From bd56c75d0db83bc0f3b68e1914ec1b8dd0547546 Mon Sep 17 00:00:00 2001
From: Christopher Jeffrey <chjjeffrey@gmail.com>
Date: Thu, 20 Jul 2017 01:04:44 -0700
Subject: [PATCH] merkle: refactor loops.

---
 lib/crypto/merkle.js | 24 +++++++++++++++---------
 1 file changed, 15 insertions(+), 9 deletions(-)

diff --git a/lib/crypto/merkle.js b/lib/crypto/merkle.js
index c54245a3..36ef202e 100644
--- a/lib/crypto/merkle.js
+++ b/lib/crypto/merkle.js
@@ -24,13 +24,14 @@ exports.createTree = function createTree(leaves) {
   let nodes = leaves;
   let size = leaves.length;
   let malleated = false;
+  let i = 0;
 
   if (size === 0) {
     nodes.push(Buffer.alloc(32));
     return [nodes, malleated];
   }
 
-  for (let i = 0; size > 1; size = (size + 1) >>> 1) {
+  while (size > 1) {
     for (let j = 0; j < size; j += 2) {
       let k = Math.min(j + 1, size - 1);
       let left = nodes[i + j];
@@ -47,6 +48,8 @@ exports.createTree = function createTree(leaves) {
       nodes.push(hash);
     }
     i += size;
+    size += 1;
+    size >>>= 1;
   }
 
   return [nodes, malleated];
@@ -65,7 +68,7 @@ exports.createRoot = function createRoot(leaves) {
 };
 
 /**
- * Collect a merkle branch at vector index.
+ * Collect a merkle branch from vector index.
  * @param {Number} index
  * @param {Buffer[]} leaves
  * @returns {Buffer[]} branch
@@ -75,33 +78,36 @@ exports.createBranch = function createBranch(index, leaves) {
   let size = leaves.length;
   let [nodes] = exports.createTree(leaves);
   let branch = [];
+  let i = 0;
 
-  for (let i = 0; size > 1; size = (size + 1) >>> 1) {
+  while (size > 1) {
     let j = Math.min(index ^ 1, size - 1);
     branch.push(nodes[i + j]);
     index >>>= 1;
     i += size;
+    size += 1;
+    size >>>= 1;
   }
 
   return branch;
 };
 
 /**
- * Check a merkle branch at vector index.
+ * Derive merkle root from branch.
  * @param {Buffer} hash
  * @param {Buffer[]} branch
  * @param {Number} index
- * @returns {Buffer} Hash.
+ * @returns {Buffer} root
  */
 
-exports.verifyBranch = function verifyBranch(hash, branch, index) {
+exports.deriveRoot = function deriveRoot(hash, branch, index) {
   let root = hash;
 
-  for (let otherside of branch) {
+  for (let hash of branch) {
     if (index & 1)
-      root = digest.root256(otherside, root);
+      root = digest.root256(hash, root);
     else
-      root = digest.root256(root, otherside);
+      root = digest.root256(root, hash);
 
     index >>>= 1;
   }