RE: [Fwd: Minutes of Verilog-AMS meeting - 31 Jan 2008]

There is also $urandom_range:

"The $urandom_range() function returns an unsigned integer within a
specified range.

The syntax for $urandom_range() is as follows:

function int unsigned $urandom_range( int unsigned maxval, int unsigned
minval = 0 );

The function shall return an unsigned integer in the range of maxval ...
minval.

Example:
val = $urandom_range(7,0);

If minval is omitted, the function shall return a value in the range of
maxval ... 0.

Example:
val = $urandom_range(7);

If maxval is less than minval, the arguments are automatically reversed
so that the first argument is larger than the second argument.

Example:
val = $urandom_range(0,7);

All of the three previous examples produce a value in the range of 0 to
7, inclusive.

$urandom_range() is automatically thread stable." 

Shalom


> -----Original Message-----
> From: Bresticker, Shalom 
> Sent: Monday, February 11, 2008 5:54 PM
> To: Sri Chandra
> Cc: Geoffrey.Coram; Verilog-AMS LRM Committee; Neil.Korpusik@Sun.COM
> Subject: RE: [Fwd: Minutes of Verilog-AMS meeting - 31 Jan 2008]
> 
> This is the description of $urandom:
> 
> The system function $urandom provides a mechanism for 
> generating pseudo-random numbers. The function returns a new 
> 32-bit random number each time it is called. The number shall 
> be unsigned.
> 
> The syntax for $urandom is as follows:
> function int unsigned $urandom [ (int seed ) ] ;
> 
> The seed is an optional argument that determines the sequence 
> of random numbers generated. The seed can be any integral 
> expression. The random number generator (RNG) shall generate 
> the same sequence of random numbers every time the same seed is used.
> The RNG is deterministic. Each time the program executes, it 
> cycles through the same random sequence.
> This sequence can be made nondeterministic by seeding the 
> $urandom function with an extrinsic random variable, such as 
> the time of day. 
> 
> For example:
> 
> bit [64:1] addr;
> bit [ 3:0] number;
> addr[32:1] = $urandom( 254 ); // Initialize the generator,
>                               // get 32-bit random number 
> addr = {$urandom, $urandom }; // 64-bit random number number 
> = $urandom & 15; // 4-bit random number
> 
> Shalom
> 
> > Option #3: Have an equivalent function for the distribution 
> functions 
> > amsrand or absrand which extends the current distribution 
> function to 
> > take in parameter and constant expressions and we can keep 
> the current 
> > random and distribution functions the same as the system verilog 
> > counterpart. Apparently SV has already done this by having 
> urand (?) 
> > as an extension to 1364 which will return an unsigned number.
> 
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Intel Israel (74) Limited

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