module.exports = {
  crypto_scalarmult,
  crypto_scalarmult_base,
  crypto_scalarmult_BYTES,
  crypto_scalarmult_SCALARBYTES
}

function crypto_scalarmult(q, n, p) {
  check(q, crypto_scalarmult_BYTES)
  check(n, crypto_scalarmult_SCALARBYTES)
  check(p, crypto_scalarmult_BYTES)
  var z = new Uint8Array(32);
  var x = new Float64Array(80), r, i;
  var a = gf(), b = gf(), c = gf(),
      d = gf(), e = gf(), f = gf();
  for (i = 0; i < 31; i++) z[i] = n[i];
  z[31]=(n[31]&127)|64;
  z[0]&=248;
  unpack25519(x,p);
  for (i = 0; i < 16; i++) {
    b[i]=x[i];
    d[i]=a[i]=c[i]=0;
  }
  a[0]=d[0]=1;
  for (i=254; i>=0; --i) {
    r=(z[i>>>3]>>>(i&7))&1;
    sel25519(a,b,r);
    sel25519(c,d,r);
    A(e,a,c);
    Z(a,a,c);
    A(c,b,d);
    Z(b,b,d);
    S(d,e);
    S(f,a);
    M(a,c,a);
    M(c,b,e);
    A(e,a,c);
    Z(a,a,c);
    S(b,a);
    Z(c,d,f);
    M(a,c,_121665);
    A(a,a,d);
    M(c,c,a);
    M(a,d,f);
    M(d,b,x);
    S(b,e);
    sel25519(a,b,r);
    sel25519(c,d,r);
  }
  for (i = 0; i < 16; i++) {
    x[i+16]=a[i];
    x[i+32]=c[i];
    x[i+48]=b[i];
    x[i+64]=d[i];
  }
  var x32 = x.subarray(32);
  var x16 = x.subarray(16);
  inv25519(x32,x32);
  M(x16,x16,x32);
  pack25519(q,x16);
  return 0;
}

module.exports = {
  crypto_scalarmult_base,
  crypto_scalarmult_base,
  crypto_scalarmult_BYTES,
  crypto_scalarmult_SCALARBYTES
}

function crypto_scalarmult_base(q, n) {
  return crypto_scalarmult(q, n, _9);
}

function check (buf, len) {
  if (!buf || (len && buf.length < len)) throw new Error('Argument must be a buffer' + (len ? ' of length ' + len : ''))
}

var crypto_scalarmult_BYTES,
    crypto_scalarmult_SCALARBYTES = 32,
    crypto_scalarmult_BYTES,
    crypto_scalarmult_SCALARBYTES = 32