pkt_switch example suggestions

[XYHZ]

We found several possible problems in the pkt_switch routine under the example folder. Here are my suggestions. First, in the fifo.cpp file, the pkt_out method lacks the logic to reset the "full", which results in no more data being read after the fifo is full. Second, in Line 204, 210, 216 in the switch.cpp file, the judgment condition of R1.free, R2.free, R3.free is wrong, which causes some data packets to be lost too early.

The code is modified as follows:

pkt fifo::pkt_out()
    {
       pkt temp;
       temp = regs[0];
       if (--pntr == 0) empty = true;
       else 
	{ 
            regs[0] = regs[1];
	    regs[1] = regs[2];
	    regs[2] = regs[3];
	    full = false;
        } 
      return(temp);  
    }

/////write the register values to output fifos////////////
	    if ((!R0.free) && (R0.val.dest0) && (!q0_out.full))
	      {
		q0_out.pkt_in(R0.val); 
		R0.val.dest0 = false;
		if (!(R0.val.dest0|R0.val.dest1|R0.val.dest2|R0.val.dest3)) R0.free = true;
	      }

	    if ((!R1.free) && (R1.val.dest1) && (!q1_out.full))
	      {
		q1_out.pkt_in(R1.val);
		R1.val.dest1 = false;
		if (!(R1.val.dest0|R1.val.dest1|R1.val.dest2|R1.val.dest3)) R1.free = true;
	      }
	    if ((!R2.free) && (R2.val.dest2) && (!q2_out.full))
	      {
		q2_out.pkt_in(R2.val);
		R2.val.dest2 = false;
		if (!(R2.val.dest0|R2.val.dest1|R2.val.dest2|R2.val.dest3)) R2.free = true;
	      }
	    if ((!R3.free) && (R3.val.dest3) && (!q3_out.full))
	      {
		q3_out.pkt_in(R3.val);
		R3.val.dest3 = false;
		if (!(R3.val.dest0|R3.val.dest1|R3.val.dest2|R3.val.dest3)) R3.free = true;
	      }

At the same time, I also submitted the modified code on github

[XYHZ]

The version is SystemC 2.3.3 (Includes TLM)

 

[maehne]

Thanks for your suggestions, I reported them to the SystemC Language Working Group.