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#------------------------------------------------------------------------------
# compress: file(1) magic for pure-compression formats (no archives)
#
# compress, gzip, pack, compact, huf, squeeze, crunch, freeze, yabba, whap, etc.
#
# Formats for various forms of compressed data
# Formats for "compress" proper have been moved into "compress.c",
# because it tries to uncompress it to figure out what's inside.
# standard unix compress
0 string \037\235 compress'd data
>2 byte&0x80 >0 block compressed
>2 byte&0x1f x %d bits
# gzip (GNU zip, not to be confused with [Info-ZIP/PKWARE] zip archiver)
0 string \037\213 gzip compressed data
>2 byte <8 - reserved method,
>2 byte 8 - deflate method,
>3 byte &0x01 ascii,
>3 byte &0x02 continuation,
>3 byte &0x04 extra field,
>3 byte &0x08 original file name,
>3 byte &0x10 comment,
>3 byte &0x20 encrypted,
>4 ledate x last modified: %s,
>8 byte 2 max compression,
>8 byte 4 max speed,
>9 byte =0x00 os: MS-DOS
>9 byte =0x01 os: Amiga
>9 byte =0x02 os: VMS
>9 byte =0x03 os: Unix
>9 byte =0x05 os: Atari
>9 byte =0x06 os: OS/2
>9 byte =0x07 os: MacOS
>9 byte =0x0A os: Tops/20
>9 byte =0x0B os: Win/32
# According to gzip.h, this is the correct byte order for packed data.
#
0 string \037\036 packed data
>2 belong >1 %d characters originally
>2 belong =1 %d character originally
#
# This magic number is byte-order-independent.
# Are there two types of old packed data? One big endian, one little endian?
#
#0 beshort 017437 old packed data, big endian
#0 leshort 017437 old packed data, little endian
0 short 017437 old packed data
# XXX - why *two* entries for "compacted data", one of which is
# byte-order independent, and one of which is byte-order dependent?
#
0 short 0x1fff compacted data
0 string \377\037 compacted data
0 short 0145405 huf output
# Squeeze and Crunch...
# These numbers were gleaned from the Unix versions of the programs to
# handle these formats. Note that I can only uncrunch, not crunch, and
# I didn't have a crunched file handy, so the crunch number is untested.
# Keith Waclena <keith@cerberus.uchicago.edu>
0 leshort 0x76FF squeezed data (CP/M, DOS)
0 leshort 0x76FE crunched data (CP/M, DOS)
# Freeze
0 string \037\237 Frozen file 2.1
0 string \037\236 Frozen file 1.0 (or gzip 0.5)
# lzh?
0 string \037\240 LZH compressed data
# European GSM 06.10 is a provisional standard for full-rate speech
# transcoding, prI-ETS 300 036, which uses RPE/LTP (residual pulse
# excitation/long term prediction) coding at 13 kbit/s.
#
# WEAK - There's only a magic nibble (4 bits); but that nibble repeats
# every 33 bytes. This magic is NOT suited for use, but maybe we can
# use it someday.
#
# This will cause very short GSM files to be declared as data and
# mismatches to be declared as data too!
#0 byte&0xF0 0xd0 data
#>33 byte&0xF0 0xd0
#>66 byte&0xF0 0xd0
#>99 byte&0xF0 0xd0
#>132 byte&0xF0 0xd0 GSM 06.10 compressed audio
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