%% ?- one_instruction(state(1, 0, [101, 102, 101], [100] ,[6, 7, 8, 9], 0), X).
%
%% X = state(103, 1, [101, 102, 101], [100], [6, 7, 8, 9], 0).
%
%
one_instruction(state(Acc, Pc, Mem, In, Out, Flag),
                state(NewAcc, NewPc, NewMem, NewIn, NewOut, Flag)):-
                nth0(Pc,Mem,Cell),
                Op is div(Cell,100),
                Address is mod(Cell,100),
                operator(Op,Address,Mem,Acc,NewAcc,Pc,NewPc, NewMem, In, NewIn,Out,NewOut).
%add
operator(1,Address,Mem,Acc,NewAcc,Pc,NewPc,Mem,In,In,Out,Out):- pc_update(Pc,NewPc),
                nth0(Address,Mem,Value),NewAcc is Acc+Value.
%sub
operator(2,Address,Mem,Acc,NewAcc,Pc,NewPc,Mem,In,In,Out,Out):- pc_update(Pc,NewPc),
                nth0(Address,Mem,Value),NewAcc is Acc-Value.

%store
operator(3,Address,Mem,Acc,Acc,Pc,NewPc,NewMem,In,In,Out,Out):- pc_update(Pc,NewPc), fun(Mem, Address, Acc, _, NewMem),!.

%load
operator(5,Address,Mem,_,NewAcc,Pc,NewPc,Mem,In,In,Out,Out):- pc_update(Pc,NewPc), nth0(Address, Mem, NewAcc).


%branch
operator(6,Address,Mem,Acc,Acc,_,Address,Mem,In,In,Out,Out):- Address < 100.

%branch if zero
operator(7,Address,Mem,Acc,Acc,_,Address,Mem,In,In,Out,Out):- Acc = 0.
operator(7,_,Mem,Acc,Acc,Pc,NewPc,Mem,In,In,Out,Out):- pc_update(Pc,NewPc).



%input:
operator(9, 01,Mem,_,NewAcc,Pc,NewPc,Mem, In, NewIn,Out,Out):- pc_update(Pc,NewPc), input(In, NewAcc), nth0(0, In, _, NewIn).

%output:
operator(9, 02, Mem,Acc,Acc,Pc,NewPc,Mem,In,In,Out,NewOut):- pc_update(Pc,NewPc), append(Out,Acc, NewOut).



%fine
operator(0,_,_,_,_,_,_,_,_,_,_,_):- halt(0).
operator(4,_,_,_,_,_,_,_,_,_,_,_):- halt(4).




%Qui sotto lo schifo. Poi creiamo un secondo file di moduli magari
%
%
%


%aggiunge in posizione indice
fun(List, Indice, Val, NewList, X):- nth0(Indice, NewList, Val, List), NewIndice is Indice+1, fun2(NewList, NewIndice, _, X),!.
%%toglie da indice +1
fun2(List, Indice,_, NewList):- nth0(Indice, List, _, NewList).

%aggiunge in testa
input([H], H).
input([H | _], H).

%non serve, ma la memoria dovra' avere 100 posizioni
mem(Index,[0|T]):- Index < 100, NewIndex is 1+Index, mem(NewIndex,T),!.
mem(Index,[0]):- Index is 99.



pc_update(Pc,NewPc):-Pc<99,NewPc is Pc+1,!.
%Pc=99 non serve ad un cazzo, è già maggiore di 99 per conoscenza
%pregressa.
pc_update(Pc,NewPc):-Pc=99,NewPc is 0.