1 ! Copyright (C) 2009 Doug Coleman.
2 ! See http://factorcode.org/license.txt for BSD license.
3 USING: accessors combinators io kernel math math.order
4 namespaces sequences vectors ;
5 QUALIFIED-WITH: bitstreams bs
17 end-of-information-code ;
19 TUPLE: tiff-lzw < lzw ;
20 TUPLE: gif-lzw < lzw ;
22 : initial-uncompress-table ( size -- seq )
23 iota [ 1vector ] V{ } map-as ;
25 : reset-lzw-uncompress ( lzw -- lzw )
26 dup end-of-information-code>> 1 + initial-uncompress-table >>table
27 dup initial-code-size>> >>code-size ;
29 ERROR: code-size-zero ;
31 : <lzw-uncompress> ( input code-size class -- obj )
33 swap [ code-size-zero ] when-zero >>code-size
34 dup code-size>> >>initial-code-size
35 dup code-size>> 1 - 2^ >>clear-code
36 dup clear-code>> 1 + >>end-of-information-code
39 reset-lzw-uncompress ;
41 ERROR: not-in-table value ;
43 : lookup-old-code ( lzw -- vector )
44 [ old-code>> ] [ table>> ] bi nth ;
46 : lookup-code ( lzw -- vector )
47 [ code>> ] [ table>> ] bi nth ;
49 : code-in-table? ( lzw -- ? )
50 [ code>> ] [ table>> length ] bi < ;
52 : code>old-code ( lzw -- lzw )
53 dup code>> >>old-code ;
55 : write-code ( lzw -- )
56 [ lookup-code ] [ output>> ] bi push-all ;
58 GENERIC: code-space-full? ( lzw -- ? )
60 : size-and-limit ( lzw -- m n ) [ table>> length ] [ code-size>> 2^ ] bi ;
62 M: tiff-lzw code-space-full? size-and-limit 1 - = ;
63 M: gif-lzw code-space-full? size-and-limit = ;
65 GENERIC: increment-code-size ( lzw -- lzw )
67 M: lzw increment-code-size [ 1 + ] change-code-size ;
68 M: gif-lzw increment-code-size [ 1 + 12 min ] change-code-size ;
70 : maybe-increment-code-size ( lzw -- lzw )
71 dup code-space-full? [ increment-code-size ] when ;
73 : add-to-table ( seq lzw -- )
75 [ maybe-increment-code-size 2drop ] 2bi ;
77 : lzw-read ( lzw -- lzw n )
78 [ ] [ code-size>> ] [ input>> ] tri bs:read ;
80 : end-of-information? ( lzw code -- ? ) swap end-of-information-code>> = ;
81 : clear-code? ( lzw code -- ? ) swap clear-code>> = ;
83 DEFER: handle-clear-code
84 : lzw-process-next-code ( lzw quot: ( lzw code -- ) -- )
86 { [ 2over end-of-information? ] [ 3drop ] }
87 { [ 2over clear-code? ] [ 2drop handle-clear-code ] }
88 [ call( lzw code -- ) ]
91 DEFER: lzw-uncompress-char
92 : handle-clear-code ( lzw -- )
99 ] lzw-process-next-code ;
101 : handle-uncompress-code ( lzw -- lzw )
107 [ lookup-code first ] bi suffix
108 ] [ add-to-table ] bi
109 ] [ code>old-code ] tri
112 [ lookup-old-code dup first suffix ] keep
113 [ output>> push-all ] [ add-to-table ] 2bi
114 ] [ code>old-code ] bi
117 : lzw-uncompress-char ( lzw -- )
118 [ >>code handle-uncompress-code lzw-uncompress-char ]
119 lzw-process-next-code ;
121 : lzw-uncompress ( bitstream code-size class -- byte-array )
123 [ lzw-uncompress-char ] [ output>> ] bi ;
125 : tiff-lzw-uncompress ( seq -- byte-array )
126 bs:<msb0-bit-reader> 9 tiff-lzw lzw-uncompress ;
128 : gif-lzw-uncompress ( seq code-size -- byte-array )
129 [ bs:<lsb0-bit-reader> ] dip gif-lzw lzw-uncompress ;