1 files changed, 40 insertions, 0 deletions
diff --git a/src/crypto/tree-hash.c b/src/crypto/tree-hash.c
new file mode 100644
index 000000000..a2b0eeaa5
--- /dev/null
+++ b/src/crypto/tree-hash.c
@@ -0,0 +1,40 @@
+// Copyright (c) 2012-2013 The Cryptonote developers
+// Distributed under the MIT/X11 software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <alloca.h>
+#include <assert.h>
+#include <stddef.h>
+#include <string.h>
+
+#include "hash-ops.h"
+
+void tree_hash(const char (*hashes)[HASH_SIZE], size_t count, char *root_hash) {
+  assert(count > 0);
+  if (count == 1) {
+    memcpy(root_hash, hashes, HASH_SIZE);
+  } else if (count == 2) {
+    cn_fast_hash(hashes, 2 * HASH_SIZE, root_hash);
+  } else {
+    size_t i, j;
+    size_t cnt = count - 1;
+    char (*ints)[HASH_SIZE];
+    for (i = 1; i < sizeof(size_t); i <<= 1) {
+      cnt |= cnt >> i;
+    }
+    cnt &= ~(cnt >> 1);
+    ints = alloca(cnt * HASH_SIZE);
+    memcpy(ints, hashes, (2 * cnt - count) * HASH_SIZE);
+    for (i = 2 * cnt - count, j = 2 * cnt - count; j < cnt; i += 2, ++j) {
+      cn_fast_hash(hashes[i], 64, ints[j]);
+    }
+    assert(i == count);
+    while (cnt > 2) {
+      cnt >>= 1;
+      for (i = 0, j = 0; j < cnt; i += 2, ++j) {
+        cn_fast_hash(ints[i], 64, ints[j]);
+      }
+    }
+    cn_fast_hash(ints[0], 64, root_hash);
+  }
+}