DEFINITION MODULE RealIO;

  (* Input and output of real numbers in decimal text form over specified channels.
     The read result is of the type IOConsts.ReadResults.
  *)

IMPORT IOChan;

  (* The text form of a signed fixed-point real number is
       ["+" | "-"], decimal digit, {decimal digit},
       [".", {decimal digit}]

     The text form of a signed floating-point real number is
       signed fixed-point real number,
       "E", ["+" | "-"], decimal digit, {decimal digit}
  *)

PROCEDURE ReadReal (cid: IOChan.ChanId; VAR real: REAL);
  (* Skips leading spaces, and removes any remaining characters from cid that form part of a
     signed fixed or floating point number.  The value of this number is assigned to real.
     The read result is set to the value allRight, outOfRange, wrongFormat, endOfLine, or
     endOfInput.
  *)

PROCEDURE WriteFloat (cid: IOChan.ChanId; real: REAL; sigFigs: CARDINAL; width:
CARDINAL);
  (* Writes the value of real to cid in floating-point text form, with sigFigs significant
     figures, in a field of the given minimum width.
  *)

PROCEDURE WriteEng (cid: IOChan.ChanId; real: REAL; sigFigs: CARDINAL; width: CARDINAL);
  (* As for WriteFloat, except that the number is scaled with one to three digits in the
     whole number part, and with an exponent that is a multiple of three.
  *)

PROCEDURE WriteFixed (cid: IOChan.ChanId; real: REAL; place: INTEGER; width: CARDINAL);
  (* Writes the value of real to cid in fixed-point text form, rounded to the given place
     relative to the decimal point, in a field of the given minimum width.
  *)

PROCEDURE WriteReal (cid: IOChan.ChanId; real: REAL; width: CARDINAL);
  (* Writes the value of real to cid, as WriteFixed if the sign and magnitude can be shown
     in the given width, or otherwise as WriteFloat.  The number of places or significant
     digits depends on the given width.
  *)

END RealIO.
