MOKA(1)                                                      CAO-VLSI Reference Manual                                                     MOKA(1)

NAME

       MOKA -  Model checker ancestor

ORIGIN

       This  software  belongs  to  the  ALLIANCE CAD SYSTEM developed by the ASIM team at LIP6 laboratory of Universite Pierre et Marie CURIE, in
       Paris, France.

       Web : http://asim.lip6.fr/recherche/alliance/
       E-mail : alliance-users@asim.lip6.fr

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 condi-
       tion 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  assump-
       tions 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 reach-
       able 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.

ENVIRONMENT VARIABLES


       MBK_WORK_LIB gives the path for the description and the CTL file.  The default value is the current directory.

       MBK_CATA_LIB gives some auxiliary pathes for the descriptions and the CTL file.  The default value is the current directory.

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

SEE ALSO

        syf (1), fsp (1), fsm (5), ctl (5), vbe(5).

BUG REPORT

       This tool is under development at the ASIM department of the LIP6 laboratory.
       We need your feedback to improve documentation and tools.

ASIM
/LIP6                                                         August 5, 2002                                                           MOKA(1)