moka - Online in the Cloud

PROGRAM:

NAME

MOKA - Model checker ancestor

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.

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

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