IMPLEMENTATION MODULE FileIO;
(* Self-hosted file I/O: SysShim only. *)

IMPORT SysShim;

VAR
  argIdx: CARDINAL;

PROCEDURE NextParameter (VAR s: ARRAY OF CHAR);
BEGIN
  IF SysShim.arg(argIdx, s, LEN(s)) THEN
    INC(argIdx)
  ELSE
    s[0] := CHR(0)
  END
END NextParameter;

PROCEDURE Open (VAR f: File; fileName: ARRAY OF CHAR; newFile: BOOLEAN);
BEGIN
  IF newFile THEN f := SysShim.fopenwrite(fileName)
  ELSE f := SysShim.fopenread(fileName)
  END;
  Okay := f # NIL
END Open;

PROCEDURE Close (VAR f: File);
BEGIN
  SysShim.fclose(f);
  f := NIL
END Close;

PROCEDURE ReadBytes (f: File; VAR buf: ARRAY OF CHAR; VAR len: CARDINAL);
BEGIN
  len := SysShim.fread(f, buf, len)
END ReadBytes;

PROCEDURE Write (f: File; ch: CHAR);
BEGIN
  IF ch = EOL THEN SysShim.fwriteln(f) ELSE SysShim.fputc(f, ch) END
END Write;

PROCEDURE WriteLn (f: File);
BEGIN
  SysShim.fwriteln(f)
END WriteLn;

PROCEDURE WriteString (f: File; str: ARRAY OF CHAR);
BEGIN
  SysShim.fputs(f, str)
END WriteString;

PROCEDURE WriteInt (f: File; int: INTEGER; wid: CARDINAL);
BEGIN
  SysShim.fwriteintw(f, int, wid)
END WriteInt;

PROCEDURE WriteCard (f: File; card, wid: CARDINAL);
BEGIN
  SysShim.fwriteintw(f, card, wid)
END WriteCard;

PROCEDURE SLENGTH (stringVal: ARRAY OF CHAR): CARDINAL;
BEGIN
  RETURN LEN(stringVal)
END SLENGTH;

PROCEDURE Assign (source: ARRAY OF CHAR; VAR destination: ARRAY OF CHAR);
  VAR i, n: CARDINAL;
BEGIN
  n := LEN(source);
  IF n > LEN(destination) THEN n := LEN(destination) END;
  i := 0;
  WHILE i < n DO
    destination[i] := source[i];
    INC(i)
  END
END Assign;

PROCEDURE Extract (source: ARRAY OF CHAR;
                   startIndex, numberToExtract: CARDINAL;
                   VAR destination: ARRAY OF CHAR);
  VAR i, n, k: CARDINAL;
BEGIN
  n := LEN(source);
  k := 0;
  i := startIndex;
  WHILE (i < n) AND (k < numberToExtract) AND (k < LEN(destination)) DO
    destination[k] := source[i];
    INC(k); INC(i)
  END
END Extract;

PROCEDURE Concat (stringVal1, stringVal2: ARRAY OF CHAR;
                  VAR destination: ARRAY OF CHAR);
  VAR i, k: CARDINAL;
BEGIN
  k := 0; i := 0;
  WHILE (i < LEN(stringVal1)) AND (k < LEN(destination)) DO
    destination[k] := stringVal1[i]; INC(k); INC(i)
  END;
  i := 0;
  WHILE (i < LEN(stringVal2)) AND (k < LEN(destination)) DO
    destination[k] := stringVal2[i]; INC(k); INC(i)
  END
END Concat;

PROCEDURE Compare (stringVal1, stringVal2: ARRAY OF CHAR): INTEGER;
  VAR i, n, m: CARDINAL;
BEGIN
  n := LEN(stringVal1); m := LEN(stringVal2);
  i := 0;
  WHILE (i < n) AND (i < m) DO
    IF stringVal1[i] < stringVal2[i] THEN RETURN -1
    ELSIF stringVal1[i] > stringVal2[i] THEN RETURN 1
    END;
    INC(i)
  END;
  IF n < m THEN RETURN -1
  ELSIF n > m THEN RETURN 1
  END;
  RETURN 0
END Compare;

BEGIN
  (* Arguments exclude argv[0] (the program name), matching the gm2
     host FileIO: user arguments start at cmdline index 1. *)
  argIdx := 1;
  Okay := TRUE;
  StdOut := SysShim.stdout();
  con := StdOut;
  StdIn := NIL;
  err := SysShim.stderr()
END FileIO.