SystemC Verification Library (SCV)

Introduction to
SystemC Verification Library (SCV)
Anupam Bakshi
Agnisys, Inc.
April 14 th 2013
ISCUG

What does SystemC Verification need?
• Test Generation
– Constrained Random
• Connection to HDL
– At various busses in the test bench
• Functional Coverage
– Scoreboard
2

What SCV provides?
• Test Generation
– Constrained Randomization
– Weighted Randomization
• Connection to HDL
– API for connection to HDL
• Functional Coverage
– Transaction monitoring & recording ability
– But no built-in coverage
– Requires post processing
3

What SCV Provides? (contd.)
• Data Introspection (similar to Verilog PLI but
for C/C++ data structures)
• Randomization and seed management for
reproducibility of simulation runs
• Transaction Monitoring and Recording
• Sparse Array Support
4

How to get started with SCV?
• Download SystemC and SCV : http://www.accellera.org
– Get SystemC lib : systemc-2.3.0.tgz
– Get SCV lib : scv-1.0p2-sysc2.2.12jun06.tgz
• Compile SystemC
• Compile SCV
– On x86_64 linux will need a patch
• http://thawedoutnow.blogspot.tw/2013/02/scv-for-x8664linux-patch.html
• OR use Simulation Vendor Tools
5

Running SCV examples
• Copy Makefile.rules.in to Makefile.rules
– Define variables to point to the SCV and SystemC
include and lib directories
includedir=/home/cae/systemc/systemc-2.3.0/include
libdir=/home/cae/systemc/systemc-2.3.0/lib-linux64
SYSC_INC_PREFIX=$includedir
SYSC_LIB_PREFIX=$libdir
• Ensure LD_LIBRARY_PATH is set for dynamic
libraries
• Patch is required : scv_constraint.h.patch
6

• Key to using SCV
SCV Smart Pointer
• No hassles of memory allocation/de-allocation
• Randomization
• Weighted Randomization
• Constrained Randomization
7

scv_smart_ptr and scv_extensions
scv_smart_ptr
Acts like a pointer to the
scv_extensions object
object
This slide © WHDL (Intro to SystemC Modeling and Verification).
Reproduced with permission.
scv_extensions
object
data_type T
scv_smart_ptr
constructor automatically
creates underlying
scv_extensions object
8

scv_smart_pointer example
scv_smart_pointer sm_int(“sm_int_label”);
sm_int->print();
sm_int->next(); // randomize values
sm_int->keep_out(1, 5);
sm_int->keep_only(-10, 10);
sm_int->write(10);
sm_int->read();
9

Randomization
• Get a new random value set
– Next()
• Initialize the random number generator
– scv_random::set_global_seed(int)
• Pick a different seed each time
– scv_random::pick_random_seed()
• Enable/disable randomization
– enable_randomization()/disable_randomization()
10

• Ranges
– keep_out()
– keep_only()
• Weighted
Distribution
– scv_bag()
Random Distribution
scv_smart_ptr data_p("data");
//create a distribution for generating the state data
//highest probabilty for states 1-4, zero chance for 3
and
//lower probability for 0, 5, and 6.
scv_bag state_dist("state_dist");
state_dist.add(STATE_0, 10);
state_dist.add(STATE_1, 25);
state_dist.add(STATE_2, 25);
state_dist.add(STATE_4, 25);
state_dist.add(STATE_5, 10);
state_dist.add(STATE_6, 5);
//set the distribution for the state variable in data_p
data_p->state.set_mode(state_dist);
11

Constraints
struct addr_constraint : public scv_constraint_base {
//create the objects that will be constrained
scv_smart_ptr row;
scv_smart_ptr col;
SCV_CONSTRAINT_CTOR(addr_constraint) {
//constraint row to be between 10 and 50 exclusive or 200 and 250 inclusive
SCV_CONSTRAINT ( (row() > 10 && row() < 50) ||
(row() >= 200 && row() ( row() - 5) );
SCV_CONSTRAINT ( col() < ( row() + 20) );
}
};
// SCV_SOFT_CONSTRAINT : Only warning, if constraint is not met, no error
12

Constraints (contd.)
scv_random::set_global_seed(1023);
//instantiate a constrained object
addr_constraint addr("addr");
//randomize the object five times and print the values
for(int i=0; i

struct reg1_t {
sc_uint field1;
sc_uint field2;
};
struct reg2_t {
sc_uint f1;
sc_uint f2;
sc_uint f3;
};
struct block_t {
reg1_t reg1;
reg2_t reg2;
};
SCV Register Example
template
class scv_extensions : public
scv_extensions_base {
public:
scv_extensions reg1;
scv_extensions reg2;
SCV_EXTENSIONS_CTOR(block_t) {
SCV_FIELD(reg1);
SCV_FIELD(reg2);
}
};
14

SCV Register Example (contd.)
scv_smart_ptr block_p ("block");
scv_random::set_global_seed(10);
block_p->reg1.field2.keep_only(1, 10);
block_p->next();
block_p->print();
block_p->next();
block_p->print();
15

SCV Register example output
Random value for block:
{
reg1 {
field1:2
field2:5 // Note the value has been constrained
}
reg2 {
f1:3
f2:13
f3:0
}
}
{
reg1 {
field1:3
field2:2
}
reg2 {
f1:0
f2:9
f3:1
}
}
16

Summary
• SCV promotes advanced verification methodology
• Where to go for more info?
– Go to the source : www.accellera.org
– Join the SystemC Verification Working Group (VWG)
• Apparently working on the next release
17

Q/A
18