test :- Strdata = [10,20,5,100,1,6,2,3],
    datagen(Strdata,Data),
    pipe(Data,Out),
    length(18),
    #write(Out).

run :- Strdata = [10,20,5,100,1,6,2,3],
    datagen(Strdata,Data),
    pipe(Data,Out),
    length(18).

        % Data Generator

datagen([],[]).
datagen([H|T],Out) :-
    Out = [H], @T = T, @datagen(T,Out).

        % Pipeline Merge Sorter

pipe(I0,Out) :-
    I1 = [], I2 = [], Out = [],
    proc_start(I0,I1, 2,1),
    proc_start(I1,I2, 4,2),
    proc_start(I2,Out,8,4).

    % Processor Unit

proc_start(I,O,P,PP) :-
    X = [], Y = [], Z = [], T = 1,
    #proc(I,O,X,Y,Z,T,P,PP).

proc(I,O,X,Y,Z,T,P,PP) :- X=[],Y=[],I=[],
    @X=X, @Y=Y, @Z=Z, @O=[], @T=1.
proc(I,O,X,Y,Z,T,P,PP) :- 
     load(I,O,X,Y,Yn,Z,Zn,T,P,PP),
    merge(I,O,X,Y,Yn,Z,Zn,T,P,PP).

load(I,O,X,Y,Yn,Z,Zn,T,P,PP) :- PP>=T,
    append(Z,I,Zn), @Z=Zn, Yn=Y, @T=T+1.
load(I,O,X,Y,Yn,Z,Zn,T,P,PP) :- T>PP,T<P,
    append(Y,I,Yn), @Z=[],@T=T+1.
load(I,O,X,Y,Yn,Z,Zn,T,P,PP) :- T>PP,T>=P,
    append(Y,I,Yn), @Z=[],@T=1.

merge(I,O,X,Y,Yn,Z,Zn,T,P,PP) :-X=[],Yn=[],
    @O=[], @Y=Yn,switch(T,PP,X,Zn,X).
merge(I,O,X,Y,Yn,Z,Zn,T,P,PP) :- X=[A|L],Yn=[],
    @O=[A], @Y=Yn,switch(T,PP,X,Zn,L).
merge(I,O,X,Y,Yn,Z,Zn,T,P,PP) :-X=[],Yn=[B|N],
    @O=[B], @Y=N,switch(T,PP,X,Zn,X).
merge(I,O,X,Y,Yn,Z,Zn,T,P,PP) :-X=[A|L],Yn=[B|N],
    A<B,
	@O=[A], @X=L, @Y=Yn.
merge(I,O,X,Y,Yn,Z,Zn,T,P,PP) :-X=[A|L],Yn=[B|N],
    A>=B,
	@O=[B], @Y=N, @X=X.

switch(T,PP,X,Zn,L) :- T=PP, @X=Zn.
switch(T,PP,X,Zn,L) :- T\=PP, @X=L.


append(Nil,L,L1) :- Nil=[],L=L1.
append(X,L,Y) :-[H|T]=X,[H1|M]=Y,
     H=H1,append(T,L,M).