Add Embree thirdparty library

thirdparty/embree/common/algorithms/parallel_reduce.cpp

@@ -0,0 +1,49 @@
+// Copyright 2009-2020 Intel Corporation
+// SPDX-License-Identifier: Apache-2.0
+
+#include "parallel_reduce.h"
+#include "../sys/regression.h"
+
+namespace embree
+{
+  struct parallel_reduce_regression_test : public RegressionTest
+  {
+    parallel_reduce_regression_test(const char* name) : RegressionTest(name) {
+      registerRegressionTest(this);
+    }
+    
+    bool run ()
+    {
+      bool passed = true;
+
+      const size_t M = 10;
+      for (size_t N=10; N<10000000; N=size_t(2.1*N))
+      {
+        /* sequentially calculate sum of squares */
+        size_t sum0 = 0;
+        for (size_t i=0; i<N; i++) {
+          sum0 += i*i;
+        }
+
+        /* parallel calculation of sum of squares */
+        for (size_t m=0; m<M; m++)
+        {
+          size_t sum1 = parallel_reduce( size_t(0), size_t(N), size_t(1024), size_t(0), [&](const range<size_t>& r) -> size_t
+          {
+            size_t s = 0;
+            for (size_t i=r.begin(); i<r.end(); i++) 
+              s += i*i;
+            return s;
+          }, 
+          [](const size_t v0, const size_t v1) {
+            return v0+v1;
+          });
+          passed = sum0 == sum1;
+        }
+      }
+      return passed;
+    }
+  };
+
+  parallel_reduce_regression_test parallel_reduce_regression("parallel_reduce_regression_test");
+}