Merge pull request #8 from dcousens/opti

Array operations optimization

lib/bs58.js

@@ -20,59 +20,62 @@ function encode(buffer) {
   var i, j, digits = [0]
   for (i = 0; i < buffer.length; i++) {
     for (j = 0; j < digits.length; j++) digits[j] <<= 8
-    digits[digits.length - 1] += buffer[i]
+
+    digits[0] += buffer[i]
 
     var carry = 0
-    for (j = digits.length - 1; j >= 0; j--){
+    for (j = 0; j < digits.length; ++j) {
       digits[j] += carry
+
       carry = (digits[j] / BASE) | 0
       digits[j] %= BASE
     }
 
     while (carry) {
-      digits.unshift(carry)
-      carry = (digits[0] / BASE) | 0
-      digits[0] %= BASE
+      digits.push(carry % BASE)
+
+      carry = (carry / BASE) | 0
     }
   }
 
   // deal with leading zeros
-  for (i = 0; i < buffer.length - 1 && buffer[i] == 0; i++) digits.unshift(0)
+  for (i = 0; i < buffer.length - 1 && buffer[i] == 0; i++) digits.push(0)
 
-  return digits.map(function(digit) { return ALPHABET[digit] }).join('')
+  return digits.reverse().map(function(digit) { return ALPHABET[digit] }).join('')
 }
 
 function decode(string) {
   if (string.length === 0) return new Buffer(0)
 
   var input = string.split('').map(function(c){
-    assert.notEqual(ALPHABET_MAP[c], undefined, 'Non-base58 character')
+    assert(c in ALPHABET_MAP, 'Non-base58 character')
     return ALPHABET_MAP[c]
   })
 
   var i, j, bytes = [0]
   for (i = 0; i < input.length; i++) {
     for (j = 0; j < bytes.length; j++) bytes[j] *= BASE
-    bytes[bytes.length - 1] += input[i]
+    bytes[0] += input[i]
 
     var carry = 0
-    for (j = bytes.length - 1; j >= 0; j--){
+    for (j = 0; j < bytes.length; ++j) {
       bytes[j] += carry
+
       carry = bytes[j] >> 8
       bytes[j] &= 0xff
     }
 
     while (carry) {
-      bytes.unshift(carry)
-      carry = bytes[0] >> 8
-      bytes[0] &= 0xff
+      bytes.push(carry & 0xff)
+
+      carry >>= 8
     }
   }
 
   // deal with leading zeros
-  for (i = 0; i < input.length - 1 && input[i] == 0; i++) bytes.unshift(0)
+  for (i = 0; i < input.length - 1 && input[i] == 0; i++) bytes.push(0)
 
-  return new Buffer(bytes)
+  return new Buffer(bytes.reverse())
 }
 
 module.exports = {