mdbx: new testset (initial, stub).

Initial stub for https://github.com/ReOpen/libmdbx/issues/8

test/keygen.cc

@@ -0,0 +1,72 @@
+/*
+ * Copyright 2017 Leonid Yuriev <leo@yuriev.ru>
+ * and other libmdbx authors: please see AUTHORS file.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted only as authorized by the OpenLDAP
+ * Public License.
+ *
+ * A copy of this license is available in the file LICENSE in the
+ * top-level directory of the distribution or, alternatively, at
+ * <http://www.OpenLDAP.org/license.html>.
+ */
+
+#include "test.h"
+
+namespace keygen {
+
+size_t ffs_fallback(serial_t serial) {
+  size_t bit = sizeof(serial_t) * 8 - 1;
+  auto mask = (serial_t)1u << bit;
+  do {
+    if (serial & mask)
+      return bit;
+    --bit;
+  } while (mask >>= 1);
+  return 0;
+}
+
+void __hot make(const serial_t serial, const params_t &params, result_t &out) {
+  assert(out.limit >= params.maxlen);
+  assert(params.maxlen >= params.minlen);
+  assert(params.maxlen >= length(serial));
+
+  out.value.mv_data = out.bytes;
+  out.value.mv_size = params.minlen;
+
+  if (params.flags & (MDB_INTEGERKEY | MDB_INTEGERDUP)) {
+    assert(params.maxlen == params.minlen);
+    assert(params.minlen == 4 || params.minlen == 8);
+    if (is_byteorder_le() || params.minlen == 8)
+      out.u64 = serial;
+    else
+      out.u32 = (uint32_t)serial;
+  } else if (params.flags & (MDB_REVERSEKEY | MDB_REVERSEDUP)) {
+    if (out.value.mv_size > 8) {
+      memset(out.bytes, '\0', out.value.mv_size - 8);
+      unaligned::store(out.bytes + out.value.mv_size - 8, htobe64(serial));
+    } else {
+      out.u64 = htobe64(serial);
+      if (out.value.mv_size < 8) {
+        out.value.mv_size = std::max(length(serial), out.value.mv_size);
+        out.value.mv_data = out.bytes + 8 - out.value.mv_size;
+      }
+    }
+  } else {
+    out.u64 = htole64(serial);
+    if (out.value.mv_size > 8)
+      memset(out.bytes + 8, '\0', out.value.mv_size - 8);
+    else
+      out.value.mv_size = std::max(length(serial), out.value.mv_size);
+  }
+
+  assert(out.value.mv_size >= params.minlen);
+  assert(out.value.mv_size <= params.maxlen);
+  assert(out.value.mv_size >= length(serial));
+  assert(out.value.mv_data >= out.bytes);
+  assert((uint8_t *)out.value.mv_data + out.value.mv_size <=
+         out.bytes + out.limit);
+}
+
+} /* namespace keygen */