rename encode func name, add decode func

2019-11-27 10:57:25 +08:00
parent 49df953d19
commit 1b98f2c6b0
2 changed files with 608 additions and 2 deletions
@@ -7,8 +7,13 @@ for (const idx in encodeTable) {
 const base32 = {}
 module.exports = base32

-base32.encode = (b) => {
-  if (!(b instanceof Buffer)) return ''
+/**
+ * encode byte data to string
+ * @param {ArrayBuffer} b buffer data
+ * @return {string}
+ */
+base32.encodeToString = (b) => {
+  if (!(b instanceof Buffer)) throw new Error('input not Buffer')
  if (b.length === 0) return ''

  let str = ''
@@ -75,3 +80,87 @@ base32.encode = (b) => {

  return str
 }
+
+/**
+ * decode base32 string to byte
+ * @param {string} str
+ * @return {ArrayBuffer}
+ */
+base32.decodeFromString = (str) => {
+  if (typeof str !== 'string' || str.length === 0) throw new Error('input not string or empty')
+  if (!/^[A-Z2-7=]+$/.test(str)) throw new Error('Invalid base32 characters')
+  str = str.toUpperCase().replace(/=/g, '')
+
+  let v = []
+  const buf = []
+  const len = str.length
+  const count = len >> 3 << 3
+  let i = 0
+
+  while (i < count) {
+    v[0] = decodeTable[str.charAt(i++)]
+    v[1] = decodeTable[str.charAt(i++)]
+    v[2] = decodeTable[str.charAt(i++)]
+    v[3] = decodeTable[str.charAt(i++)]
+    v[4] = decodeTable[str.charAt(i++)]
+    v[5] = decodeTable[str.charAt(i++)]
+    v[6] = decodeTable[str.charAt(i++)]
+    v[7] = decodeTable[str.charAt(i++)]
+    buf.push(
+      (v[0] << 3 | v[1] >>> 2) & 0xff,
+      (v[1] << 6 | v[2] << 1 | v[3] >>> 4) & 0xff,
+      (v[3] << 4 | v[4] >>> 1) & 0xff,
+      (v[4] << 7 | v[5] << 2 | v[6] >>> 3) & 0xff,
+      (v[6] << 5 | v[7]) & 0xff
+    )
+  }
+
+  switch (len - count) {
+    case 2:
+      v[0] = decodeTable[str.charAt(i++)]
+      v[1] = decodeTable[str.charAt(i++)]
+      buf.push(
+        (v[0] << 3 | v[1] >>> 2) & 0xff
+      )
+      break
+    case 4:
+      v[0] = decodeTable[str.charAt(i++)]
+      v[1] = decodeTable[str.charAt(i++)]
+      v[2] = decodeTable[str.charAt(i++)]
+      v[3] = decodeTable[str.charAt(i++)]
+      buf.push(
+        (v[0] << 3 | v[1] >>> 2) & 0xff,
+        (v[1] << 6 | v[2] << 1 | v[3] >>> 4) & 0xff
+      )
+      break
+    case 5:
+      v[0] = decodeTable[str.charAt(i++)]
+      v[1] = decodeTable[str.charAt(i++)]
+      v[2] = decodeTable[str.charAt(i++)]
+      v[3] = decodeTable[str.charAt(i++)]
+      v[4] = decodeTable[str.charAt(i++)]
+      buf.push(
+        (v[0] << 3 | v[1] >>> 2) & 0xff,
+        (v[1] << 6 | v[2] << 1 | v[3] >>> 4) & 0xff,
+        (v[3] << 4 | v[4] >>> 1) & 0xff
+      )
+      break
+    case 7:
+      v[0] = decodeTable[str.charAt(i++)]
+      v[1] = decodeTable[str.charAt(i++)]
+      v[2] = decodeTable[str.charAt(i++)]
+      v[3] = decodeTable[str.charAt(i++)]
+      v[4] = decodeTable[str.charAt(i++)]
+      v[5] = decodeTable[str.charAt(i++)]
+      v[6] = decodeTable[str.charAt(i++)]
+      buf.push(
+        (v[0] << 3 | v[1] >>> 2) & 0xff,
+        (v[1] << 6 | v[2] << 1 | v[3] >>> 4) & 0xff,
+        (v[3] << 4 | v[4] >>> 1) & 0xff,
+        (v[4] << 7 | v[5] << 2 | v[6] >>> 3) & 0xff
+      )
+      break
+  }
+
+  return Buffer.from(buf)
+}