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Groups > comp.sys.acorn.programmer > #6529

Re: File type of machine code? Where does it start?

From Bob Latham <bob@sick-of-spam.invalid>
Newsgroups comp.sys.acorn.programmer
Subject Re: File type of machine code? Where does it start?
Date 2025-06-25 09:29 +0100
Organization None
Message-ID <5c326b84c7bob@sick-of-spam.invalid> (permalink)
References (1 earlier) <lKm*MFveA@news.chiark.greenend.org.uk> <5c29d67fbebavariasound@chiemgau-net.de> <5c2f4363e6bavariasound@chiemgau-net.de> <ac6d592f5c.jmb@jmc.bruck.orange.fr> <103evcp$27cdp$1@dont-email.me>

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In article <103evcp$27cdp$1@dont-email.me>,
   druck <news@druck.org.uk> wrote:
> On 19/06/2025 10:23, Jean-Michel wrote:
> >  From DDE.Codestds.AOF
> > There are two sorts of AOF: <little-endian> and <big-endian>.
> > 
> > In little-endian AOF, the least significant byte of a word or
> > half-word has the lowest address of any byte in the (half-)word.
> > This <byte sex> is used by DEC,Intel and Acorn, amongst others.
> > 
> > In big-endian AOF, the most significant byte of a (half-)word has
> > the lowest.address. This byte sex is used by IBM, Motorola and
> > Apple, amongst others.

> Never seen a big endian AOF in the wild, and suspect no-one else
> has either.

> I can only guess it was specified as a result of Sam Wauchope's
> crazed ideas about running a successor to RISC OS on Power PC or
> something.


At first sight there is a strangeness to the data inside flac music
files. They appear to use both big and little endian vaules which
they do in a way and they don't at the same time. They often use the
hi-byte for flags and blockid purposes.

Here is the start of a flac file...

0000       fLaC
0004       [00][00][00][22]        (low byte last  Big-endian)
0008       <34 bytes of data for STREAMINFO BLOCK>

002A [04][00][02][B7]  <= 04 says vorbis comment not last block,     
                         length = &02B7 (low byte last)
002E  [20][00][00][00]reference libFLAC 1.2.1 20070917               
                         (low byte first)
0032  [16][00][00][00]     <= number of items in list

But also in the same file..

  [0E][00][00][00]TOTALTRACKS=28
  [0C][00][00][00]TOTALDISCS=2
  [26][00][00][00]TITLE=Third Movement (Cellos & Basses)
  [14][00][00][00]ARTIST=Gustav Mahler
  [2C][00][00][00]ALBUM=Symphony No. 2 "Resurrection" [Kaplan]
  [09][00][00][00]DATE=1988

These are actual values taken from a flac track.

Bob.

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Thread

File type of machine code? Where does it start? Alexander Ausserstorfer <bavariasound@chiemgau-net.de> - 2025-06-07 17:41 +0200
  Re: File type of machine code? Where does it start? Martin <News03@avisoft.f9.co.uk> - 2025-06-07 18:14 +0100
    Re: File type of machine code? Where does it start? Alexander Ausserstorfer <bavariasound@chiemgau-net.de> - 2025-06-08 18:26 +0200
  Re: File type of machine code? Where does it start? Theo <theom+news@chiark.greenend.org.uk> - 2025-06-08 11:02 +0100
    Re: File type of machine code? Where does it start? Alexander Ausserstorfer <bavariasound@chiemgau-net.de> - 2025-06-08 18:32 +0200
      Re: File type of machine code? Where does it start? Alexander Ausserstorfer <bavariasound@chiemgau-net.de> - 2025-06-19 07:22 +0200
        Re: File type of machine code? Where does it start? Jean-Michel <jmc.bruck@orange.fr> - 2025-06-19 11:23 +0200
          Re: File type of machine code? Where does it start? druck <news@druck.org.uk> - 2025-06-24 20:47 +0100
            Re: File type of machine code? Where does it start? Bob Latham <bob@sick-of-spam.invalid> - 2025-06-25 09:29 +0100
        Re: File type of machine code? Where does it start? Martin <News03@avisoft.f9.co.uk> - 2025-06-19 10:48 +0100
          Re: File type of machine code? Where does it start? Alexander Ausserstorfer <bavariasound@chiemgau-net.de> - 2025-06-20 17:22 +0200
            Re: File type of machine code? Where does it start? Matthew Phillips <spam2011m@yahoo.co.uk> - 2025-06-21 08:20 +0100
        Re: File type of machine code? Where does it start? Theo <theom+news@chiark.greenend.org.uk> - 2025-06-20 17:25 +0100

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