Consider an array.
pipe
I am trying to constraint it by using similar to following code.
pipe[i].sum with (item.index < j)
But I keep getting these failures
“This is not a valid built in method name for this object.”
How can I rewrite this. I did not want to do something like below which is hanging my solver. Something inbuilt is helpful
function int sumUntil(row, idx);
for(int i = 0; i < idx; i++) begin
sumUntil += int’(pipe[row][i]);
end
endfunction
In reply to sharatk:
You want to sum only some columns of your 2d array? Something like below? It was straight forward using a helper array, but I’d like to know if there is a single array solution.
module tb;
class twod;
rand bit [7:0] cells[5][5];
rand bit [7:0] trunc[5][5]; // helper array
constraint c {
// constrain the first two columns of cells to add up to 30
foreach ( cells[r,c] ) {
cells[r][c] inside { 5,10,15,20 };
if ( c < 2 )
trunc[r][c] == cells[r][c];
else
trunc[r][c] == 0;
}
foreach ( trunc[r,c] ) {
if ( c == 0 ) {
trunc[r].sum() == 30;
}
}
}
function void show();
$write("trunc\n");
foreach ( trunc[r,c] ) begin
$write( "%3d ", trunc[r][c] );
if ( c == 4 )
$write("\n");
end
$write("cells\n");
foreach ( cells[r,c] ) begin
$write( "%3d ", cells[r][c] );
if ( c == 4 )
$write("\n");
end
endfunction
endclass
initial begin
automatic twod td = new;
$display( "randomize == %0b\n", td.randomize() );
td.show();
end
endmodule
trunc
20 10 0 0 0
10 20 0 0 0
10 20 0 0 0
15 15 0 0 0
20 10 0 0 0
cells
20 10 10 20 20
10 20 15 10 20
10 20 15 20 10
15 15 5 15 15
20 10 5 5 20
In reply to warnerrs:
Thanks for your reply.
I am not trying to sum all the columns. Here is my complete constraint.
constraint constraint_c3_c {
foreach(pipe[i,j]){
foreach(pipe[k,l]){
if(({i,j} != {k,l}) && (pipe[i][j] == pipe[k][l])) {
//if((i+sumUntil(i,j)) >= (k+sumUntil(k,l))) {
// i+sumUntil(i,j) >= (k+sumUntil(k,l))+int'(pipe[i][j]);
//}else {
// i+sumUntil(i,j)+int'(pipe[i][j]) <= (k+sumUntil(k,l));
//}
if(i+pipe[i].sum with (item.index < j) >= (k+pipe[k].sum with (item.index < l))) {
i+pipe[i].sum with (item.index < j) >= k+pipe[k].sum with (item.index < l);
}else {
i+pipe[i].sum with (item.index < j) +int'(pipe[i][j]) <= k+pipe[k].sum with (item.index < l);
}
}
} }
}
Its basically adding a subset of the array together. The solver hangs if I use commented portion instead.
In reply to sharatk:
It might help to show some examples of array values you’re looking to see and explain in words, nut SystemVerilog syntax the requirements that the arrays need to meet.
Also, pipe[i].sum with (item.index < j) just returns j-1; a count of items whose index is less than j. You are probably looking for pipe[i].sum with ((item.index < j) ? item : 0 )
In reply to dave_59:
Hi Dave,
Sorry for being terse on my example.
Adding more details.
rand oper_e pipe[][]; //oper_e is an enum
Complete constraints that refuses to compile is. I corrected it.
constraint constraint_c3_c {
foreach(pipe[i,j]){
foreach(pipe[k,l]){
if(({i,j} != {k,l}) && (pipe[i][j] == pipe[k][l])) {
if(i+pipe[i].sum with ((item.index < j)*item)>= (k+pipe[k].sum with ((item.index < l)*item))) {
i+pipe[i].sum with ((item.index < j)*item)>= k+pipe[k].sum with ((item.index < l)*item);
}else {
i+pipe[i].sum with ((item.index < j)*item) +int'(pipe[i][j]) <= k+pipe[k].sum with ((item.index < l)*item);
}
}
} }
}
Error:
if(i+pipe[i].sum with ((item.index < j)*item)>= (k+pipe[k].sum with ((item.index < l)*item))) {
|
xmvlog: *E,QAANBI (fbPipe.sv,33|53): This is not a valid built in method name for this object. [SystemVerilog].
In reply to sharatk:
It seems that it is a simulator problem,
module sumExpt;
int arr[] = '{1, 2, 3, 4, 5, 6, 7, 8, 9, 3, 3, 3};
initial begin
$display("arr.sum(item) with ((item._index_ < 3) ? item : 0) = %0d", (arr.sum with ((item.index < 3) ? item : 0)));
end
endmodule
Hierarchical name component lookup failed at ‘index’.
In reply to dave_59:
Hi Dave,
So changing my example, is the following supposed to work? I want it to behave the same as my other example above.
module tb;
class twod;
rand bit [7:0] cells[5][5];
constraint c {
// constrain the first two columns of cells to add up to 30
foreach ( cells[r,c] ) {
cells[r][c] inside { 5,10,15,20 };
cells[r].sum() with ( item.index < 2 ? item : 0 ) == 30;
}
}
function void show();
$write("cells\n");
foreach ( cells[r,c] ) begin
$write( "%3d ", cells[r][c] );
if ( c == 4 )
$write("\n");
end
endfunction
endclass
initial begin
automatic twod td = new;
$display( "randomize == %0b\n", td.randomize() );
td.show();
end
endmodule
In reply to dave_59:
Dave,
Thanks for the confirmation.
Doesn’t work on my local simulator though :(
Do you have a better work around to suggest than my previous example? I don’t like solution space partitioning that the function call approach creates.
In reply to dave_59:
Hi Dave ,
I didn’t quite understand the 2nd line of constraint c ::
constraint c {
// constrain the first two columns of cells to add up to 30
foreach ( cells[r,c] ) {
cells[r][c] inside { 5,10,15,20 };
cells[r].sum() with ( item.index < 2 ? item : 0 ) == 30; // How does it work ?
}
}
If ternary condition is false , how is the 0 used ?
In reply to Have_A_Doubt:
It means if the index is less than 2, 0 is used instead of the array element, effectively not contributing to the sum.
In reply to dave_59:
Was trying this at my end in Edaplayground and have been hitting errors. Wanted to know if my logic is wrong.
To start with I want to constraint a 2-D array which has its column values sum up to 30. Here’s my code inside a class -
rand bit [7:0] array[5][5];
constraint c_col_val {
foreach(array[col,row])
array[col].sum() == 30;
};