FIFO Registers

class uvm.reg.uvm_reg_fifo.UVMRegFIFO(name, size, n_bits, has_cover)

Bases: UVMReg

Class: UVMRegFIFO

This special register models a DUT FIFO accessed via write/read, where writes push to the FIFO and reads pop from it.

Backdoor access is not enabled, as it is not yet possible to force complete FIFO state, i.e. the write and read indexes used to access the FIFO data.

build()

set_compare(check=1)

size()

capacity()

set(value, fname='', lineno=0)

Set the desired value for this register

Sets the desired value of the fields in the register to the specified value. Does not actually set the value of the register in the design, only the desired value in its corresponding abstraction class in the RegModel model. Use the UVMReg.update method to update the actual register with the mirrored value or the UVMReg.write method to set the actual register and its mirrored value.

Unless this method is used, the desired value is equal to the mirrored value.

Refer <uvm_reg_field::set()> for more details on the effect of setting mirror values on fields with different access policies.

To modify the mirrored field values to a specific value, and thus use the mirrored as a scoreboard for the register values in the DUT, use the UVMReg.predict method.

Parameters

• value –

• fname –

• lineno –

async update(status, path=3, map=None, parent=None, prior=-1, extension=None, fname='', lineno=0)

Task: update

Updates the content of the register in the design to match the desired value

This method performs the reverse operation of UVMReg.mirror. Write this register if the DUT register is out-of-date with the desired/mirrored value in the abstraction class, as determined by the UVMReg.needs_update method.

The update can be performed using the using the physical interfaces (frontdoor) or UVMReg.poke (backdoor) access. If the register is mapped in multiple address maps and physical access is used (front-door), an address map must be specified.

extern virtual task update(output uvm_status_e status,

input uvm_path_e path = UVM_DEFAULT_PATH, input uvm_reg_map map = None, input uvm_sequence_base parent = None, input int prior = -1, input uvm_object extension = None, input string fname = “”, input int lineno = 0)

Parameters

• status –

• path –

• UVM_DEFAULT_PATH –

• _map –

• parent –

• prior –

• extension –

• fname –

• lineno –

get(fname='', lineno=0)

Function: get

Return the desired value of the fields in the register.

Does not actually read the value of the register in the design, only the desired value in the abstraction class. Unless set to a different value using the UVMReg.set, the desired value and the mirrored value are identical.

Use the UVMReg.read or UVMReg.peek method to get the actual register value.

If the register contains write-only fields, the desired/mirrored value for those fields are the value last written and assumed to reside in the bits implementing these fields. Although a physical read operation would something different for these fields, the returned value is the actual content.

Parameters

• fname –

• lineno –

Returns:

do_predict(rw, kind=0, be=-1)

async pre_write(rw)

async pre_read(rw)

Task: pre_read

Called before register read.

If the specified access path or address map are modified, the updated access path or address map will be used to perform the register operation. If the status is modified to anything other than UVM_IS_OK, the operation is aborted.

The registered callback methods are invoked after the invocation of this method. All register callbacks are executed before the corresponding field callbacks

Parameters

rw –

post_randomize()

Classes derived from sv_obj can implement this callback, which is called after the actual randomization in randomize or randomize_with.