Removed fixed dependencies

packages/crypto/lib/src/hash_sink.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.
+
+import 'dart:typed_data';
+
+import 'package:typed_data/typed_data.dart';
+
+import 'digest.dart';
+import 'utils.dart';
+
+/// A base class for [Sink] implementations for hash algorithms.
+///
+/// Subclasses should override [updateHash] and [digest].
+abstract class HashSink implements Sink<List<int>> {
+  /// The inner sink that this should forward to.
+  final Sink<Digest> _sink;
+
+  /// Whether the hash function operates on big-endian words.
+  final Endianness _endian;
+
+  /// The words in the current chunk.
+  ///
+  /// This is an instance variable to avoid re-allocating, but its data isn't
+  /// used across invocations of [_iterate].
+  final Uint32List _currentChunk;
+
+  /// Messages with more than 2^64-1 bits are not supported.
+  /// So the maximum length in bytes is (2^64-1)/8.
+  static const _maxMessageLengthInBytes = 0x1fffffffffffffff;
+
+  /// The length of the input data so far, in bytes.
+  int _lengthInBytes = 0;
+
+  /// Data that has yet to be processed by the hash function.
+  final _pendingData = new Uint8Buffer();
+
+  /// Whether [close] has been called.
+  bool _isClosed = false;
+
+  /// The words in the current digest.
+  ///
+  /// This should be updated each time [updateHash] is called.
+  Uint32List get digest;
+
+  /// Creates a new hash.
+  ///
+  /// [chunkSizeInWords] represents the size of the input chunks processed by
+  /// the algorithm, in terms of 32-bit words.
+  HashSink(this._sink, int chunkSizeInWords,
+      {Endianness endian: Endianness.BIG_ENDIAN})
+      : _endian = endian,
+        _currentChunk = new Uint32List(chunkSizeInWords);
+
+  /// Runs a single iteration of the hash computation, updating [digest] with
+  /// the result.
+  ///
+  /// [chunk] is the current chunk, whose size is given by the
+  /// `chunkSizeInWords` parameter passed to the constructor.
+  void updateHash(Uint32List chunk);
+
+  @override
+  void add(List<int> data) {
+    if (_isClosed) throw new StateError('Hash.add() called after close().');
+    _lengthInBytes += data.length;
+    _pendingData.addAll(data);
+    _iterate();
+  }
+
+  @override
+  void close() {
+    if (_isClosed) return;
+    _isClosed = true;
+
+    _finalizeData();
+    _iterate();
+    assert(_pendingData.isEmpty);
+    _sink.add(new Digest(_byteDigest()));
+    _sink.close();
+  }
+
+  Uint8List _byteDigest() {
+    if (_endian == Endianness.HOST_ENDIAN) return digest.buffer.asUint8List();
+
+    var byteDigest = new Uint8List(digest.lengthInBytes);
+    var byteData = byteDigest.buffer.asByteData();
+    for (var i = 0; i < digest.length; i++) {
+      byteData.setUint32(i * bytesPerWord, digest[i]);
+    }
+    return byteDigest;
+  }
+
+  /// Iterates through [_pendingData], updating the hash computation for each
+  /// chunk.
+  void _iterate() {
+    var pendingDataBytes = _pendingData.buffer.asByteData();
+    var pendingDataChunks = _pendingData.length ~/ _currentChunk.lengthInBytes;
+    for (var i = 0; i < pendingDataChunks; i++) {
+      // Copy words from the pending data buffer into the current chunk buffer.
+      for (var j = 0; j < _currentChunk.length; j++) {
+        _currentChunk[j] = pendingDataBytes.getUint32(
+            i * _currentChunk.lengthInBytes + j * bytesPerWord, _endian);
+      }
+
+      // Run the hash function on the current chunk.
+      updateHash(_currentChunk);
+    }
+
+    // Remove all pending data up to the last clean chunk break.
+    _pendingData.removeRange(
+        0, pendingDataChunks * _currentChunk.lengthInBytes);
+  }
+
+  /// Finalizes [_pendingData].
+  ///
+  /// This adds a 1 bit to the end of the message, and expands it with 0 bits to
+  /// pad it out.
+  void _finalizeData() {
+    // Pad out the data with 0x80, eight 0s, and as many more 0s as we need to
+    // land cleanly on a chunk boundary.
+    _pendingData.add(0x80);
+    var contentsLength = _lengthInBytes + 9;
+    var finalizedLength = _roundUp(contentsLength, _currentChunk.lengthInBytes);
+    for (var i = 0; i < finalizedLength - contentsLength; i++) {
+      _pendingData.add(0);
+    }
+
+    if (_lengthInBytes > _maxMessageLengthInBytes) {
+      throw new UnsupportedError(
+          "Hashing is unsupported for messages with more than 2^64 bits.");
+    }
+
+    var lengthInBits = _lengthInBytes * bitsPerByte;
+
+    // Add the full length of the input data as a 64-bit value at the end of the
+    // hash.
+    var offset = _pendingData.length;
+    _pendingData.addAll(new Uint8List(8));
+    var byteData = _pendingData.buffer.asByteData();
+
+    // We're essentially doing byteData.setUint64(offset, lengthInBits, _endian)
+    // here, but that method isn't supported on dart2js so we implement it
+    // manually instead.
+    var highBits = lengthInBits >> 32;
+    var lowBits = lengthInBits & mask32;
+    if (_endian == Endianness.BIG_ENDIAN) {
+      byteData.setUint32(offset, highBits, _endian);
+      byteData.setUint32(offset + bytesPerWord, lowBits, _endian);
+    } else {
+      byteData.setUint32(offset, lowBits, _endian);
+      byteData.setUint32(offset + bytesPerWord, highBits, _endian);
+    }
+  }
+
+  /// Rounds [val] up to the next multiple of [n], as long as [n] is a power of
+  /// two.
+  int _roundUp(int val, int n) => (val + n - 1) & -n;
+}