/vqdr/trunk

namespace VQDR.Common {

  /**

   * Fast Numbers are a decimal representanion of numbers in the folm of 

   * a normal integer value. All internal nummbers are multiples of 1000, so the

   * there is room for two three decimal ponts.

   * 

   * Math done on these numbers are done using standard integer operations, and

   * not floating point math.

   */

  class FastNumber {

    public const long MUL_FACTOR = 1000;

    public long raw_number { public get; private set; }

    public long number {

      get {return raw_number / MUL_FACTOR;}

      set {raw_number = number * MUL_FACTOR;}

    }

    public FastNumber (long val = 0) {

      this.number = val;

    }

    public FastNumber.copy (FastNumber other) {

      this.raw_number = other.raw_number;

    }

    public FastNumber.from_string (string str) {

      this.raw_number = parse_raw_number (str);

    }

    private static long parse_raw_number (string str) {

      long ret_val = 0;

      int i_of_dot = str.index_of_char ('.');

      if (i_of_dot >= 0) {

        // Get the decimal number from the string, if such a thing exists.

        if ((str.length - 1 > i_of_dot)) {

          ret_val = long.parse ((str + "000").substring (i_of_dot + 1));

        }

        // Normalise the digits.

        while (ret_val > MUL_FACTOR) {

          ret_val = ret_val / 10;

        }

        // Add intiger number

        ret_val = ret_val + (long.parse ("0" + str.substring (0, i_of_dot))

                            * MUL_FACTOR);

      } else {

        ret_val = long.parse (str) * MUL_FACTOR;

      }

      return ret_val;

    }

    public FastNumber add (FastNumber? other) {

      if (other == null) {

        return new FastNumber.copy (this);

      }

      var v = new FastNumber (this.raw_number + other.raw_number);

      return v;

    }

    public FastNumber subtract (FastNumber? other) {

      if (other == null) {

        return new FastNumber.copy (this);

      }

      var v = new FastNumber (this.raw_number - other.raw_number);

      return v;

    }

    public FastNumber multiply (FastNumber? other) {

      if (other == null || other.raw_value == 0) {

        return new FastNumber ();

      }

      return new FastNumber ((this.raw_number * other.raw_number) / MUL_FACTOR);

    }

    public FastNumber divide (FastNumber? other) throws MathError {

      if (other.raw_number == 0) {

        throw new MathError.DIVIDE_BY_ZERO

                                      ("FantNumber - trying to divide by zero");

      }

      return new FastNumber ((this.raw_number * MUL_FACTOR) / other.raw_number);

    }

  }

}