/* $XFree86: xc/lib/GL/dri/dri_util.c,v 1.7 2003/04/28 17:01:25 dawes Exp $ */ /** * \file dri_util.c * DRI utility functions. * * This module acts as glue between GLX and the actual hardware driver. A DRI * driver doesn't really \e have to use any of this - it's optional. But, some * useful stuff is done here that otherwise would have to be duplicated in most * drivers. * * Basically, these utility functions take care of some of the dirty details of * screen initialization, context creation, context binding, DRM setup, etc. * * These functions are compiled into each DRI driver so libGL.so knows nothing * about them. */ #include #include #include #include #include #ifndef MAP_FAILED #define MAP_FAILED ((void *)-1) #endif #include "imports.h" #define None 0 #include "dri_util.h" #include "drm_sarea.h" #ifndef GLX_OML_sync_control typedef GLboolean ( * PFNGLXGETMSCRATEOMLPROC) (__DRIdrawable *drawable, int32_t *numerator, int32_t *denominator); #endif /* This pointer *must* be set by the driver's __driCreateNewScreen funciton! */ const __DRIinterfaceMethods * dri_interface = NULL; /** * This is used in a couple of places that call \c driCreateNewDrawable. */ static const int empty_attribute_list[1] = { None }; /** * Cached copy of the internal API version used by libGL and the client-side * DRI driver. */ static int api_ver = 0; /* forward declarations */ static int driQueryFrameTracking( void *priv, int64_t *sbc, int64_t *missedFrames, float *lastMissedUsage, float *usage ); static void *driCreateNewDrawable(__DRIscreen *screen, const __GLcontextModes *modes, __DRIdrawable *pdraw, drm_drawable_t hwDrawable, int renderType, const int *attrs); static void driDestroyDrawable(void *drawablePrivate); /** * Print message to \c stderr if the \c LIBGL_DEBUG environment variable * is set. * * Is called from the drivers. * * \param f \c printf like format string. */ void __driUtilMessage(const char *f, ...) { va_list args; if (getenv("LIBGL_DEBUG")) { fprintf(stderr, "libGL error: \n"); va_start(args, f); vfprintf(stderr, f, args); va_end(args); fprintf(stderr, "\n"); } } /*****************************************************************/ /** \name Context (un)binding functions */ /*****************************************************************/ /*@{*/ /** * Unbind context. * * \param scrn the screen. * \param gc context. * * \return \c GL_TRUE on success, or \c GL_FALSE on failure. * * \internal * This function calls __DriverAPIRec::UnbindContext, and then decrements * __DRIdrawablePrivateRec::refcount which must be non-zero for a successful * return. * * While casting the opaque private pointers associated with the parameters * into their respective real types it also assures they are not \c NULL. */ static GLboolean driUnbindContext(__DRIcontext *ctx) { __DRIcontextPrivate *pcp; __DRIscreenPrivate *psp; __DRIdrawablePrivate *pdp; __DRIdrawablePrivate *prp; /* ** Assume error checking is done properly in glXMakeCurrent before ** calling driUnbindContext. */ if (ctx == NULL) return GL_FALSE; pcp = (__DRIcontextPrivate *)ctx->private; psp = (__DRIscreenPrivate *)pcp->driScreenPriv; pdp = (__DRIdrawablePrivate *)pcp->driDrawablePriv; prp = (__DRIdrawablePrivate *)pcp->driReadablePriv; /* Let driver unbind drawable from context */ (*psp->DriverAPI.UnbindContext)(pcp); if (pdp->refcount == 0) { /* ERROR!!! */ return GL_FALSE; } pdp->refcount--; if (prp != pdp) { if (prp->refcount == 0) { /* ERROR!!! */ return GL_FALSE; } prp->refcount--; } /* XXX this is disabled so that if we call SwapBuffers on an unbound * window we can determine the last context bound to the window and * use that context's lock. (BrianP, 2-Dec-2000) */ #if 0 /* Unbind the drawable */ pcp->driDrawablePriv = NULL; pdp->driContextPriv = &psp->dummyContextPriv; #endif return GL_TRUE; } /** * This function takes both a read buffer and a draw buffer. This is needed * for \c glXMakeCurrentReadSGI or GLX 1.3's \c glXMakeContextCurrent * function. */ static GLboolean DoBindContext(__DRIdrawable *pdraw, __DRIdrawable *pread, __DRIcontext *ctx) { __DRIdrawablePrivate *pdp; __DRIdrawablePrivate *prp; __DRIcontextPrivate * const pcp = ctx->private; __DRIscreenPrivate *psp = pcp->driScreenPriv; pdp = (__DRIdrawablePrivate *) pdraw->private; prp = (__DRIdrawablePrivate *) pread->private; /* Bind the drawable to the context */ pcp->driDrawablePriv = pdp; pcp->driReadablePriv = prp; pdp->driContextPriv = pcp; pdp->refcount++; if ( pdp != prp ) { prp->refcount++; } /* ** Now that we have a context associated with this drawable, we can ** initialize the drawable information if has not been done before. */ if (!pdp->pStamp || *pdp->pStamp != pdp->lastStamp) { DRM_SPINLOCK(&psp->pSAREA->drawable_lock, psp->drawLockID); __driUtilUpdateDrawableInfo(pdp); DRM_SPINUNLOCK(&psp->pSAREA->drawable_lock, psp->drawLockID); } if ((pdp != prp) && (!prp->pStamp || *prp->pStamp != prp->lastStamp)) { DRM_SPINLOCK(&psp->pSAREA->drawable_lock, psp->drawLockID); __driUtilUpdateDrawableInfo(prp); DRM_SPINUNLOCK(&psp->pSAREA->drawable_lock, psp->drawLockID); } /* Call device-specific MakeCurrent */ (*psp->DriverAPI.MakeCurrent)(pcp, pdp, prp); return GL_TRUE; } /** * This function takes both a read buffer and a draw buffer. This is needed * for \c glXMakeCurrentReadSGI or GLX 1.3's \c glXMakeContextCurrent * function. */ static GLboolean driBindContext(__DRIdrawable *pdraw, __DRIdrawable *pread, __DRIcontext * ctx) { /* ** Assume error checking is done properly in glXMakeCurrent before ** calling driBindContext. */ if (ctx == NULL || pdraw == None || pread == None) return GL_FALSE; return DoBindContext( pdraw, pread, ctx ); } /*@}*/ /*****************************************************************/ /** \name Drawable handling functions */ /*****************************************************************/ /*@{*/ /** * Update private drawable information. * * \param pdp pointer to the private drawable information to update. * * This function basically updates the __DRIdrawablePrivate struct's * cliprect information by calling \c __DRIinterfaceMethods::getDrawableInfo. * This is usually called by the DRI_VALIDATE_DRAWABLE_INFO macro which * compares the __DRIdrwablePrivate pStamp and lastStamp values. If * the values are different that means we have to update the clipping * info. */ void __driUtilUpdateDrawableInfo(__DRIdrawablePrivate *pdp) { __DRIscreenPrivate *psp; __DRIcontextPrivate *pcp = pdp->driContextPriv; if (!pcp || ((pdp != pcp->driDrawablePriv) && (pdp != pcp->driReadablePriv))) { /* ERROR!!! * ...but we must ignore it. There can be many contexts bound to a * drawable. */ } psp = pdp->driScreenPriv; if (!psp) { /* ERROR!!! */ _mesa_problem(NULL, "Warning! Possible infinite loop due to bug " "in file %s, line %d\n", __FILE__, __LINE__); return; } if (pdp->pClipRects) { _mesa_free(pdp->pClipRects); pdp->pClipRects = NULL; } if (pdp->pBackClipRects) { _mesa_free(pdp->pBackClipRects); pdp->pBackClipRects = NULL; } DRM_SPINUNLOCK(&psp->pSAREA->drawable_lock, psp->drawLockID); if (! (*dri_interface->getDrawableInfo)(pdp->pdraw, &pdp->index, &pdp->lastStamp, &pdp->x, &pdp->y, &pdp->w, &pdp->h, &pdp->numClipRects, &pdp->pClipRects, &pdp->backX, &pdp->backY, &pdp->numBackClipRects, &pdp->pBackClipRects )) { /* Error -- eg the window may have been destroyed. Keep going * with no cliprects. */ pdp->pStamp = &pdp->lastStamp; /* prevent endless loop */ pdp->numClipRects = 0; pdp->pClipRects = NULL; pdp->numBackClipRects = 0; pdp->pBackClipRects = NULL; } else pdp->pStamp = &(psp->pSAREA->drawableTable[pdp->index].stamp); DRM_SPINLOCK(&psp->pSAREA->drawable_lock, psp->drawLockID); } /*@}*/ /*****************************************************************/ /** \name GLX callbacks */ /*****************************************************************/ /*@{*/ /** * Swap buffers. * * \param drawablePrivate opaque pointer to the per-drawable private info. * * \internal * This function calls __DRIdrawablePrivate::swapBuffers. * * Is called directly from glXSwapBuffers(). */ static void driSwapBuffers(void *drawablePrivate) { __DRIdrawablePrivate *dPriv = (__DRIdrawablePrivate *) drawablePrivate; drm_clip_rect_t rect; dPriv->swapBuffers(dPriv); /* Check that we actually have the new damage report method */ if (api_ver < 20070105 || dri_interface->reportDamage == NULL) return; /* Assume it's affecting the whole drawable for now */ rect.x1 = 0; rect.y1 = 0; rect.x2 = rect.x1 + dPriv->w; rect.y2 = rect.y1 + dPriv->h; /* Report the damage. Currently, all our drivers draw directly to the * front buffer, so we report the damage there rather than to the backing * store (if any). */ (*dri_interface->reportDamage)(dPriv->pdraw, dPriv->x, dPriv->y, &rect, 1, GL_TRUE); } /** * Called directly from a number of higher-level GLX functions. */ static int driGetMSC( void *screenPrivate, int64_t *msc ) { __DRIscreenPrivate *sPriv = (__DRIscreenPrivate *) screenPrivate; return sPriv->DriverAPI.GetMSC( sPriv, msc ); } /** * Called directly from a number of higher-level GLX functions. */ static int driGetSBC( void *drawablePrivate, int64_t *sbc ) { __DRIdrawablePrivate *dPriv = (__DRIdrawablePrivate *) drawablePrivate; __DRIswapInfo sInfo; int status; status = dPriv->driScreenPriv->DriverAPI.GetSwapInfo( dPriv, & sInfo ); *sbc = sInfo.swap_count; return status; } static int driWaitForSBC( void *drawablePriv, int64_t target_sbc, int64_t * msc, int64_t * sbc ) { __DRIdrawablePrivate *dPriv = (__DRIdrawablePrivate *) drawablePriv; return dPriv->driScreenPriv->DriverAPI.WaitForSBC( dPriv, target_sbc, msc, sbc ); } static int driWaitForMSC( void *drawablePriv, int64_t target_msc, int64_t divisor, int64_t remainder, int64_t * msc, int64_t * sbc ) { __DRIdrawablePrivate *dPriv = (__DRIdrawablePrivate *) drawablePriv; __DRIswapInfo sInfo; int status; status = dPriv->driScreenPriv->DriverAPI.WaitForMSC( dPriv, target_msc, divisor, remainder, msc ); /* GetSwapInfo() may not be provided by the driver if GLX_SGI_video_sync * is supported but GLX_OML_sync_control is not. Therefore, don't return * an error value if GetSwapInfo() is not implemented. */ if ( status == 0 && dPriv->driScreenPriv->DriverAPI.GetSwapInfo ) { status = dPriv->driScreenPriv->DriverAPI.GetSwapInfo( dPriv, & sInfo ); *sbc = sInfo.swap_count; } return status; } static int64_t driSwapBuffersMSC( void *drawablePriv, int64_t target_msc, int64_t divisor, int64_t remainder ) { __DRIdrawablePrivate *dPriv = (__DRIdrawablePrivate *) drawablePriv; return dPriv->driScreenPriv->DriverAPI.SwapBuffersMSC( dPriv, target_msc, divisor, remainder ); } static void driCopySubBuffer( void *drawablePrivate, int x, int y, int w, int h) { __DRIdrawablePrivate *dPriv = (__DRIdrawablePrivate *) drawablePrivate; dPriv->driScreenPriv->DriverAPI.CopySubBuffer(dPriv, x, y, w, h); } /** * This is called via __DRIscreenRec's createNewDrawable pointer. */ static void *driCreateNewDrawable(__DRIscreen *screen, const __GLcontextModes *modes, __DRIdrawable *pdraw, drm_drawable_t hwDrawable, int renderType, const int *attrs) { __DRIscreenPrivate *psp; __DRIdrawablePrivate *pdp; pdraw->private = NULL; /* Since pbuffers are not yet supported, no drawable attributes are * supported either. */ (void) attrs; pdp = (__DRIdrawablePrivate *)_mesa_malloc(sizeof(__DRIdrawablePrivate)); if (!pdp) { return NULL; } pdp->hHWDrawable = hwDrawable; pdp->pdraw = pdraw; pdp->refcount = 0; pdp->pStamp = NULL; pdp->lastStamp = 0; pdp->index = 0; pdp->x = 0; pdp->y = 0; pdp->w = 0; pdp->h = 0; pdp->numClipRects = 0; pdp->numBackClipRects = 0; pdp->pClipRects = NULL; pdp->pBackClipRects = NULL; psp = (__DRIscreenPrivate *)screen->private; pdp->driScreenPriv = psp; pdp->driContextPriv = &psp->dummyContextPriv; if (!(*psp->DriverAPI.CreateBuffer)(psp, pdp, modes, renderType == GLX_PIXMAP_BIT)) { _mesa_free(pdp); return NULL; } pdraw->private = pdp; pdraw->destroyDrawable = driDestroyDrawable; pdraw->swapBuffers = driSwapBuffers; /* called by glXSwapBuffers() */ pdraw->getSBC = driGetSBC; pdraw->waitForSBC = driWaitForSBC; pdraw->waitForMSC = driWaitForMSC; pdraw->swapBuffersMSC = driSwapBuffersMSC; pdraw->frameTracking = NULL; pdraw->queryFrameTracking = driQueryFrameTracking; if (driCompareGLXAPIVersion (20060314) >= 0) pdraw->copySubBuffer = driCopySubBuffer; /* This special default value is replaced with the configured * default value when the drawable is first bound to a direct * rendering context. */ pdraw->swap_interval = (unsigned)-1; pdp->swapBuffers = psp->DriverAPI.SwapBuffers; return (void *) pdp; } static void driDestroyDrawable(void *drawablePrivate) { __DRIdrawablePrivate *pdp = (__DRIdrawablePrivate *) drawablePrivate; __DRIscreenPrivate *psp; if (pdp) { psp = pdp->driScreenPriv; (*psp->DriverAPI.DestroyBuffer)(pdp); if (pdp->pClipRects) { _mesa_free(pdp->pClipRects); pdp->pClipRects = NULL; } if (pdp->pBackClipRects) { _mesa_free(pdp->pBackClipRects); pdp->pBackClipRects = NULL; } _mesa_free(pdp); } } /*@}*/ /*****************************************************************/ /** \name Context handling functions */ /*****************************************************************/ /*@{*/ /** * Destroy the per-context private information. * * \param contextPrivate opaque pointer to the per-drawable private info. * * \internal * This function calls __DriverAPIRec::DestroyContext on \p contextPrivate, calls * drmDestroyContext(), and finally frees \p contextPrivate. */ static void driDestroyContext(void *contextPrivate) { __DRIcontextPrivate *pcp = (__DRIcontextPrivate *) contextPrivate; if (pcp) { (*pcp->driScreenPriv->DriverAPI.DestroyContext)(pcp); (void) (*dri_interface->destroyContext)(pcp->driScreenPriv->psc, pcp->contextID); _mesa_free(pcp); } } /** * Create the per-drawable private driver information. * * \param dpy The display handle. * \param modes Mode used to create the new context. * \param render_type Type of rendering target. \c GLX_RGBA is the only * type likely to ever be supported for direct-rendering. * \param sharedPrivate The shared context dependent methods or \c NULL if * non-existent. * \param pctx DRI context to receive the context dependent methods. * * \returns An opaque pointer to the per-context private information on * success, or \c NULL on failure. * * \internal * This function allocates and fills a __DRIcontextPrivateRec structure. It * performs some device independent initialization and passes all the * relevent information to __DriverAPIRec::CreateContext to create the * context. * */ static void * driCreateNewContext(__DRIscreen *screen, const __GLcontextModes *modes, int render_type, void *sharedPrivate, __DRIcontext *pctx) { __DRIcontextPrivate *pcp; __DRIcontextPrivate *pshare = (__DRIcontextPrivate *) sharedPrivate; __DRIscreenPrivate *psp; void * const shareCtx = (pshare != NULL) ? pshare->driverPrivate : NULL; psp = (__DRIscreenPrivate *)screen->private; pcp = (__DRIcontextPrivate *)_mesa_malloc(sizeof(__DRIcontextPrivate)); if (!pcp) { return NULL; } if (! (*dri_interface->createContext)(screen, modes->fbconfigID, &pcp->contextID, &pcp->hHWContext)) { _mesa_free(pcp); return NULL; } pcp->driScreenPriv = psp; pcp->driDrawablePriv = NULL; /* When the first context is created for a screen, initialize a "dummy" * context. */ if (!psp->dummyContextPriv.driScreenPriv) { psp->dummyContextPriv.contextID = 0; psp->dummyContextPriv.hHWContext = psp->pSAREA->dummy_context; psp->dummyContextPriv.driScreenPriv = psp; psp->dummyContextPriv.driDrawablePriv = NULL; psp->dummyContextPriv.driverPrivate = NULL; /* No other fields should be used! */ } pctx->destroyContext = driDestroyContext; pctx->bindContext = driBindContext; pctx->unbindContext = driUnbindContext; if ( !(*psp->DriverAPI.CreateContext)(modes, pcp, shareCtx) ) { (void) (*dri_interface->destroyContext)(screen, pcp->contextID); _mesa_free(pcp); return NULL; } return pcp; } /*@}*/ /*****************************************************************/ /** \name Screen handling functions */ /*****************************************************************/ /*@{*/ /** * Destroy the per-screen private information. * * \param dpy the display handle. * \param scrn the screen number. * \param screenPrivate opaque pointer to the per-screen private information. * * \internal * This function calls __DriverAPIRec::DestroyScreen on \p screenPrivate, calls * drmClose(), and finally frees \p screenPrivate. */ static void driDestroyScreen(void *screenPrivate) { __DRIscreenPrivate *psp = (__DRIscreenPrivate *) screenPrivate; if (psp) { /* No interaction with the X-server is possible at this point. This * routine is called after XCloseDisplay, so there is no protocol * stream open to the X-server anymore. */ if (psp->DriverAPI.DestroyScreen) (*psp->DriverAPI.DestroyScreen)(psp); (void)drmUnmap((drmAddress)psp->pSAREA, SAREA_MAX); (void)drmUnmap((drmAddress)psp->pFB, psp->fbSize); (void)drmCloseOnce(psp->fd); if ( psp->modes != NULL ) { (*dri_interface->destroyContextModes)( psp->modes ); } _mesa_free(psp); } } /** * Utility function used to create a new driver-private screen structure. * * \param dpy Display pointer * \param scrn Index of the screen * \param psc DRI screen data (not driver private) * \param modes Linked list of known display modes. This list is, at a * minimum, a list of modes based on the current display mode. * These roughly match the set of available X11 visuals, but it * need not be limited to X11! The calling libGL should create * a list that will inform the driver of the current display * mode (i.e., color buffer depth, depth buffer depth, etc.). * \param ddx_version Version of the 2D DDX. This may not be meaningful for * all drivers. * \param dri_version Version of the "server-side" DRI. * \param drm_version Version of the kernel DRM. * \param frame_buffer Data describing the location and layout of the * framebuffer. * \param pSAREA Pointer the the SAREA. * \param fd Device handle for the DRM. * \param internal_api_version Version of the internal interface between the * driver and libGL. * \param driverAPI Driver API functions used by other routines in dri_util.c. * * \note * There is no need to check the minimum API version in this function. Since * the \c __driCreateNewScreen function is versioned, it is impossible for a * loader that is too old to even load this driver. */ __DRIscreenPrivate * __driUtilCreateNewScreen(int scr, __DRIscreen *psc, __GLcontextModes * modes, const __DRIversion * ddx_version, const __DRIversion * dri_version, const __DRIversion * drm_version, const __DRIframebuffer * frame_buffer, drm_sarea_t *pSAREA, int fd, int internal_api_version, const struct __DriverAPIRec *driverAPI) { __DRIscreenPrivate *psp; api_ver = internal_api_version; psp = (__DRIscreenPrivate *)_mesa_malloc(sizeof(__DRIscreenPrivate)); if (!psp) { return NULL; } psp->psc = psc; psp->modes = modes; /* ** NOT_DONE: This is used by the X server to detect when the client ** has died while holding the drawable lock. The client sets the ** drawable lock to this value. */ psp->drawLockID = 1; psp->drmMajor = drm_version->major; psp->drmMinor = drm_version->minor; psp->drmPatch = drm_version->patch; psp->ddxMajor = ddx_version->major; psp->ddxMinor = ddx_version->minor; psp->ddxPatch = ddx_version->patch; psp->driMajor = dri_version->major; psp->driMinor = dri_version->minor; psp->driPatch = dri_version->patch; /* install driver's callback functions */ memcpy( &psp->DriverAPI, driverAPI, sizeof(struct __DriverAPIRec) ); psp->pSAREA = pSAREA; psp->pFB = frame_buffer->base; psp->fbSize = frame_buffer->size; psp->fbStride = frame_buffer->stride; psp->fbWidth = frame_buffer->width; psp->fbHeight = frame_buffer->height; psp->devPrivSize = frame_buffer->dev_priv_size; psp->pDevPriv = frame_buffer->dev_priv; psp->fbBPP = psp->fbStride * 8 / frame_buffer->width; psp->fd = fd; psp->myNum = scr; /* ** Do not init dummy context here; actual initialization will be ** done when the first DRI context is created. Init screen priv ptr ** to NULL to let CreateContext routine that it needs to be inited. */ psp->dummyContextPriv.driScreenPriv = NULL; psc->destroyScreen = driDestroyScreen; psc->createNewDrawable = driCreateNewDrawable; psc->getMSC = driGetMSC; psc->createNewContext = driCreateNewContext; if (internal_api_version >= 20070121) psc->setTexOffset = psp->DriverAPI.setTexOffset; if ( (psp->DriverAPI.InitDriver != NULL) && !(*psp->DriverAPI.InitDriver)(psp) ) { _mesa_free( psp ); return NULL; } return psp; } /** * Compare the current GLX API version with a driver supplied required version. * * The minimum required version is compared with the API version exported by * the \c __glXGetInternalVersion function (in libGL.so). * * \param required_version Minimum required internal GLX API version. * \return A tri-value return, as from strcmp is returned. A value less * than, equal to, or greater than zero will be returned if the * internal GLX API version is less than, equal to, or greater * than \c required_version. * * \sa __glXGetInternalVersion(). */ int driCompareGLXAPIVersion( GLint required_version ) { if ( api_ver > required_version ) { return 1; } else if ( api_ver == required_version ) { return 0; } return -1; } static int driQueryFrameTracking( void * priv, int64_t * sbc, int64_t * missedFrames, float * lastMissedUsage, float * usage ) { __DRIswapInfo sInfo; int status; int64_t ust; __DRIdrawablePrivate * dpriv = (__DRIdrawablePrivate *) priv; status = dpriv->driScreenPriv->DriverAPI.GetSwapInfo( dpriv, & sInfo ); if ( status == 0 ) { *sbc = sInfo.swap_count; *missedFrames = sInfo.swap_missed_count; *lastMissedUsage = sInfo.swap_missed_usage; (*dri_interface->getUST)( & ust ); *usage = driCalculateSwapUsage( dpriv, sInfo.swap_ust, ust ); } return status; } /** * Calculate amount of swap interval used between GLX buffer swaps. * * The usage value, on the range [0,max], is the fraction of total swap * interval time used between GLX buffer swaps is calculated. * * \f$p = t_d / (i * t_r)\f$ * * Where \f$t_d\f$ is the time since the last GLX buffer swap, \f$i\f$ is the * swap interval (as set by \c glXSwapIntervalSGI), and \f$t_r\f$ time * required for a single vertical refresh period (as returned by \c * glXGetMscRateOML). * * See the documentation for the GLX_MESA_swap_frame_usage extension for more * details. * * \param dPriv Pointer to the private drawable structure. * \return If less than a single swap interval time period was required * between GLX buffer swaps, a number greater than 0 and less than * 1.0 is returned. If exactly one swap interval time period is * required, 1.0 is returned, and if more than one is required then * a number greater than 1.0 will be returned. * * \sa glXSwapIntervalSGI glXGetMscRateOML * * \todo Instead of caching the \c glXGetMscRateOML function pointer, would it * be possible to cache the sync rate? */ float driCalculateSwapUsage( __DRIdrawablePrivate *dPriv, int64_t last_swap_ust, int64_t current_ust ) { int32_t n; int32_t d; int interval; float usage = 1.0; if ( (*dri_interface->getMSCRate)(dPriv->pdraw, &n, &d) ) { interval = (dPriv->pdraw->swap_interval != 0) ? dPriv->pdraw->swap_interval : 1; /* We want to calculate * (current_UST - last_swap_UST) / (interval * us_per_refresh). We get * current_UST by calling __glXGetUST. last_swap_UST is stored in * dPriv->swap_ust. interval has already been calculated. * * The only tricky part is us_per_refresh. us_per_refresh is * 1000000 / MSC_rate. We know the MSC_rate is n / d. We can flip it * around and say us_per_refresh = 1000000 * d / n. Since this goes in * the denominator of the final calculation, we calculate * (interval * 1000000 * d) and move n into the numerator. */ usage = (current_ust - last_swap_ust); usage *= n; usage /= (interval * d); usage /= 1000000.0; } return usage; } /*@}*/