added cuda examples

examples_cuda/mandelbrot_tasks3d/mandel_task_cu.cu

@@ -0,0 +1,53 @@
+#include <stdio.h>
+#define blockIndex0 (blockIdx.x)
+#define blockIndex1 (blockIdx.y)
+#define vectorWidth (32)
+#define vectorIndex (threadIdx.x & (vectorWidth-1))
+
+  int __device__ __forceinline__
+mandel(float c_re, float c_im, int count) 
+{
+  float z_re = c_re, z_im = c_im;
+  int i;
+  for (i = 0; i < count; ++i) {
+    if (z_re * z_re + z_im * z_im > 4.0f)
+      break;
+
+    float new_re = z_re*z_re - z_im*z_im;
+    float new_im = 2.0f * z_re * z_im;
+    {
+      z_re = c_re + new_re;
+      z_im = c_im + new_im;
+    }
+  }
+
+  return i;
+}
+
+extern "C"
+__global__ void mandelbrot_scanline(
+    float x0, float dx, 
+    float y0, float dy,
+    int width, int height, 
+    int xspan, int yspan,
+    int maxIterations, int output[]) 
+{
+  const int xstart = blockIndex0 * xspan;
+  const int xend   = min(xstart  + xspan, width);
+
+  const int ystart = blockIndex1 * yspan;
+  const int yend   = min(ystart  + yspan, height);
+
+  for (int yi = ystart; yi < yend; yi++)
+    for (int xi = xstart; xi < xend; xi += vectorWidth)
+    {
+      const float x = x0 + (xi + vectorIndex) * dx;
+      const float y = y0 +  yi              * dy;
+
+      const int res = mandel(x,y,maxIterations);
+      const int index = yi * width + (xi + vectorIndex);
+      if (xi + vectorIndex < xend)
+        output[index] = res;
+    }
+}
+