How to get the read data from a vr_ad_sequence - uvm

Question

I have a register read sequence that goes something like this:
extend vr_ad_sequence_kind: [READ_REG];
extend READ_REG vr_ad_sequence {
// register to read
reg_kind : vr_ad_reg_kind;
!reg : vr_ad_reg;
// more fields no longer shown here
body() #driver.clock is {
var reg_item : vr_ad_reg; // reg_item gets a value from a
// method that returns the correct
// register instance from the addr_map,
// which I no longer want to show here
reg = new vr_ad_reg with { .kind = reg_kind; };
read_reg { .static_item == reg_item; } reg;
};
};
Now, I have a virtual sequence that does the vr_ad_sequence above:
extend MAIN MAIN_TEST sample_vseq {
!reg_read : READ_REG vr_ad_sequence;
body() #driver.clock is first {
do reg_read keeping {
.driver == driver.reg_driver;
.reg_kind == MY_REGISTER;
};
// how to get the value of MY_REGISTER.MY_FIELD from
// the reg_read sequence above?
};
};
My main objective is to read the value of a specific register bit field which is MY_FIELD in the above example. Is there a way to do it without modifying anything in the original READ_REG vr_ad_sequence? If it can't be helped, how do I make the READ_REG vr_ad_sequence return the read value to the calling sample_vseq?
Thanks very much in advance.

Answer 1

To obtain the register value after the read you first must make sure that the read is finished on the bus. So either your BFM is blocking (which often it isn't) or you add a flag to the sequence that tells whether the response has been received (this can be set from the BFM/driver).
Next, you can get the value from the vr_ad_map instance.
E.g.
body() #driver.clock is first {
do reg_read keeping {
.driver == driver.reg_driver;
.reg_kind == MY_REGISTER;
};
// Wait for read response
sync true(reg_read != NULL and reg_read.done);
// Access shadow register through pointer to vr_ad_map instance
print addr_map.get_register_by_kind(MY_REGISTER).as_a(MY_REGISTER vr_ad_reg).MY_FIELD;
};
(I can't check the syntax right now)