(* 31V4 Assignment 2 - PD subset assembler *)
(* Written by: J.G.Harston, (C)HCE         *)

(* Pass_2 module. Entry at pass2 to do the second pass of the source file. *)

IMPLEMENTATION MODULE Pass_2;

FROM FileSystem IMPORT Eof, Reset;
FROM InOut IMPORT WriteString, WriteLn, WriteOct, in;
FROM Parser IMPORT Do_This_Line;
FROM Symbols IMPORT init_list, get_label, Label;

VAR line_num:INTEGER;
    error:BOOLEAN;

PROCEDURE pass2;
BEGIN
  WriteString('Pass 2'); WriteLn;
  Reset(in); (* Rewind to start of file *)
  line_num=1;
  REPEAT
    error:=Do_This_Line(2,line_num);
    line_num:=line_num+1;
  UNTIL Eof(in) OR error; (* Stop at end or error *)
  DoListing;       (* Display the symbol table *)
END pass2;

PROCEDURE DoListing;
VAR num,loop,colm,value:INTEGER;
    lbl:Label;
    end:BOOLEAN;
BEGIN
  WriteLn;
  colm:=1;
  num:=0
  init_list(num); (* Get the number of entries *)
  IF num=0 THEN
    WriteString('No labels defined.'); WriteLn;
    RETURN;
  END;
  WriteString('Symbol table:'); WriteLn; WriteLn;
  FOR loop:=1 TO num DO      (* Display all the entries *)
    end:=get_label(lbl,value); (* Get an entry *)
    disp(lbl);               (* Display it with padding spaces *)
    WriteOct(value,6);
    WriteString('      ');
    colm:=colm+1;            (* Move to next column *)
    IF colm=4 THEN           (* We're in column four, it's time for *)
      colm:=1; WriteLn;      (* another line *)
    END;
  END;
  IF colm<>1 THEN WriteLn; END; (* Do another line if needed *)
END DoListing;

PROCEDURE disp(lbl:Label);
(* Display the label with padding spaces in a field of 8 characters *)
VAR ptr,loop:INTEGER;
BEGIN
  ptr:=0;
  LOOP
    WriteString(lbl[ptr]);
    ptr:=ptr+1;
    IF ptr=7 THEN EXIT; END;
    IF lbl[ptr]=0c THEN EXIT; END;
  END;
  FOR loop:=ptr TO 8 DO
    WriteString(' ');
  END;
END disp;

END Pass_2