Is there a way to use inside operator for every element of enum? for e.g. I've the following enum:

typedef enum {ADD, SUB, MUL, DIV, MOD} Instr_t;

While writing constraints or checking if received opcode is any one of the valid Instructions, is there an easier way I've tried the following:

if (opcode inside {Instr_t})

This fails and I need to use expanded enum:

if (opcode inside {ADD, SUB, MUL, DIV, MOD})

This is easy when enum is small but gets annoying with bigger enum, other way I could think is using define.

3 Answers

There's no need for this constraint. The constraint solver is not allowed to assign a value to a random enum variable that is outside the set of declared enum labels.

The IEEE just approved a clarification to the LRM that will be release in the next update to the standard.

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Update

If you want to create instruction subsets, you can put groups of enum labels into an array, and use the array with the inside operator

typedef enum {ADD, SUB, MUL, DIV, MOD,OR, AND, XOR} opcode_t;
const opcode_t arithmetic_ops[] = {ADD, SUB, MUL, DIV, MOD};
const opcode_t logical_ops[] = {OR, AND, XOR};
if (opcode inside {arithmetic_ops})

3

You need to first declare a variable of that enum and use it with inside.

For example:

opcode_t op;
if(opcode inside {op})
//continue

If you wish to check a value against the entire enum space, you can do:

opcode_t op = opcode_t'(42);
if (op.name()=="") begin $display("Invalid opcode: %s (%d)", op.name(), op);
end