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- #------------------------------------------------------------------------------
- # $File: acorn,v 1.8 2021/04/26 15:56:00 christos Exp $
- # acorn: file(1) magic for files found on Acorn systems
- #
- # RISC OS Chunk File Format
- # From RISC OS Programmer's Reference Manual, Appendix D
- # We guess the file type from the type of the first chunk.
- 0 lelong 0xc3cbc6c5 RISC OS Chunk data
- >12 string OBJ_ \b, AOF object
- >12 string LIB_ \b, ALF library
- # RISC OS AIF, contains "SWI OS_Exit" at offset 16.
- 16 lelong 0xef000011 RISC OS AIF executable
- # RISC OS Draw files
- # From RISC OS Programmer's Reference Manual, Appendix E
- 0 string Draw RISC OS Draw file data
- # RISC OS new format font files
- # From RISC OS Programmer's Reference Manual, Appendix E
- 0 string FONT\0 RISC OS outline font data,
- >5 byte x version %d
- 0 string FONT\1 RISC OS 1bpp font data,
- >5 byte x version %d
- 0 string FONT\4 RISC OS 4bpp font data
- >5 byte x version %d
- # RISC OS Music files
- # From RISC OS Programmer's Reference Manual, Appendix E
- 0 string Maestro\r RISC OS music file
- >8 byte x version %d
- >8 byte x type %d
- # Digital Symphony data files
- # From: Bernard Jungen (bern8817@euphonynet.be)
- 0 string \x02\x01\x13\x13\x13\x01\x0d\x10 Digital Symphony sound sample (RISC OS),
- >8 byte x version %d,
- >9 pstring x named "%s",
- >(9.b+19) byte =0 8-bit logarithmic
- >(9.b+19) byte =1 LZW-compressed linear
- >(9.b+19) byte =2 8-bit linear signed
- >(9.b+19) byte =3 16-bit linear signed
- >(9.b+19) byte =4 SigmaDelta-compressed linear
- >(9.b+19) byte =5 SigmaDelta-compressed logarithmic
- >(9.b+19) byte >5 unknown format
- 0 string \x02\x01\x13\x13\x14\x12\x01\x0b Digital Symphony song (RISC OS),
- >8 byte x version %d,
- >9 byte =1 1 voice,
- >9 byte !1 %d voices,
- >10 leshort =1 1 track,
- >10 leshort !1 %d tracks,
- >12 leshort =1 1 pattern
- >12 leshort !1 %d patterns
- 0 string \x02\x01\x13\x13\x10\x14\x12\x0e
- >9 byte =0 Digital Symphony sequence (RISC OS),
- >>8 byte x version %d,
- >>10 byte =1 1 line,
- >>10 byte !1 %d lines,
- >>11 leshort =1 1 position
- >>11 leshort !1 %d positions
- >9 byte =1 Digital Symphony pattern data (RISC OS),
- >>8 byte x version %d,
- >>10 leshort =1 1 pattern
- >>10 leshort !1 %d patterns
- # From: Joerg Jenderek
- # URL: https://www.kyzer.me.uk/pack/xad/#PackDir
- # reference: https://www.kyzer.me.uk/pack/xad/xad_PackDir.lha/PackDir.c
- # GRR: line below is too general as it matches also "Git pack" in ./revision
- 0 string PACK\0
- # check for valid compression method 0-4
- >5 ulelong <5
- # https://www.riscosopen.org/wiki/documentation/show/Introduction%20To%20Filing%20Systems
- # To skip "Git pack" version 0 test for root directory object like
- # ADFS::RPC.$.websitezip.FONTFIX
- >>9 string >ADFS\ PackDir archive (RISC OS)
- # TrID labels above as "Acorn PackDir compressed Archive"
- # compression mode y (0 - 4) for GIF LZW with a maximum n bits
- # (y~n,0~12,1~13,2~14,3~15,4~16)
- >>>5 ulelong+12 x \b, LZW %u-bits compression
- # https://www.filebase.org.uk/filetypes
- # !Packdir compressed archive has three hexadecimal digits code 68E
- !:mime application/x-acorn-68E
- !:ext pkd/bin
- # null terminated root directory object like IDEFS::IDE-4.$.Apps.GRAPHICS.!XFMPdemo
- >>>9 string x \b, root "%s"
- # load address 0xFFFtttdd, ttt is the object filetype and dddddddddd is time
- >>>>&1 ulelong x \b, load address %#x
- # execution address 0xdddddddd dddddddddd is 40 bit unsigned centiseconds since 1.1.1900 UTC
- >>>>&5 ulelong x \b, exec address %#x
- # attributes (bits: 0~owner read,1~owner write,3~no delete,4~public read,5~public write)
- >>>>&9 ulelong x \b, attributes %#x
- # number of entries in this directory. for root dir 0
- #>>>&13 ulelong x \b, entries %#x
- # the entries start here with object name
- >>>>&17 string x \b, 1st object "%s"
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