SystemC- sensitivity list - c++

Question

I have recently started learning SystemC and I have got an error with sensitivity list in "SC_METHOD". I am trying to implement a fifo and the error corresponds to following part of the code:
SC_MODULE(fifo){
...
int rd_addr, wr_addr;
...
void buffer_full();
...
SC_CTOR(fifo){
SC_METHOD(buffer_full);
sensitive << rd_addr << wr_addr;
}
};
I get error when compiling the code and it complains about sensitivity list. The error is
fifo_simple.h:32:22: error: invalid user-defined conversion from 'int' to 'const sc_core::sc_event&' [-fpermissive]
I would appreciate if someone could let me know what is wrong with the sensitivity list. how should I make "buffer_full" process sensitive to the changes in rd_addr and wr_addr.
I also tried following syntax to see if it works with single bit sensitivity but still no success
sensitive << rd_addr[0]
Many thanks

Answer 1

You cannot be sensitive to plain integers, only to (events of) ports or plain events.
As suggested by #jakub_d in the comments above, try changing the int variables to signal ports (although I'd suggest using inputs rather than output ports):
SC_MODULE(fifo)
{
...
// use ports instead of plain integers
sc_in<int> rd_addr, wr_addr;
...
void buffer_full();
...
SC_CTOR(fifo)
: rd_addr("rd_addr") // name your ports
, wr_addr("wr_addr")
{
SC_METHOD(buffer_full);
sensitive << rd_addr << wr_addr; // sensitivity works now
}
};
When using your FIFO, you then need to bind matching sc_signal<int> instances to these address ports:
int sc_main(int, char*[]) {
sc_signal<int> rd_addr_s("rd_addr_s"), wr_addr_s("wr_addr_s");
fifo fifo_i("fifo_i");
// bind signals to ports
fifo_i.rd_addr(rd_addr_s);
fifo_i.wr_addr(wr_addr_s);
// ...
return 0;
}