32 lines
798 B
Factor
32 lines
798 B
Factor
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! Copyright (C) 2006 Doug Coleman
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! See http://factorcode.org/license.txt for BSD license.
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USING: kernel math sequences sequences-internals namespaces
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words io ;
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IN: crc32
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: crc32-polynomial HEX: edb88320 ; inline
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! Generate the table at load time and define a new word with it,
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! instead of using a variable, so that the compiler can inline
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! the call to nth-unsafe
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SYMBOL: crc32-table inline
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\ crc32-table
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256 [
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8 [
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dup 1 bitand zero? >r -1 shift r>
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[ crc32-polynomial bitxor ] unless
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] times
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] map
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unit define-compound
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: (crc32) ( crc ch -- crc )
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dupd bitxor
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HEX: ff bitand crc32-table nth-unsafe
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swap -8 shift bitxor ;
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: crc32 ( seq -- n )
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>r HEX: ffffffff dup r> [ (crc32) ] each bitxor ;
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: file-crc32 ( path -- n ) <file-reader> contents crc32 ;
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