Procedural

void Function Calls

Declare a function that no return value.

WIP

return Statement

Returns a value to the caller from a function or exec block. Syntax:

return expression ;

• expression : An optional value need for returned to the caller.

repeat Statement

v1.0.0

Executes procedural_stmt repeatedly by specified the number of iteration. Syntax:

repeat (index_identifier : expression) procedural_stmt

• index_identifier : An optional index-variable identifier can be specified that ranges from 0 to *iteration* - 1.
• expression : Specify iteration by a non-negative integer (e.g., int or bit).
• procedural_stmt : Iterated by the number of iteration. Not executed if iteration is 0.

int intVal = 0;

repeat (i : 3) {
    intVal = i;     //  intVal: 0 -> 1 -> 2 -> 3
}

repeat-while Statement

v2.2.0

Executes procedural_stmt repeatedly as long as the expression is true. Syntax:

repeat procedural_stmt while (expression);

• procedural_stmt : Iterated so long as the expression is true.
• expression : Evaluates true or false everytime after procedural_stmt.

int intVal = 1;

repeat {
    intVal += 1;    //  intVal: 1 -> 2
} while (intVal < 1);

while Statement

v2.2.0

Executes procedural_stmt repeatedly as long as the expression is true. Syntax:

while (expression) procedural_stmt

• procedural_stmt : Iterated so long as the expression is true.
• expression : Evaluates true or false everytime before procedural_stmt.

int intVal = 0;

while (intVal < 3) {
    intVal += 1;    //  intVal: 0 -> 1 -> 2 -> 3
}

foreach Statement

v2.2.0

Executes procedural_stmt for each element of the expression. Syntax:

foreach (iterator_identifier : expression [index_identifier]) procedural_stmt

• iterator_identifier : An optional iterator-variable identifier with collection element type, an is an lias to current element.
• index_identifier : An optional index-variable identifier can be specified that ranges from 0 to size() - 1 when expression is array-type or list-type; or can be specified of all keys when expression is map-type.
• expression : A collection type (e.g., array, list, map, or set).
• procedural_stmt : Iterated by the number of size() of the expression.

Warning

• For set-type, index_identifier should NOT be specified.
• At least one of iterator_identifier or index_identifier should be specified.
• Both iterator_identifier and index_identifier should NOT be changed inside procedural_stmt.

Note

• A colon (:) must be append after iterator_identifier if its specified.
• A pair of square brackets ([]) must be used to contain index_identifier if its specified.
• The order of keys are undetermined when expression is map-type.

array<bit [4], 3> nibbleArray = {4'd4, 4'd5, 4'd6};
bit [4] nibbleVal = 0;
int intVal = 0;

foreach (i : intArray[j]) {
    nibbleVal = i;  //  nibbleVal: 0 -> 4'd4 -> 4'd5 -> 4'd6
    intVal    = j;  //  intVal   : 0 ->   0  ->   1  ->   2
}

Usage: iterating over a sequence without declare collection

When needing to iterate over a sequence of elements, the sequence can defined inside foreach directly. Even defined a collection inside foreach also acceptable.

Defined outside Defined inside Defined a collection inside

array<int, 4> sequenceArray = {2, 4, 6, 8};
foreach (i : sequenceArray[j]) {
    (void) printf(i);   //  i: 2 -> 4 -> 6 -> 8
}

foreach (i : {2, 4, 6, 8}[j]) {
    (void) printf(i);   //  i: 2 -> 4 -> 6 -> 8
    (void) printf(j);   //  j: 0 -> 1 -> 2 -> 3
}

foreach (i : {"A":10, "B":11, "C":12, "D":13, "E":14, "F":15}[j]) {
    (void) printf(i);   //  i: 10  -> 11  -> 12  -> 13  -> 14  -> 15
    (void) printf(j);   //  j: "A" -> "B" -> "C" -> "D" -> "E" -> "F"
}

if-else Statement

v1.0.0

Executes procedural_stmt_for_true when expression is true. Syntax:

if (expression) procedural_stmt_for_true else procedural_stmt_for_false

• expression : Evaluates true or false.
• procedural_stmt_for_true : Executed when the expression is true.
• procedural_stmt_for_false : An optional procedural will be executed when the expression is false.

int intVal = 3;
bit bitVal = 0;

if (intVal > 0) {
    bitVal = 1;     //  bitVal: 0 -> 1
}
else {
    bitVal = 0;
}

Bug

When if statement is used in constraint block to constraint random-variable, the else statement SHOULD be used to prevent incorrect possible values.

rand bit [2] val;
constraint {
    if (true) val in [1, 2];
    else {} //  (1)!
}

1. Even an empty procedural_stmt_for_false can prevents incorrect possible values.

match Statement

v2.2.0

Not support yet

PSSGen: Not support used in constraint block.

Executes procedural_stmt when corresponding range is match to the expression. Syntax:

match (expression) {
[range] : procedural_stmt
[range] : procedural_stmt
...
default : procedural_stmt
}

• expression : The item to be evaluated.
• range : An open range list is compared to expression.
• procedural_stmt : Executed when expression matches any one in corresponding range.
• default : An optional procedural will be executed when not any range was matched.

Warning

• Only one of ranges should be matched.
• The default must be exist and executed if no any range was matched.

int intVal = 3;
bit [4] nibbleVal = 0;

match (intVal) {
    [-100..-1]   : nibbleVal = 4'b0001;
    [0..9]       : nibbleVal = 4'b0010;
    [10, 12, 14] : nibbleVal = 4'b0100; //  nibbleVal: 0 -> 4'b0100
    [100..199]   : nibbleVal = 4'b1000;
    default      : nibbleVal = 4'b1111;
}

break Statement

v2.2.0

Not support yet

PSSGen: Not support used in constraint and activity block.

Continues execution after enclosing innermost loop construct. Syntax:

break;

Warning

The break statement may only appear within loop statements (repeat, repeat-while, while, or foreach).

int intVal = 1;

while (intVal > 0) {
    intVal += 1;    //  intVal: 0 -> 1 -> 2 -> 3
    if (intVal > 2) break;
}

continue Statement

v2.2.0

Not support yet

PSSGen: Not support used in constraint and activity block.

Continues next loop iteration. Syntax:

continue;

Warning

The continue statement may only appear within loop statements (repeat, repeat-while, while, or foreach).

int intVal = 0;

repeat (i : 3) {
    if (i < 2) continue;
    intVal = i;     //  intVal: 0 -> 2
}

randomize Statement

Not support yet v2.1

Randomize the specified data attributes or variables.

Syntax:

randomize variable, .., variable with constraints

• variable: A set variables of plain-data type to randomized together.
• constraints: Optional constraint rules.

bit [4] nibbleVal_0 = 0;
bit [4] nibbleVal_1 = 0;

exec post_solve {
    randomize nibbleVal_0, nibbleVal_1 with {nibbleVal_0 < nibbleVal_1;}
}

exec Block

v1.0.0

int intVal = 0;

exec body {
    intVal = 2; //  intVal: 0 -> 2
}

---

Last update: 2023-11-03
Created: 2023-10-24