Pseudo Randomization - muneeb-mbytes/computerArchitectureCourse GitHub Wiki
What is Pseudo-random number?
A pseudorandom sequence of numbers seems random, even though it's created by a predictable and repeatable process.
Why is it called Pseudorandom?
Random numbers generated by software are not genuinely random; instead, they are pseudorandom. This is because computers use predictable algorithms based on a specific distribution. These numbers are not secure because they depend on deterministic and predictable algorithms.
What is random number?
A random number is a value selected by chance from a particular distribution. These numbers should ideally be independent, meaning there's no connection between one number and the next
Difference between random and pseudorandom number?
| Property | Random | Pseudorandom |
|---|---|---|
| Approach | Extract randomness from physical phenomena and introduce in computer | Algorithm of mathematical formula later translated into relatively bits of programming code |
| Efficiency | Slow response in generating numbers | Fast response in generating numbers |
| Determinism | Sequence of numbers cannot be reproduced | Sequence of numbers can be reproduced |
Types of Pseudorandomization
1.$urandom( )
The system function $urandom provides a mechanism for generating pseudorandom numbers. The function returns a new 32-bit random number each time it is called. The number shall be unsigned.
2.$random( )
The system function $random provides a mechanism for generating pseudorandom numbers. $random() is same as $urandom() but it generates signed numbers.
3.$urandom_range( )
The $urandom_range() function returns an unsigned integer within a specified range.
4.std::randomize()
It is also called a Scope-Randomize Function. Scope randomize gives you the ability to randomize variables that are not members of a Class and even multiple variables can be randomized at the same time.
Example:
module pseudorandomization();
integer a; // integer is a signed data type
logic [2:0] b;// logic is a unsigned data type
byte c; //byte is a signed data type
bit [4:0] d ;// bit is an unsigned data type
initial begin
a = $random();
b = $urandom();
c= $urandom_range(4,2);
std::randomize (d);
$display ("a=$random() - Returns 32 bit signed random variable");
$display("Random Value of a = %0d",a);
$display("--------------------------------------------------------------------");
$display("b = $urandom() - Returns unsigned random value .");
$display("Random Value of b = %0d",b);
$display("--------------------------------------------------------------------");
$display ("c = $random_range(4,2) Returns the random number between 4 and 2");
$display("Random value of c = %0d",c);
$display("--------------------------------------------------------------------");
$display ("d = std::randomize (d) // Return 5 bit unsigned random number");
$display("Random value of d = %0d",d);
$display("--------------------------------------------------------------------");
end
endmodule:pseudorandomization