run-length-uncompress-bitmap8 ( byte-array m n -- byte-array' )

Vocabulary

compression.run-length

Inputs

byte-array	an object
m	an object
n	an object

Outputs

byte-array'

an object

Definition

USING: arrays combinators kernel math math.matrices math.order
sequences sequences.parser ;

IN: compression.run-length

:: run-length-uncompress-bitmap8
    ( byte-array m n -- byte-array' )
    byte-array <sequence-parser> :> sp m 1 + n <zero-matrix>
    :> matrix n 4 mod n + :> stride 0 :> i! 0 :> j! f :> done?! 
    [
        sp consume dup 0 = [
            sp consume dup 3 255 between? [
                nip [ sp ] dip dup odd?
                [ 1 + take-n but-last ] [ take-n ] if
                [ j matrix i swap nth copy ] [ length j + j! ]
                bi
            ] [
                nip {
                    { 0 ~quotation~ }
                    { 1 ~quotation~ }
                    { 2 ~quotation~ }
                } case
            ] if
        ] [
            sp consume <array>
            [ j matrix i swap nth copy ] [ length j + j! ] bi
        ] if j stride >= [ 0 j! ] when done? not
    ] loop matrix B{ } concat-as ;