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ARCHIVES.SWG
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0002_ARJ.pas
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Pascal/Delphi Source File
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1996-09-03
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3KB
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72 lines
--------A-ARJ-------------------------------
The ARJ program by Robert K. Jung is a "newcomer" which compares well to
PKZip and LhArc in both compression and speed. An ARJ archive contains
two types of header blocks, one archive main header at the head of the
archive and local file headers before each archived file.
OFFSET Count TYPE Description
0000h 1 word ID=0EA60h
0002h 1 word Basic header size (0 if end of archive)
0004h 1 byte Size of header including extra data
0005h 1 byte Archiver version number
0006h 1 byte Minimum version needed to extract
0007h 1 byte Host OS (see table 0002)
0008h 1 byte Internal flags, bitmapped :
0 - no password / password
1 - reserved
2 - file continues on next disk
3 - file start position field is available
4 - path translation ( "\" to "/" )
0009h 1 byte Compression method :
0 - stored
1 - compressed most
2 - compressed
3 - compressed faster
4 - compressed fastest
Methods 1 to 3 use Lempel-Ziv 77 sliding window with static Huffman
encoding, method 4 uses Lempel-Ziv 77 sliding window with pointer/
length unary encoding.
000Ah 1 byte File type :
0 - binary
1 - 7-bit text
2 - comment header
3 - directory
4 - volume label
000Bh 1 byte reserved
000Ch 1 dword Date/Time of original file in MS-DOS format
0010h 1 dword Compressed size of file
0014h 1 dword Original size of file
0018h 1 dword Original file's CRC-32
001Ah 1 word Filespec position in filename
001Ch 1 word File attributes
001Eh 1 word Host data (currently not used)
? 1 dword Extended file starting position when used
(see above)
? char ASCIIZ file name
? char Comment
????h 1 dword Basic header CRC-32
????h 1 word Size of first extended header (0 if none)
="SIZ"
????h+"SIZ"+2 1 dword Extended header CRC-32
????h+"SIZ"+6 ? byte Compressed file
(Table 0002)
ARJ HOST-OS types
0 - MS-DOS
1 - PRIMOS
2 - UNIX
3 - AMIGA
4 - MAC-OS (System xx)
5 - OS/2
6 - APPLE GS
7 - ATARI ST
8 - NeXT
9 - VAX VMS
EXTENSION:ARJ
OCCURENCES:PC
PROGRAMS:ARJ.EXE