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pic_emulator.erl
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pic_emulator.erl
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-module(pic_emulator).
%-compile(export_all). %% REPLACE
-export([new/0, print/1, load_program/2,
run_program/1,run_program/2, cycle/3]).
-record(pic200,{
accumulator = <<0>>, % 8 bits
register = pic_register:new(), % 32 bytes
callstack = [<<0>>,<<0>>], % 2 bytes
program, % 256 x 12 bits
option, % 8 bits
trisgpio, % 8 bits (but only 4bits used)
instruction_register = <<0:12>>,
current_opcode,
current_value
}).
-record(opcode,{
opcode = nop,
address = 16#1F, % Last register is safe default
whence = accumulator,
constant = 0,
bit = 0
}).
new() ->
#pic200{
register = pic_register:new(),
program = lists:duplicate(255,<<0:12>>)
}.
load_program(P, File) ->
{ok, Bin} = file:read_file(File),
Program = read_program(Bin,[]),
E = 255 - length(Program),
P#pic200{ program = Program ++ lists:duplicate(E,<<0:12>>) }.
read_program(<<>>, Acc) -> lists:reverse(Acc);
read_program(<<H:12,Rest/bitstring>>, Acc) ->
read_program(Rest, [<<H:12>>|Acc]).
%read_program(<<_/bitstring>>, Acc) -> lists:reverse(Acc).
%% Description of one cycle (4 clocks)
% Fetch cycle Execution cycle
% Q1. inc_pc fetch_instr -> ir2
% Q2. - read_memory (from reg)
% Q3. - execute_instr
% Q4. fetch_pc -> ir1 write_result (to reg)
cycle(P,q1,fetch) -> increment_program_counter(P);
cycle(P,q4,fetch) ->
<<PC:8>> = pic_register:get( 2, P#pic200.register ),
NextInstr = pic_register:get( PC, P#pic200.program ),
P#pic200{ instruction_register = NextInstr };
cycle(P,_,fetch) -> P;
cycle(P,q1,execute) ->
O = unpack_opcode(P#pic200{ instruction_register } ),
P#pic200{ current_opcode = O };
cycle(P,q2,execute) ->
O = P#pic200.current_opcode,
<<FVal:8>> = pic_register:get( O#opcode.address, P#pic200.register ),
P#pic200{ current_value = FVal };
cycle(P,q3,execute) -> P;
cycle(P,q4,execute) -> P.
run_program(P , 0 ) -> P;
run_program(P, Steps ) ->
PN = run_program(P),
run_program(PN, Steps - 1).
run_program(P = #pic200{ register = R, program = Program } ) ->
<<PC:8>> = pic_register:get( 2, R ),
OpcodeBin = pic_register:get( PC, Program ),
execute_opcode(OpcodeBin, P).
execute_opcode(OpcodeBin, P = #pic200{accumulator = <<Acc:8>>}) ->
#opcode{opcode = Opcode, address = Addr, whence = Whence, constant = K, bit = B}
= unpack_opcode(OpcodeBin),
valid_addr(Addr),
<<FVal:8>> = pic_register:get( Addr, P#pic200.register ),
Func = orddict:fetch(Opcode,opcode_table()),
{Store,Res,ResP,Status} = Func(increment_program_counter(P), Acc, FVal, K, B), % Should we really increment here
case store(Store,Whence) of
accumulator -> ResP#pic200{ accumulator = <<Res:8>> };
source_register -> ResP#pic200{ register = pic_register:set(Addr, <<Res:8>>, ResP#pic200.register) };
no -> ResP
end.
chain(Obj, []) -> Obj;
chain(Obj, [F|Funcs]) -> chain(F(Obj), Funcs).
print(#pic200{
accumulator = <<A>>, register = R, callstack = [<<C1>>,<<C2>>],
program = P
}) ->
io:format("Accumulator: ~8.2B ~3.10B Callstack: ~8.2B ~8.2b~n",[A,A,C1,C2]),
io:format("Registers:~n"),
pic_register:print(R),
io:format("Program:~n"),
program_print(P),
ok.
program_print(P) ->
program_print(lists:sublist(P,1,9),0).
program_print([],_) -> io:nl();
program_print([HeadBin|R],A) ->
<<H:12>> = HeadBin,
OT = opcode_term(HeadBin),
io:format(" ~2.10B : ~12.2.0B ~5.10B [~6w]~n",[A,H,H,OT]), program_print(R,A+1).
opcode_term(OpcodeBin) ->
#opcode{opcode = Opcode} = unpack_opcode(OpcodeBin),
Opcode.
valid_addr(_) -> ok. % Should check in future
store(store,W) -> W;
store(S,_) -> S.
%% fun(#pic200, Acc, RVal, K, bits) -> {store, res, P}
opcode_table() -> orddict:from_list([
{nop, fun(P,_,_,_,_) -> { no, 0 , P, []} end },
{clrwdt,fun(P,_,_,_,_) -> { no, 0 , P, [to,pd]} end },
{sleep, fun(P,_,_,_,_) -> { no, 0 , P, [to,pd]} end },
{clrw, fun(P,_,_,_,_) -> { accumulator, 0 , P, [z]} end },
{clrf, fun(P,_,_,_,_) -> {source_register, 0 , P, [z]} end },
{movwf, fun(P,A,_,_,_) -> {source_register, A , P, []} end },
{subwf, fun(P,A,F,_,_) -> {store, F-A , P, [z,c,dc]} end },
{decf, fun(P,_,F,_,_) -> {store, F-1 , P, [z]} end },
{iorwf, fun(P,A,F,_,_) -> {store, A bor F , P, [z]} end },
{andwf, fun(P,A,F,_,_) -> {store, A band F , P, [z]} end },
{xorwf, fun(P,A,F,_,_) -> {store, A bxor F , P, [z]} end },
{addwf, fun(P,A,F,_,_) -> {store, A+F , P, [z,c,dc]} end },
{movf, fun(P,_,F,_,_) -> {store, F , P, [z]} end },
{comf, fun(P,_,F,_,_) -> {store, bnot F , P, [z]} end },
{incf, fun(P,_,F,_,_) -> {store, F+1 , P, [z]} end },
{decfsz,fun(P,_,1,_,_) -> {accumulator, 0 , skip(P), []};
(P,_,F,_,_) -> {store, F-1 , P, []} end },
{rrf, fun(P,_,F,_,_) -> {store, F bsr 1 , P, [c]} end }, % TODO: carry
{rlf, fun(P,_,F,_,_) -> {store, F bsl 1 , P, [c]} end }, % TODO: carry
{swapf, fun(P,_,F,_,_) -> {store, swapf(F) , P, []} end },
{incfsz,fun(P,_,255,_,_) -> {accumulator, 0 , skip(P), []};
(P,_,F,_,_) -> {store, F+1 , P, []} end },
{bcf, fun(P,_,F,_,B) -> {source_register,F bxor (F band (1 bsl (B-1))), P, []} end},
{bsf, fun(P,_,F,_,B) -> {source_register,F bor (1 bsl (B-1)), P, []} end },
{btfsc, fun(P,_,F,_,B) -> {no, F band (1 bsl (B-1)), P, []} end }, % TODO: check condition
{btfss, fun(P,_,F,_,B) -> {no, F band (1 bsl (B-1)), P, []} end }, % TODO: check condition
{retlw, fun(P,_,_,K,_) -> {accumulator, K, return(P), []} end },
{call, fun(P,_,_,K,_) -> {no , 0, call(P,K), []} end },
{goto, fun(P,_,_,K,_) -> {no , 0, goto(P,K), []} end },
{movlw, fun(P,_,_,K,_) -> {accumulator, K, P, []} end },
{iorlw, fun(P,A,_,K,_) -> {accumulator, K bor A, P, [z]} end },
{andlw, fun(P,A,_,K,_) -> {accumulator, K band A, P, [z]} end },
{xorlw, fun(P,A,_,K,_) -> {accumulator, K bxor A, P, []} end }
]).
clear_insreg(P) -> P#pic200{ instruction_register = <<0:12>> }.
skip(P = #pic200{ register = R}) ->
<<O:8>> = pic_register:get(2,R),
clear_insreg(P#pic200{ register = pic_register:set(2,O+1,R) }).
goto(P = #pic200{ register = R }, K) ->
Pn = case bit_size(K) of
8 -> P#pic200{ register = pic_register:set(2, K, R) };
9 -> <<_:1,RealK:8>> = K,
P#pic200{ register = pic_register:set(2, RealK, R) }
end,
clear_insreg(Pn).
call(P = #pic200{ register = R, callstack = C }, K) ->
goto( P#pic200{ callstack = [pic_register:get(2,R),hd(C)] }, K ).
return(P = #pic200{ callstack = [A|R] } ) ->
goto( P#pic200{ callstack = R }, A ).
swapf(V) ->
<<A:4,B:4>> = <<V>>,
<<R:8>> = <<B:4,A:4>>,
R.
increment_program_counter(P = #pic200{ register = Reg } ) ->
<<PC:8>> = pic_register:get(2, Reg),
Inc = PC + 1,
P#pic200{ register = pic_register:set(2, <<Inc:8>>, Reg) }.
whence(0) -> accumulator;
whence(1) -> source_register.
unpack_opcode(<<0:12>>) -> #opcode{opcode = nop };
unpack_opcode(<<2:12>>) -> #opcode{opcode = option };
unpack_opcode(<<3:12>>) -> #opcode{opcode = sleep };
unpack_opcode(<<4:12>>) -> #opcode{opcode = clrwdt };
unpack_opcode(<<1:10,A:2>>) -> #opcode{opcode = tris, address = A};
unpack_opcode(<<1:7,A:5>>) -> #opcode{opcode = movwf, address = A};
unpack_opcode(<<2:7,_:5>>) -> #opcode{opcode = clrw };
unpack_opcode(<<3:7,A:5>>) -> #opcode{opcode = clrf, address = A};
unpack_opcode(<< 2:6,W:1,A:5>>) -> #opcode{opcode = subwf, address = A, whence = whence(W)};
unpack_opcode(<< 3:6,W:1,A:5>>) -> #opcode{opcode = decf, address = A, whence = whence(W)};
unpack_opcode(<< 4:6,W:1,A:5>>) -> #opcode{opcode = iorwf, address = A, whence = whence(W)};
unpack_opcode(<< 5:6,W:1,A:5>>) -> #opcode{opcode = andwf, address = A, whence = whence(W)};
unpack_opcode(<< 6:6,W:1,A:5>>) -> #opcode{opcode = xorwf, address = A, whence = whence(W)};
unpack_opcode(<< 7:6,W:1,A:5>>) -> #opcode{opcode = addwf, address = A, whence = whence(W)};
unpack_opcode(<< 8:6,W:1,A:5>>) -> #opcode{opcode = movf, address = A, whence = whence(W)};
unpack_opcode(<< 9:6,W:1,A:5>>) -> #opcode{opcode = comf, address = A, whence = whence(W)};
unpack_opcode(<<10:6,W:1,A:5>>) -> #opcode{opcode = incf, address = A, whence = whence(W)};
unpack_opcode(<<11:6,W:1,A:5>>) -> #opcode{opcode = decfsz, address = A, whence = whence(W)};
unpack_opcode(<<12:6,W:1,A:5>>) -> #opcode{opcode = rrf, address = A, whence = whence(W)};
unpack_opcode(<<13:6,W:1,A:5>>) -> #opcode{opcode = rlf, address = A, whence = whence(W)};
unpack_opcode(<<14:6,W:1,A:5>>) -> #opcode{opcode = swapf, address = A, whence = whence(W)};
unpack_opcode(<<15:6,W:1,A:5>>) -> #opcode{opcode = incfsz, address = A, whence = whence(W)};
unpack_opcode(<<4:4,B:3,A:5>>) -> #opcode{opcode = bcf, address = A, bit = B};
unpack_opcode(<<5:4,B:3,A:5>>) -> #opcode{opcode = bsf, address = A, bit = B};
unpack_opcode(<<6:4,B:3,A:5>>) -> #opcode{opcode = btfsc, address = A, bit = B};
unpack_opcode(<<7:4,B:3,A:5>>) -> #opcode{opcode = btfss, address = A, bit = B};
unpack_opcode(<< 8:4, K:8>>) -> #opcode{opcode = retlw, constant = K};
unpack_opcode(<< 9:4, K:8>>) -> #opcode{opcode = call, constant = K};
unpack_opcode(<< 5:3, K:9>>) -> #opcode{opcode = goto, constant = K};
unpack_opcode(<<12:4, K:8>>) -> #opcode{opcode = movlw, constant = K};
unpack_opcode(<<13:4, K:8>>) -> #opcode{opcode = iorlw, constant = K};
unpack_opcode(<<14:4, K:8>>) -> #opcode{opcode = andlw, constant = K};
unpack_opcode(<<15:4, K:8>>) -> #opcode{opcode = xorlw, constant = K}.