add lzw compression

db4
Doug Coleman 2009-02-12 17:44:04 -06:00
parent 8993e0536b
commit 745e011ccc
3 changed files with 201 additions and 0 deletions

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Doug Coleman

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! Copyright (C) 2009 Doug Coleman.
! See http://factorcode.org/license.txt for BSD license.
USING: accessors tools.test compression.lzw ;
IN: compression.lzw.tests
[ V{ 7 258 8 8 258 6 } ]
[ B{ 7 7 7 8 8 7 7 6 6 } lzw-compress output>> ] unit-test
[ B{ 7 7 7 8 8 7 7 6 6 } ]
[ V{ 7 258 8 8 258 6 } lzw-uncompress output>> ] unit-test

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! Copyright (C) 2009 Doug Coleman.
! See http://factorcode.org/license.txt for BSD license.
USING: accessors assocs bitstreams byte-vectors combinators io
io.encodings.binary io.streams.byte-array kernel math sequences
vectors ;
IN: compression.lzw
CONSTANT: clear-code 256
CONSTANT: end-of-information 257
TUPLE: lzw input output end-of-input? table count k omega omega-k #bits
code old-code ;
SYMBOL: table-full
ERROR: index-too-big n ;
: lzw-bit-width ( n -- n' )
{
{ [ dup 510 <= ] [ drop 9 ] }
{ [ dup 1022 <= ] [ drop 10 ] }
{ [ dup 2046 <= ] [ drop 11 ] }
{ [ dup 4094 <= ] [ drop 12 ] }
[ drop table-full ]
} cond ;
: lzw-bit-width-compress ( lzw -- n )
count>> lzw-bit-width ;
: lzw-bit-width-uncompress ( lzw -- n )
table>> length lzw-bit-width ;
: initial-compress-table ( -- assoc )
258 iota [ [ 1vector ] keep ] H{ } map>assoc ;
: initial-uncompress-table ( -- seq )
258 iota [ 1vector ] V{ } map-as ;
: reset-lzw ( lzw -- lzw )
257 >>count
V{ } clone >>omega
V{ } clone >>omega-k
9 >>#bits ;
: reset-lzw-compress ( lzw -- lzw )
f >>k
initial-compress-table >>table reset-lzw ;
: reset-lzw-uncompress ( lzw -- lzw )
initial-uncompress-table >>table reset-lzw ;
: <lzw-compress> ( input -- obj )
lzw new
swap >>input
binary <byte-writer> <bitstream-writer> >>output
reset-lzw-compress ;
: <lzw-uncompress> ( input -- obj )
lzw new
swap >>input
BV{ } clone >>output
reset-lzw-uncompress ;
: push-k ( lzw -- lzw )
[ ]
[ k>> ]
[ omega>> clone [ push ] keep ] tri >>omega-k ;
: omega-k-in-table? ( lzw -- ? )
[ omega-k>> ] [ table>> ] bi key? ;
ERROR: not-in-table ;
: write-output ( lzw -- )
[
[ omega>> ] [ table>> ] bi at* [ not-in-table ] unless
] [
[ lzw-bit-width-compress ]
[ output>> write-bits ] bi
] bi ;
: omega-k>omega ( lzw -- lzw )
dup omega-k>> clone >>omega ;
: k>omega ( lzw -- lzw )
dup k>> 1vector >>omega ;
: add-omega-k ( lzw -- )
[ [ 1+ ] change-count count>> ]
[ omega-k>> clone ]
[ table>> ] tri set-at ;
: lzw-compress-char ( lzw k -- )
>>k push-k dup omega-k-in-table? [
omega-k>omega drop
] [
[ write-output ]
[ add-omega-k ]
[ k>omega drop ] tri
] if ;
: (lzw-compress-chars) ( lzw -- )
dup lzw-bit-width-compress table-full = [
drop
] [
dup input>> stream-read1
[ [ lzw-compress-char ] [ drop (lzw-compress-chars) ] 2bi ]
[ t >>end-of-input? drop ] if*
] if ;
: lzw-compress-chars ( lzw -- )
{
[ [ clear-code lzw-compress-char ] [ reset-lzw-compress drop ] bi ]
[ (lzw-compress-chars) ]
[ end-of-information lzw-compress-char ]
[ ]
} cleave dup end-of-input?>> [ drop ] [ lzw-compress-chars ] if ;
: lzw-compress ( byte-array -- seq )
binary <byte-reader> <lzw-compress>
[ lzw-compress-chars ] [ output>> stream>> ] bi ;
: lookup-old-code ( lzw -- vector )
[ old-code>> ] [ table>> ] bi nth ;
: lookup-code ( lzw -- vector )
[ code>> ] [ table>> ] bi nth ;
: code-in-table? ( lzw -- ? )
[ code>> ] [ table>> length ] bi < ;
: code>old-code ( lzw -- lzw )
dup code>> >>old-code ;
: write-code ( lzw -- )
[ lookup-code ] [ output>> ] bi push-all ;
: add-to-table ( seq lzw -- ) table>> push ;
: lzw-read ( lzw -- lzw n )
[ ] [ lzw-bit-width-uncompress ] [ input>> ] tri read-bits ;
DEFER: lzw-uncompress-char
: handle-clear-code ( lzw -- )
reset-lzw-uncompress
lzw-read dup end-of-information = [
2drop
] [
>>code
[ write-code ]
[ code>old-code ] bi
lzw-uncompress-char
] if ;
: handle-uncompress-code ( lzw -- lzw )
dup code-in-table? [
[ write-code ]
[
[
[ lookup-old-code ]
[ lookup-code first ] bi suffix
] [ add-to-table ] bi
] [ code>old-code ] tri
] [
[
[ lookup-old-code dup first suffix ] keep
[ output>> push-all ] [ add-to-table ] 2bi
] [ code>old-code ] bi
] if ;
: lzw-uncompress-char ( lzw -- )
lzw-read [
>>code
dup code>> end-of-information = [
drop
] [
dup code>> clear-code = [
handle-clear-code
] [
handle-uncompress-code
lzw-uncompress-char
] if
] if
] [
drop
] if* ;
: lzw-uncompress ( seq -- byte-array )
binary <byte-reader> <bitstream-reader>
<lzw-uncompress> [ lzw-uncompress-char ] [ output>> ] bi ;