[SOLVED]A case of blindness, probably. Old hands, plz help.

[Thaddy]

I found some old code by me, myself and I, but it is not correct and I can not see where it fails.
DON'T comment on the programming style - that is sound, but old -, but find the error, please...

Code: Pascal  [Select][+][-]

1. program hexdump;
2. { Simple Hexdump, unix like clone.
3.   Has error! Where?
4.   This is an adapted version of my original.
5.   (c)1991-2024, Thaddy de Koning.
6.   Use as you like, no license }
7. {$mode objfpc}{$I-}{$H-}
8. const
9.   maxchar = 15;
10. type
11.   TByteOrChar  = packed record
12.   case boolean of
13.     false:(asByte : packed array[0..maxchar] of byte);
14.     true :(asChar : packed array[0..maxchar] of AnsiChar);
15.   end;
16.  
17.   function ByteToHex(const value:byte):string;inline;
18.   const
19.     HexDigits = '0123456789ABCDEF';
20.   begin
21.     ByteToHex := HexDigits[hi(value)+1]+HexDigits[lo(value)+1];
22.   end;
23.  
24. var
25.   f: file of TByteOrChar;
26.   bor: TByteOrChar;
27.   i,r: integer;
28. begin
29.   if ParamCount > 0 then
30.   begin
31.     Assign(f,paramstr(1));
32.     filemode := 0;
33.     reset(f);
34.     r:= IOResult;
35.     if r = 0 then
36.     begin
37.       while not eof(f) do
38.       begin
39.         write(HexStr(FilePos(f) * 16,8):10);
40.         read(f,bor);
41.         for i := 0 to maxchar do
42.         begin
43.           write(ByteToHex(bor.asbyte[i]):3);
44.           if (bor.asbyte[i] < 32 ) or  (bor.asbyte[i] > 127 ) then bor.aschar[i]:='.';
45.         end;
46.         writeln('|':2,bor.asChar,'|');
47.       end;
48.       close(f);
49.     end
50.     else
51.       case r of
52.       2:writeln('File not found');
53.       5:writeln('Access denied');
54.       else
55.         writeln('A less common error occurred:',r:4);
56.     end;
57.  end
58.  else
59.    writeln('Use: hexdump <filename>');
60. end.

Problem at hand is that I am missing the last line, compared to e.g. the standard hexdump on linux.
I can't see it? must be easy for old hands...
The error is the last line of the output missing.
   

[MarkMLl]

Nothing springs out. I suspect that the issue is that the unix variant of the code first outputs an address and then looks to see how much (if any) data is to follow it, then repeats.

MarkMLl

[Zvoni]

Copy line 38 between line 46 and 47
The writing of the FilePos (L38) happens within the loop, so the moment Line39 returns EOF....

EDIT: Modified to reflect Mark's answer

Code: Pascal  [Select][+][-]

1. program hexdump;
2. { Simple Hexdump, unix like clone.
3.   Has error! Where?
4.   (c)1991-2024, Thaddy de Koning.
5.   Use as you like, no license }
6. {$mode objfpc}{$I-}{$H-}
7. const
8.   maxchar = 15;
9. type
10.   TByteOrChar  = packed record
11.   case boolean of
12.     false:(asByte : packed array[0..maxchar] of byte);
13.     true :(asChar : packed array[0..maxchar] of AnsiChar);
14.   end;
15.  
16.   function ByteToHex(const value:byte):string;inline;
17.   const
18.     HexDigits = '0123456789ABCDEF';
19.   begin
20.     ByteToHex := HexDigits[hi(value)+1]+HexDigits[lo(value)+1];
21.   end;
22.  
23. var
24.   f: file of TByteOrChar;
25.   bor: TByteOrChar;
26.   i,r: integer;
27. begin
28.   if ParamCount > 0 then
29.   begin
30.     Assign(f,paramstr(1));
31.     filemode := 0;
32.     reset(f);
33.     r:= IOResult;
34.     if r = 0 then
35.     begin
36.       write(HexStr(FilePos(f) * 16,8):10);   //Added/Moved
37.       while not eof(f) do
38.       begin
39.         //write(HexStr(FilePos(f) * 16,8):10);
40.         read(f,bor);
41.         for i := 0 to maxchar do
42.         begin
43.           write(ByteToHex(bor.asbyte[i]):3);
44.           if (bor.asbyte[i] < 32 ) or  (bor.asbyte[i] > 127 ) then bor.aschar[i]:='.';
45.         end;
46.         writeln('|':2,bor.asChar,'|');    
47.         write(HexStr(FilePos(f) * 16,8):10);   //Added
48.       end;
49.       close(f);
50.     end
51.     else
52.       case r of
53.       2:writeln('File not found');
54.       5:writeln('Access denied');
55.       else
56.         writeln('A less common error occurred:',r:4);
57.     end;
58.  end
59.  else
60.    writeln('Use: hexdump <filename>');
61. end.

[Thaddy]

TNX Zvoni and Mark! Identical output. (apart from the space, but that does not matter).
Sometimes you need 4 extra eyes... Again, thanks.
Code compiles in all modes that I use and is cross platform.

[Zvoni]

Identical output. (apart from the space, but that does not matter).

Line 36 / 47 in my modified code: Remove the ":10" (or change to ":8")
In Line 43 add two leading spaces to the Write
*shrug*

[Thaddy]

Hey, Zvoni, it was a 33 year old bug... I did only know about minix at the time...
Code compiles in the real TP7, btw. just remove inline.

[MarkMLl]

EDIT: Modified to reflect Mark's answer

Sorry, I was getting ready to fire another radio test run on the hour, and really didn't want to get too deep into it.

MarkMLl

[Zvoni]

Hey, Zvoni, it was a 33 year old bug... I did only know about minix at the time...
Code compiles in the real TP7, btw. just remove inline.

Well then.... "Full steam ahead, and damn the torpedos".... or however that quote goes... 

EDIT: Modified to reflect Mark's answer

Sorry, I was getting ready to fire another radio test run on the hour, and really didn't want to get too deep into it.

MarkMLl

Nothing to be sorry about....

[Thaddy]

Well, we now have a small, old school, hexdump tool that is very useful. I wonder why I remembered that code and why? maybe somebody asked a question recently? I can't find anything or think of anything. Must be getting old.

[MarkMLl]

Well, we now have a small, old school, hexdump tool that is very useful. I wonder why I remembered that code and why? maybe somebody asked a question recently? I can't find anything or think of anything. Must be getting old.

Something I found /very/ useful, somewhat more than 33 years ago when there was significantly less prepackaged software around, was an undump program which allowed a hexdump to be edited as text and then converted back to a binary. I can't remember, but I might even have done that as an elementary patch program, i.e. it could seek into the binary file and change only the hex digits given (the others being dots as placeholders).

Since then there's been at least one commercial program to patch/relocate executables rather than sending out a whole binary, and I believe that Oracle now owns the rights to a way to patch the Linux kernel without having to reboot.

MarkMLl

[Thaddy]

Mark, I also wrote - and found - the reverse, but that is much more complicated to get to work.
That is basically a hex editor, based on one I wrote for my C64. One could not really work without hex editors in these days. (I lost a lot of code since 1982, not everything made it to DOS)

[BrunoK]

That program seems to still not dump the end of the file.

Win10

Modifiying the comment to

Code: Pascal  [Select][+][-]

1. { Simple Hexdump, unix like clone.
2.   Has error! Where?
3.   (c)1991-2024, Thaddy de Koning.
4.   Use as you like, no license.
5.   ~bk dumping itself still dump en of file }

   
and dumping the program itself gives an end of program

000005F0 20 20 77 72 69 74 65 6C 6E 28 27 55 73 65 3A 20 |  writeln('Use: |
00000600 68 65 78 64 75 6D 70 20 3C 66 69 6C 65 6E 61 6D |hexdump <filenam|
00000610

[Thaddy]

What do you mean? That is not clear to me.I get the same output as linux hexdump after Zvoni's fix.

[BrunoK]

What do you mean? That is not clear to me.I get the same output as linux hexdump after Zvoni's fix.

I mean that dumping the program itself should also display the end of the source that is

Code: Pascal  [Select][+][-]

1. >');
2. end.

[Zvoni]

It's true. There is something fishy going on.
As if EOF(f) becomes true before reaching the end of the file