SystemC 28 Communication - port 2 port
So far we covered the cases of
- Connecting two processes of same module via channel:
- process1() $\rightarrow$ channel $\rightarrow$ process2()
- connecting two processes of different modules via port and channel:
- module1::process1() $\rightarrow$ module1::port1 $\rightarrow$ channel $\rightarrow$ module2::port2 $\rightarrow$ module2::process2()
- connecting two processes of different modules via export:
- module1::process1() $\rightarrow$ module1::channel $\rightarrow$ module1::export1 $\rightarrow$ module2::port2 $\rightarrow$ module2::process2()
port 2 port
In all these cases, a channel is needed to connect the ports. There is a special case that allows a port to directly connect to a port of submodules. I.e., module::port1 $\rightarrow$ module::submodule::port2
Code
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// Learn with Examples, 2020, MIT license
#include <systemc>
using namespace sc_core;
SC_MODULE(SUBMODULE1) { // a submodule that writes to channel
sc_port<sc_signal_out_if<int>> p;
SC_CTOR(SUBMODULE1) {
SC_THREAD(writer);
}
void writer() {
int val = 1; // init value
while (true) {
p->write(val++); // write to channel through port
wait(1, SC_SEC);
}
}
};
SC_MODULE(SUBMODULE2) { // a submodule that reads from channel
sc_port<sc_signal_in_if<int>> p;
SC_CTOR(SUBMODULE2) {
SC_THREAD(reader);
sensitive << p; // triggered by value change on the channel
dont_initialize();
}
void reader() {
while (true) {
std::cout << sc_time_stamp() << ": reads from channel, val=" << p->read() << std::endl;
wait(); // receives from channel through port
}
}
};
SC_MODULE(MODULE1) { // top-level module
sc_port<sc_signal_out_if<int>> p; // port
SUBMODULE1 sub1; // declares submodule
SC_CTOR(MODULE1): sub1("sub1") { // instantiate submodule
sub1.p(p); // bind submodule's port directly to parent's port
}
};
SC_MODULE(MODULE2) {
sc_port<sc_signal_in_if<int>> p;
SUBMODULE2 sub2;
SC_CTOR(MODULE2): sub2("sub2") {
sub2.p(p); // bind submodule's port directly to parent's port
}
};
int sc_main(int, char*[]) {
MODULE1 module1("module1"); // instantiate module1
MODULE2 module2("module2"); // instantiate module2
sc_signal<int> s; // define channel outside module1 and module2
module1.p(s); // bind module1's port to channel, for writing purpose
module2.p(s); // bind module2's port to channel, for reading purpose
sc_start(2, SC_SEC);
return 0;
}
// Result:
// module1::sub1::write()
// --> module1::sub1::p
// --> module1::p
// --> s
// --> module2::p
// --> module2::sub2::p
// --> module2::sub2::read()
0 s: reads from channel, val=1
1 s: reads from channel, val=2