/*
* Port of Andrew Moon's Poly1305-donna-16. Public domain.
* https://github.com/floodyberry/poly1305-donna
*/

if (new Uint16Array([1])[0] !== 1) throw new Error('Big endian architecture is not supported.')

var poly1305 = function(key) {
  this.buffer = new Uint8Array(16);
  this.r = new Uint16Array(10);
  this.h = new Uint16Array(10);
  this.pad = new Uint16Array(8);
  this.leftover = 0;
  this.fin = 0;

  var t0, t1, t2, t3, t4, t5, t6, t7;

  t0 = key[ 0] & 0xff | (key[ 1] & 0xff) << 8; this.r[0] = ( t0                     ) & 0x1fff;
  t1 = key[ 2] & 0xff | (key[ 3] & 0xff) << 8; this.r[1] = ((t0 >>> 13) | (t1 <<  3)) & 0x1fff;
  t2 = key[ 4] & 0xff | (key[ 5] & 0xff) << 8; this.r[2] = ((t1 >>> 10) | (t2 <<  6)) & 0x1f03;
  t3 = key[ 6] & 0xff | (key[ 7] & 0xff) << 8; this.r[3] = ((t2 >>>  7) | (t3 <<  9)) & 0x1fff;
  t4 = key[ 8] & 0xff | (key[ 9] & 0xff) << 8; this.r[4] = ((t3 >>>  4) | (t4 << 12)) & 0x00ff;
  this.r[5] = ((t4 >>>  1)) & 0x1ffe;
  t5 = key[10] & 0xff | (key[11] & 0xff) << 8; this.r[6] = ((t4 >>> 14) | (t5 <<  2)) & 0x1fff;
  t6 = key[12] & 0xff | (key[13] & 0xff) << 8; this.r[7] = ((t5 >>> 11) | (t6 <<  5)) & 0x1f81;
  t7 = key[14] & 0xff | (key[15] & 0xff) << 8; this.r[8] = ((t6 >>>  8) | (t7 <<  8)) & 0x1fff;
  this.r[9] = ((t7 >>>  5)) & 0x007f;

  this.pad[0] = key[16] & 0xff | (key[17] & 0xff) << 8;
  this.pad[1] = key[18] & 0xff | (key[19] & 0xff) << 8;
  this.pad[2] = key[20] & 0xff | (key[21] & 0xff) << 8;
  this.pad[3] = key[22] & 0xff | (key[23] & 0xff) << 8;
  this.pad[4] = key[24] & 0xff | (key[25] & 0xff) << 8;
  this.pad[5] = key[26] & 0xff | (key[27] & 0xff) << 8;
  this.pad[6] = key[28] & 0xff | (key[29] & 0xff) << 8;
  this.pad[7] = key[30] & 0xff | (key[31] & 0xff) << 8;
};

poly1305.prototype.blocks = function(m, mpos, bytes) {
  var hibit = this.fin ? 0 : (1 << 11);
  var t0, t1, t2, t3, t4, t5, t6, t7, c;
  var d0, d1, d2, d3, d4, d5, d6, d7, d8, d9;

  var h0 = this.h[0],
      h1 = this.h[1],
      h2 = this.h[2],
      h3 = this.h[3],
      h4 = this.h[4],
      h5 = this.h[5],
      h6 = this.h[6],
      h7 = this.h[7],
      h8 = this.h[8],
      h9 = this.h[9];

  var r0 = this.r[0],
      r1 = this.r[1],
      r2 = this.r[2],
      r3 = this.r[3],
      r4 = this.r[4],
      r5 = this.r[5],
      r6 = this.r[6],
      r7 = this.r[7],
      r8 = this.r[8],
      r9 = this.r[9];

  while (bytes >= 16) {
    t0 = m[mpos+ 0] & 0xff | (m[mpos+ 1] & 0xff) << 8; h0 += ( t0                     ) & 0x1fff;
    t1 = m[mpos+ 2] & 0xff | (m[mpos+ 3] & 0xff) << 8; h1 += ((t0 >>> 13) | (t1 <<  3)) & 0x1fff;
    t2 = m[mpos+ 4] & 0xff | (m[mpos+ 5] & 0xff) << 8; h2 += ((t1 >>> 10) | (t2 <<  6)) & 0x1fff;
    t3 = m[mpos+ 6] & 0xff | (m[mpos+ 7] & 0xff) << 8; h3 += ((t2 >>>  7) | (t3 <<  9)) & 0x1fff;
    t4 = m[mpos+ 8] & 0xff | (m[mpos+ 9] & 0xff) << 8; h4 += ((t3 >>>  4) | (t4 << 12)) & 0x1fff;
    h5 += ((t4 >>>  1)) & 0x1fff;
    t5 = m[mpos+10] & 0xff | (m[mpos+11] & 0xff) << 8; h6 += ((t4 >>> 14) | (t5 <<  2)) & 0x1fff;
    t6 = m[mpos+12] & 0xff | (m[mpos+13] & 0xff) << 8; h7 += ((t5 >>> 11) | (t6 <<  5)) & 0x1fff;
    t7 = m[mpos+14] & 0xff | (m[mpos+15] & 0xff) << 8; h8 += ((t6 >>>  8) | (t7 <<  8)) & 0x1fff;
    h9 += ((t7 >>> 5)) | hibit;

    c = 0;

    d0 = c;
    d0 += h0 * r0;
    d0 += h1 * (5 * r9);
    d0 += h2 * (5 * r8);
    d0 += h3 * (5 * r7);
    d0 += h4 * (5 * r6);
    c = (d0 >>> 13); d0 &= 0x1fff;
    d0 += h5 * (5 * r5);
    d0 += h6 * (5 * r4);
    d0 += h7 * (5 * r3);
    d0 += h8 * (5 * r2);
    d0 += h9 * (5 * r1);
    c += (d0 >>> 13); d0 &= 0x1fff;

    d1 = c;
    d1 += h0 * r1;
    d1 += h1 * r0;
    d1 += h2 * (5 * r9);
    d1 += h3 * (5 * r8);
    d1 += h4 * (5 * r7);
    c = (d1 >>> 13); d1 &= 0x1fff;
    d1 += h5 * (5 * r6);
    d1 += h6 * (5 * r5);
    d1 += h7 * (5 * r4);
    d1 += h8 * (5 * r3);
    d1 += h9 * (5 * r2);
    c += (d1 >>> 13); d1 &= 0x1fff;

    d2 = c;
    d2 += h0 * r2;
    d2 += h1 * r1;
    d2 += h2 * r0;
    d2 += h3 * (5 * r9);
    d2 += h4 * (5 * r8);
    c = (d2 >>> 13); d2 &= 0x1fff;
    d2 += h5 * (5 * r7);
    d2 += h6 * (5 * r6);
    d2 += h7 * (5 * r5);
    d2 += h8 * (5 * r4);
    d2 += h9 * (5 * r3);
    c += (d2 >>> 13); d2 &= 0x1fff;

    d3 = c;
    d3 += h0 * r3;
    d3 += h1 * r2;
    d3 += h2 * r1;
    d3 += h3 * r0;
    d3 += h4 * (5 * r9);
    c = (d3 >>> 13); d3 &= 0x1fff;
    d3 += h5 * (5 * r8);
    d3 += h6 * (5 * r7);
    d3 += h7 * (5 * r6);
    d3 += h8 * (5 * r5);
    d3 += h9 * (5 * r4);
    c += (d3 >>> 13); d3 &= 0x1fff;

    d4 = c;
    d4 += h0 * r4;
    d4 += h1 * r3;
    d4 += h2 * r2;
    d4 += h3 * r1;
    d4 += h4 * r0;
    c = (d4 >>> 13); d4 &= 0x1fff;
    d4 += h5 * (5 * r9);
    d4 += h6 * (5 * r8);
    d4 += h7 * (5 * r7);
    d4 += h8 * (5 * r6);
    d4 += h9 * (5 * r5);
    c += (d4 >>> 13); d4 &= 0x1fff;

    d5 = c;
    d5 += h0 * r5;
    d5 += h1 * r4;
    d5 += h2 * r3;
    d5 += h3 * r2;
    d5 += h4 * r1;
    c = (d5 >>> 13); d5 &= 0x1fff;
    d5 += h5 * r0;
    d5 += h6 * (5 * r9);
    d5 += h7 * (5 * r8);
    d5 += h8 * (5 * r7);
    d5 += h9 * (5 * r6);
    c += (d5 >>> 13); d5 &= 0x1fff;

    d6 = c;
    d6 += h0 * r6;
    d6 += h1 * r5;
    d6 += h2 * r4;
    d6 += h3 * r3;
    d6 += h4 * r2;
    c = (d6 >>> 13); d6 &= 0x1fff;
    d6 += h5 * r1;
    d6 += h6 * r0;
    d6 += h7 * (5 * r9);
    d6 += h8 * (5 * r8);
    d6 += h9 * (5 * r7);
    c += (d6 >>> 13); d6 &= 0x1fff;

    d7 = c;
    d7 += h0 * r7;
    d7 += h1 * r6;
    d7 += h2 * r5;
    d7 += h3 * r4;
    d7 += h4 * r3;
    c = (d7 >>> 13); d7 &= 0x1fff;
    d7 += h5 * r2;
    d7 += h6 * r1;
    d7 += h7 * r0;
    d7 += h8 * (5 * r9);
    d7 += h9 * (5 * r8);
    c += (d7 >>> 13); d7 &= 0x1fff;

    d8 = c;
    d8 += h0 * r8;
    d8 += h1 * r7;
    d8 += h2 * r6;
    d8 += h3 * r5;
    d8 += h4 * r4;
    c = (d8 >>> 13); d8 &= 0x1fff;
    d8 += h5 * r3;
    d8 += h6 * r2;
    d8 += h7 * r1;
    d8 += h8 * r0;
    d8 += h9 * (5 * r9);
    c += (d8 >>> 13); d8 &= 0x1fff;

    d9 = c;
    d9 += h0 * r9;
    d9 += h1 * r8;
    d9 += h2 * r7;
    d9 += h3 * r6;
    d9 += h4 * r5;
    c = (d9 >>> 13); d9 &= 0x1fff;
    d9 += h5 * r4;
    d9 += h6 * r3;
    d9 += h7 * r2;
    d9 += h8 * r1;
    d9 += h9 * r0;
    c += (d9 >>> 13); d9 &= 0x1fff;

    c = (((c << 2) + c)) | 0;
    c = (c + d0) | 0;
    d0 = c & 0x1fff;
    c = (c >>> 13);
    d1 += c;

    h0 = d0;
    h1 = d1;
    h2 = d2;
    h3 = d3;
    h4 = d4;
    h5 = d5;
    h6 = d6;
    h7 = d7;
    h8 = d8;
    h9 = d9;

    mpos += 16;
    bytes -= 16;
  }
  this.h[0] = h0;
  this.h[1] = h1;
  this.h[2] = h2;
  this.h[3] = h3;
  this.h[4] = h4;
  this.h[5] = h5;
  this.h[6] = h6;
  this.h[7] = h7;
  this.h[8] = h8;
  this.h[9] = h9;
};

poly1305.prototype.finish = function(mac, macpos) {
  var g = new Uint16Array(10);
  var c, mask, f, i;

  if (this.leftover) {
    i = this.leftover;
    this.buffer[i++] = 1;
    for (; i < 16; i++) this.buffer[i] = 0;
    this.fin = 1;
    this.blocks(this.buffer, 0, 16);
  }

  c = this.h[1] >>> 13;
  this.h[1] &= 0x1fff;
  for (i = 2; i < 10; i++) {
    this.h[i] += c;
    c = this.h[i] >>> 13;
    this.h[i] &= 0x1fff;
  }
  this.h[0] += (c * 5);
  c = this.h[0] >>> 13;
  this.h[0] &= 0x1fff;
  this.h[1] += c;
  c = this.h[1] >>> 13;
  this.h[1] &= 0x1fff;
  this.h[2] += c;

  g[0] = this.h[0] + 5;
  c = g[0] >>> 13;
  g[0] &= 0x1fff;
  for (i = 1; i < 10; i++) {
    g[i] = this.h[i] + c;
    c = g[i] >>> 13;
    g[i] &= 0x1fff;
  }
  g[9] -= (1 << 13);

  mask = (c ^ 1) - 1;
  for (i = 0; i < 10; i++) g[i] &= mask;
  mask = ~mask;
  for (i = 0; i < 10; i++) this.h[i] = (this.h[i] & mask) | g[i];

  this.h[0] = ((this.h[0]       ) | (this.h[1] << 13)                    ) & 0xffff;
  this.h[1] = ((this.h[1] >>>  3) | (this.h[2] << 10)                    ) & 0xffff;
  this.h[2] = ((this.h[2] >>>  6) | (this.h[3] <<  7)                    ) & 0xffff;
  this.h[3] = ((this.h[3] >>>  9) | (this.h[4] <<  4)                    ) & 0xffff;
  this.h[4] = ((this.h[4] >>> 12) | (this.h[5] <<  1) | (this.h[6] << 14)) & 0xffff;
  this.h[5] = ((this.h[6] >>>  2) | (this.h[7] << 11)                    ) & 0xffff;
  this.h[6] = ((this.h[7] >>>  5) | (this.h[8] <<  8)                    ) & 0xffff;
  this.h[7] = ((this.h[8] >>>  8) | (this.h[9] <<  5)                    ) & 0xffff;

  f = this.h[0] + this.pad[0];
  this.h[0] = f & 0xffff;
  for (i = 1; i < 8; i++) {
    f = (((this.h[i] + this.pad[i]) | 0) + (f >>> 16)) | 0;
    this.h[i] = f & 0xffff;
  }

  mac[macpos+ 0] = (this.h[0] >>> 0) & 0xff;
  mac[macpos+ 1] = (this.h[0] >>> 8) & 0xff;
  mac[macpos+ 2] = (this.h[1] >>> 0) & 0xff;
  mac[macpos+ 3] = (this.h[1] >>> 8) & 0xff;
  mac[macpos+ 4] = (this.h[2] >>> 0) & 0xff;
  mac[macpos+ 5] = (this.h[2] >>> 8) & 0xff;
  mac[macpos+ 6] = (this.h[3] >>> 0) & 0xff;
  mac[macpos+ 7] = (this.h[3] >>> 8) & 0xff;
  mac[macpos+ 8] = (this.h[4] >>> 0) & 0xff;
  mac[macpos+ 9] = (this.h[4] >>> 8) & 0xff;
  mac[macpos+10] = (this.h[5] >>> 0) & 0xff;
  mac[macpos+11] = (this.h[5] >>> 8) & 0xff;
  mac[macpos+12] = (this.h[6] >>> 0) & 0xff;
  mac[macpos+13] = (this.h[6] >>> 8) & 0xff;
  mac[macpos+14] = (this.h[7] >>> 0) & 0xff;
  mac[macpos+15] = (this.h[7] >>> 8) & 0xff;
};

poly1305.prototype.update = function(m, mpos, bytes) {
  var i, want;

  if (this.leftover) {
    want = (16 - this.leftover);
    if (want > bytes)
      want = bytes;
    for (i = 0; i < want; i++)
      this.buffer[this.leftover + i] = m[mpos+i];
    bytes -= want;
    mpos += want;
    this.leftover += want;
    if (this.leftover < 16)
      return;
    this.blocks(this.buffer, 0, 16);
    this.leftover = 0;
  }

  if (bytes >= 16) {
    want = bytes - (bytes % 16);
    this.blocks(m, mpos, want);
    mpos += want;
    bytes -= want;
  }

  if (bytes) {
    for (i = 0; i < bytes; i++)
      this.buffer[this.leftover + i] = m[mpos+i];
    this.leftover += bytes;
  }
};

module.exports = poly1305