IMPLEMENTATION MODULE IOChan;
(* A ChanId is a C FILE* handle; all operations go through SysShim
   (which degrades a NIL handle to a safe no-op / 0C). *)

IMPORT SysShim;

TYPE ChanId = ADDRESS;

PROCEDURE StdInChan() : ChanId;
BEGIN
  RETURN SysShim.stdin()
END StdInChan;

PROCEDURE StdOutChan() : ChanId;
BEGIN
  RETURN SysShim.stdout()
END StdOutChan;

PROCEDURE StdErrChan() : ChanId;
BEGIN
  RETURN SysShim.stderr()
END StdErrChan;

PROCEDURE ReadChar(cid : ChanId) : CHAR;
BEGIN
  RETURN SysShim.fgetc(cid)
END ReadChar;

PROCEDURE WriteChar(cid : ChanId; c : CHAR);
BEGIN
  SysShim.fputc(cid, c)
END WriteChar;

PROCEDURE WriteString(cid : ChanId; VAR s : ARRAY OF CHAR);
BEGIN
  SysShim.fputs(cid, s)
END WriteString;

PROCEDURE WriteLn(cid : ChanId);
BEGIN
  SysShim.fwriteln(cid)
END WriteLn;

PROCEDURE WriteInt(cid : ChanId; n : INTEGER);
BEGIN
  SysShim.fwriteint(cid, n)
END WriteInt;

END IOChan.