Testbench or Verification Environment is used to check the functional correctness of the Design Under Test (DUT) by generating and driving a predefined input sequence to a design, capturing the design output and comparing with-respect-to expected output.
Verification environment is a group of class’s performing specific operation. i.e, generating stimulus, driving, monitoring, etc. and those classes will be named based on the operation
TestBench Components
Name
Type
Description
transaction
class
Defines the pin level activity generated by agent (to drive to DUT through the driver) or the activity has to be observed by agent (Placeholder for the activity monitored by the monitor on DUT signals)
generator
class
Generates the stimulus (create and randomize the transaction class) and send it to Driver
driver
class
Receives the stimulus (transaction) from a generator and drives the packet level data inside the transaction into pin level (to DUT
monitor
class
Observes pin level activity on interface signals and converts into packet level which is sent to the components such as scoreboard
agent
class
An agent is a container class, which groups the class’s (generator, driver, and monitor) specific to an interface or protocol
scoreboard
class
Receives data items from monitors and compares them with expected values.
Expected values can be either golden reference values or generated from the reference model
environment
class
The environment is a container class for grouping higher level components like agent’s and scoreboard
test
program
The test is responsible for,
Configuring the testbench
Initiate the testbench components construction process
Initiate the stimulus driving
testbench_top
class
This is the topmost file, which connects the DUT and TestBench. It consists of DUT, Test and interface instances, the interface connects the DUT and TestBench
A multidimensional array is an array containing one or more arrays.
Multidimensional arrays can be of more than two levels deep. However, arrays more than three levels deep are hard to manage.
Number of indices required to access an array element differs on array dimension,
Two indices are required to access a two-dimensional array element
Three indices are required to access a three-dimensional array element
Multidimensional Dynamic array
SystemVerilog dynamic array can be,
regular array
irregular array
regular array
A regular array is a multidimensional array with member arrays of the same sizes.
for example,
2-D array with the number of columns same for all the rows
In below 3 x 2 array diagram,
All the 3 rows have 2 columns.
SystemVerilog regular array
Irregular array
An irregular array is a multidimensional array with member arrays of different sizes.
for example,
2-D array with the number of columns different for the rows
In below array with 3 rows,
row 1, 2 and 3 have 2, 1 and 3 columns respectively.
SystemVerilog irregular array
2-Dimensional dynamic array example
Regular array
Below is a 3×2 2D dynamic array example.
In example shows the array declaration, creation, assignment and displaying the array elements.
SystemVerilog 2D Dynamic array
program dynamic_array;
//dynamic array declaration
bit [7:0] d_array[][];
initial begin
//memory allocation
d_array = new[3];
foreach(d_array[i])
d_array[i] = new[2];
//assigning random value to elements
foreach(d_array[i,j]) d_array[i][j] = $random;
//displaying array elements
foreach(d_array[i,j])
$display("\td_aaray[%0d,%0d] = %0d",i,j, d_array[i][j]);
end
endprogram
Below is a 2D irregular dynamic array example.
In example shows the array declaration, creation, assignment and displaying the array elements.
SystemVerilog 2d irregular array
program dynamic_array;
//dynamic array declaration
bit [7:0] d_array[][];
initial begin
//memory allocation
d_array = new[3];
d_array[0] = new[2];
d_array[1] = new[1];
d_array[2] = new[4];
//assigning random value to elements
foreach(d_array[i,j]) d_array[i][j] = $random;
//displaying array elements
foreach(d_array[i,j])
$display("\td_aaray[%0d,%0d] = %0d",i,j, d_array[i][j]);
end
endprogram
Below is a 2x2x4 3D dynamic array example.
In example shows the array declaration, creation, assignment and displaying the array elements.
SystemVerilog 3d dynamic array
program dynamic_array;
//dynamic array declaration
bit [7:0] d_array[][][];
initial begin
//memory allocation
d_array = new[2];
foreach(d_array[i]) begin //{
d_array[i] = new[2];
foreach(d_array[i,j]) begin //{
d_array[i][j] = new[4];
end //}
end //}
//assigning random value to elements
foreach(d_array[i,j,k]) d_array[i][j][k] = $random;
//displaying array elements
foreach(d_array[i,j,k])
$display("\td_aaray[%0d,%0d,%0d] = %0d",i,j,k,d_array[i][j][k]);
end
endprogram
Most of the array usage application needs randomization of an array. randomization is possible for array size as well as for array elements.
constrained randomization of array
It is possible to get the specific value on randomization, this can be achieved by writing/specifying the constraints.
During randomization, constraints of size are solved first, and then the elements constraints.
Array randomization is applicable to all the array types, The below section describes examples on array randomization and using array methods in constrained randomization.
In a fixed size array, randomization is possible only for the array elements. as the size is fixed, it is not possible to change.
Generating random value for array elements.
In the below example, random values will be generated for array elements.
Declare array as rand
On randomization, the array will get random values
class fs_array;
rand bit [3:0] array1[4];
rand bit [7:0] array2[6];
function void display();
$display("array1 = %p",array1);
$display("array2 = %p",array2);
endfunction
endclass
program fixedsize_array_randomization;
fs_array pkt;
initial begin
pkt = new();
pkt.randomize();
pkt.display();
end
endprogram
In the above example, we have seen randomization with random values. The below example shows the randomization with unique values by using the shuffle array method.
Constrain array with element value same as an index value
In post randomization shuffle the array, so that array will not have incremental value.
class fs_array;
rand bit [7:0] array1[6];
constraint array_c { foreach(array1[i]) array1[i] == i;}
function void post_randomize();
array1.shuffle();
endfunction
function void display();
$display("array1 = %p",array1);
endfunction
endclass
program fixedsize_array_randomization;
fs_array pkt;
initial begin
pkt = new();
pkt.randomize();
pkt.display();
end
endprogram
In the previous example, only the sum of array elements is considered, array elements can take any value. But in the below example array sum and also the value of each element is constrained.
declare an array with rand
Constraint sum of an array using the array method sum().
Constraint array elements value.
class fs_array;
rand bit [7:0] array1[6];
constraint array_c { array1.sum() == 30;}
constraint array_c_e { foreach(array1[i]) array1[i] > 2;}
function void display();
$display("array1 = %p",array1);
endfunction
endclass
program fixedsize_array_randomization;
fs_array pkt;
initial begin
pkt = new();
pkt.randomize();
pkt.display();
end
endprogram
As associative array stores entries in the sparse matrix, there is no meaning of randomizing array size. It is good to have randomization only for associative array elements.
There are no many use cases in randomizing associative array. Only to look array operations below example’s shows the possibility to randomize associative array size and elements.
randomize associative array size
In below example, associative array size will get randomized based on size constraint, and array elements will get random values
Declare array with rand
On randomization, the array will get random values
class assoc_array;
rand bit [7:0] array[*];
constraint size_c { array.size() inside {[4:10]}; }
function void display();
$display("array size is = %0d",array.size());
$display("array = %p",array);
endfunction
endclass
program assoc_array_randomization;
assoc_array pkt;
initial begin
pkt = new();
pkt.randomize();
pkt.display();
end
endprogram
Slice is a selection of one or more contiguous elements of an array, whereas part select is a selection of one or more contiguous bits of an element.
what is the difference between an array slice and part select?
As mentioned above part select operates on bits of an element, whereas slice operates on elements of an array. Part select and Slice is explained below.
array part select
SystemVerilog uses the term part select to refer to a selection of one or more contiguous bits of a single dimension packed array.
bit [31:0] data;
bit [07:0] byte[4];
byte[0] = data[07:0];
byte[1] = data[15:8];
byte[2] = data[23:16];
byte[3] = data[31:24];
The above example refers to copying 32-bit data to a byte array. this is done with the part selection of data variables.
program array_slice;
bit [31:0] data;
byte byte_data[4];
initial begin
std::randomize(data);
$display("Value of data is %h",data);
$display("Before the assignment,");
foreach(byte_data[i])
$display("\t byte_data[%0d] = %h",i,byte_data[i]);
byte_data[0] = data[07:0];
byte_data[1] = data[15:8];
byte_data[2] = data[23:16];
byte_data[3] = data[31:24];
$display("After the array part select,");
foreach(byte_data[i])
$display("\t byte_data[%0d] = %h",i,byte_data[i]);
end
endprogram
Simulator Output
Values of data is 05e23536
Before the assignement,
byte_data[0] = 00
byte_data[1] = 00
byte_data[2] = 00
byte_data[3] = 00
After the array part select,
byte_data[0] = 36
byte_data[1] = 35
byte_data[2] = e2
byte_data[3] = 05
SystemVerilog uses the term slice to refer to a selection of one or more contiguous elements of an array.
bit [31:0] packet_type_A [7:0]; //array of 8 elements of width 32bit
bit [31:0] packet_type_B [1:0]; //array of 2 elements of width 32bit
packet_type_B = packet_type_A[5:4]; //assigning 2 elements of array packet_type_A to packet_type_B
program array_slice;
bit [31:0] packet_type_A [7:0];
bit [31:0] packet_type_B [1:0];
initial begin
std::randomize(packet_type_A);
$display("Value of packet_type_A are %p",packet_type_A);
$display("Before the array part select,");
$display("\tValues of packet_type_B are %p",packet_type_B);
packet_type_B = packet_type_A[5:4];
$display("After the array part select,");
$display("\tValues of packet_type_B are %p",packet_type_B);
end
endprogram
Simulator Output
Before the array part select,
Values of packet_type_B are '{'h0, 'h0}
After the array part select,
Values of packet_type_B are '{'hbe7fe77d, 'h30aa33e2}
program array_slice;
bit [31:0] data;
byte byte_data[4];
initial begin
std::randomize(data);
$display("Value of data is %h",data);
$display("Before the assignement,");
foreach(byte_data[i])
$display("\t byte_data[%0d] = %h",i,byte_data[i]);
foreach(byte_data[i]) byte_data[i] = data[8*i +: 8];
$display("After the array part select,");
foreach(byte_data[i])
$display("\t byte_data[%0d] = %h",i,byte_data[i]);
end
endprogram
Simulator Output
Value of data is 05e23536
Before the assignement,
byte_data[0] = 00
byte_data[1] = 00
byte_data[2] = 00
byte_data[3] = 00
After the array part select,
byte_data[0] = 36
byte_data[1] = 35
byte_data[2] = e2
byte_data[i3] = 05
program array_slice;
bit [31:0] data;
byte byte_data[4];
initial begin
std::randomize(data);
$display("Value of data is %h",data);
$display("Before the assignement,");
foreach(byte_data[i])
$display("\t byte_data[%0d] = %h",i,byte_data[i]);
foreach(byte_data[i]) byte_data[i] = data[(8*(i+1))-1 -: 8];
$display("After the array part select,");
foreach(byte_data[i])
$display("\t byte_data[%0d] = %h",i,byte_data[i]);
end
endprogram
Simulator Output
Value of data is 05e23536
Before the assignement,
byte_data[0] = 00
byte_data[1] = 00
byte_data[2] = 00
byte_data[3] = 00
After the array part select,
byte_data[0] = 36
byte_data[1] = 35
byte_data[2] = e2
byte_data[i3] = 05
Methods discussed before works on an index or an element, but Array iterator index querying methods shall operate on both index and element.
Find array element with index example
Below example shows two types of conditions,
array_1.find with ( item == item.index );
returns the array element whose value is equal to the index value.
array_1.find(item) with ( item > item.index);
returns the array element whose value is greater than the index value.
module fixedsize_array;
//declaration of array’s
int array_1[6],array_2[6];
int temp_qu[$],temp_cnt,temp_value;
initial begin
//array initialization
array_1 = '{10,20,2,40,67,5};
array_2 = '{80,4,2,40,67,5};
//Type-1
temp_qu = array_1.find with ( item == item.index );
temp_cnt = temp_qu.size();
$display("Index and Elments are same for %0d index's.",temp_cnt);
for(int i=0;i<temp_cnt;i++) begin //{
temp_value = temp_qu.pop_front();
$display("\tsame for value %0d",temp_value);
end //}
//Type-2
temp_qu = array_1.find(item) with ( item > item.index);
temp_cnt = temp_qu.size();
$display("Index and Elments conndition satisfied for %0d index's.",temp_cnt);
for(int i=0;i<temp_cnt;i++) begin //{
temp_value = temp_qu.pop_front();
$display("\tfor value %0d",temp_value);
end //}
end
endmodule
Simulator Output
Index and Elments are same for 2 index's.
same for value 2
same for value 5
Index and Elments conndition satisfied for 4 index's.
for value 10
for value 20
for value 40
for value 67
On calling xor() method, logical xor (^) will be performed on all the array elements and returned.
Let’s consider an example of an array with 2, 3 and 4 elements.
sim
Before looking into examples, see to the Truth table for OR.
A
B
Y = A ^ B
0
0
0
0
1
1
1
0
1
1
1
0
1. Array with 2 elements.
Consider A=2 and B=3.
Y = A ^ B;
Binary
Decimal
A
0010
2
B
0011
3
Y = A ^ B
0001
1
Consider A=2 and B=1.
Y = A ^ B;
Binary
Decimal
A
0010
2
B
0001
1
Y = A ^ B
0011
3
2. Array with 3 elements.
Consider A=10, B=9, and C=8.
OR operation of 3 elements performed in 2 steps, In the first step A ^ B will be performed. In the second step result of the first step ^ C will be done. Considering X as the first step result.
X = A ^ B;
Y = X ^ C;
Binary
Decimal
A
1010
10
B
1001
9
X = A ^ B
0011
3
C
1000
8
Y = X ^ C
1011
11
2. Array with 4 elements.
Consider A=3, B=5, C=7, and D=9.
Consider X and Y as intermediate results.
X = A ^ B;
Y = X ^ C;
Z = Y ^ D;
Binary
Decimal
A
0011
3
B
0101
5
X = A ^ B
0110
6
C
0111
7
Y = X ^ C
0001
1
D
1001
9
Z = Y ^ D
1000
8
Complete code with above examples.
module fixedsize_array;
//declaration of array’s
int array_1[2];
int array_2[2];
int array_3[3];
int array_4[4];
int l_xor;
initial begin
//array initialization
array_1 = '{2,3};
array_2 = '{2,1};
array_3 = '{10,9,8};
array_4 = '{3,5,7,9};
l_xor = array_1.xor();
$display("Logical XOR of array_1 is \t%0d",l_xor);
l_xor = array_2.xor();
$display("Logical XOR of array_2 is \t%0d",l_xor);
l_xor = array_3.xor();
$display("Logical XOR of array_3 is \t%0d",l_xor);
l_xor = array_4.xor();
$display("Logical XOR of array_4 is \t%0d",l_xor);
end
endmodule
Simulator Output
Logical XOR of array_1 is 1
Logical XOR of array_2 is 3
Logical XOR of array_3 is 11
Logical XOR of array_4 is 8
Array reduction methods SUM, PRODUCT using ‘with’ clause
Condition or expression specified within the with clause will be applied to all the array elements during array reduction methods.
array_1 = '{1,2,3,4};
array_1.sum with (item * 2);
the item indicates the array element.
each array element will be multiplied by 2 and then the sum method will be performed.
Intermediate array elements after multiplication with 2 is ‘{2,4,6,12};
sum method will be performed on new array elements. sum = 2+4+6+12;
Below is an example of sum and product methods using with clause.
module fixedsize_array;
//declaration of array’s
int array_1[4];
int t_sum,t_product;
initial begin
//array initialization
array_1 = '{1,2,3,4};
t_sum = array_1.sum with (item * 2);
//t_sum = (1*2)+(2*2)+(3*2)+(4*2) = 2+4+6+8
$display("Sum of array_1 is \t%0d",t_sum);
t_product = array_1.product with (item + 2);
//t_product = (1+2)*(2+2)*(3+2)*(4+2) = 3*4*5*6
$display("product of array_1 is \t%0d",t_product);
end
endmodule
Array reduction methods AND, OR and XOR using ‘with’ clause
The operation of these methods is the same as the above example.
module fixedsize_array;
//declaration of array’s
int array_1[2];
int array_2[2];
int array_3[2];
int b_and,b_or,l_xor;
initial begin
//array initialization
array_1 = '{2,3};
array_2 = '{2,1};
array_3 = '{1,3};
b_and = array_1.and with (item * 2);
$display("Bit-wise AND of array_1 is \t%0d",b_and);
b_or = array_2.or with (item + 3);
$display("Bit-wise OR of array_2 is \t%0d",b_or);
l_xor = array_3.xor with (item * 3);
$display("Logical XOR of array_3 is \t%0d",l_xor);
end
endmodule
Simulator Output
Bit-wise AND of array_1 is 4
Bit-wise OR of array_2 is 5
Logical XOR of array_3 is 10
Array locator methods are useful for finding the index or elements of an array.
operate on any unpacked arrays and queues.
the return type of these methods is a queue.
with an expression, Array elements or indexes can be searched.
Built-in array locator methods can be classified as, element finder and index finder.
element finder methods:
Method
Description
find()
returns all the elements satisfying the given expression
find_first()
returns the first element satisfying the given expression
find_last()
returns the last element satisfying the given expression
min()
returns the element with the minimum value or whose expression evaluates to a minimum
max()
returns the element with the maximum value or whose expression evaluates to a maximum
unique()
returns all elements with unique values or whose expression is unique
index finder methods:
Method
Description
find_index()
returns the indexes of all the elements satisfying the given expression
find_first_index()
returns the index of the first element satisfying the given expression
find_last_index()
returns the index of the last element satisfying the given expression
unique_index()
returns the indexes of all elements with unique values or whose expression is unique
‘with’ clause is optional for min,max,unique and unique_index methods
Array Index Finder methods
Index finder method shall return single or multiple indexes which satisfies the condition.
The condition also shall be single or multiple conditions. multiple conditions can be written on using conditional expressions. example: &&, || etc.
Below example shows the return of single and multiple index return.
class packet;
int a;
int b;
function void display();
$display("\tValue of a = %0d",a);
$display("\tValue of b = %0d",b);
endfunction
endclass
module assoc_array;
//declaration of array
packet assoc_array[*];
packet pkt;
int count,qu[$],tmp_var;
initial begin
pkt = new();
pkt.a = 8;
pkt.b = 3;
assoc_array[2] = pkt;
pkt = new();
pkt.a = 0;
pkt.b = 6;
assoc_array[5] = pkt;
pkt = new();
pkt.a = 2;
pkt.b = 6;
assoc_array[6] = pkt;
pkt = new();
pkt.a = 1;
pkt.b = 6;
assoc_array[9] = pkt;
//----------------------------------------------------------------------------
//------- Find Index Method -------
//----------------------------------------------------------------------------
//Type-1: returning one matching index
qu = assoc_array.find_index with (item.a == 'h2);
count = qu.size();
for(int i=0;i<count;i++) begin //{
tmp_var = qu.pop_front();
$display("Index of Asoc Array for a == 2 is %0d",tmp_var);
end //}
//Type-2: returning mutiple matching index
qu = assoc_array.find_index with (item.b == 6);
count = qu.size();
for(int i=0;i<count;i++) begin //{
tmp_var = qu.pop_front();
$display("Index of Asoc Array for b == 6 is %0d",tmp_var);
end //}
//Type-3: with multiple conditions
qu = assoc_array.find_index with (item.a == 2 && item.b == 6);
count = qu.size();
for(int i=0;i<count;i++) begin //{
tmp_var = qu.pop_front();
$display("Index of Asoc Array for a == 2, b == 6 is %0d",tmp_var);
end //}
//Type-4: with multiple conditions
qu = assoc_array.find_index with (item.a < 2 && item.b > 5);
count = qu.size();
for(int i=0;i<count;i++) begin //{
tmp_var = qu.pop_front();
$display("Index of Asoc Array for a < 2, b > 5 is %0d",tmp_var);
end //}
end
endmodule
Simulator Output
Index of Asoc Array for a == 2 is 6
Index of Asoc Array for b == 6 is 5
Index of Asoc Array for b == 6 is 6
Index of Asoc Array for b == 6 is 9
Index of Asoc Array for a == 2, b == 6 is 6
Index of Asoc Array for a < 2, b > 5 is 5
Index of Asoc Array for a < 2, b > 5 is 9
Array Index Finder methods FIRST_MATCH and LAST_MATCH
class packet;
int a;
int b;
function void display();
$display("\tValue of a = %0d",a);
$display("\tValue of b = %0d",b);
endfunction
endclass
module assoc_array;
//declaration of array
packet assoc_array[*];
packet pkt;
int cnt,qu[$],tmp_var;
initial begin
pkt = new();
pkt.a = 3;
pkt.b = 8;
assoc_array[2] = pkt;
pkt = new();
pkt.a = 8;
pkt.b = 3;
assoc_array[5] = pkt;
pkt = new();
pkt.a = 2;
pkt.b = 6;
assoc_array[6] = pkt;
pkt = new();
pkt.a = 8;
pkt.b = 3;
assoc_array[8] = pkt;
pkt = new();
pkt.a = 8;
pkt.b = 3;
assoc_array[9] = pkt;
//----------------------------------------------------------------------------
//------- Find First/Last Index Method -------
//----------------------------------------------------------------------------
//Type-1: returning first matching index
qu = assoc_array.find_first_index with (item.a == 8);
cnt = qu.size();
for(int i=0;i<cnt;i++) begin //{
tmp_var = qu.pop_front();
$display("First Index of Asoc Array for a == 8 is %0d",tmp_var);
end //}
//Type-2: returning first matching index
qu = assoc_array.find_first_index with (item.a == 8 && item.b == 3);
cnt = qu.size();
for(int i=0;i<cnt;i++) begin //{
tmp_var = qu.pop_front();
$display("First Index of Asoc Array for a == 8, b == 3 is %0d",tmp_var);
end //}
//Type-3: returning last matching index
qu = assoc_array.find_last_index with (item.a == 8 && item.b == 3);
cnt = qu.size();
for(int i=0;i<cnt;i++) begin //{
tmp_var = qu.pop_front();
$display("Last Index of Asoc Array for a == 8, b == 3 is %0d",tmp_var);
end //}
end
endmodule
Simulator Output
First Index of Asoc Array for a == 8 is 5
First Index of Asoc Array for a == 8, b == 3 is 5
Last Index of Asoc Array for a == 8, b == 3 is 9
class packet;
int a;
int b;
function void display();
$display("\tValue of a = %0d",a);
$display("\tValue of b = %0d",b);
endfunction
endclass
module assoc_array;
//declaration of array
packet assoc_array[*];
packet pkt,tmp_var,qu[$];
int cnt;
initial begin
pkt = new();
pkt.a = 8;
pkt.b = 3;
assoc_array[2] = pkt;
pkt = new();
pkt.a = 0;
pkt.b = 6;
assoc_array[5] = pkt;
pkt = new();
pkt.a = 2;
pkt.b = 6;
assoc_array[6] = pkt;
pkt = new();
pkt.a = 1;
pkt.b = 6;
assoc_array[9] = pkt;
//----------------------------------------------------------------------------
//------- Find Element Method -------
//----------------------------------------------------------------------------
//Type-1: returning one matching element
qu = assoc_array.find with (item.a == 'h2);
cnt = qu.size();
$display("Elements of Asoc Array for a == 2 are,");
for(int i=0;i<cnt;i++) begin //{
tmp_var = qu.pop_front();
$display("Element No: %0d",i+1);
tmp_var.display();
end //}
//Type-2: returning mutiple matching element
qu = assoc_array.find with (item.b == 6);
cnt = qu.size();
$display("Elements of Asoc Array for b == 6 are,");
for(int i=0;i<cnt;i++) begin //{
tmp_var = qu.pop_front();
$display("Element No: %0d",i+1);
tmp_var.display();
end //}
//Type-3: with multiple conditions
qu = assoc_array.find with (item.a == 2 && item.b == 6);
cnt = qu.size();
$display("Elements of Asoc Array for a == 2, b == 6,");
for(int i=0;i<cnt;i++) begin //{
tmp_var = qu.pop_front();
$display("Element No: %0d",i+1);
tmp_var.display();
end //}
//Type-4: with multiple conditions
qu = assoc_array.find with (item.a < 2 && item.b > 5);
cnt = qu.size();
$display("Elements of Asoc Array for a < 2, b > 5,");
for(int i=0;i<cnt;i++) begin //{
tmp_var = qu.pop_front();
$display("Element No: %0d",i+1);
tmp_var.display();
end //}
end
endmodule
Simulator Output
Elements of Asoc Array for a == 2 are,
Element No: 1
Value of a = 2
Value of b = 6
Elements of Asoc Array for b == 6 are,
Element No: 1
Value of a = 0
Value of b = 6
Element No: 2
Value of a = 2
Value of b = 6
Element No: 3
Value of a = 1
Value of b = 6
Elements of Asoc Array for a == 2, b == 6,
Element No: 1
Value of a = 2
Value of b = 6
Elements of Asoc Array for a < 2, b > 5,
Element No: 1
Value of a = 0
Value of b = 6
Element No: 2
Value of a = 1
Value of b = 6
Array Element Finder methods FIND_FIRST and FIND_LAST along ‘with’ clause
class packet;
int a;
int b;
function void display();
$display("\tValue of a = %0d",a);
$display("\tValue of b = %0d",b);
endfunction
endclass
module assoc_array;
//declaration of array
packet assoc_array[*];
packet pkt,qu[$],tmp_var;
int cnt;
initial begin
pkt = new();
pkt.a = 3;
pkt.b = 8;
assoc_array[2] = pkt;
pkt = new();
pkt.a = 8;
pkt.b = 3;
assoc_array[5] = pkt;
pkt = new();
pkt.a = 2;
pkt.b = 6;
assoc_array[6] = pkt;
pkt = new();
pkt.a = 8;
pkt.b = 3;
assoc_array[8] = pkt;
pkt = new();
pkt.a = 8;
pkt.b = 3;
assoc_array[9] = pkt;
//----------------------------------------------------------------------------
//------- Find First/Last element Method -------
//----------------------------------------------------------------------------
//Type-1: returning first matching element
qu = assoc_array.find_first with (item.a == 8);
cnt = qu.size();
$display("First Element of Asoc Array for a == 8 are,");
for(int i=0;i<cnt;i++) begin //{
tmp_var = qu.pop_front();
$display("Element No: %0d",i+1);
tmp_var.display();
end //}
//Type-2: returning first matching element
qu = assoc_array.find_first with (item.a == 8 && item.b == 3);
cnt = qu.size();
$display("First Element of Asoc Array for a == 8 , b == 3 are,");
for(int i=0;i<cnt;i++) begin //{
tmp_var = qu.pop_front();
$display("Element No: %0d",i+1);
tmp_var.display();
end //}
//Type-3: returning last matching element
qu = assoc_array.find_last with (item.a == 8 && item.b == 3);
cnt = qu.size();
$display("Last Element of Asoc Array for a == 8 , b == 3 are,");
for(int i=0;i<cnt;i++) begin //{
tmp_var = qu.pop_front();
$display("Element No: %0d",i+1);
tmp_var.display();
end //}
end
endmodule
Simulator Output
First Element of Asoc Array for a == 8 are,
Element No: 1
Value of a = 8
Value of b = 3
First Element of Asoc Array for a == 8 , b == 3 are,
Element No: 1
Value of a = 8
Value of b = 3
Last Element of Asoc Array for a == 8 , b == 3 are,
Element No: 1
Value of a = 8
Value of b = 3
module fixedsize_array;
//declaration of array’s
int array_1[4];
int temp_value[$];
initial begin
//array initialization
array_1 = '{80,20,3,40};
temp_value = array_1.min();
$display("Min value elenent of array_1 is \t%p",temp_value);
temp_value = array_1.max();
$display("Max value elenent of array_1 is \t%p",temp_value);
end
endmodule
Simulator Output
Min value elenent of array_1 is '{3}
Max value elenent of array_1 is '{80}
