compress 3.6 KB

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  1. #------------------------------------------------------------------------------
  2. # compress: file(1) magic for pure-compression formats (no archives)
  3. #
  4. # compress, gzip, pack, compact, huf, squeeze, crunch, freeze, yabba, etc.
  5. #
  6. # Formats for various forms of compressed data
  7. # Formats for "compress" proper have been moved into "compress.c",
  8. # because it tries to uncompress it to figure out what's inside.
  9. # standard unix compress
  10. 0 string \037\235 compress'd data
  11. >2 byte&0x80 >0 block compressed
  12. >2 byte&0x1f x %d bits
  13. # gzip (GNU zip, not to be confused with Info-ZIP or PKWARE zip archiver)
  14. 0 string \037\213 gzip compressed data
  15. >2 byte <8 \b, reserved method,
  16. >2 byte 8 \b, deflated,
  17. >3 byte &0x01 ASCII,
  18. >3 byte &0x02 continuation,
  19. >3 byte &0x04 extra field,
  20. >3 byte &0x08 original filename,
  21. >3 byte &0x10 comment,
  22. >3 byte &0x20 encrypted,
  23. >4 ledate x last modified: %s,
  24. >8 byte 2 max compression,
  25. >8 byte 4 max speed,
  26. >9 byte =0x00 os: MS-DOS
  27. >9 byte =0x01 os: Amiga
  28. >9 byte =0x02 os: VMS
  29. >9 byte =0x03 os: Unix
  30. >9 byte =0x05 os: Atari
  31. >9 byte =0x06 os: OS/2
  32. >9 byte =0x07 os: MacOS
  33. >9 byte =0x0A os: Tops/20
  34. >9 byte =0x0B os: Win/32
  35. # packed data, Huffman (minimum redundancy) codes on a byte-by-byte basis
  36. 0 string \037\036 packed data
  37. >2 belong >1 \b, %d characters originally
  38. >2 belong =1 \b, %d character originally
  39. #
  40. # This magic number is byte-order-independent. XXX - Does that mean this
  41. # is big-endian, little-endian, either, or that you can't tell?
  42. # this short is valid for SunOS
  43. 0 short 017437 old packed data
  44. # XXX - why *two* entries for "compacted data", one of which is
  45. # byte-order independent, and one of which is byte-order dependent?
  46. #
  47. 0 short 0x1fff compacted data
  48. # This string is valid for SunOS (BE) and a matching "short" is listed
  49. # in the Ultrix (LE) magic file.
  50. 0 string \377\037 compacted data
  51. 0 short 0145405 huf output
  52. # bzip2
  53. 0 string BZh bzip2 compressed data
  54. >3 byte >47 \b, block size = %c00k
  55. # squeeze and crunch
  56. # Michael Haardt <michael@cantor.informatik.rwth-aachen.de>
  57. 0 leshort 0xFF76 squeezed data,
  58. >4 string x original name %s
  59. 0 leshort 0xFE76 crunched data,
  60. >2 string x original name %s
  61. 0 leshort 0xFD76 LZH compressed data,
  62. >2 string x original name %s
  63. # Freeze
  64. 0 string \037\237 frozen file 2.1
  65. 0 string \037\236 frozen file 1.0 (or gzip 0.5)
  66. # SCO compress -H (LZH)
  67. 0 string \037\240 SCO compress -H (LZH) data
  68. # European GSM 06.10 is a provisional standard for full-rate speech
  69. # transcoding, prI-ETS 300 036, which uses RPE/LTP (residual pulse
  70. # excitation/long term prediction) coding at 13 kbit/s.
  71. #
  72. # There's only a magic nibble (4 bits); that nibble repeats every 33
  73. # bytes. This isn't suited for use, but maybe we can use it someday.
  74. #
  75. # This will cause very short GSM files to be declared as data and
  76. # mismatches to be declared as data too!
  77. #0 byte&0xF0 0xd0 data
  78. #>33 byte&0xF0 0xd0
  79. #>66 byte&0xF0 0xd0
  80. #>99 byte&0xF0 0xd0
  81. #>132 byte&0xF0 0xd0 GSM 06.10 compressed audio
  82. # bzip a block-sorting file compressor
  83. # by Julian Seward <sewardj@cs.man.ac.uk> and others
  84. #
  85. 0 string BZ bzip compressed data
  86. >2 byte x \b, version: %c
  87. >3 string =1 \b, compression block size 100k
  88. >3 string =2 \b, compression block size 200k
  89. >3 string =3 \b, compression block size 300k
  90. >3 string =4 \b, compression block size 400k
  91. >3 string =5 \b, compression block size 500k
  92. >3 string =6 \b, compression block size 600k
  93. >3 string =7 \b, compression block size 700k
  94. >3 string =8 \b, compression block size 800k
  95. >3 string =9 \b, compression block size 900k