returning 1d tasking in mandelbrot_tasks under ifdef

examples/mandelbrot_tasks/mandelbrot_tasks.ispc

@@ -31,6 +31,8 @@
    SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.  
 */
 
+#define _3D_TASKING
+
 static inline int
 mandel(float c_re, float c_im, int count) {
     float z_re = c_re, z_im = c_im;
@@ -57,26 +59,34 @@ task void
 mandelbrot_scanline(uniform float x0, uniform float dx, 
                     uniform float y0, uniform float dy,
                     uniform int width, uniform int height, 
+#ifdef _3D_TASKING
                     uniform int xspan, uniform int yspan,
+#else
+                    uniform int span,
+#endif
                     uniform int maxIterations, uniform int output[]) {
+#ifdef _3D_TASKING
     const uniform int xstart = taskIndex0 * xspan;
     const uniform int xend   = min(xstart  + xspan, width);
-
     const uniform int ystart = taskIndex1 * yspan;
     const uniform int yend   = min(ystart  + yspan, height);
-    
 
     foreach (yi = ystart ... yend, xi = xstart ... xend) {
+#else
+    uniform int ystart = taskIndex * span;
+    uniform int yend = min((taskIndex+1) * span, (unsigned int)height);
+
+    foreach (yi = ystart ... yend, xi = 0 ... width) {
+#endif
         float x = x0 + xi * dx;
         float y = y0 + yi * dy;
 
         int index = yi * width + xi;
         output[index] = mandel(x, y, maxIterations);
     }
-    
 }
 
-#if 1
+
 export void
 mandelbrot_ispc(uniform float x0, uniform float y0, 
                 uniform float x1, uniform float y1,
@@ -84,16 +94,17 @@ mandelbrot_ispc(uniform float x0, uniform float y0,
                 uniform int maxIterations, uniform int output[]) {
     uniform float dx = (x1 - x0) / width;
     uniform float dy = (y1 - y0) / height;
+#ifdef _3D_TASKING
     const uniform int xspan = max(32, programCount*2);  /* make sure it is big enough to avoid false-sharing */
     const uniform int yspan = 16; 
 
-
-#if 1
     launch [width/xspan, height/yspan]
-#else
-    launch [height/yspan][width/xspan]
-#endif
-      mandelbrot_scanline(x0, dx, y0, dy, width, height, xspan, yspan,
+    mandelbrot_scanline(x0, dx, y0, dy, width, height, xspan, yspan,
                           maxIterations, output);
-}
+#else
+    uniform int span = 4;
+
+    launch[height/span] mandelbrot_scanline(x0, dx, y0, dy, width, height, span,
+                                            maxIterations, output);
 #endif
+}