decode-huffman-tables ( bitstream -- tables )

Vocabulary

compression.inflate.private

Inputs

bitstream

an object

Outputs

tables

an object

Definition

USING: accessors arrays bitstreams combinators
combinators.short-circuit compression.huffman kernel math
sequences ;

IN: compression.inflate.private

:: decode-huffman-tables ( bitstream -- tables )
    5 bitstream read 257 + 5 bitstream read 1 + 4 bitstream read
    4 + clen-shuffle swap head dup length
    [ 3 bitstream read ] replicate get-table
    bitstream swap <huffman-decoder> [ 2dup + ] dip swap :> k! [
        read1-huff2 {
            { [ dup 16 = ] [ 2 bitstream read 3 + 2array ] }
            { [ dup 17 = ] [ 3 bitstream read 3 + 2array ] }
            { [ dup 18 = ] [ 7 bitstream read 11 + 2array ] }
            [ ]
        } cond dup array? [ dup second ] [ 1 ] if k swap -
        dup k! 0 >
    ] curry [ ] produce swap suffix
    { } [
        dup { [ array? ] [ first 16 = ] } 1&& [
            [ unclip-last-slice ]
            [ second 1 + swap <repetition> append ] bi*
        ] [ suffix ] if
    ] reduce
    [ dup array? [ second 0 <repetition> ] [ 1array ] if ] map
    concat nip swap cut 2array
    [ [ length>> <iota> ] [ ] bi get-table ] map ;