( ESNUG 390 Item 3 ) --------------------------------------------- [03/20/02]
From: Alexandre Gnusin <alexandre.gnusin@tundra.com>
Subject: Alexandre's Easier To Use Vera Randomization/Semi-Random Functions
Hi John,
In my opinion, Vera is too object-oriented. This Vera obession on object
orientation means that some straightforward functions, built-in into
classes, are not available for straightforward procedural programming.
For example, there are no simple randomization functions that are easily
useable for random and semi-random tests. We had to overcome this problem
creating our own random functions:
class RL {
rand integer num;
integer low, high, flag;
constraint main {
num <= high;
num >= low;
num dist {low:low+(high-low)/3 :/80,
low+(high-low)/3:high-(high-low)/3:/15,
high-(high-low)/3:high :/5};
}
}
class RN {
rand integer num;
integer low, high, flag;
constraint main {
num <= high;
num >= low;
}
}
class RH {
rand integer num;
integer low, high, flag;
constraint main {
num <= high;
num >= low;
num dist {low:low+(high-low)/3 :/5,
low+(high-low)/3:high-(high-low)/3:/15,
high-(high-low)/3:high :/80};
}
}
function integer rl (integer low, integer high) {
RL p= new;
p.low = low;
p.high = high;
if(!p.randomize()) error("Randomization error") ;
rl = p.num;
}
function integer rn (integer low, integer high) {
RN p= new;
p.low = low;
p.high = high;
if(!p.randomize()) error("Randomization error") ;
rn = p.num;
}
function integer rh (integer low, integer high) {
RH p= new;
p.low = low;
p.high = high;
if(!p.randomize()) error("Randomization error") ;
rh = p.num;
}
Here is an example of random functions usage:
for (i=1; i<20;i=i+1) Send_NWRITE (rl(0,2), 64, 0, rn(0,2), 8*rl(1,31), 0);
Each of these functions, rl, rn, and rh returns a random integer between
our specified low and high limits. The difference between them is that
rl will return more likely a "small" number, rn - any number and rh - a
"high" number.
- Alexander Gnusin
Tundra Semiconductors Ottawa, Ontario, Canada
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