Aldec Verification Seminar SeriesMay 12, 2007

Object Oriented ProgrammingDemystified

Mike MintzCo-authorHardware Verification with C++,Hardware Verification with SystemVerilogmike@trusster.com

mfm, www.trusster.com, OOP Lessons Learned, October 20062

Overview

• Common Currency• Data Abstraction• Virtual Functions• Base Classes• Q&A

mfm, www.trusster.com, OOP Lessons Learned, October 20063

Common Currency

generator checker

monitordriver

DUT

“There is nothing new under the sun.”

mfm, www.trusster.com, OOP Lessons Learned, October 20064

Data Abstraction

• Procedural code has separate data structures and functions

• OOP moves the functions into the data structure• Every possible function for that structure is now

in one place.• This works well for a driver.

mfm, www.trusster.com, OOP Lessons Learned, October 20065

Data Abstraction –Code details

void send_packet (int type, int* data, int length);

struct usb_driver {

void init ();

void enumerate ();

void usb_send_packet (usb_driver * d, int type, int* data, int length);

struct usb_driver {wire d_plus, d_minus;}

void usb_init (usb_driver * d);

void usb_enumerate (usb_driver * d); };

Procedural: Data Abstraction:

wire d_plus, d_minus;

begin usb_driver driver;usb_init (&driver);usb_enumerate (&driver);usb_send (&driver, 0, {0,12}, 2);

end

begin usb_driver driver;driver. init ();driver.enumerate ();driver.send (0, {0,12}, 2);

end

mfm, www.trusster.com, OOP Lessons Learned, October 20066

Virtual Functions• Is a run-time function call• Separates “when to do” from “what to do” • Great for separating concerns (and increasing

portability)• This works well for a monitor.

mfm, www.trusster.com, OOP Lessons Learned, October 20067

Virtual Functions

virtual void packet_completed (int length, int* data) =0;

struct usb_monitor {

void start_monitor_thread ();

};

Monitor class: Derived for printing:virtual void packet_completed (int length, int* data) { for (int i(0); I < length; ++i) { printf (“Packet [%d] : 0x%x\n”, I, data[i]); }}

struct usb_monitor_printer : public usb_monitor {

};

wire d_plus, d_minus;

Derived for Checker:virtual void packet_completed (int length, int* data) { checker_->ckeck (length, data);}

struct usb_monitor_checker : public usb_monitor {

};

Derived for channel:

virtual void packet_completed (int length, int* data) { channel_->put (data_packet (length, data));}

struct usb_monitor_agent : public usb_monitor {

};

mfm, www.trusster.com, OOP Lessons Learned, October 20068

Base Classes• A class with one or more virtual methods• Separates “what to do” from “who does it” • Sets up a framework or interface• This works well for a test irritator.

mfm, www.trusster.com, OOP Lessons Learned, October 20069

Base ClassesCode Details

virtual void wait_for_completion () =0;

struct irritator {

virtual void start () =0;

};

Irritator class: Derived for usb:struct usb_irritator : public irritator {

};

virtual void out_of_reset () =0;

Derived for pcie:struct pcie_irritatpr : public irritator {

};

Derived for ethernet:struct ethernet_irritator : public irritator {

};

virtual void start () =0;

virtual void start ();

virtual void out_of_reset ();

virtual void start () ;

virtual void wait_for_completion ();

virtual void start ();

virtual void out_of_reset ();

virtual void start () ;

virtual void wait_for_completion ();

virtual void start ();

virtual void out_of_reset ();

virtual void start () ;

virtual void wait_for_completion ();

mfm, www.trusster.com, OOP Lessons Learned, October 200610

Summary

• OOP is a little bit syntax and a large amount of attitude

• Learning OOP is gradual process, making mistakes is in integral part

• Its not really that different, just different packaging

• See www.trusster.com for forums, articles, etc.