From 9cabb1126d0e6bd6ac0267e5da3d7e871df6cd2b Mon Sep 17 00:00:00 2001
From: George J <george@penguingeorge.com>
Date: Sun, 6 May 2018 15:42:30 +0100
Subject: [PATCH] Adds Base85 operation to resolve #286

---
 src/core/config/OperationConfig.js |  2 +-
 src/core/operations/Base85.js      | 22 ++++++++++++----------
 2 files changed, 13 insertions(+), 11 deletions(-)

diff --git a/src/core/config/OperationConfig.js b/src/core/config/OperationConfig.js
index 4ca00f48..cd6cd1b8 100644
--- a/src/core/config/OperationConfig.js
+++ b/src/core/config/OperationConfig.js
@@ -1,8 +1,8 @@
 import Arithmetic from "../operations/Arithmetic.js";
 import Base from "../operations/Base.js";
 import Base58 from "../operations/Base58.js";
-import Base85 from "../operations/Base85.js";
 import Base64 from "../operations/Base64.js";
+import Base85 from "../operations/Base85.js";
 import BCD from "../operations/BCD.js";
 import BitwiseOp from "../operations/BitwiseOp.js";
 import ByteRepr from "../operations/ByteRepr.js";
diff --git a/src/core/operations/Base85.js b/src/core/operations/Base85.js
index 2be772c6..d8a4288b 100644
--- a/src/core/operations/Base85.js
+++ b/src/core/operations/Base85.js
@@ -1,6 +1,3 @@
-import Utils from "../Utils.js";
-
-
 /**
  * Base85 operations.
  *
@@ -50,7 +47,9 @@ const Base85 = {
             encoding = Base85._alphabetName(alphabet),
             result = "";
 
-        alphabet = Utils.expandAlphRange(alphabet).join("");
+        if (alphabet.length !== 85 || [].unique.call(alphabet).length !== 85) {
+            throw ("Alphabet must be of length 85");
+        }
 
         let block;
         for (let i = 0; i < input.length; i += 4) {
@@ -61,7 +60,7 @@ const Base85 = {
                 ((input[i + 3] || 0))
             ) >>> 0;
 
-            if (block > 0) {
+            if (encoding !== "Standard" || block > 0) {
                 let digits = [];
                 for (let j = 0; j < 5; j++) {
                     digits.push(block % 85);
@@ -73,10 +72,10 @@ const Base85 = {
                 if (input.length < i + 4) {
                     digits.splice(input.length - (i + 4), 4);
                 }
-
+                
                 result += digits.map(digit => alphabet[digit]).join("");
             } else {
-                if (encoding === "Standard") result += "z";
+                result += (encoding === "Standard") ? "z" : null;
             }
         }
 
@@ -98,18 +97,21 @@ const Base85 = {
             encoding = Base85._alphabetName(alphabet),
             result = [];
 
+        if (alphabet.length !== 85 || [].unique.call(alphabet).length !== 85) {
+            throw ("Alphabet must be of length 85");
+        }
+
         let matches = input.match(/<~(.+?)~>/);
         if (matches !== null) input = matches[1];
 
-        alphabet = Utils.expandAlphRange(alphabet).join("");
-
         let i = 0;
-        let digits, block, blockBytes;
+        let block, blockBytes;
         while (i < input.length) {
             if (encoding === "Standard" && input[i] === "z") {
                 result.push(0, 0, 0, 0);
                 i++;
             } else {
+                let digits = [];
                 digits = input
                     .substr(i, 5)
                     .split("")