41 lines
875 B
Factor
41 lines
875 B
Factor
! Copyright (C) 2006 Doug Coleman
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! See http://factorcode.org/license.txt for BSD license.
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USING: checksums io.binary kernel math sequences
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sequences.private ;
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IN: checksums.crc32
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CONSTANT: crc32-polynomial 0xedb88320
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CONSTANT: crc32-table V{ }
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256 <iota> [
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8 [
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[ 2/ ] [ even? ] bi [ crc32-polynomial bitxor ] unless
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] times
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] map 0 crc32-table copy
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: (crc32) ( crc ch -- crc )
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dupd bitxor
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mask-byte crc32-table nth-unsafe
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swap -8 shift bitxor ; inline
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SINGLETON: crc32
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INSTANCE: crc32 checksum
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: init-crc32 ( input checksum -- x y input )
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drop [ 0xffffffff dup ] dip ; inline
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: finish-crc32 ( x y -- bytes )
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bitxor 4 >be ; inline
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M: crc32 checksum-bytes
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init-crc32
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[ (crc32) ] each
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finish-crc32 ; inline
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M: crc32 checksum-lines
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init-crc32
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[ [ (crc32) ] each CHAR: \n (crc32) ] each
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finish-crc32 ; inline
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