Get Ready for SystemVerilog 2012
The latest revision of the IEEE 1800-2012 SystemVerilog Language Reference Manual (LRM) is about to hit the press; though I doubt people will be printing the 1300+ pages on their own from the soon to be readily available online version. Here’s a little background into what’s in all those pages.
The first SystemVerilog LRM came from Accellera in 2002 as a set of extensions to the IEEE 1364-2001 LRM. This first LRM was called version 3.0 because it was considered the third generation of Verilog. Accellera released a few more versions and turned version 3.1a over to the IEEE in 2004. The IEEE released the 1800-2005 SystemVerilog LRM as a set of extensions to the 1364-2005 Verilog LRM, which became the last revision of the 1364 LRM. Four years later, the IEEE combined the SystemVerilog extensions with the Verilog LRM producing a single 1800-2009 SystemVerilog LRM.
Now, a short three years later, the SystemVerilog IEEE 1800-2012 LRM is ready having addressed 225 issues. The majority of these issues are clarifications and corrections to the existing LRM. However, a few enhancements ranging from the simple removal of the restriction on non-blocking assignments to class members to the major addition of multiple class interface inheritance made their way into the new LRM. A number of those enhancements will undoubtedly be presented at the upcoming Design & Verification Conference.
I’d like to demonstrate two enhancements that should be of value to most verification engineers. They address two of the more commonly asked SystemVerilog questions I receive: How do I generate an array of unique values? and How to I create covergroup bins to get toggle or one-hot functional coverage?
Generating unique array of random values
Many verification scenarios require creating sets of random instructions or addresses with no repeating values, usually represented as elements in a dynamic array. Earlier versions of SystemVerilog required you to use either nested foreach loops to constrain all combinations of array elements so that they would not be equal to each other. Or else repeatedly randomize one element at a time, and then constraining the next element to not be in the list of already generated values.
The new unique constraint lets you use one statement to constrain a set of variables or array elements to have unique values. When randomized, this class generates a set of ten unique values from 0 to 15.
You can also add other non-random variables to the set of unique values which has the effect of excluding the values of those variables from the set of unique values. When randomized, this class generates a set of ten unique values excluding the values 0, 7 and 15.
Complex coverpoint bin expressions
The previous SystemVerilog syntax for specifying functional coverage bins was very limiting. Unless you could explicitly state the individual bin values or range of bin values in your coverpoint definition, or could figure out a way to instantiate multiple copies of your covergroup passing in a different bin value as an argument, you were out of luck. This also made defining coverage crosses extremely difficult.
The new SystemVerilog bin syntax lets you specify a bin expression that is evaluated over the range of possible values of the coverpoint expression. The bin expression acts like a constraint, and the set of coverpoint values where the bin expression is true become the set of bins. The coverpoint below generates as set of bin values between 0 and 127 that are divisible by 3. The range is 0 to 127 because sbyte is a 7 bit variable.
Probably the most powerful feature is the coverpoint bin set that simply allows you to define an array of values that you want as bins. This is useful for specifying one-hot encodings, toggle coverage of a register, or any complex algorithm that can generate the set of bin values you want. The code below builds a list of onehot values in the encodings array, and then constructs the protocol_cg covergroup using the array as a set of bin values.
Available in the latest version of Questa
By the way, every feature discussed in this post is available in the latest version of Questa, 10.2.
Posted February 7th, 2013, by Dave Rich
- Loading tweets...
- Loading tweets...
- Loading tweets...
- Mentor Enterprise Verification Platform Debuts
- New Verification Academy ABV Course
- DVCon 2014 Issue of Verification Horizons Now Available
- DVCon–The FREE Side
- More DVCon–More Mentor Tutorials!
- UVM 1.2: Open Public Review
- DVCon 2014: Standards on Display
- Just because FPGAs are programmable doesn’t mean verification is dead
- Managing Verification Coverage Information
- Epilogue: The 2012 Wilson Research Group Functional Verification Study
- April 2014 (1)
- March 2014 (2)
- February 2014 (5)
- January 2014 (1)
- November 2013 (2)
- October 2013 (3)
- September 2013 (2)
- August 2013 (4)
- July 2013 (6)
- Part 7: The 2012 Wilson Research Group Functional Verification Study
- Walking in the Desert or Drinking from a Fire Hose?
- Part 6: The 2012 Wilson Research Group Functional Verification Study
- A Short Class on SystemVerilog Classes
- Part 5: The 2012 Wilson Research Group Functional Verification Study
- Part 4: The 2012 Wilson Research Group Functional Verification Study
- June 2013 (2)
- May 2013 (4)
- April 2013 (2)
- March 2013 (2)
- February 2013 (5)
- January 2013 (1)
- December 2012 (1)
- November 2012 (1)
- October 2012 (4)
- September 2012 (1)
- August 2012 (1)
- July 2012 (6)
- June 2012 (1)
- May 2012 (3)
- March 2012 (1)
- February 2012 (6)
- January 2012 (2)
- December 2011 (2)
- November 2011 (2)
- October 2011 (3)
- September 2011 (1)
- July 2011 (3)
- June 2011 (6)
- Intelligent Testbench Automation Delivers 10X to 100X Faster Functional Verification
- Part 9: The 2010 Wilson Research Group Functional Verification Study
- Verification Horizons DAC Issue Now Available Online
- Accellera & OSCI Unite
- The IEEE’s Most Popular EDA Standards
- UVM Register Kit Available for OVM 2.1.2
- May 2011 (2)
- April 2011 (7)
- User-2-User’s Functional Verification Track
- Part 7: The 2010 Wilson Research Group Functional Verification Study
- Part 6: The 2010 Wilson Research Group Functional Verification Study
- SystemC Day 2011 Videos Available Now
- Part 5: The 2010 Wilson Research Group Functional Verification Study
- Part 4: The 2010 Wilson Research Group Functional Verification Study
- Part 3: The 2010 Wilson Research Group Functional Verification Study
- March 2011 (5)
- February 2011 (4)
- January 2011 (1)
- December 2010 (2)
- October 2010 (3)
- September 2010 (4)
- August 2010 (1)
- July 2010 (3)
- June 2010 (9)
- The reports of OVM’s death are greatly exaggerated (with apologies to Mark Twain)
- New Verification Academy Advanced OVM (&UVM) Module
- OVM/UVM @DAC: The Dog That Didn’t Bark
- DAC: Day 1; An Ode to an Old Friend
- UVM: Joint Statement Issued by Mentor, Cadence & Synopsys
- Static Verification
- OVM/UVM at DAC 2010
- DAC Panel: Bridging Pre-Silicon Verification and Post-Silicon Validation
- Accellera’s DAC Breakfast & Panel Discussion
- May 2010 (9)
- Easier UVM Testbench Construction – UVM Sequence Layering
- North American SystemC User Group (NASCUG) Meeting at DAC
- An Extension to UVM: The UVM Container
- UVM Register Package 2.0 Available for Download
- Accellera’s OVM: Omnimodus Verification Methodology
- High-Level Design Validation and Test (HLDVT) 2010
- New OVM Sequence Layering Package – For Easier Tests
- OVM 2.0 Register Package Released
- OVM Extensions for Testbench Reuse
- April 2010 (6)
- SystemC Day Videos from DVCon Available Now
- On Committees and Motivations
- The Final Signatures (the meeting during the meeting)
- UVM Adoption: Go Native-UVM or use OVM Compatibility Kit?
- UVM-EA (Early Adopter) Starter Kit Available for Download
- Accellera Adopts OVM 2.1.1 for its Universal Verification Methodology (UVM)
- March 2010 (4)
- February 2010 (5)
- January 2010 (5)
- December 2009 (15)
- A Cliffhanger ABV Seminar, Jan 19, Santa Clara, CA
- Truth in Labeling: VMM2.0
- IEEE Std. 1800™-2009 (SystemVerilog) Ready for Purchase & Download
- December Verification Horizons Issue Out
- Evolution is a tinkerer
- It Is Better to Give than It Is to Receive
- Zombie Alert! (Can the CEDA DTC “User Voice” Be Heard When They Won’t Let You Listen)
- DVCon is Just Around the Corner
- The “Standards Corner” Becomes a Blog
- I Am Honored to Honor
- IEEE Standards Association Awards Ceremony
- ABV and being from Missouri…
- Time hogs, blogs, and evolving underdogs…
- Full House – and this is no gamble!
- Welcome to the Verification Horizons Blog!
- September 2009 (2)
- July 2009 (1)
- May 2009 (1)