At 10:59 �� 1/7/2001 +0100, you wrote:
> > >Executables can be tested via the FTYP function (type 1 is executable)
> > >of Toolkit 2.
> >
> > Yes, they could also be identified (and some more interesting info gleaned)
> > from the first couple of bytes, the executable header. Don't remember the
> > definition of the top of my head, but I know hex 4AFB appears in it :-)
>
>It's only a 'suggestion' (that most [commercial] programs obey), code
>will still execute if it doesn't have this format - it's just that
>extensions (like 'JOBS') will not be able to display any 'job name'.
>
>When a program is EXEC'd it starts executing with the first byte of the
>file. The suggestion was that the program should start:
>
> 00: xx xx xx xx xx xx xx 4A FB
> 08: LL LL nn nn nn nn nn nn nn
> 10: nn ....
>
>where xx = executable code (usually it's just a BRA[.S] instruction =
>$60 ..), LLLL = the length of the program name (.W, usually 00LL), nn =
>the bytes of the name, eg:
>
> 00: 60 00 04 E0 00 00 4A FB �.....J.
> 08: 00 06 45 64 69 74 6F 72 ..Editor
> 10: 6D 64 76 32 5F 00 00 7E mdv2_..~
> etc
>
>is the start of my file editor. On 'JOBS', this appears as:
>
>Job tag owner priority
>0 0 0 32
>4 5 0 s40 Editor
>
> > Resident extensions cannot be recognized as they are just pieces of code,
> > they are called after they are loaded (LRESPR), but don't have any defined
> > headers etc.
>
>Although there is no defined header, they usually start with code that
>links the next names in and then exits, and looks something like:
>
> 00: 43 FA 00 0C LEA table,A1
> 04: 34 78 01 10 MOVE.W $0110,A2
> 08: 4E 92 JSR (A2)
> 0A: 70 00 MOVEQ #$00,D0
> 0C: 4E 75 RTS
> 10: 00 nn table DC.W 4 ; Number of PROCs
> 12: oo oo DC.W proc1-* ; offset to 1st proc code
> 14: 00 LL DC.W 5 ; length of name
> 16: 70 72 6F 63 49 DC.B 'proc1' ; name of 1st proc
> 1B: 00 ALIGN ; Words must be on even
>boundaries
> 1C: ..... <rest of proc defn's>
>
>Tho' the LEA and MOVE.W may be the other way round, in which case the
>file will start:
>
> 00: 34 78 01 10 MOVE.W $0110,A2
> 04: 43 FA 00 08 LEA table,A1
>
>But when you get to pure executable code as opposed to a job (eg the
>Breakout game that came with the QL), there's no defined standard or
>suggestion, so good luck.
>
>Robert
A-ha! this gets better and better :-) At least now I have an idea :-) Thx
all for the info :-)
Phoebus
