add test

tests/examples/testSubsets.nim

@@ -0,0 +1,48 @@
+import qex
+import physics/qcdTypes
+
+proc test =
+  qexInit()
+
+  var lat = [8,8,8,8]
+  var lo = newLayout(lat)
+  let vnc = lo.physVol * getDefaultNc()
+
+  var v1 = lo.ColorVector()
+  var v2 = lo.ColorVector()
+  var v3 = lo.ColorVector()
+  var v1e = v1.even
+
+  # start thread block ("omp parallel")
+  threads:
+    v1 := 1
+    threadBarrier()  # required when changing subsets if potential race condition
+    v1.even := 2
+    threadBarrier()
+
+    # loop over all (vectorized) site indices in v1
+    for e in v1.all:
+      v2[e] := 2 * v1[e]
+      v3[e] += v2[e]
+
+    echo v1.norm2, "\t", v2.norm2, "\t", v3.norm2
+    doAssert v1.norm2 ==  2.5*vnc   # even: 2, odd: 1
+    doAssert v2.norm2 == 10.0*vnc   # even: 4, odd: 2
+    doAssert v3.norm2 == 10.0*vnc   # even: 4, odd: 2
+
+    threadBarrier()
+    v1e := 3
+    threadBarrier()
+    for e in v1.even:
+      v2[e] := 2 * v1[e]
+      v3[e] += v2[e]
+    threadBarrier()
+
+    echo v1.norm2, "\t", v2.norm2, "\t", v3.norm2
+    doAssert v1.norm2 ==  5.0*vnc   # even:  3, odd: 1
+    doAssert v2.norm2 == 20.0*vnc   # even:  6, odd: 2
+    doAssert v3.norm2 == 52.0*vnc   # even: 10, odd: 2
+
+  qexFinalize()
+
+test()