drunken-bishop ( bytes -- board )

Vocabulary

drunken-bishop.private

Inputs

bytes

an object

Outputs

board

an object

Definition

USING: byte-arrays combinators kernel math math.bitwise
math.order namespaces sequences ;

IN: drunken-bishop.private

:: drunken-bishop ( bytes -- board )
    board-width get :> w board-height get :> h h
    [ w <byte-array> ] replicate
    :> board h 2/ :> y! w 2/ :> x! 15 x y board nth set-nth
    bytes [
        { 0 -2 -4 -6 } [
            shift 2 bits {
                { 0 [ -1 -1 ] }
                { 1 [ -1 1 ] }
                { 2 [ 1 -1 ] }
                { 3 [ 1 1 ] }
            } case :> ( dy dx ) dy y + 0 h 1 - clamp y! dx x +
            0 w 1 - clamp x! x y board nth
            [ dup 14 < [ 1 + ] when ] change-nth
        ] with each
    ] each 16 x y board nth set-nth board ;