76 lines
2.2 KiB
Factor
76 lines
2.2 KiB
Factor
! Copyright (C) 2009 Marc Fauconneau.
|
|
! See http://factorcode.org/license.txt for BSD license.
|
|
USING: accessors arrays assocs fry
|
|
hashtables io kernel locals math math.order math.parser
|
|
math.ranges multiline sequences bitstreams bit-arrays ;
|
|
IN: compression.huffman
|
|
|
|
QUALIFIED-WITH: bitstreams bs
|
|
|
|
<PRIVATE
|
|
|
|
TUPLE: huffman-code
|
|
{ value fixnum }
|
|
{ size fixnum }
|
|
{ code fixnum } ;
|
|
|
|
: <huffman-code> ( -- huffman-code )
|
|
0 0 0 huffman-code boa ; inline
|
|
|
|
: next-size ( huffman-code -- )
|
|
[ 1 + ] change-size
|
|
[ 2 * ] change-code drop ; inline
|
|
|
|
: next-code ( huffman-code -- )
|
|
[ 1 + ] change-code drop ; inline
|
|
|
|
:: all-patterns ( huffman-code n -- seq )
|
|
n log2 huffman-code size>> - :> free-bits
|
|
free-bits 0 >
|
|
[ free-bits 2^ iota [ huffman-code code>> free-bits 2^ * + ] map ]
|
|
[ huffman-code code>> free-bits neg 2^ /i 1array ] if ;
|
|
|
|
:: huffman-each ( ... tdesc quot: ( ... huffman-code -- ... ) -- ... )
|
|
<huffman-code> :> code
|
|
tdesc
|
|
[
|
|
code next-size
|
|
[ code (>>value) code clone quot call code next-code ] each
|
|
] each ; inline
|
|
|
|
: update-reverse-table ( huffman-code n table -- )
|
|
[ drop all-patterns ]
|
|
[ nip '[ _ swap _ set-at ] each ] 3bi ;
|
|
|
|
:: reverse-table ( tdesc n -- rtable )
|
|
n f <array> <enum> :> table
|
|
tdesc [ n table update-reverse-table ] huffman-each
|
|
table seq>> ;
|
|
|
|
PRIVATE>
|
|
|
|
TUPLE: huffman-decoder
|
|
{ bs bit-reader }
|
|
{ tdesc array }
|
|
{ rtable array }
|
|
{ bits/level fixnum } ;
|
|
|
|
: <huffman-decoder> ( bs tdesc -- huffman-decoder )
|
|
huffman-decoder new
|
|
swap >>tdesc
|
|
swap >>bs
|
|
16 >>bits/level
|
|
dup [ tdesc>> ] [ bits/level>> 2^ ] bi reverse-table >>rtable ; inline
|
|
|
|
: read1-huff ( huffman-decoder -- elt )
|
|
16 over [ bs>> bs:peek ] [ rtable>> nth ] bi
|
|
[ size>> swap bs>> bs:seek ] [ value>> ] bi ; inline
|
|
|
|
: reverse-bits ( value bits -- value' )
|
|
[ integer>bit-array ] dip
|
|
f pad-tail reverse bit-array>integer ; inline
|
|
|
|
: read1-huff2 ( huffman-decoder -- elt )
|
|
16 over [ bs>> bs:peek 16 reverse-bits ] [ rtable>> nth ] bi
|
|
[ size>> swap bs>> bs:seek ] [ value>> ] bi ; inline
|