/*
 * SGI FREE SOFTWARE LICENSE B (Version 2.0, Sept. 18, 2008)
 * Copyright (C) 1991-2000 Silicon Graphics, Inc. All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice including the dates of first publication and
 * either this permission notice or a reference to
 * http://oss.sgi.com/projects/FreeB/
 * shall be included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * SILICON GRAPHICS, INC. BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF
 * OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 *
 * Except as contained in this notice, the name of Silicon Graphics, Inc.
 * shall not be used in advertising or otherwise to promote the sale, use or
 * other dealings in this Software without prior written authorization from
 * Silicon Graphics, Inc.
 */

/**
 * \file glxcurrent.c
 * Client-side GLX interface for current context management.
 */

#include "glxclient.h"
#include "glapi.h"
#include "glheader.h"
#include "indirect_init.h"

#ifdef GLX_DIRECT_RENDERING
#include "xf86dri.h"
#endif

/*
** We setup some dummy structures here so that the API can be used
** even if no context is current.
*/

static GLubyte dummyBuffer[__GLX_BUFFER_LIMIT_SIZE];

/*
** Dummy context used by small commands when there is no current context.
** All the
** gl and glx entry points are designed to operate as nop's when using
** the dummy context structure.
*/
static __GLXcontext dummyContext = {
    &dummyBuffer[0],
    &dummyBuffer[0],
    &dummyBuffer[0],
    &dummyBuffer[__GLX_BUFFER_LIMIT_SIZE],
    sizeof(dummyBuffer),
};


/*
** All indirect rendering contexts will share the same indirect dispatch table.
*/
static __GLapi *IndirectAPI = NULL;


/*
 * Current context management and locking
 */

#if defined( USE_XTHREADS )

/* thread safe */
static GLboolean TSDinitialized = GL_FALSE;
static xthread_key_t ContextTSD;

_X_HIDDEN __GLXcontext *__glXGetCurrentContext(void)
{
   if (!TSDinitialized) {
      xthread_key_create(&ContextTSD, NULL);
      TSDinitialized = GL_TRUE;
      return &dummyContext;
   }
   else {
      void *p;
      xthread_get_specific(ContextTSD, &p);
      if (!p)
         return &dummyContext;
      else
         return (__GLXcontext *) p;
   }
}

_X_HIDDEN void __glXSetCurrentContext(__GLXcontext *c)
{
   if (!TSDinitialized) {
      xthread_key_create(&ContextTSD, NULL);
      TSDinitialized = GL_TRUE;
   }
   xthread_set_specific(ContextTSD, c);
}


/* Used by the __glXLock() and __glXUnlock() macros */
_X_HIDDEN xmutex_rec __glXmutex;

#elif defined( PTHREADS )

_X_HIDDEN pthread_mutex_t __glXmutex = PTHREAD_MUTEX_INITIALIZER;

# if defined( GLX_USE_TLS )

/**
 * Per-thread GLX context pointer.
 * 
 * \c __glXSetCurrentContext is written is such a way that this pointer can
 * \b never be \c NULL.  This is important!  Because of this
 * \c __glXGetCurrentContext can be implemented as trivial macro.
 */
__thread void * __glX_tls_Context __attribute__((tls_model("initial-exec")))
    = &dummyContext;

_X_HIDDEN void __glXSetCurrentContext( __GLXcontext * c )
{
    __glX_tls_Context = (c != NULL) ? c : &dummyContext;
}

# else

static pthread_once_t once_control = PTHREAD_ONCE_INIT;

/**
 * Per-thread data key.
 * 
 * Once \c init_thread_data has been called, the per-thread data key will
 * take a value of \c NULL.  As each new thread is created the default
 * value, in that thread, will be \c NULL.
 */
static pthread_key_t ContextTSD;

/**
 * Initialize the per-thread data key.
 * 
 * This function is called \b exactly once per-process (not per-thread!) to
 * initialize the per-thread data key.  This is ideally done using the
 * \c pthread_once mechanism.
 */
static void init_thread_data( void )
{
    if ( pthread_key_create( & ContextTSD, NULL ) != 0 ) {
	perror( "pthread_key_create" );
	exit( -1 );
    }
}

_X_HIDDEN void __glXSetCurrentContext( __GLXcontext * c )
{
    pthread_once( & once_control, init_thread_data );
    pthread_setspecific( ContextTSD, c );
}

_X_HIDDEN __GLXcontext * __glXGetCurrentContext( void )
{
    void * v;

    pthread_once( & once_control, init_thread_data );

    v = pthread_getspecific( ContextTSD );
    return (v == NULL) ? & dummyContext : (__GLXcontext *) v;
}

# endif /* defined( GLX_USE_TLS ) */

#elif defined( THREADS )

#error Unknown threading method specified.

#else

/* not thread safe */
_X_HIDDEN __GLXcontext *__glXcurrentContext = &dummyContext;

#endif


_X_HIDDEN void __glXSetCurrentContextNull(void)
{
    __glXSetCurrentContext(&dummyContext);
#ifdef GLX_DIRECT_RENDERING
    _glapi_set_dispatch(NULL);  /* no-op functions */
#endif
}


/************************************************************************/

PUBLIC GLXContext glXGetCurrentContext(void)
{
    GLXContext cx = __glXGetCurrentContext();
    
    if (cx == &dummyContext) {
	return NULL;
    } else {
	return cx;
    }
}

PUBLIC GLXDrawable glXGetCurrentDrawable(void)
{
    GLXContext gc = __glXGetCurrentContext();
    return gc->currentDrawable;
}


/************************************************************************/

/**
 * Sends a GLX protocol message to the specified display to make the context
 * and the drawables current.
 *
 * \param dpy     Display to send the message to.
 * \param opcode  Major opcode value for the display.
 * \param gc_id   Context tag for the context to be made current.
 * \param draw    Drawable ID for the "draw" drawable.
 * \param read    Drawable ID for the "read" drawable.
 * \param reply   Space to store the X-server's reply.
 *
 * \warning
 * This function assumes that \c dpy is locked with \c LockDisplay on entry.
 */
static Bool SendMakeCurrentRequest(Display *dpy, CARD8 opcode,
				   GLXContextID gc_id, GLXContextTag gc_tag,
				   GLXDrawable draw, GLXDrawable read,
				   xGLXMakeCurrentReply *reply)
{
    Bool ret;


    LockDisplay(dpy);

    if (draw == read) {
	xGLXMakeCurrentReq *req;

	GetReq(GLXMakeCurrent,req);
	req->reqType = opcode;
	req->glxCode = X_GLXMakeCurrent;
	req->drawable = draw;
	req->context = gc_id;
	req->oldContextTag = gc_tag;
    }
    else {
	__GLXdisplayPrivate *priv = __glXInitialize(dpy);

	/* If the server can support the GLX 1.3 version, we should
	 * perfer that.  Not only that, some servers support GLX 1.3 but
	 * not the SGI extension.
	 */

	if ((priv->majorVersion > 1) || (priv->minorVersion >= 3)) {
	    xGLXMakeContextCurrentReq *req;

	    GetReq(GLXMakeContextCurrent,req);
	    req->reqType = opcode;
	    req->glxCode = X_GLXMakeContextCurrent;
	    req->drawable = draw;
	    req->readdrawable = read;
	    req->context = gc_id;
	    req->oldContextTag = gc_tag;
	}
	else {
	    xGLXVendorPrivateWithReplyReq *vpreq;
	    xGLXMakeCurrentReadSGIReq *req;

	    GetReqExtra(GLXVendorPrivateWithReply,
			sz_xGLXMakeCurrentReadSGIReq-sz_xGLXVendorPrivateWithReplyReq,vpreq);
	    req = (xGLXMakeCurrentReadSGIReq *)vpreq;
	    req->reqType = opcode;
	    req->glxCode = X_GLXVendorPrivateWithReply;
	    req->vendorCode = X_GLXvop_MakeCurrentReadSGI;
	    req->drawable = draw;
	    req->readable = read;
	    req->context = gc_id;
	    req->oldContextTag = gc_tag;
	}
    }

    ret = _XReply(dpy, (xReply*) reply, 0, False);

    UnlockDisplay(dpy);
    SyncHandle();

    return ret;
}


#ifdef GLX_DIRECT_RENDERING
static __GLXDRIdrawable *
FetchDRIDrawable(Display *dpy,
		 GLXDrawable glxDrawable, GLXContext gc, Bool pre13)
{
    __GLXdisplayPrivate * const priv = __glXInitialize(dpy);
    __GLXDRIdrawable *pdraw;
    __GLXscreenConfigs *psc;
    XID drawable;

    if (priv == NULL)
	return NULL;
    
    psc = &priv->screenConfigs[gc->screen];
    if (psc->drawHash == NULL)
	return NULL;

    if (__glxHashLookup(psc->drawHash, glxDrawable, (void *) &pdraw) == 0)
	return pdraw;

    /* If this is glXMakeCurrent (pre GLX 1.3) we allow creating the
     * GLX drawable on the fly.  Otherwise we pass None as the X
     * drawable */
    if (pre13)
	drawable = glxDrawable;
    else
	drawable = None;

    pdraw = psc->driScreen->createDrawable(psc, drawable,
					   glxDrawable, gc->mode);
    if (__glxHashInsert(psc->drawHash, glxDrawable, pdraw)) {
	(*pdraw->destroyDrawable)(pdraw);
	return NULL;
    }

    return pdraw;
}
#endif /* GLX_DIRECT_RENDERING */


/**
 * Make a particular context current.
 * 
 * \note This is in this file so that it can access dummyContext.
 */
static Bool MakeContextCurrent(Display *dpy, GLXDrawable draw,
			       GLXDrawable read, GLXContext gc,
			       Bool pre13)
{
    xGLXMakeCurrentReply reply;
    const GLXContext oldGC = __glXGetCurrentContext();
    const CARD8 opcode = __glXSetupForCommand(dpy);
    const CARD8 oldOpcode = ((gc == oldGC) || (oldGC == &dummyContext))
      ? opcode : __glXSetupForCommand(oldGC->currentDpy);
    Bool bindReturnValue;


    if (!opcode || !oldOpcode) {
	return GL_FALSE;
    }

    /* Make sure that the new context has a nonzero ID.  In the request,
     * a zero context ID is used only to mean that we bind to no current
     * context.
     */
    if ((gc != NULL) && (gc->xid == None)) {
	return GL_FALSE;
    }

    _glapi_check_multithread();

#ifdef GLX_DIRECT_RENDERING
    /* Bind the direct rendering context to the drawable */
    if (gc && gc->driContext) {
	__GLXDRIdrawable *pdraw = FetchDRIDrawable(dpy, draw, gc, pre13);
	__GLXDRIdrawable *pread = FetchDRIDrawable(dpy, read, gc, pre13);

	bindReturnValue =
	    (gc->driContext->bindContext) (gc->driContext, pdraw, pread);
    } else
#endif
    {
	/* Send a glXMakeCurrent request to bind the new context. */
	bindReturnValue = 
	  SendMakeCurrentRequest(dpy, opcode, gc ? gc->xid : None,
				 ((dpy != oldGC->currentDpy) || oldGC->isDirect)
				 ? None : oldGC->currentContextTag,
				 draw, read, &reply);
    }


    if (!bindReturnValue) {
	return False;
    }

#ifdef GLX_DIRECT_RENDERING
    if ((dpy != oldGC->currentDpy || (gc && gc->driContext)) &&
	!oldGC->isDirect && oldGC != &dummyContext) {
#else
    if ((dpy != oldGC->currentDpy) && oldGC != &dummyContext) {
#endif
	xGLXMakeCurrentReply dummy_reply;

	/* We are either switching from one dpy to another and have to
	 * send a request to the previous dpy to unbind the previous
	 * context, or we are switching away from a indirect context to
	 * a direct context and have to send a request to the dpy to
	 * unbind the previous context.
	 */
	(void) SendMakeCurrentRequest(oldGC->currentDpy, oldOpcode, None,
				      oldGC->currentContextTag, None, None,
				      & dummy_reply);
    }
#ifdef GLX_DIRECT_RENDERING
    else if (oldGC->driContext) {
	oldGC->driContext->unbindContext(oldGC->driContext);
    }
#endif


    /* Update our notion of what is current */
    __glXLock();
    if (gc == oldGC) {
	/* Even though the contexts are the same the drawable might have
	 * changed.  Note that gc cannot be the dummy, and that oldGC
	 * cannot be NULL, therefore if they are the same, gc is not
	 * NULL and not the dummy.
	 */
	gc->currentDrawable = draw;
	gc->currentReadable = read;
    } else {
	if (oldGC != &dummyContext) {
	    /* Old current context is no longer current to anybody */
	    oldGC->currentDpy = 0;
	    oldGC->currentDrawable = None;
	    oldGC->currentReadable = None;
	    oldGC->currentContextTag = 0;

	    if (oldGC->xid == None) {
		/* We are switching away from a context that was
		 * previously destroyed, so we need to free the memory
		 * for the old handle.
		 */
#ifdef GLX_DIRECT_RENDERING
		/* Destroy the old direct rendering context */
		if (oldGC->driContext) {
		    oldGC->driContext->destroyContext(oldGC->driContext,
						      oldGC->psc,
						      oldGC->createDpy);
		    oldGC->driContext = NULL;
		}
#endif
		__glXFreeContext(oldGC);
	    }
	}
	if (gc) {
	    __glXSetCurrentContext(gc);

	    gc->currentDpy = dpy;
	    gc->currentDrawable = draw;
	    gc->currentReadable = read;

#ifdef GLX_DIRECT_RENDERING    
            if (!gc->driContext) {
#endif
               if (!IndirectAPI)
                  IndirectAPI = __glXNewIndirectAPI();
               _glapi_set_dispatch(IndirectAPI);

#ifdef GLX_USE_APPLEGL
               do {
                   extern void XAppleDRIUseIndirectDispatch(void);
                   XAppleDRIUseIndirectDispatch();
               } while (0);
#endif

		__GLXattribute *state = 
		  (__GLXattribute *)(gc->client_state_private);

		gc->currentContextTag = reply.contextTag;
		if (state->array_state == NULL) {
		    (void) glGetString(GL_EXTENSIONS);
		    (void) glGetString(GL_VERSION);
		    __glXInitVertexArrayState(gc);
		}
#ifdef GLX_DIRECT_RENDERING    
	    }
	    else {
		gc->currentContextTag = -1;
	    }
#endif
	} else {
	    __glXSetCurrentContextNull();
	}
    }
    __glXUnlock();
    return GL_TRUE;
}


PUBLIC Bool glXMakeCurrent(Display *dpy, GLXDrawable draw, GLXContext gc)
{
    return MakeContextCurrent(dpy, draw, draw, gc, True);
}

PUBLIC GLX_ALIAS(Bool, glXMakeCurrentReadSGI,
	  (Display *dpy, GLXDrawable d, GLXDrawable r, GLXContext ctx),
	  (dpy, d, r, ctx, False), MakeContextCurrent)

PUBLIC GLX_ALIAS(Bool, glXMakeContextCurrent,
	  (Display *dpy, GLXDrawable d, GLXDrawable r, GLXContext ctx),
	  (dpy, d, r, ctx, False), MakeContextCurrent)