1 files changed, 48 insertions, 30 deletions
diff --git a/std/encoding/base64.ts b/std/encoding/base64.ts
index 4c9aa4059..e631e5b88 100644
--- a/std/encoding/base64.ts
+++ b/std/encoding/base64.ts
@@ -1,41 +1,59 @@
 // Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
 
-/**
- * Converts given data with base64 encoding
- * @param data input to encode
- */
-export function encode(data: string | ArrayBuffer): string {
-  if (typeof data === "string") {
-    return btoa(data);
-  } else {
-    const d = new Uint8Array(data);
-    let dataString = "";
-    for (let i = 0; i < d.length; ++i) {
-      dataString += String.fromCharCode(d[i]);
-    }
-
-    return btoa(dataString);
-  }
-}
+// deno-fmt-ignore
+const base64abc = ["A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", 
+  "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z", "a", 
+  "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", 
+  "q", "r", "s", "t", "u", "v", "w", "x", "y", "z", "0", "1", "2", "3", "4", 
+  "5", "6", "7", "8", "9", "+", "/"];
 
 /**
- * Converts given base64 encoded data back to original
- * @param data input to decode
+ * CREDIT: https://gist.github.com/enepomnyaschih/72c423f727d395eeaa09697058238727
+ * Encodes a given Uint8Array, ArrayBuffer or string into RFC4648 base64 representation
+ * @param data
  */
-export function decode(data: string): ArrayBuffer {
-  const binaryString = decodeString(data);
-  const binary = new Uint8Array(binaryString.length);
-  for (let i = 0; i < binary.length; ++i) {
-    binary[i] = binaryString.charCodeAt(i);
+export function encode(data: ArrayBuffer | string): string {
+  const uint8 =
+    typeof data === "string"
+      ? new TextEncoder().encode(data)
+      : data instanceof Uint8Array
+      ? data
+      : new Uint8Array(data);
+  let result = "",
+    i;
+  const l = uint8.length;
+  for (i = 2; i < l; i += 3) {
+    result += base64abc[uint8[i - 2] >> 2];
+    result += base64abc[((uint8[i - 2] & 0x03) << 4) | (uint8[i - 1] >> 4)];
+    result += base64abc[((uint8[i - 1] & 0x0f) << 2) | (uint8[i] >> 6)];
+    result += base64abc[uint8[i] & 0x3f];
   }
-
-  return binary.buffer;
+  if (i === l + 1) {
+    // 1 octet yet to write
+    result += base64abc[uint8[i - 2] >> 2];
+    result += base64abc[(uint8[i - 2] & 0x03) << 4];
+    result += "==";
+  }
+  if (i === l) {
+    // 2 octets yet to write
+    result += base64abc[uint8[i - 2] >> 2];
+    result += base64abc[((uint8[i - 2] & 0x03) << 4) | (uint8[i - 1] >> 4)];
+    result += base64abc[(uint8[i - 1] & 0x0f) << 2];
+    result += "=";
+  }
+  return result;
 }
 
 /**
- * Decodes data assuming the output is in string type
- * @param data input to decode
+ * Decodes a given RFC4648 base64 encoded string
+ * @param b64
  */
-export function decodeString(data: string): string {
-  return atob(data);
+export function decode(b64: string): Uint8Array {
+  const binString = atob(b64);
+  const size = binString.length;
+  const bytes = new Uint8Array(size);
+  for (let i = 0; i < size; i++) {
+    bytes[i] = binString.charCodeAt(i);
+  }
+  return bytes;
 }