Design and Implementation of TinyGALS: A Programming Model for ...

Component implementation for COUNTER.
char init(){
_counter = 0;
return 1;
}
void fire(){
_counter++;
CALL_COMMAND(fireOut)(_counter);
}
Figure 3: Fragment of code for implementation of the COUNTER component
shown in Figure 1. This provides the method bodes for the interface defined
in Figure 2. The internal variable counter is of type short.
and USESC refer to method calls and may be connected to ports in INPORT SM and
OUT PORT SM, INPORT SM and OUT PORT SM are not executable. Additionally, ports
in INPORT SM that are connected to ports in OUT PORT SM contain an implicit queue (see
Section 2.3.4).
Initialization methods in INITM are slightly different from input ports in INPORT SM;
they do not contain implicit queues since buffering of data is not needed during initializa-
tion.
Figure 4 gives the module definition code for the module count in the application
shown in Figure 1. The definition states that module count contains two components,
COUNTER and CLOCK. Note that component CLOCK accepts init() and uses fireOut();
component COUNTER accepts init() and fire(), and uses fireOut() (see Figure
2. The init section states that the init() method of component COUNTER belongs
to the initialization list of the module. The connection section at the bottom of Figure 4
declares that the fireOut() method of component CLOCK is mapped to the fire()
method of component COUNTER; the fireOut() method of component COUNTER is
mapped to the count_out outport of module count; and that the count_start in-
port of module count is mapped to the init() method of component CLOCK.
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