'use strict';
/**
 * QRMath
 * @author Kazuhiko Arase
 */
export class QRMath {

  constructor() {
    throw 'error';
  }

  private static EXP_TABLE: number[];
  private static LOG_TABLE: number[];

  private static initialize = function () {
    QRMath.EXP_TABLE = [];
    QRMath.LOG_TABLE = [];
    for (var i = 0; i < 256; i += 1) {
      QRMath.EXP_TABLE.push(i < 8 ? 1 << i :
        QRMath.EXP_TABLE[i - 4] ^
        QRMath.EXP_TABLE[i - 5] ^
        QRMath.EXP_TABLE[i - 6] ^
        QRMath.EXP_TABLE[i - 8]);
      QRMath.LOG_TABLE.push(0);
    }
    for (var i = 0; i < 255; i += 1) {
      QRMath.LOG_TABLE[QRMath.EXP_TABLE[i]] = i;
    }
  } ();

  public static glog(n: number): number {
    if (n < 1) {
      throw 'log(' + n + ')';
    }
    return QRMath.LOG_TABLE[n];
  }

  public static gexp(n: number): number {
    while (n < 0) {
      n += 255;
    }
    while (n >= 256) {
      n -= 255;
    }
    return QRMath.EXP_TABLE[n];
  }
}