTHREADS )
77
78_X_HIDDEN pthread_mutex_t __glXmutex = PTHREAD_MUTEX_INITIALIZER;
79
80# if defined( GLX_USE_TLS )
81
82/**
83 * Per-thread GLX context pointer.
84 *
85 * \c __glXSetCurrentContext is written is such a way that this pointer can
86 * \b never be \c NULL.  This is important!  Because of this
87 * \c __glXGetCurrentContext can be implemented as trivial macro.
88 */
89__thread void *__glX_tls_Context __attribute__ ((tls_model("initial-exec")))
90   = &dummyContext;
91
92_X_HIDDEN void
93__glXSetCurrentContext(struct glx_context * c)
94{
95   __glX_tls_Context = (c != NULL) ? c : &dummyContext;
96}
97
98# else
99
100static pthread_once_t once_control = PTHREAD_ONCE_INIT;
101
102/**
103 * Per-thread data key.
104 *
105 * Once \c init_thread_data has been called, the per-thread data key will
106 * take a value of \c NULL.  As each new thread is created the default
107 * value, in that thread, will be \c NULL.
108 */
109static pthread_key_t ContextTSD;
110
111/**
112 * Initialize the per-thread data key.
113 *
114 * This function is called \b exactly once per-process (not per-thread!) to
115 * initialize the per-thread data key.  This is ideally done using the
116 * \c pthread_once mechanism.
117 */
118static void
119init_thread_data(void)
120{
121   if (pthread_key_create(&ContextTSD, NULL) != 0) {
122      perror("pthread_key_create");
123      exit(-1);
124   }
125}
126
127_X_HIDDEN void
128__glXSetCurrentContext(struct glx_context * c)
129{
130   pthread_once(&once_control, init_thread_data);
131   pthread_setspecific(ContextTSD, c);
132}
133
134_X_HIDDEN struct glx_context *
135__glXGetCurrentContext(void)
136{
137   void *v;
138
139   pthread_once(&once_control, init_thread_data);
140
141   v = pthread_getspecific(ContextTSD);
142   return (v == NULL) ? &dummyContext : (struct glx_context *) v;
143}
144
145# endif /* defined( GLX_USE_TLS ) */
146
147#elif defined( THREADS )
148
149#error Unknown threading method specified.
150
151#else
152
153/* not thread safe */
154_X_HIDDEN struct glx_context *__glXcurrentContext = &dummyContext;
155
156#endif
157
158
159_X_HIDDEN void
160__glXSetCurrentContextNull(void)
161{
162   __glXSetCurrentContext(&dummyContext);
163#if defined(GLX_DIRECT_RENDERING)
164   _glapi_set_dispatch(NULL);   /* no-op functions */
165   _glapi_set_context(NULL);
166#endif
167}
168
169_X_EXPORT GLXContext
170glXGetCurrentContext(void)
171{
172   struct glx_context *cx = __glXGetCurrentContext();
173
174   if (cx == &dummyContext) {
175      return NULL;
176   }
177   else {
178      return (GLXContext) cx;
179   }
180}
181
182_X_EXPORT GLXDrawable
183glXGetCurrentDrawable(void)
184{
185   struct glx_context *gc = __glXGetCurrentContext();
186   return gc->currentDrawable;
187}
188
189static void
190__glXGenerateError(Display * dpy, XID resource,
191                   BYTE errorCode, CARD16 minorCode)
192{
193   xError error;
194
195   error.errorCode = errorCode;
196   error.resourceID = resource;
197   error.sequenceNumber = dpy->request;
198   error.type = X_Error;
199   error.majorCode = __glXSetupForCommand(dpy);
200   error.minorCode = minorCode;
201   _XError(dpy, &error);
202}
203
204/**
205 * Make a particular context current.
206 *
207 * \note This is in this file so that it can access dummyContext.
208 */
209static Bool
210MakeContextCurrent(Display * dpy, GLXDrawable draw,
211                   GLXDrawable read, GLXContext gc_user)
212{
213   struct glx_context *gc = (struct glx_context *) gc_user;
214   struct glx_context *oldGC = __glXGetCurrentContext();
215
216   /* XXX: If this is left out, then libGL ends up not having this
217    * symbol, and drivers using it fail to load.  Compare the
218    * implementation of this symbol to _glapi_noop_enable_warnings(),
219    * though, which gets into the library despite no callers, the same
220    * prototypes, and the same compile flags to the files containing
221    * them.  Moving the definition to glapi_nop.c gets it into the
222    * library, though.
223    */
224   (void)_glthread_GetID();
225
226   /* Make sure that the new context has a nonzero ID.  In the request,
227    * a zero context ID is used only to mean that we bind to no current
228    * context.
229    */
230   if ((gc != NULL) && (gc->xid == None)) {
231      return GL_FALSE;
232   }
233
234   if (gc == NULL && (draw != None || read != None)) {
235      __glXGenerateError(dpy, (draw != None) ? draw : read,
236                         BadMatch, X_GLXMakeContextCurrent);
237      return False;
238   }
239   if (gc != NULL && (draw == None || read == None)) {
240      __glXGenerateError(dpy, None, BadMatch, X_GLXMakeContextCurrent);
241      return False;
242   }
243
244   _glapi_check_multithread();
245
246   __glXLock();
247   if (oldGC == gc &&
248       gc->currentDrawable == draw && gc->currentReadable == read) {
249      __glXUnlock();
250      return True;
251   }
252
253   if (oldGC != &dummyContext) {
254      if (--oldGC->thread_refcount == 0) {
255	 oldGC->vtable->unbind(oldGC, gc);
256	 oldGC->currentDpy = 0;
257      }
258   }
259
260   if (gc) {
261      /* Attempt to bind the context.  We do this before mucking with
262       * gc and __glXSetCurrentContext to properly handle our state in
263       * case of an error.
264       *
265       * If an error occurs, set the Null context since we've already
266       * blown away our old context.  The caller is responsible for
267       * figuring out how to handle setting a valid context.
268       */
269      if (gc->vtable->bind(gc, oldGC, draw, read) != Success) {
270         __glXSetCurrentContextNull();
271         __glXUnlock();
272         __glXGenerateError(dpy, None, GLXBadContext, X_GLXMakeContextCurrent);
273         return GL_FALSE;
274      }
275
276      if (gc->thread_refcount == 0) {
277         gc->currentDpy = dpy;
278         gc->currentDrawable = draw;
279         gc->currentReadable = read;
280      }
281      gc->thread_refcount++;
282      __glXSetCurrentContext(gc);
283   } else {
284      __glXSetCurrentContextNull();
285   }
286
287   if (oldGC->thread_refcount == 0 && oldGC != &dummyContext && oldGC->xid == None) {
288      /* We are switching away from a context that was
289       * previously destroyed, so we need to free the memory
290       * for the old handle. */
291      oldGC->vtable->destroy(oldGC);
292   }
293
294   __glXUnlock();
295
296   return GL_TRUE;
297}
298
299
300_X_EXPORT Bool
301glXMakeCurrent(Display * dpy, GLXDrawable draw, GLXContext gc)
302{
303   return MakeContextCurrent(dpy, draw, draw, gc);
304}
305
306_X_EXPORT
307GLX_ALIAS(Bool, glXMakeCurrentReadSGI,
308          (Display * dpy, GLXDrawable d, GLXDrawable r, GLXContext ctx),
309          (dpy, d, r, ctx), MakeContextCurrent)
310
311_X_EXPORT
312GLX_ALIAS(Bool, glXMakeContextCurrent,
313          (Display * dpy, GLXDrawable d, GLXDrawable r,
314           GLXContext ctx), (dpy, d, r, ctx), MakeContextCurrent)
315