16 lines
386 B
Factor
16 lines
386 B
Factor
! Copyright (C) 2010 John Benediktsson
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! See http://factorcode.org/license.txt for BSD license
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USING: checksums grouping io.binary kernel math sequences ;
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IN: checksums.internet
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SINGLETON: internet ! RFC 1071
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INSTANCE: internet checksum
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M: internet checksum-bytes
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drop 2 <groups> [ le> ] map-sum
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[ -16 shift ] [ 0xffff bitand ] bi +
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[ -16 shift ] keep + bitnot 2 >le ;
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