SystemC 25 Buffer
sc_buffer
is a predefined primitive channel derived from class sc_signal.
It differs from class sc_signal in that a value-changed event is notified whenever the buffer is written rather than only when the value of the signal is changed.
E.g.,
- if current value of a “signal” == 1: write 1 to it won’t trigger value update event.
- if current value of a “buffer” == 1: write 1 to it will trigger value update event.
Code
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// Learn with Examples, 2020, MIT license
#include <systemc>
using namespace sc_core;
SC_MODULE(BUFFER) {
sc_signal<int> s; // declares a signal channel
sc_buffer<int> b; // declares a buffer channel
SC_CTOR(BUFFER) {
SC_THREAD(writer); // writes to both signal and buffer
SC_THREAD(consumer1);
sensitive << s; // triggered by signal
dont_initialize();
SC_THREAD(consumer2);
sensitive << b; // triggered by buffer
dont_initialize();
}
void writer() {
int val = 1; // init value
while (true) {
for (int i = 0; i < 2; ++i) { // write same value to channel twice
s.write(val); // write to signal
b.write(val); // write to buffer
wait(1, SC_SEC); // wait after 1 s
}
val++; // value change
}
}
void consumer1() {
while (true) {
std::cout << sc_time_stamp() << ": consumer1 receives " << s.read() << std::endl;
wait(); // receives from signal
}
}
void consumer2() {
while (true) {
std::cout << sc_time_stamp() << ": consumer2 receives " << b.read() << std::endl;
wait(); // receives from buffer
}
}
};
int sc_main(int, char*[]) {
BUFFER buffer("buffer");
sc_start(4, SC_SEC);
return 0;
}
// Result:
// receives 1 from signal channel once
0 s: consumer1 receives 1
// receives 1 from buffer channel once
0 s: consumer2 receives 1
// receives 1 from buffer channel twice
1 s: consumer2 receives 1
// receives 2 from signal channel once
2 s: consumer1 receives 2
// receives 2 from buffer channel once
2 s: consumer2 receives 2
// receives 2 from buffer channel twice
3 s: consumer2 receives 2