Array Constraints

SystemVerilog
1

HI,
I have a fixed array of size 32.
I need to write a constraint such that maximum of 4 values can overlap and minimum of 2 values should overlap.
Could anyone help.

Thanks,
Vdas

2

Same approach can be used for minimum.

3

HI Dave,
Thanks Dave that helps.
I need help for writing one more constraint.
I have a region where start and size can be configured. there are 8 such regions with respective start and size.
Example: if start_0 = 10 & size_0 = 10, then region 0 is from 10 to 20. Likewise for other regions.
Here the constraint is 2 regions can overlap like below
start_0 = 10 & size_0 = 10; (region 0 from 10 to 20)
start_1 = 15 & size_1 = 10; (region 1 from 15 to 25)
Could you pls help

4

It would help if you made an attempt at the code and showed us what data structures you need. There is nothing random in what you just described.

5

HI Dave
I apologize for providing bits and piece of information. Just made an attempt.

class C;
  rand int unsigned start[8];
  rand int unsigned size[8];
  
  constraint c_start { foreach(start[i]) start[i] <= 1000;}
  constraint c_size { foreach(size[i]) size[i] <= 100;}
  constraint c_overlap {foreach(start[i]) !(start[i+1] inside {(start[i] + size[i])}); }
endclass
module  test() ;
C c_reg ;
initial begin
    c_reg = new() ;
    c_reg.randomize() ;
  foreach ( c_reg.start[i] )
    $display(" start[%0d] = %0d, size[%0d]=%0d", i, c_reg.start[i], i, c_reg.size[i]) ;
end
endmodule

Here i want only 2 regions to overlap out of 8.
start[3] = 10 & size[3] = 10; (region 3 starts from 10 ends at 20)
start[5] = 15 & size[5] = 20; (region 5 starts from 15 ends at 35)
15 to 20 got overlapped b/w region 3 & 5.

6 
class C;
  rand int unsigned start[8];
  rand int unsigned size[8];
  rand bit overlap[8];
  constraint c_start { foreach(start[i]) start[i] <= 1000;}
  constraint c_size  { foreach(size[i] ) size[i]  <= 100;}
  constraint c_overlap {foreach(overlap[i]) 
    overlap[i] == (start.or(r) with (r.index == i ? 0 : (start[i] inside {[r:r+size[r.index]]})));
                        overlap.sum() with (int'(item)) ==4; // each overlap gets counted twice
                       }
                   
endclass
module  test() ;
C c_reg ;
initial begin
    c_reg = new() ;
  assert(c_reg.randomize());
  c_reg.size.sort() with (c_reg.start[item.index]);

  c_reg.start.sort;
  foreach ( c_reg.start[i] )
    $display(" start[%0d] = %3d, size[%0d]=%3d end %3d", i, c_reg.start[i], i, c_reg.size[i], c_reg.start[i]+c_reg.size[i] ) ;
end
endmodule