(* Copyright (C) 1991, Digital Equipment Corporation           *)
(* All rights reserved.                                        *)
(* See the file COPYRIGHT for a full description.              *)

(* Last modified on Thu Nov 21 11:32:06 PST 1991 by muller         *)
(*      modified on Wed Sep 25 01:21:28 1991 by kalsow         *)


UNSAFE MODULE ExtendedFloat;

IMPORT Math, FPU;

PROCEDURE Scalb(x: T; n: INTEGER): T =
  BEGIN
    RETURN FLOAT (Math.ldexp (FLOAT (x, LONGREAL), n), T);
  END Scalb;

PROCEDURE Logb(<*UNUSED*> x: T): T =
  BEGIN
    <* ASSERT FALSE *>
  END Logb;

PROCEDURE ILogb(<*UNUSED*> x: T): INTEGER =
  BEGIN
    <* ASSERT FALSE *>
  END ILogb;

PROCEDURE NextAfter(<*UNUSED*> x, y: T): T =
  BEGIN
    <* ASSERT FALSE *>
  END NextAfter;

PROCEDURE CopySign(x, y: T): T =
  VAR xx, yy: FPU.ExtendedRep;
  BEGIN
    xx := LOOPHOLE (x, FPU.ExtendedRep);
    yy := LOOPHOLE (y, FPU.ExtendedRep);
    xx.sign := yy.sign;
    RETURN LOOPHOLE (xx, T);
  END CopySign;

PROCEDURE Finite(<*UNUSED*> x: T): BOOLEAN =
  BEGIN
    RETURN TRUE;
  END Finite;

PROCEDURE IsNaN(x: T): BOOLEAN =
  VAR xx := LOOPHOLE (x, FPU.ExtendedRep);
  BEGIN
    RETURN (xx.sign # 0) AND (xx.exponent = 0);
  END IsNaN;

PROCEDURE Sign(x: T): [0..1] =
  VAR xx := LOOPHOLE (x, FPU.ExtendedRep);
  BEGIN
    RETURN xx.sign;
  END Sign;

PROCEDURE Differs(x, y: T): BOOLEAN =
  BEGIN
    RETURN (NOT (IsNaN (x) OR IsNaN (y))) AND (x # y);
  END Differs;

PROCEDURE Unordered(x, y: T): BOOLEAN =
  BEGIN
    RETURN IsNaN (x) OR IsNaN (y);
  END Unordered;

PROCEDURE Sqrt(x: T): T =
  BEGIN
    RETURN FLOAT (Math.sqrt (FLOAT (x, LONGREAL)), T);
  END Sqrt;
  
PROCEDURE Class(x: T): IEEEClass =
  BEGIN
    IF IsNaN (x) THEN
      RETURN IEEEClass.SignalingNaN;
    ELSIF (x = 0.0x+0) THEN
      RETURN IEEEClass.Zero;
    ELSE
      RETURN IEEEClass.Normal;
    END;
  END Class;

BEGIN       
END ExtendedFloat.