Add a example computing Mandelbrot fractal and display it using X11 if the lib

is available.

configure.ac

@@ -824,6 +824,12 @@ AC_MSG_CHECKING(whether OpenGL rendering is enabled)
 AC_SUBST(STARPU_OPENGL_RENDER, $enable_opengl_render)
 AC_MSG_RESULT($enable_opengl_render)
 
+have_x11=yes
+AC_CHECK_LIB(X11, XOpenDisplay,,[have_x11=no]) 
+if test x$have_x11 = xyes; then
+	AC_DEFINE(STARPU_HAVE_X11, [1], [enable X11])
+fi
+
 # In case there are BLAS kernels that are used by the example applications
 # we may specify which library to use. Note that this is not used for StarPU
 # itself.

examples/Makefile.am

@@ -623,3 +623,13 @@ examplebin_PROGRAMS +=				\
 
 reductions_minmax_reduction_SOURCES =		\
 	reductions/minmax_reduction.c
+
+##################
+# Mandelbrot Set #
+##################
+
+examplebin_PROGRAMS +=				\
+	mandelbrot/mandelbrot
+
+mandelbrot_mandelbrot_SOURCES =			\
+	mandelbrot/mandelbrot.c

examples/mandelbrot/mandelbrot.c

@@ -0,0 +1,299 @@
+/*
+ * StarPU
+ * Copyright (C) Université Bordeaux 1, CNRS 2008-2010 (see AUTHORS file)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation; either version 2.1 of the License, or (at
+ * your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ *
+ * See the GNU Lesser General Public License in COPYING.LGPL for more details.
+ */
+
+#include <starpu.h>
+#ifdef STARPU_HAVE_X11
+#include <X11/Xlib.h>
+#include <X11/Xutil.h>
+#endif
+
+/* NB: The X11 code is inspired from the http://locklessinc.com/articles/mandelbrot/ article */
+
+static int nblocks = 32;
+static int height = 1280;
+static int width = 1600;
+static int maxIt = 20000;
+
+static double leftX = -0.745;
+static double rightX = -0.74375;
+static double topY = .15;
+static double bottomY = .14875;
+
+#ifdef STARPU_HAVE_X11
+/* X11 data */
+static Display *dpy;
+static Window win;
+static XImage *bitmap;
+static GC gc;
+static KeySym Left=-1, Right, Down, Up, Alt ;
+static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
+
+static void exit_x11(void)
+{
+	XDestroyImage(bitmap);
+	XDestroyWindow(dpy, win);
+	XCloseDisplay(dpy);
+}
+
+static void init_x11(int width, int height, unsigned *buffer)
+{
+	/* Attempt to open the display */
+	dpy = XOpenDisplay(NULL);
+	
+	/* Failure */
+	if (!dpy)
+		exit(0);
+	
+	unsigned long white = WhitePixel(dpy,DefaultScreen(dpy));
+	unsigned long black = BlackPixel(dpy,DefaultScreen(dpy));
+
+	win = XCreateSimpleWindow(dpy, DefaultRootWindow(dpy), 0, 0,
+					width, height, 0, black, white);
+	
+	/* We want to be notified when the window appears */
+	XSelectInput(dpy, win, StructureNotifyMask);
+	
+	/* Make it appear */
+	XMapWindow(dpy, win);
+	
+	XTextProperty tp;
+	char name[128] = "Mandelbrot";
+	char *n = name;
+	Status st = XStringListToTextProperty(&n, 1, &tp);
+	if (st)
+		XSetWMName(dpy, win, &tp);
+
+	/* Wait for the MapNotify event */
+	XFlush(dpy);
+	
+	int depth = DefaultDepth(dpy, DefaultScreen(dpy));
+	Visual *visual = DefaultVisual(dpy, DefaultScreen(dpy));
+
+	/* Make bitmap */
+	bitmap = XCreateImage(dpy, visual, depth,
+		ZPixmap, 0, (char *)buffer,
+		width, height, 32, 0);
+	
+	/* Init GC */
+	gc = XCreateGC(dpy, win, 0, NULL);
+	XSetForeground(dpy, gc, black);
+	
+	XSelectInput(dpy, win, ExposureMask | KeyPressMask | StructureNotifyMask);
+	
+	Atom wmDeleteMessage;
+	wmDeleteMessage = XInternAtom(dpy, "WM_DELETE_WINDOW", False);
+	XSetWMProtocols(dpy, win, &wmDeleteMessage, 1);
+
+        Left = XStringToKeysym ("Left");
+        Right = XStringToKeysym ("Right");
+        Up = XStringToKeysym ("Up");
+        Down = XStringToKeysym ("Down");
+        Alt = XStringToKeysym ("Alt");
+}
+#endif
+
+static void compute_block(void *descr[], void *cl_arg)
+{
+	int ix, iy;
+
+	int iby, block_size;
+	double stepX, stepY;
+	starpu_unpack_cl_args(cl_arg, &iby, &block_size, &stepX, &stepY);
+
+	unsigned *data = (unsigned *)STARPU_VECTOR_GET_PTR(descr[0]);
+
+	int local_iy;
+	for (local_iy = 0; local_iy < block_size; local_iy++)
+	{
+		iy = iby*block_size + local_iy;
+		for (ix = 0; ix < width; ix++)
+		{
+			double cx = leftX + ix * stepX;
+			double cy = topY - iy * stepY;
+			// Z = X+I*Y
+			double x = 0;
+			double y = 0;
+			int it;
+			for (it = 0; it < maxIt; it++)
+			{
+				double x2 = x*x;
+				double y2 = y*y;
+
+				// Stop iterations when |Z| > 2
+				if (x2 + y2 > 4.0)
+					break;
+
+				double twoxy = 2.0*x*y;
+
+				// Z = Z^2 + C
+				x = x2 - y2 + cx;
+				y = twoxy + cy;
+			}
+	
+			unsigned int v = STARPU_MIN((1024*((float)(it)/(2000))), 256);
+			data[ix + local_iy*width] = (v<<16|(255-v)<<8);
+		}
+	}
+}
+
+static starpu_codelet mandelbrot_cl = {
+	.where = STARPU_CPU,
+	.type = STARPU_SEQ,
+	.cpu_func = compute_block,
+	.nbuffers = 1
+};
+
+#ifdef STARPU_HAVE_X11
+static int handle_events(void)
+{
+	XEvent event;
+	XNextEvent(dpy, &event);
+
+	KeySym key;
+	char text[255];
+
+	if (event.type == KeyPress)
+	{
+		XLookupString(&event.xkey,text,255,&key,0);
+		if (key == Left)
+		{
+			double widthX = rightX - leftX;
+			leftX -= 0.25*widthX;
+			rightX -= 0.25*widthX;
+		}
+		else if (key == Right)
+		{
+			double widthX = rightX - leftX;
+			leftX += 0.25*widthX;
+			rightX += 0.25*widthX;
+		}
+		else if (key == Up)
+		{
+			double heightY = topY - bottomY;
+			topY += 0.25*heightY;
+			bottomY += 0.25*heightY;
+		}
+		else if (key == Down)
+		{
+			double heightY = topY - bottomY;
+			topY -= 0.25*heightY;
+			bottomY -= 0.25*heightY;
+		}
+		else {
+			double widthX = rightX - leftX;
+			double heightY = topY - bottomY;
+
+			if (text[0] == '-')
+			{
+				/* Zoom out */
+				leftX -= 0.125*widthX;
+				rightX += 0.125*widthX;
+				topY += 0.125*heightY;
+				bottomY -= 0.125*heightY;
+			}
+			else if (text[0] == '+')
+			{
+				/* Zoom in */
+				leftX += 0.125*widthX;
+				rightX -= 0.125*widthX;
+				topY -= 0.125*heightY;
+				bottomY += 0.125*heightY;
+			}
+		}
+
+		if (text[0]=='q') {
+			return -1;
+		}
+	}
+
+	if (event.type==ButtonPress) {
+	/* tell where the mouse Button was Pressed */
+		printf("You pressed a button at (%i,%i)\n",
+			event.xbutton.x,event.xbutton.y);
+	}
+
+	return 0;
+}
+#endif
+
+int main(int argc, char **argv)
+{
+	unsigned *buffer;
+	buffer = malloc(height*width*sizeof(unsigned));
+
+#ifdef STARPU_HAVE_X11
+	init_x11(width, height, buffer);
+#endif
+
+	int block_size = height/nblocks;
+	STARPU_ASSERT((height % nblocks) == 0);
+
+	starpu_init(NULL);
+
+	starpu_data_handle block_handles[nblocks];
+	
+	int iby;
+	for (iby = 0; iby < nblocks; iby++)
+	{
+		unsigned *data = &buffer[iby*block_size*width];
+		starpu_vector_data_register(&block_handles[iby], 0,
+                        (uintptr_t)data, block_size*width, sizeof(unsigned));
+	}
+
+	while (1)
+	{
+		double stepX = (rightX - leftX)/width;
+		double stepY = (topY - bottomY)/height;
+
+		for (iby = 0; iby < nblocks; iby++)
+		{
+			starpu_insert_task(&mandelbrot_cl,
+				STARPU_VALUE, &iby, sizeof(iby),
+				STARPU_VALUE, &block_size, sizeof(block_size),
+				STARPU_VALUE, &stepX, sizeof(stepX),
+				STARPU_VALUE, &stepY, sizeof(stepY),
+				STARPU_W, block_handles[iby],
+				0);
+		}
+
+		for (iby = 0; iby < nblocks; iby++)
+		{
+			starpu_data_acquire(block_handles[iby], STARPU_R);
+#ifdef STARPU_HAVE_X11
+			pthread_mutex_lock(&mutex);
+			XPutImage(dpy, win, gc, bitmap,
+				0, iby*block_size,
+				0, iby*block_size,
+				width, block_size);
+			pthread_mutex_unlock(&mutex);
+#endif
+			starpu_data_release(block_handles[iby]);
+		}
+
+#ifdef STARPU_HAVE_X11
+		if (handle_events())
+			break;
+#endif
+	}
+
+#ifdef STARPU_HAVE_X11
+	exit_x11();
+#endif
+
+	starpu_shutdown();
+
+	return 0;
+}

include/starpu_config.h.in

@@ -18,8 +18,8 @@
 #undef STARPU_HAVE_MAGMA
 
 #undef STARPU_OPENGL_RENDER
-
 #undef STARPU_USE_GTK
+#undef STARPU_HAVE_X11
 
 #undef STARPU_HAVE_POSIX_MEMALIGN