1 files changed, 44 insertions, 0 deletions
diff --git a/test/hash.cpp b/test/hash.cpp
new file mode 100644
index 00000000..3a8af600
--- /dev/null
+++ b/test/hash.cpp
@@ -0,0 +1,44 @@
+#include "app.hpp"
+#include "compat/int-hash.hpp"
+#include <bitset>
+#include <memory>
+
+namespace floormat {
+
+void test_app::test_hash()
+{
+    constexpr int max = 8;
+    constexpr size_t size = (2*max+1)*(2*max+1)*4 * 10;
+    constexpr size_t max_collisions = size*2/100;
+    size_t iter = 0, num_collisions = 0;
+    auto bitset_ = std::make_unique<std::bitset<size>>(false);
+    auto& bitset = *bitset_;
+
+    for (int j = -max; j <= max; j++)
+    {
+        for (int i = -max; i <= max; i++)
+        {
+            for (int k = -2; k <= 1; k++)
+            {
+                ++iter;
+                uint64_t value = 0;
+                value |= (uint64_t)(uint16_t)(int16_t)i << 0;
+                value |= (uint64_t)(uint16_t)(int16_t)j << 16;
+                value |= (uint64_t)(uint16_t)(int16_t)k << 32;
+                auto x = (size_t)int_hash(value);
+                //Debug {} << "bitset:" << i << j << k << "=" << x % size << "/" << x;
+                x %= size;
+#if 1
+                if (bitset.test(x) && ++num_collisions >= max_collisions)
+                    fm_abort("test/bitset: %zu collisions at iter %zu id %zu (%d;%d:%d)", num_collisions, iter, x, i, j, k);
+#else
+                if ((void)max_collisions, bitset.test(x))
+                    fm_warn("test/bitset: %zu collisions at iter %zu id %zu (%d;%d:%d)", ++num_collisions, iter, x, i, j, k);
+#endif
+                bitset.set(x);
+            }
+        }
+    }
+}
+
+} // namespace floormat