add BadSeeds test

for now just exhaustive, against some simple 16byte keys.
need to check the bad_seeds lists also, as these tests will
actually terminate

See GH #99

KeysetTest.h

@@ -79,6 +79,44 @@ bool PrngTest ( hashfunc<hashtype> hash,
   return result;
 }
 
+//-----------------------------------------------------------------------------
+// Find bad seeds, and test against the known bad hashes.
+
+template< typename hashtype >
+bool BadSeedsTest ( hashfunc<hashtype> hash, bool testAll )
+{
+
+  bool result = true;
+  if (sizeof(hashtype) > 8) {
+      printf("BadSeedsTest is designed for hashes <= 64-bit \n");
+      return false;
+  }
+
+  const size_t max_seed = sizeof(hashtype) == 8 ? 0xffffffffffffffff : 0xffffffff;
+  // TODO: testAll: checking known or suspected bad seeds
+  printf("Testing 0x%lx seeds ...\n", max_seed);
+
+  for (size_t y=0; y < max_seed; y++) {
+    static hashtype zero;
+    hashtype h;
+    Hash_Seed_init (hash, y);
+    for (int x = 0; x < 256; x++) {
+      std::vector<hashtype> hashes;
+      uint8_t key[16];
+      memset(&key, x, sizeof(key));
+      hash(key, 16, y, &h);
+      if (memcmp(&zero, &h, sizeof(hashtype)) == 0)
+        printf("Broken seed 0x%x => 0\n", y);
+      else
+        hashes.push_back(h);
+      if (!TestHashList(hashes,false, true, false, false, false, false)) {
+        printf("Bad seed 0x%x => %d\n", y, x);
+        result = false;
+      }
+    }
+  }
+  return result;
+}
 
 //-----------------------------------------------------------------------------
 // Keyset 'Perlin Noise' - X,Y coordinates on input & seed

Stats.h

@@ -539,25 +539,29 @@ hashtype bitreverse(hashtype n, size_t b = sizeof(hashtype) * 8)
 template < typename hashtype >
 bool TestHashList ( std::vector<hashtype> & hashes, bool drawDiagram,
                     bool testCollision = true, bool testDist = true,
-                    bool testHighBits = true, bool testLowBits = true)
+                    bool testHighBits = true, bool testLowBits = true,
+                    bool verbose = true)
 {
   bool result = true;
 
   if (testCollision)
   {
     size_t const count = hashes.size();
     double const expected = EstimateNbCollisions(count, sizeof(hashtype) * 8);
-    printf("Testing collisions (%3i-bit) - Expected %6.1f, ",
-           (int)sizeof(hashtype)*8, expected);
+    if (verbose)
+      printf("Testing collisions (%3i-bit) - Expected %6.1f, ",
+             (int)sizeof(hashtype)*8, expected);
     const int i_expected = (int)expected;
 
     int collcount = 0;
     HashSet<hashtype> collisions;
     collcount = FindCollisions(hashes, collisions, 1000, drawDiagram);
     double ratio = double(collcount) / expected;
-    printf("actual %6i (%.2fx)", (int)collcount, expected > 0.0 ? ratio : (double)collcount);
-    if (ratio > 0.98 && collcount != i_expected)
-      printf(" (%i)", collcount - i_expected);
+    if (verbose) {
+      printf("actual %6i (%.2fx)", (int)collcount, expected > 0.0 ? ratio : (double)collcount);
+      if (ratio > 0.98 && collcount != i_expected)
+        printf(" (%i)", collcount - i_expected);
+    }
 
     if (sizeof(hashtype) <= sizeof(uint32_t))
     {
@@ -606,7 +610,9 @@ bool TestHashList ( std::vector<hashtype> & hashes, bool drawDiagram,
       }
     }
 
-    printf("\n");
+    if (verbose) {
+      printf("\n");
+    }
     fflush(NULL);
 
     if (testHighBits) {

main.cpp

@@ -37,6 +37,7 @@ bool g_testDiffDist    = false;
 bool g_testMomentChi2  = false;
 bool g_testPrng        = false;
 bool g_testBIC         = false;
+bool g_testBadSeeds    = false;
 //bool g_testLongNeighbors = false;
 
 double g_speed = 0.0;
@@ -67,6 +68,7 @@ TestOpts g_testopts[] =
   { g_testBIC, 	        "BIC" },
   { g_testMomentChi2,   "MomentChi2" },
   { g_testPrng,         "Prng" },
+  { g_testBadSeeds,     "BadSeeds" },
   //{ g_testLongNeighbors,"LongNeighbors" }
 };
 
@@ -1397,7 +1399,6 @@ void test ( hashfunc<hashtype> hash, HashInfo* info )
     fflush(NULL);
   }
 
-
   if (g_testPrng || g_testAll)
   {
     printf("[[[ Prng Tests ]]]\n\n");
@@ -1465,6 +1466,18 @@ void test ( hashfunc<hashtype> hash, HashInfo* info )
     fflush(NULL);
   }
 
+  if (g_testBadSeeds)
+  {
+    printf("[[[ BadSeeds Tests ]]]\n\n");
+    // g_testExtra: test all seeds, or just some known bad seeds
+
+    Seed_init (info, 0);
+    bool result = BadSeedsTest<hashtype>( hash, g_testExtra );
+    if(!result) printf("\n*********FAIL*********\n");
+    printf("\n");
+    fflush(NULL);
+  }
+
 }
 
 //-----------------------------------------------------------------------------