Returned code

src/crypto/tree-hash.c

@@ -0,0 +1,132 @@
+// 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) << 3; 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], 2 * HASH_SIZE, 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], 2 * HASH_SIZE, root_hash);
+  }
+}
+
+size_t tree_depth(size_t count)
+{
+  size_t i;
+  size_t depth = 0;
+  assert(count > 0);
+  for (i = sizeof(size_t) << 2; i > 0; i >>= 1)
+  {
+    if (count >> i > 0)
+    {
+      count >>= i;
+      depth += i;
+    }
+  }
+  return depth;
+}
+
+void tree_branch(const char (*hashes)[HASH_SIZE], size_t count, char (*branch)[HASH_SIZE])
+{
+  size_t i, j;
+  size_t cnt = 1;
+  size_t depth = 0;
+  char (*ints)[HASH_SIZE];
+  assert(count > 0);
+  for (i = sizeof(size_t) << 2; i > 0; i >>= 1)
+  {
+    if (cnt << i <= count)
+    {
+      cnt <<= i;
+      depth += i;
+    }
+  }
+  assert(cnt == 1ULL << depth);
+  assert(depth == tree_depth(count));
+  ints = alloca((cnt - 1) * HASH_SIZE);
+  memcpy(ints, hashes + 1, (2 * cnt - count - 1) * HASH_SIZE);
+  for (i = 2 * cnt - count, j = 2 * cnt - count - 1; j < cnt - 1; i += 2, ++j)
+  {
+    cn_fast_hash(hashes[i], 2 * HASH_SIZE, ints[j]);
+  }
+  assert(i == count);
+  while (depth > 0)
+  {
+    assert(cnt == 1ULL << depth);
+    cnt >>= 1;
+    --depth;
+    memcpy(branch[depth], ints[0], HASH_SIZE);
+    for (i = 1, j = 0; j < cnt - 1; i += 2, ++j)
+    {
+      cn_fast_hash(ints[i], 2 * HASH_SIZE, ints[j]);
+    }
+  }
+}
+
+void tree_hash_from_branch(const char (*branch)[HASH_SIZE], size_t depth, const char* leaf, const void* path, char* root_hash)
+{
+  if (depth == 0)
+  {
+    memcpy(root_hash, leaf, HASH_SIZE);
+  }
+  else
+  {
+    char buffer[2][HASH_SIZE];
+    int from_leaf = 1;
+    char *leaf_path, *branch_path;
+    while (depth > 0)
+    {
+      --depth;
+      if (path && (((const char*) path)[depth >> 3] & (1 << (depth & 7))) != 0)
+      {
+        leaf_path = buffer[1];
+        branch_path = buffer[0];
+      }
+      else
+      {
+        leaf_path = buffer[0];
+        branch_path = buffer[1];
+      }
+      if (from_leaf)
+      {
+        memcpy(leaf_path, leaf, HASH_SIZE);
+        from_leaf = 0;
+      }
+      else
+      {
+        cn_fast_hash(buffer, 2 * HASH_SIZE, leaf_path);
+      }
+      memcpy(branch_path, branch[depth], HASH_SIZE);
+    }
+    cn_fast_hash(buffer, 2 * HASH_SIZE, root_hash);
+  }
+}