Declarations

Pure Signals: signals have a present status:

• absent or present
• must be set for input signals
• computed for local and output signals:
  
  • for each tick absent by default unless signal is emitted
• Example:
  
  • Emit signal S: S
  • Test for presence: S

Valued Signals:

• are pure signals than additionally are able to store a value
• values are persistent across ticks
• Example:
  • Emit signal V with value 3: V(3)
  • Test for presence: V
  • Get the last emitted value of V: ?V
    
    

Variables: 

• Are not shared between concurrent regions
• Currently implemented by host type  variables

Events:

• interface scope: events can either be ingoing (in event event)
  or outgoing (out event event).
• local scope: events are able to store a value.internal: event localEvent : bool

Variables:

• variable:var variable: string

• read-only variable:var readonly size: int = 10 

• external variable: can be referenced by the environment
  var external variable: int = 44External variables are not used at the moment.

Types

• int
• bool
• string
  
  
• pure: only makes sense for Signals. Signals are absent or present.
• unsigned
• float
• double
• host: no actual type is given. The given type in the hostType attribute is used.

• integer
• boolean 
• string
  
  
• real
• void
  New types are going to be added. A type system abstraction is present.
  
  

Expressions

• Logical AND: var1 && var2
• Logical OR: var1 || var2
• Logical NOT: !var1

(A and B) or ((not C) and D) 

• Logical AND: var1 && var2
• Logical OR: var1 || var2
• Logical NOT: !var1
• Conditional Expression: var1 ? var2 : var3

Operations

• Equal: '='
• Less Than: '<'
• Equal Or Less Than: '<='
• Greater Than: '>'
• Equal Or Greater Than: '>='
• NOT: '!='
• Add: '+'
• Minus : '-'
• Multiply: '*'
• Divide: '/'
• Modulo: 'mod'
• Value: '?'

?B = 3

• PRE: 'pre':

pre(S):gives the presence status of S at

the previous tick. 

pre(?S):returns the value of S at the

previous tick.

• NE: '<>'

• Equal: '=='
• less than: '<'
• Equal Or Less Than: '<='
• Greater Than: '>'
• Equal Or Greater Than '>='
• Not Equal: '!='
• Plus: '+'
• Minus: '-'
• Multiply: '*'
• Divide: '/'
• Modulo: '%'
• valueof()
  
  
• Shift Left: '<<'
• Shift Right: '>>'
• Positive: '+'
• Negative: '-'
• Complement: '~'

Trigger

• Simple signal reference: I / O
• Boolean expression: 

(A and B) or ((not C) and D)

• Valued Signals and Variables can be used in conditions in these boolean expressions 

variable &#x3e; 1 

?A = 1

• Comparison 

?A &#x3e; (variable + 1)  

A and (3 > ?B) or ((var5 + 2) = 6)

• Pre

A and pre(B)

3 < pre(?A)

• Immediate, #S: the trigger is satisfied as soon as the state is entered..

• Count Delays, 3 S

• Time in SyncCharts: Multiform notion of time,
  e.g., signal SECOND appears every second (depending on the physical tick length).

   

• event:
  I / raise O

• after:after 20 s

• everyevery 200 ms

• always: 
  enables a reaction to be executed in every run to completion step
• default: 
  enables a reaction to be executed in every run to completion step
• else: 
  used in transitions and implies the lowest evaluation priority for that transition.
• entry
• exit
• oncycle 
  

Effects

• Emission of a simple signal

/ A

• Emission of value of a valued Signal

/ A(3)

• Assignment of a variable 

/ varA := 42

• Multiple effects get comma- or whitespace separated 

/ A, B, C(25), varA := 2

• New values may use value expressions as explained above

/ A(3 + pre(?B)), varC := (varD + 1)

• Assignment of a variable: S / varA = 5
• raise myvar
• myvar = valueof(event): Returns the value of an valued event
                                         that it passed to the function as parameter.
• mybool = active(StateA): Returns „true” if a state is active or „false” otherwise.