Array manipulation methods
Table of Contents
SystemVerilog Array manipulation methods provide several built-in methods to operate on arrays.
they are,
- Array Ordering methods
- Array Reduction methods
- Array Locator methods
- Array Iterator index querying
Array Ordering methods
- operate on single dimensional arrays or queues.
- these methods useful for reordering the array elements.
built-in array ordering methods are,
| Method | Description |
|---|---|
| reverse() | reverses all the elements of the array(packed or unpacked) |
| sort() | sorts the unpacked array in ascending order |
| rsort() | sorts the unpacked array in descending order |
| shuffle() | randomizes the order of the elements in the array |
โwithโ clause is allowed for sort and rsort methods.
About โwithโ:
expression specified in โwithโ clause will be evaluated for each array element and performs the operation on an array.
As mentioned above, these methods operate on all kinds of array types. below are the examples of using array ordering methods.
Array Ordering methods On Fixed Size Array
Below example is for using reverse, sort, rsort and shuffle method on fixed size array.
module fixedsize_array;
//declaration of arrayโs
int array_1[4];
int array_2[4];
int array_3[4];
int array_4[4];
initial begin
//array initialization
array_1 = '{0,1,2,3};
array_2 = '{2,3,1,0};
array_3 = '{2,3,1,0};
array_4 = '{0,1,2,3};
$display("-======= reverse =======-");
$display("Before:\t %p",array_1);
array_1.reverse();
$display("After :\t %p",array_1);
$display("-=======================-");
$display("\n-======= sort =======-");
$display("Before:\t %p",array_2);
array_2.sort();
$display("After :\t %p",array_2);
$display("-=======================-");
$display("\n-======= rsort =======-");
$display("Before:\t %p",array_3);
array_3.rsort();
$display("After :\t %p",array_3);
$display("-=======================-");
$display("\n-======= shuffle =======-");
$display("Before:\t %p",array_4);
array_4.shuffle();
$display("After :\t %p",array_4);
$display("-=======================-");
end
endmodule
Simulator Output
-======= reverse =======-
Before: '{0, 1, 2, 3}
After : '{3, 2, 1, 0}
-=======================-
-======= sort =======-
Before: '{2, 3, 1, 0}
After : '{0, 1, 2, 3}
-=======================-
-======= rsort =======-
Before: '{2, 3, 1, 0}
After : '{3, 2, 1, 0}
-=======================-
-======= shuffle =======-
Before: '{0, 1, 2, 3}
After : '{2, 3, 1, 0}
-=======================-
Array Ordering methods On Dynamic Array
Below example is for using reverse, sort, rsort and shuffle method on the dynamic array.
module dynamic_size_array;
//declaration of arrayโs
int array_1[];
int array_2[];
int array_3[];
int array_4[];
initial begin
array_1 = new[4];
array_2 = new[4];
array_3 = new[4];
array_4 = new[4];
//array initialization
array_1 = '{0,1,2,3};
array_2 = '{2,3,1,0};
array_3 = '{2,3,1,0};
array_4 = '{0,1,2,3};
$display("-======= reverse =======-");
$display("Before:\t %p",array_1);
array_1.reverse();
$display("After :\t %p",array_1);
$display("-=======================-");
$display("\n-======= sort =======-");
$display("Before:\t %p",array_2);
array_2.sort();
$display("After :\t %p",array_2);
$display("-=======================-");
$display("\n-======= rsort =======-");
$display("Before:\t %p",array_3);
array_3.rsort();
$display("After :\t %p",array_3);
$display("-=======================-");
$display("\n-======= shuffle =======-");
$display("Before:\t %p",array_4);
array_4.shuffle();
$display("After :\t %p",array_4);
$display("-=======================-");
end
endmodule
Simulator Output
-======= reverse =======-
Before: '{0, 1, 2, 3}
After : '{3, 2, 1, 0}
-=======================-
-======= sort =======-
Before: '{2, 3, 1, 0}
After : '{0, 1, 2, 3}
-=======================-
-======= rsort =======-
Before: '{2, 3, 1, 0}
After : '{3, 2, 1, 0}
-=======================-
-======= shuffle =======-
Before: '{0, 1, 2, 3}
After : '{2, 3, 1, 0}
-=======================-
Array Ordering methods On Associative Array
Below example is for using reverse, sort, rsort and shuffle method on the associative array.
Note:
whereas in fixed/dynamic/queue array types index will be incremental but in associative array index shall be random.
In associative array, based on ordering methods elements will be stored to available different index locations.
module assoc_size_array;
//declaration of arrayโs
int array_1[*];
int array_2[*];
int array_3[*];
int array_4[*];
initial begin
//array initialization
array_1[3] = 8;
array_1[5] = 2;
array_1[7] = 6;
array_1[9] = 1;
array_2[3] = 8;
array_2[5] = 2;
array_2[7] = 6;
array_2[9] = 1;
array_3[3] = 8;
array_3[5] = 2;
array_3[7] = 6;
array_3[9] = 1;
array_4[3] = 8;
array_4[5] = 2;
array_4[7] = 6;
array_4[9] = 1;
$display("-======= reverse =======-");
$display("Before:\t %p",array_1);
array_1.reverse();
$display("After :\t %p",array_1);
$display("-=======================-");
$display("\n-======= sort =======-");
$display("Before:\t %p",array_2);
array_2.sort();
$display("After :\t %p",array_2);
$display("-=======================-");
$display("\n-======= rsort =======-");
$display("Before:\t %p",array_3);
array_3.rsort();
$display("After :\t %p",array_3);
$display("-=======================-");
$display("\n-======= shuffle =======-");
$display("Before:\t %p",array_4);
array_4.shuffle();
$display("After :\t %p",array_4);
$display("-=======================-");
end
endmodule
Simulator Output
-======= reverse =======-
Before: '{0x3:8, 0x5:2, 0x7:6, 0x9:1}
After : '{0x3:1, 0x5:6, 0x7:2, 0x9:8}
-=======================-
-======= sort =======-
Before: '{0x3:8, 0x5:2, 0x7:6, 0x9:1}
After : '{0x3:1, 0x5:2, 0x7:6, 0x9:8}
-=======================-
-======= rsort =======-
Before: '{0x3:8, 0x5:2, 0x7:6, 0x9:1}
After : '{0x3:8, 0x5:6, 0x7:2, 0x9:1}
-=======================-
-======= shuffle =======-
Before: '{0x3:8, 0x5:2, 0x7:6, 0x9:1}
After : '{0x3:6, 0x5:1, 0x7:2, 0x9:8}
-=======================-
Array Ordering methods On Queue
Below example is for using reverse, sort, rsort and shuffle method on the queue.
module queue_manipulation;
//declaration of arrayโs
int queue_1[$];
int queue_2[$];
int queue_3[$];
int queue_4[$];
initial begin
queue_1.push_back(8);
queue_1.push_back(2);
queue_1.push_back(6);
queue_1.push_back(1);
queue_2.push_back(8);
queue_2.push_back(2);
queue_2.push_back(6);
queue_2.push_back(1);
queue_3.push_back(8);
queue_3.push_back(2);
queue_3.push_back(6);
queue_3.push_back(1);
queue_4.push_back(8);
queue_4.push_back(2);
queue_4.push_back(6);
queue_4.push_back(1);
//array initialization
$display("-======= reverse =======-");
$display("Before:\t %p",queue_1);
queue_1.reverse();
$display("After :\t %p",queue_1);
$display("-=======================-");
$display("\n-======= sort =======-");
$display("Before:\t %p",queue_2);
queue_2.sort();
$display("After :\t %p",queue_2);
$display("-=======================-");
$display("\n-======= rsort =======-");
$display("Before:\t %p",queue_3);
queue_3.rsort();
$display("After :\t %p",queue_3);
$display("-=======================-");
$display("\n-======= shuffle =======-");
$display("Before:\t %p",queue_4);
queue_4.shuffle();
$display("After :\t %p",queue_4);
$display("-=======================-");
end
endmodule
Simulator Output
-======= reverse =======-
Before: '{8, 2, 6, 1}
After : '{1, 6, 2, 8}
-=======================-
-======= sort =======-
Before: '{8, 2, 6, 1}
After : '{1, 2, 6, 8}
-=======================-
-======= rsort =======-
Before: '{8, 2, 6, 1}
After : '{8, 6, 2, 1}
-=======================-
-======= shuffle =======-
Before: '{8, 2, 6, 1}
After : '{6, 1, 2, 8}
-=======================-
Array Ordering methods โSORTโ Associative Array using โwithโ clause
In the below example, Objects of type packet are stored in an associative array. elements of an array can be sorted for particular type on using sort along with โwithโ clause.
On sort method, an item with the lower value of โaโ will move into a lower index position of the array, the same will be repeated for all the array elements.
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 arrayโs
packet array_1[*];
packet pkt;
initial begin
pkt = new();
pkt.a = 8;
pkt.b = 3;
array_1[3] = pkt;
pkt = new();
pkt.a = 0;
pkt.b = 6;
array_1[7] = pkt;
pkt = new();
pkt.a = 2;
pkt.b = 1;
array_1[9] = pkt;
$display("-======= sort =======-");
$display("Before:");
foreach(array_1[i]) begin //{
$display("array_1[%0d]:",i);
array_1[i].display();
end //}
array_1.sort with (item.a);
$display("\nAfter:");
foreach(array_1[i]) begin //{
$display("array_1[%0d]:",i);
array_1[i].display();
end //}
$display("-=======================-");
end
endmodule
Simulator Output
-======= sort =======- Before: array_1[3]: Value of a = 8 Value of b = 3 array_1[7]: Value of a = 0 Value of b = 6 array_1[9]: Value of a = 2 Value of b = 1 After: array_1[3]: Value of a = 0 Value of b = 6 array_1[7]: Value of a = 2 Value of b = 1 array_1[9]: Value of a = 8 Value of b = 3 -=======================- Description: As explained above, on calling sort method. items are sorted w.r.t value of 'a' and stored in different index location. item with a=0 stored to index 3, a=2 to next index 7 and a=8 to next index 9
Array Ordering methods โRSORTโ Associative Array using โwithโ 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 arrayโs
packet array_1[*];
packet pkt;
initial begin
pkt = new();
pkt.a = 8;
pkt.b = 3;
array_1[3] = pkt;
pkt = new();
pkt.a = 0;
pkt.b = 6;
array_1[7] = pkt;
pkt = new();
pkt.a = 2;
pkt.b = 1;
array_1[9] = pkt;
$display("-======= rsort =======-");
$display("Before:");
foreach(array_1[i]) begin //{
$display("array_1[%0d]:",i);
array_1[i].display();
end //}
array_1.rsort with (item.a);
$display("\nAfter:");
foreach(array_1[i]) begin //{
$display("array_1[%0d]:",i);
array_1[i].display();
end //}
$display("-=======================-");
end
endmodule
Simulator Output
-======= rsort =======- Before: array_1[3]: Value of a = 8 Value of b = 3 array_1[7]: Value of a = 0 Value of b = 6 array_1[9]: Value of a = 2 Value of b = 1 After: array_1[3]: Value of a = 8 Value of b = 3 array_1[7]: Value of a = 2 Value of b = 1 array_1[9]: Value of a = 0 Value of b = 6 -=======================-