Merge pull request #941 from ronawho/fix-sort-bitsPerDigit-boundary

Fix sorting arrays with values on bitsPerDigit boundaries

src/RadixSortLSD.chpl

@@ -30,8 +30,9 @@ module RadixSortLSD
       var aMin = min reduce a;
       var aMax = max reduce a;
       var wPos = if aMax >= 0 then numBits(int) - clz(aMax) else 0;
-      var wNeg = if aMin < 0 then numBits(int) - clz((-aMin)-1) + 1 else 0;
-      const bitWidth = max(wPos, wNeg);
+      var wNeg = if aMin < 0 then numBits(int) - clz((-aMin)-1) else 0;
+      const signBit = if aMin < 0 then 1 else 0;
+      const bitWidth = max(wPos, wNeg) + signBit;
       const negs = aMin < 0;
       return (bitWidth, negs);
     }

tests/sort_test.py

@@ -12,7 +12,33 @@ def testSort(self):
         spda = ak.sort(pda)
         maxIndex = spda.argmax()
         self.assertTrue(maxIndex > 0)
-
+
+    def testBitBoundaryHardcode(self):
+
+        # test hardcoded 16/17-bit boundaries with and without negative values
+        a = ak.array([1, -1, 32767]) # 16 bit
+        b = ak.array([1,  0, 32768]) # 16 bit
+        c = ak.array([1, -1, 32768]) # 17 bit
+        assert ak.is_sorted(ak.sort(a))
+        assert ak.is_sorted(ak.sort(b))
+        assert ak.is_sorted(ak.sort(c))
+
+        # test hardcoded 64-bit boundaries with and without negative values
+        d = ak.array([1, -1, 2**63-1])
+        e = ak.array([1,  0, 2**63-1])
+        f = ak.array([1, -2**63, 2**63-1])
+        assert ak.is_sorted(ak.sort(d))
+        assert ak.is_sorted(ak.sort(e))
+        assert ak.is_sorted(ak.sort(f))
+
+    def testBitBoundary(self):
+
+        # test 17-bit sort
+        L = -2**15
+        U = 2**16
+        a = ak.randint(L, U, 100)
+        assert ak.is_sorted(ak.sort(a))
+
     def testErrorHandling(self):
 
         # Test RuntimeError from bool NotImplementedError