INTERFACE BigInteger;

Arithmetic for Modula-3, see doc for details

Abstract: Integers of arbitrary size

DragonInt seems to be less flexible and lacks some essential operations like multiplication and division.

Daniel Beer, Henning Thielemann

FROM Arithmetic IMPORT Error;

CONST Brand = "BigInteger";

BigIntegers are immutable, do not change them manually, because some routines use references to existing BigIntegers for performance reasons.

TYPE
  Value <: REFANY;
  T = RECORD
        data: Value;
        size: INTEGER;           (* not all entries in 'data' may be
                                    used *)
        sign: BOOLEAN;
      END;
  QuotRem = RECORD quot, rem: T END;

PROCEDURE FromInteger (x: INTEGER; ): T;
PROCEDURE ToInteger (READONLY x: T; ): INTEGER;
PROCEDURE Copy (READONLY x: T; ): T;

VAR
  (*CONST*)
  Zero,
  (*CONST*) One,
  (*CONST*) Two,
  (*CONST*) MinusOne: T;

PROCEDURE Add (READONLY x, y: T; ): T;
PROCEDURE Sub (READONLY x, y: T; ): T;
<* INLINE *>
PROCEDURE Neg (READONLY x: T; ): T;
<* INLINE *>
PROCEDURE Conj (READONLY x: T; ): T;

<* INLINE *>
PROCEDURE IsZero (READONLY x: T; ): BOOLEAN;
PROCEDURE Equal (READONLY x, y: T; ): BOOLEAN;
PROCEDURE Compare (READONLY x, y: T; ): [-1 .. 1];

PROCEDURE Mul (READONLY x, y: T; ): T;
PROCEDURE Div (READONLY x, y: T; ): T RAISES {Error};
PROCEDURE Rec (READONLY x: T; ): T RAISES {Error};
PROCEDURE Mod (READONLY x, y: T; ): T RAISES {Error};
PROCEDURE DivMod (READONLY x, y: T; ): QuotRem RAISES {Error};

END BigInteger.