// 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.

// The SHA1 hasher is used to compute an SHA1 message digest.
class _SHA1 extends _HashBase implements SHA1 {
  // Construct a SHA1 hasher object.
  _SHA1() : _w = new List(80), super(16, 5, true) {
    _h[0] = 0x67452301;
    _h[1] = 0xEFCDAB89;
    _h[2] = 0x98BADCFE;
    _h[3] = 0x10325476;
    _h[4] = 0xC3D2E1F0;
  }

  // Returns a new instance of this Hash.
  SHA1 newInstance() {
    return new SHA1();
  }

  // Compute one iteration of the SHA1 algorithm with a chunk of
  // 16 32-bit pieces.
  void _updateHash(List<int> m) {
    assert(m.length == 16);

    var a = _h[0];
    var b = _h[1];
    var c = _h[2];
    var d = _h[3];
    var e = _h[4];

    for (var i = 0; i < 80; i++) {
      if (i < 16) {
        _w[i] = m[i];
      } else {
        var n = _w[i - 3] ^ _w[i - 8] ^ _w[i - 14] ^ _w[i - 16];
        _w[i] = _rotl32(n, 1);
      }
      var t = _rotl32(a, 5) + e + _w[i];
      if (i < 20) {
        t = t + ((b & c) | (~b & d)) + 0x5A827999;
      } else if (i < 40) {
        t = t + (b ^ c ^ d) + 0x6ED9EBA1;
      } else if (i < 60) {
        t = t + ((b & c) | (b & d) | (c & d)) + 0x8F1BBCDC;
      } else {
        t = t + (b ^ c ^ d) + 0xCA62C1D6;
      }

      e = d;
      d = c;
      c = _rotl32(b, 30);
      b = a;
      a = t & _MASK_32;
    }

    _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]);
  }

  List<int> _w;
}