CODEWITHSUNDEEP
specman
user3444042
user3444042

Reputation: 21

how can i implement a switch-case type constraint in specman?

I am familiar with the ternary constraints:

Keep exp1 ? exp2 : exp3;

Where exp2 is kept true if exp1 is true, and exp3 is kept true if exp1 is false. However, in my case exp1 can hold multiple values, and I would like to that many expressions affected by it. accordingly, and would like all this to be done through the generator (not procedurally).

For example I would like something like this:

keep a =>   a==1 : exp1 
       a==2 : exp2
       a==3: exp3
        …

Thanks,

Upvotes: 1

Views: 495

Answers (2)

Thorsten
Thorsten

Reputation: 700

You can express this easily in a structured way as:

keep c_switch is all of {
    a==1 => exp1;
    a==2 => exp2;
    ...
};

Upvotes: 1

yuvalg
yuvalg

Reputation: 331

Such switch-case constraining capabilities are not implemented in specman. However, the developers have granted us with macros with which we can realize many Creative ideas such as this one.

The switch-case constraint that you are asking for can be easily implemented by using concatenation of ternary constraints:

Keep a==1 ? exp1 : a==2 ? exp2 : exp3;

Of course, a macro that will create such constraints should be able to handle any number of different cases. Consider this macro:

 define <switch_case_gen'struct_member> "keep map <exp> \[<exp>,...\] to <exp> \[<exp>,...\]" as computed {

var num_s:string = str_expand_dots(<2>);
var str_s: string = str_expand_dots(<4>);
var ln:list of string = str_split(num_s,",");;
var ls:list of string = str_split(str_s,",");

if (ln.size() != ls.size()) {
    error("keep map - you need to specify an equal number for items for both lists");
};
if (ln.size()<2) {
    error("keep map - this macro should recieve lists of at least size 2");
};

var constraint:string;
constraint="keep ";
for each in ln {
    if (index == ln.size()-1) {constraint = append(constraint,<3>,"==",ls[index],";");}
    else {constraint = append(constraint,<1>,"==",ln[index]," ? ", <3>,"==",ls[index],":");};
};
out("parsed constraint is : ",constraint);
return constraint;
 };

A usage example in this case would be :

 struct s {
      id:uint(bits:2);
      str:string;
      keep map id [0,1,2,3] to str ["id0","id1","id2","id3"]    
 };

Upvotes: 2

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