For example,
module MM;
MM mm[128]();
I want to get mm[i].signle1,i from 0 to 120.
but I cannot use "for", and I do not want to write 120 statments.
what can I do?
You can create a list of ports and you can use a for loop:
signals : list of simple_port of bit is instance;
keep signals.size() == 128;
keep for each (s) in signals {
s.hdl_path() == append("mm[",dec(i),"].signal1");
};
Related
I want to choose index from list, so the element[index] complies my condition.
MyList[index].num==0
I tried the code bellow:
gen DescIdx2Choose keeping {
it < MyList.size();
MyList[it].num==0;//I tried a few way of read_only
};
How can I do it without using all_indices?
Thanks
Since you generating DescIdx2Choose then MyList will be input to the problem.
Therefore,
If seeking for the first index (if exists) then using random generation isn't required. Use the procedural code "first_index" as user3467290 suggested which is much more efficient:
var fidx := MyList.first_index(.num == 0);
if ( fidx != UNDEF ) {
DescIdx2Choose = fidx;
} else {
// error handling
};
If there are multiple indices and it is required to choose a random one, the most efficient way would be using "all_indices" as Thorsten suggested:
gen DescIdx2Choose keeping {
it in read_only( MyList.all_indices(.num == 0) );
};
The reason is the random generator doesn't need to read all possible values of "MyList.num" only a shorter list of valid indices.
This should do it, but MyList must fulfill the condition otherwise you get a contradiction. Pseudo-method first_index() is not bi-directional which is what we need here.
gen DescIdx2Choose keeping {
MyList.first_index(.num == 0) == it;
};
Maybe i missed something in the question, but If you always want the index of the first element that its num == 0, then why use constraints? can assign DescIdx2Choose == MyList.first_index(.num == 0).
To ensure that there is at least one such element, can constrain MyList.has(.num == 0).
Do you have additional constraints on DescIdx2Choose ?
I am trying to use system verilog constraint solver to solve the following problem statement :
We have N balls each with unique weight and these balls need to be distributed into groups , such that weight of each group does not exceed a threshold ( MAX_WEIGHT) .
Now i want to find all such possible solutions . The code I wrote in SV is as follows :
`define NUM_BALLS 5
`define MAX_WEIGHT_BUCKET 100
class weight_distributor;
int ball_weight [`NUM_BALLS];
rand int unsigned solution_array[][];
constraint c_solve_bucket_problem
{
foreach(solution_array[i,j]) {
solution_array[i][j] inside {ball_weight};
//unique{solution_array[i][j]};
foreach(solution_array[ii,jj])
if(!((ii == i) & (j == jj))) solution_array[ii][jj] != solution_array[i][j];
}
foreach(solution_array[i,])
solution_array[i].sum() < `MAX_WEIGHT_BUCKET;
}
function new();
ball_weight = {10,20,30,40,50};
endfunction
function void post_randomize();
foreach(solution_array[i,j])
$display("solution_array[%0d][%0d] = %0d", i,j,solution_array[i][j]);
$display("solution_array size = %0d",solution_array.size);
endfunction
endclass
module top;
weight_distributor weight_distributor_o;
initial begin
weight_distributor_o = new();
void'(weight_distributor_o.randomize());
end
endmodule
The issue i am facing here is that i want the size of both the dimentions of the array to be randomly decided based on the constraint solution_array[i].sum() < `MAX_WEIGHT_BUCKET; . From my understanding of SV constraints i believe that the size of the array will be solved before value assignment to the array .
Moreover i also wanted to know if unique could be used for 2 dimentional dynamic array .
You can't use the random number generator (RNG) to enumerate all possible solutions of your problem. It's not built for this. An RNG can give you one of these solutions with each call to randomize(). It's not guaranteed, though, that it gives you a different solution with each call. Say you have 3 solutions, S0, S1, S2. The solver could give you S1, then S2, then S1 again, then S1, then S0, etc. If you know how many solutions there are, you can stop once you've seen them all. Generally, though, you don't know this beforehand.
What an RNG can do, however, is check whether a solution you provide is correct. If you loop over all possible solutions, you can filter out only the ones that are correct. In your case, you have N balls and up to N groups. You can start out by putting each ball into one group and trying if this is a correct solution. You can then put 2 balls into one group and all the other N - 2 into a groups of one. You can put two other balls into one group and all the others into groups of one. You can start putting 2 balls into one group, 2 other balls into one group and all the other N - 4 into groups of one. You can continue this until you put all N balls into the same group. I'm not really sure how you can easily enumerate all solutions. Combinatorics can help you here. At each step of the way you can check whether a certain ball arrangement satisfies the constraints:
// Array describing an arrangement of balls
// - the first dimension is the group
// - the second dimension is the index within the group
typedef unsigned int unsigned arrangement_t[][];
// Function that gives you the next arrangement to try out
function arrangement_t get_next_arrangement();
// ...
endfunction
arrangement = get_next_arrangement();
if (weight_distributor_o.randomize() with {
solution.size() == arrangement.size();
foreach (solution[i]) {
solution[i].size() == arrangement[i].size();
foreach (solution[i][j])
solution[i][j] == arrangement[i][j];
}
})
all_solutions.push_back(arrangement);
Now, let's look at weight_distributor. I'd recommend you write each requirement in an own constraint as this makes the code much more readable.
You can shorten you uniqueness constraint that you wrote as a double loop to using the unique operator:
class weight_distributor;
// ...
constraint unique_balls {
unique { solution_array };
}
endclass
You already had a constraint that each group can have at most MAX_WEIGHT in it:
class weight_distributor;
// ...
constraint max_weight_per_group {
foreach (solution_array[i])
solution_array[i].sum() < `MAX_WEIGHT_BUCKET;
}
endclass
Because of the way array sizes are solved, it's not possible to write constraints that will ensure that you can compute a valid solution using simple calls randomize(). You don't need this, though, if you want to check whether a solution is valid. This is due to the constraints on array sizes in the between arrangement and solution_array.
Try this.!
class ABC;
rand bit[3:0] md_array [][]; // Multidimansional Arrays with unknown size
constraint c_md_array {
// First assign the size of the first dimension of md_array
md_array.size() == 2;
// Then for each sub-array in the first dimension do the following:
foreach (md_array[i]) {
// Randomize size of the sub-array to a value within the range
md_array[i].size() inside {[1:5]};
// Iterate over the second dimension
foreach (md_array[i][j]) {
// Assign constraints for values to the second dimension
md_array[i][j] inside {[1:10]};
}
}
}
endclass
module tb;
initial begin
ABC abc = new;
abc.randomize();
$display ("md_array = %p", abc.md_array);
end
endmodule
https://www.chipverify.com/systemverilog/systemverilog-foreach-constraint
I am using a collection to represent available trucks in a system. I am using a 1 or 0 for a given index number, using a 1 to say that indexed truck is available. I am then trying to assign that index number to a customer ID. I am trying to randomly select an available truck from those listed as available. I am getting an error saying the left-hand side of an assignment must be a variable and highlighting the portion of the code reading Available_Trucks() = 1. This is the code:
agent.ID = randomWhere(Available_Trucks, Available_Trucks() = 1);
The way you are doing it won't work... randomWhere when applied to a collection of integers, will return the element of the collection (in this case 1 or 0).
So doing
randomWhere(Available_Trucks,at->at==1); //this is the right synthax
will return 1 always since that's the value of the number chosen in the collection. So what you need is to get the index of the number of the collection that is equal to 1. But you will have to create a function to do that yourself... something like this (probably not the best way but it works: agent.ID=getRandomAvailbleTruck(Available_Trucks);
And the function getRandomAvailbleTruck will take as an argument a collection (arrayList probably).. it will return -1 if there is no availble truck
int availableTrucks=count(collection,c->c==1);
if(availableTrucks==0) return -1;
int rand=uniform_discr(1,availableTrucks);
int i=0;
int j=0;
while(i<rand){
if(collection.get(j)==1){
i++;
if(i==rand){
return j;
}
}
j++;
}
return -1;
Now another idea is to instead of using 0 and 1 for the availability, you can use correlative numbers: 1,2,3,4,5 ... etc and use a 0 if it's not available. For instance if truck 3 is not availble, the array will be 1,2,0,4,5 and if it's available it will be 1,2,3,4,5.
In that case you can use
agent.ID=randomTrue(available_trucks,at->at>0);
But you will get an error if there is no available truck, so check that.
Nevertheless, what you are doing is horrible practice... And there is a much easier way to do it if you put the availability in your truck if your truck is an agent...
Then you can just do
Truck truck=randomWhere(trucks,t->t.available==1);
if(truck!=null)
agent.ID=truck.ID;
I have a struct (mystruct_s for example) under which there are several same type structs (packet_s for example) in different hierarchies.
struct packet_s {
size:uint;
active:bool;
};
struct mystruct_s {
// packet struct paths:
// p
// q.p
// w.p
};
I would like to generate an instance of mystruct_s and enforce that the sum of the sizes of all active packets would be less than 1K.
var s : mystruct_s;
gen s keeping {
// it.p.size (if it.p.active) + it.q.p.size (if it.q.p.active) + it.w.p.size (if it.w.p.active) < 1024 ;
};
Is there a simple way to approach this problem?
The straightforward solution would be using ternary and plus to sum the sizes if active :
var s : mystruct_s;
gen s keeping {
(it.p.active ? it.p.size : 0) + (it.q.p.active ? it.q.p.size : 0) + (it.w.p.active ? it.w.p.size : 0) < 1024 ;
};
If you using Specman 14.1 (or above) you can use generative literal list and sum to write the following constraint:
var s : mystruct_s;
gen s keeping {
{it.p; it.q.p; it.w.p}.sum(it.active ? it.size : 0)) < 1024 ;
};
Using generative literal list will also give you better distribution on the sizes.
If you using Specman 14.2 (or above) you can use conditional sum instead of sum with ternary:
var s : mystruct_s;
gen s keeping {
{it.p; it.q.p; it.w.p}.sum(it.size, it.active) < 1024 ;
};
Replace all instances of packet_s with a single list.
Then use list pseudo method .sum constraint
Try (not sure if this will work):
extend my_struct {
keep {p.sizep.active.as_a(bit),w.p.sizew.p.active.as_a(bit),...}.sum(it) < 1024;
}
Keep %{mystruct.p.size, mystruct.q.p, ...}.count(it) < 1K
I created a list of structs and I like to sum the value of a field in each struct that satisfied a specific condition.
For example:
struct packet {
val:int;
cond:bool;
};
l:list of packet;
When I write the following:
keep l.all(it.cond).sum(it.val) == 1000;
I get an error: GEN_NO_GENERATABLE_NOTIF.
When I define a result variable:
sum_val : int;
keep sum_val == 100;
and change the constraint to:
keep l.all(it.cond).sum(it.val) == sum_val;
I get a contradiction!
How do I make it work?
You should use the list pseudo method "sum" and the ternary operation:
keep l.sum(it.cond ? It.val : 0) == 1000
From the question it seems you want to sum some elements in existing list, not generate a new one. In this case, use simply :
var sum : int = l.all(it.cond).sum(it.val);