more generic fix

contracts/lib/Lib_MerkleTrie.sol

@@ -443,7 +443,7 @@ library Lib_MerkleTrie {
                     // We're dealing with an unnecessary extension node.
                     // We're going to delete the node entirely.
                     // Simply insert its current value into the branch index.
-                    newBranch = _editBranchIndexRLP(newBranch, branchKey, lastNode.decoded[lastNode.decoded.length-1]);
+                    newBranch = _editBranchIndex(newBranch, branchKey, _getNodeValue(lastNode));
                 }
             }
 
@@ -648,7 +648,19 @@ library Lib_MerkleTrie {
             bytes memory _value
         )
     {
-        return Lib_RLPReader.readBytes(_node.decoded[_node.decoded.length - 1]);
+        Lib_RLPReader.RLPItem memory _in = _node.decoded[_node.decoded.length - 1];
+        // this is bytes only if the length is 32
+        (
+            uint256 itemOffset,
+            uint256 itemLength,
+            Lib_RLPReader.RLPItemType itemType
+        ) = Lib_RLPReader._decodeLength(_in);
+
+        if (itemType == Lib_RLPReader.RLPItemType.DATA_ITEM) {
+            return Lib_RLPReader._copy(_in.ptr, itemOffset, itemLength);
+        } else {
+            return Lib_RLPReader._copy(_in.ptr, 0, _in.length);
+        }
     }
 
     /**
@@ -908,21 +920,6 @@ library Lib_MerkleTrie {
         return _makeNode(_branch.decoded);
     }
 
-    function _editBranchIndexRLP(
-        TrieNode memory _branch,
-        uint8 _index,
-        Lib_RLPReader.RLPItem memory encoded
-    )
-        private
-        pure
-        returns (
-            TrieNode memory _updatedNode
-        )
-    {
-        _branch.decoded[_index] = encoded;
-        return _makeNode(_branch.decoded);
-    }
-
     /**
      * @notice Utility; adds a prefix to a key.
      * @param _key Key to prefix.

contracts/lib/Lib_RLPReader.sol

@@ -457,7 +457,7 @@ library Lib_RLPReader {
     function _decodeLength(
         RLPItem memory _in
     )
-        private
+        internal
         pure
         returns (
             uint256,
@@ -564,7 +564,7 @@ library Lib_RLPReader {
         uint256 _offset,
         uint256 _length
     )
-        private
+        internal
         pure
         returns (
             bytes memory

test/mips_test_memory.js

@@ -39,7 +39,7 @@ describe("MIPSMemory contract", function () {
     expect(await mm.ReadMemory(root, 4)).to.equal(2)
     expect(await mm.ReadMemory(root, 0x40)).to.equal(3)
   })
-  /*it("write four should work", async function() {
+  it("write four should work", async function() {
     await mm.AddTrieNode(new Uint8Array([0x80]))
     let root = "0x56e81f171bcc55a6ff8345e692c0f86e5b48e01b996cadc001622fb5e363b421"
 
@@ -51,5 +51,5 @@ describe("MIPSMemory contract", function () {
     expect(await mm.ReadMemory(root, 0x7fffd00c)).to.equal(1)
     expect(await mm.ReadMemory(root, 0x7fffd010)).to.equal(2)
     expect(await mm.ReadMemory(root, 0x7fffcffc)).to.equal(3)
-  })*/
+  })
 })