Improve the style of code in lib/.

lib/src/sha256.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library crypto.sha256;
 
 import 'dart:typed_data';
 
 import 'hash.dart';
 import 'hash_base.dart';
 import 'utils.dart';
 
 /// An implementation of the [SHA-256][rfc] hash function.
 ///
 /// [rfc]: http://tools.ietf.org/html/rfc6234
 abstract class SHA256 implements Hash {
   factory SHA256() = _SHA256;
 
   SHA256 newInstance();
 }
 
+/// Data from a non-linear function that functions as reproducible noise.
+const List<int> _noise = const [
+  0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b, 0x59f111f1,
+  0x923f82a4, 0xab1c5ed5, 0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3,
+  0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174, 0xe49b69c1, 0xefbe4786,
+  0x0fc19dc6, 0x240ca1cc, 0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
+  0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7, 0xc6e00bf3, 0xd5a79147,
+  0x06ca6351, 0x14292967, 0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13,
+  0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85, 0xa2bfe8a1, 0xa81a664b,
+  0xc24b8b70, 0xc76c51a3, 0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
+  0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5, 0x391c0cb3, 0x4ed8aa4a,
+  0x5b9cca4f, 0x682e6ff3, 0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208,
+  0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2
+];
+
 /// The concrete implementation of [SHA256].
 ///
 /// This is separate so that it can extend [HashBase] without leaking additional
 /// public memebers.
 class _SHA256 extends HashBase implements SHA256 {
+  final digest = new Uint32List(8);
+
   /// The sixteen words from the original chunk, extended to 64 words.
   ///
   /// This is an instance variable to avoid re-allocating, but its data isn't
   /// used across invocations of [updateHash].
-  final Uint32List _w;
+  final Uint32List _extended;
 
   _SHA256()
-      : _w = new Uint32List(64),
-        super(16, 8, true) {
+      : _extended = new Uint32List(64),
+        super(16) {
     // Initial value of the hash parts. First 32 bits of the fractional parts
     // of the square roots of the first 8 prime numbers.
-    h[0] = 0x6a09e667;
-    h[1] = 0xbb67ae85;
-    h[2] = 0x3c6ef372;
-    h[3] = 0xa54ff53a;
-    h[4] = 0x510e527f;
-    h[5] = 0x9b05688c;
-    h[6] = 0x1f83d9ab;
-    h[7] = 0x5be0cd19;
+    digest[0] = 0x6a09e667;
+    digest[1] = 0xbb67ae85;
+    digest[2] = 0x3c6ef372;
+    digest[3] = 0xa54ff53a;
+    digest[4] = 0x510e527f;
+    digest[5] = 0x9b05688c;
+    digest[6] = 0x1f83d9ab;
+    digest[7] = 0x5be0cd19;
   }
 
-  SHA256 newInstance() {
-    return new _SHA256();
-  }
-
-  /// Data from a non-linear function that functions as reproducible noise.
-  static const List<int> _K = const [
-    0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b,
-    0x59f111f1, 0x923f82a4, 0xab1c5ed5, 0xd807aa98, 0x12835b01,
-    0x243185be, 0x550c7dc3, 0x72be5d74, 0x80deb1fe, 0x9bdc06a7,
-    0xc19bf174, 0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc,
-    0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da, 0x983e5152,
-    0xa831c66d, 0xb00327c8, 0xbf597fc7, 0xc6e00bf3, 0xd5a79147,
-    0x06ca6351, 0x14292967, 0x27b70a85, 0x2e1b2138, 0x4d2c6dfc,
-    0x53380d13, 0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
-    0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3, 0xd192e819,
-    0xd6990624, 0xf40e3585, 0x106aa070, 0x19a4c116, 0x1e376c08,
-    0x2748774c, 0x34b0bcb5, 0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f,
-    0x682e6ff3, 0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208,
-    0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2
-  ];
+  SHA256 newInstance() => new _SHA256();
 
   // The following helper functions are taken directly from
   // http://tools.ietf.org/html/rfc6234.
 
-  _rotr32(n, x) => (x >> n) | ((x << (32 - n)) & MASK_32);
-  _ch(x, y, z) => (x & y) ^ ((~x & MASK_32) & z);
-  _maj(x, y, z) => (x & y) ^ (x & z) ^ (y & z);
-  _bsig0(x) => _rotr32(2, x) ^ _rotr32(13, x) ^ _rotr32(22, x);
-  _bsig1(x) => _rotr32(6, x) ^ _rotr32(11, x) ^ _rotr32(25, x);
-  _ssig0(x) => _rotr32(7, x) ^ _rotr32(18, x) ^ (x >> 3);
-  _ssig1(x) => _rotr32(17, x) ^ _rotr32(19, x) ^ (x >> 10);
+  _rotr32(int n, int x) => (x >> n) | ((x << (32 - n)) & mask32);
+  _ch(int x, int y, int z) => (x & y) ^ ((~x & mask32) & z);
+  _maj(int x, int y, int z) => (x & y) ^ (x & z) ^ (y & z);
+  _bsig0(int x) => _rotr32(2, x) ^ _rotr32(13, x) ^ _rotr32(22, x);
+  _bsig1(int x) => _rotr32(6, x) ^ _rotr32(11, x) ^ _rotr32(25, x);
+  _ssig0(int x) => _rotr32(7, x) ^ _rotr32(18, x) ^ (x >> 3);
+  _ssig1(int x) => _rotr32(17, x) ^ _rotr32(19, x) ^ (x >> 10);
 
-  void updateHash(Uint32List M) {
-    assert(M.length == 16);
+  void updateHash(Uint32List chunk) {
+    assert(chunk.length == 16);
 
     // Prepare message schedule.
-    var i = 0;
-    for (; i < 16; i++) {
-      _w[i] = M[i];
+    for (var i = 0; i < 16; i++) {
+      _extended[i] = chunk[i];
     }
-    for (; i < 64; i++) {
-      _w[i] = add32(add32(_ssig1(_w[i - 2]), _w[i - 7]),
-          add32(_ssig0(_w[i - 15]), _w[i - 16]));
+    for (var i = 16; i < 64; i++) {
+      _extended[i] = add32(
+          add32(_ssig1(_extended[i - 2]),  _extended[i - 7]),
+          add32(_ssig0(_extended[i - 15]), _extended[i - 16]));
     }
 
     // Shuffle around the bits.
-    var a = h[0];
-    var b = h[1];
-    var c = h[2];
-    var d = h[3];
-    var e = h[4];
-    var f = h[5];
-    var g = h[6];
-    var j = h[7];
+    var a = digest[0];
+    var b = digest[1];
+    var c = digest[2];
+    var d = digest[3];
+    var e = digest[4];
+    var f = digest[5];
+    var g = digest[6];
+    var h = digest[7];
 
-    for (var t = 0; t < 64; t++) {
-      var t1 = add32(
-          add32(j, _bsig1(e)), add32(_ch(e, f, g), add32(_K[t], _w[t])));
-      var t2 = add32(_bsig0(a), _maj(a, b, c));
-      j = g;
+    for (var i = 0; i < 64; i++) {
+      var temp1 = add32(
+          add32(h, _bsig1(e)),
+          add32(
+              _ch(e, f, g),
+              add32(_noise[i], _extended[i])));
+      var temp2 = add32(_bsig0(a), _maj(a, b, c));
+      h = g;
       g = f;
       f = e;
-      e = add32(d, t1);
+      e = add32(d, temp1);
       d = c;
       c = b;
       b = a;
-      a = add32(t1, t2);
+      a = add32(temp1, temp2);
     }
 
     // Update hash values after iteration.
-    h[0] = add32(a, h[0]);
-    h[1] = add32(b, h[1]);
-    h[2] = add32(c, h[2]);
-    h[3] = add32(d, h[3]);
-    h[4] = add32(e, h[4]);
-    h[5] = add32(f, h[5]);
-    h[6] = add32(g, h[6]);
-    h[7] = add32(j, h[7]);
+    digest[0] = add32(a, digest[0]);
+    digest[1] = add32(b, digest[1]);
+    digest[2] = add32(c, digest[2]);
+    digest[3] = add32(d, digest[3]);
+    digest[4] = add32(e, digest[4]);
+    digest[5] = add32(f, digest[5]);
+    digest[6] = add32(g, digest[6]);
+    digest[7] = add32(h, digest[7]);
   }
 }