SYNOPSIS

moka [-VDB] fsm_filename ctl_filename

DESCRIPTION

moka is a CTL model checker.

Made to run on FSM or RTL descriptions, moka supports the same VHDL subset as syf or boom (for further informations about this subset see SYF(1), BOOM(1), FSM(5), VBE(5) ). Nevertheless moka imposes that each register of the behavioral description have the same clock condition and that there are no tristate or multiplexed buses. In particular VHDL type MUX_BIT and WOR_BIT aren't not supported.
First of all moka build the fonction transition of the FSM using a Reduced Ordered Binary Decision Diagrams representation.
It then applies the initial conditions to find the first state (keyword INITIAL and/or RESET_COND in the CTL(5) file format).
After it computes a symbolic simulation of the FSM in order to find all reachable states. This computation takes into account the assumptions conditions (ASSUME keyword in the CTL(5) file format).
moka finally verifies one by one each CTL formulae. (see CTL(5) for CTL file format details).

CTL OPERATORS

For each CTL sub-expression moka will return the set of states that verifies the formula. For example EX(p) will return the set of reachable states that verifies EX(p).
CTL operators :

EX(p) : returns all states which have almost one primary state successor that verifies p.
EU(p,q) : returns all states that are the root of almost one path, such that p is true until q is always true.
EG(p) : returns all states that are the root of almost one path, such that p is always true.
AX(p) : returns all states which have all their primary state successor that verifies p.
AU(p,q) : returns all states that are the root of only pathes from which p is true until q is always true.
AG(p) : returns all states that are the root of only pathes, such that p is always true.

OPTIONS

        -V Sets verbose mode on. Each step of the model checking is displayed on the standard output.

-D Sets debug mode on. Each step of the model checking is detailed on the standard output. In particular all states set are displayed for each CTL sub-expression.

-B The input file is a VHDL description using the Alliance VHDL subset (see VBE(5) file format).

FSM EXAMPLE

-- A multi fsm example
ENTITY example is
PORT 
( 
   ck       : in  BIT;
   data_in  : in  BIT;
   reset    : in  BIT; 
   data_out : out BIT
);
END example;
ARCHITECTURE FSM OF example is
   TYPE A_ETAT_TYPE IS (A_E0, A_E1);
   SIGNAL A_NS, A_CS : A_ETAT_TYPE;
   TYPE B_ETAT_TYPE IS (B_E0, B_E1);
   SIGNAL B_NS, B_CS : B_ETAT_TYPE;
--PRAGMA CURRENT_STATE A_CS  FSM_A
--PRAGMA NEXT_STATE A_NS     FSM_A
--PRAGMA CLOCK ck            FSM_A
--PRAGMA FIRST_STATE A_E0    FSM_A
--PRAGMA CURRENT_STATE B_CS  FSM_B
--PRAGMA NEXT_STATE B_NS     FSM_B
--PRAGMA CLOCK ck            FSM_B
--PRAGMA FIRST_STATE B_E0    FSM_B
   SIGNAL ACK, REQ, DATA_INT : BIT;
BEGIN
A_1 : PROCESS ( A_CS, ACK )
BEGIN
  IF ( reset = '1' )
  THEN A_NS     <= A_E0;
       DATA_OUT <= '0';
       REQ      <= '0';
  ELSE
  CASE A_CS is
    WHEN A_E0 =>
      IF ( ACK ='1') THEN A_NS <= A_E1;
                     ELSE A_NS <= A_E0;
      END IF;
      DATA_OUT <= '0';
      REQ      <= '1';
    WHEN A_E1 =>
      IF ( ACK ='1') THEN A_NS <= A_E1;
                     ELSE A_NS <= A_E0;
      END IF;
      DATA_OUT <= DATA_INT;
      REQ      <= '0';
  END CASE;
  END IF;
END PROCESS A_1;
A_2 : PROCESS( ck )
BEGIN
    IF ( ck = '1' AND NOT ck'STABLE )
    THEN A_CS <= A_NS;
    END IF;
END PROCESS A_2;
-------
B_1 : PROCESS ( B_CS, ACK )
BEGIN
  IF ( reset = '1' )
  THEN B_NS     <= B_E0;
       DATA_INT <= '0';
       ACK      <= '0';
  ELSE
  CASE B_CS is
    WHEN B_E0 =>
      IF ( REQ ='1') THEN B_NS <= B_E1;
                     ELSE B_NS <= B_E0;
      END IF;
      DATA_INT <= '0';
      ACK      <= '0';
    WHEN B_E1 =>
      IF ( REQ ='1') THEN B_NS <= B_E1;
                     ELSE B_NS <= B_E0;
      END IF;
      DATA_INT <= DATA_IN;
      ACK      <= '1';
  END CASE;
  END IF;
END PROCESS B_1;
B_2 : PROCESS( ck )
BEGIN
    IF ( ck = '1' AND NOT ck'STABLE )
    THEN B_CS <= B_NS;
    END IF;
END PROCESS B_2;
END FSM;

CTL EXAMPLE

-- A CTL file example
   TYPE A_ETAT_TYPE IS (A_E0, A_E1);
   TYPE B_ETAT_TYPE IS (B_E0, B_E1);
   VARIABLE A_NS, A_CS : A_ETAT_TYPE;
   VARIABLE B_NS, B_CS : B_ETAT_TYPE;
   VARIABLE    ck       : BIT;
   VARIABLE    data_in  : BIT;
   VARIABLE    data_out : BIT;
   VARIABLE    reset    : BIT;
   VARIABLE    ack      : BIT;
   VARIABLE    req      : BIT;
   RESET_COND init1 := (reset='1');
   ASSUME     ass1  := (reset='0');
begin
       prop1 : EX( ack='1' );
       prop2 : AG( req -> AF( ack ) );
       prop4 : AU( req='1', ack='1');
end;

MOKA EXAMPLE

       moka -V example example