Date: Mon Oct 16 2006 - 14:54:52 PDT
Hi John, I was digging into pipes some more and noticed that the original Pipes proposal stated that the Pipe ID was a "unique intra-module pipe identifier", meaning that the pipe could only be used within a single scope (cannot be shared). The recent version of Pipes using interfaces does not have the restriction of only calling the pipe from the parent scope. In a SystemVerilog compliant simulator, I can instantiate a pipe in a parent module and pass the interface to its children as well as its grandchildren, and so on. Was this intended? I can imagine that this can make the pipes implementation more complex (but not impossible). Attached is a small example that should work in any SystemVerilog simulator to illustrate the pipe instance 'top.pipe0' is shared among scopes: 'top', 'top.c1', 'top.c2', 'top.c1.c1', 'top.c2.c1'. You can compile scemi_pipe.sv and example.sv and elaborate 'top'. Please let me know if this is the desired behavior for pipes, otherwise we should discuss how to get the desired behavior at our next meeting. See below for simulator output of this test case: 0 top.c1 sending 1 0 send called (top.pipe0.send.send_body) 0 top.pipe0.send.send_body.unmblk1.send_for_loop.buffer[0] = 1 0 send buffer addr 0 0 top.c1.c1 sending 100 0 send called (top.pipe0.send.send_body) 0 top.pipe0.send.send_body.unmblk1.send_for_loop.buffer[1] = 100 0 send buffer addr 1 0 top.c2 sending 1 0 send called (top.pipe0.send.send_body) 0 top.pipe0.send.send_body.unmblk1.send_for_loop.buffer[2] = 1 0 send buffer addr 2 0 top.c2.c1 sending 100 0 send called (top.pipe0.send.send_body) 0 top.pipe0.send.send_body.unmblk1.send_for_loop.buffer[3] = 100 0 send buffer addr 3 5 top.c1 sending 2 5 send called (top.pipe0.send.send_body) 5 top.pipe0.send.send_body.unmblk1.send_for_loop.buffer[4] = 2 5 send buffer addr 4 5 top.c1.c1 sending 99 5 send called (top.pipe0.send.send_body) 5 top.pipe0.send.send_body.unmblk1.send_for_loop.buffer[5] = 99 5 send buffer addr 5 5 top.c2 sending 2 5 send called (top.pipe0.send.send_body) 5 top.pipe0.send.send_body.unmblk1.send_for_loop.buffer[6] = 2 5 send buffer addr 6 5 top.c2.c1 sending 99 5 send called (top.pipe0.send.send_body) 5 top.pipe0.send.send_body.unmblk1.send_for_loop.buffer[7] = 99 5 send buffer addr 7 Regards, Jason Jason Rothfuss Verification Acceleration R&D Cadence Design Systems, Inc. 54 Columbia Irvine, CA 92612 Office: +1 (408) 944-7180 Mobile: +1 (310) 210-2754 rothfuss@cadence.com www.cadence.com <http://www.cadence.com>
- application/x-compressed attachment: pipe_intf_example.tgz