(*---------------------------------------------------------------------------
    :Program.    .mod
    :Author.     Bernd Preusing
    :Address.    Gerhardstr. 16  D-2200 Elmshorn
    :Phone.      04121/22486
    :Shortcut.   [bep]
    :Version.    1.0
    :Date.       Aug-87
    :Copyright.  PD
    :Language.   Modula-II
    :Translator. M2Amiga
    :Imports.    
    :UpDate.     
    :Contents.   Show differences of two files
    :Remark.     
---------------------------------------------------------------------------*)
MODULE Diff;

FROM SYSTEM IMPORT
    ADR, ADDRESS, CAST;

FROM InOut IMPORT
    Write, WriteString, WriteLn, WriteHex, WriteInt;

FROM Arts IMPORT
    Assert;

FROM FileSystem IMPORT
    File, Lookup, Close, ReadBytes, Response, Length;

FROM Arguments IMPORT
     NumArgs, GetArg;

FROM Heap IMPORT Allocate, Deallocate;

VAR i,l1,l2,errs:LONGINT;
    f1,f2:File;
    len:INTEGER;
    s1,s2:ARRAY[0..50] OF CHAR;
    a1,a2: ADDRESS;

(* $R- $V- *)

PROCEDURE ShowDiff;
VAR c1,c2:CHAR;
BEGIN
  c1:=CAST(CHAR,a1^); c2:=CAST(CHAR,a2^);
  WriteHex(i,6);
  WriteString(":  ");
  WriteHex(ORD(c1),2);
  WriteString(" ");
  IF (c1<' ') OR (ORD(c1)>126) THEN
    Write('.');
  ELSE
    Write(c1);
  END;
  WriteString("  |  ");
  WriteHex(ORD(c2),2);
  Write(' ');
  IF (c2<' ') OR (ORD(c2)>126) THEN
    Write('.');
  ELSE
    Write(c2);
  END;
  WriteLn;
  INC(errs);
END ShowDiff;


BEGIN
  i:=NumArgs();
  errs:=0;
  IF i#2 THEN
    WriteString("usage: Diff file1 file2");
    WriteLn;
  ELSE
    GetArg(1,s1,len);
    GetArg(2,s2,len);
    Lookup(f1,s1,0,FALSE);
    Assert(f1.res=done,ADR("1.File nicht zu öffnen."));
    Lookup(f2,s2,0,FALSE);
    IF f2.res#done THEN
      Close(f1);
      Assert(f2.res=done,ADR("2.File nicht zu öffnen."));
    END;

    Length(f1,l1);
    Length(f2,l2);
    Allocate(a1,l1);
    Assert(a1#NIL,ADR("Nicht genug Speicher für File1"));
    Allocate(a2,l2);
    Assert(a2#NIL,ADR("Nicht genug Speicher für File1"));
    ReadBytes(f1,a1,l1,i);
    Assert(f1.res=done,ADR("Lesefehler File1"));
    ReadBytes(f2,a2,l2,i);
    Assert(f2.res=done,ADR("Lesefehler File2"));
    Close(f1); Close(f2);
    i:=0;
    REPEAT
      IF CAST(CHAR,a1^)#CAST(CHAR,a2^) THEN ShowDiff END;
      INC(a1); INC(a2);
      INC(i); DEC(l1); DEC(l2);
    UNTIL (l1<=0) OR (l2<=0);
    IF (l1=0) AND (l2#0) THEN
      WriteString(s1);
      WriteString(" vorzeitig beendet.");
      WriteLn;
    ELSIF (l1#0) AND (l2=0) THEN
      WriteString(s2);
      WriteString(" vorzeitig beendet.");
      WriteLn;
    END;
    IF errs#0 THEN
      WriteInt(errs,5);
    ELSE
      WriteString("Keine");
    END;
    WriteString(" Unterschiede gefunden.");
    WriteLn;
  END;
END Diff.