Add Embree thirdparty library

thirdparty/embree/common/algorithms/parallel_prefix_sum.cpp

@@ -0,0 +1,48 @@
+// Copyright 2009-2020 Intel Corporation
+// SPDX-License-Identifier: Apache-2.0
+
+#include "parallel_prefix_sum.h"
+#include "../sys/regression.h"
+
+namespace embree
+{
+  struct parallel_prefix_sum_regression_test : public RegressionTest
+  {
+    parallel_prefix_sum_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))
+      {
+	/* initialize array with random numbers */
+        uint32_t sum0 = 0;
+	std::vector<uint32_t> src(N);
+	for (size_t i=0; i<N; i++) {
+	  sum0 += src[i] = rand();
+        }
+        
+	/* calculate parallel prefix sum */
+	std::vector<uint32_t> dst(N);
+	for (auto& v : dst) v = 0;
+	
+	for (size_t i=0; i<M; i++) {
+	  uint32_t sum1 = parallel_prefix_sum(src,dst,N,0,std::plus<uint32_t>());
+          passed &= (sum0 == sum1);
+        }
+        
+	/* check if prefix sum is correct */
+	for (size_t i=0, sum=0; i<N; sum+=src[i++])
+	  passed &= ((uint32_t)sum == dst[i]);
+      }
+      
+      return passed;
+    }
+  };
+
+  parallel_prefix_sum_regression_test parallel_prefix_sum_regression("parallel_prefix_sum_regression");
+}