uvm_event

class uvm.base.uvm_event.UVMEventBase(name='')

Bases: uvm.base.uvm_object.UVMObject

The UVMEventBase class is an abstract wrapper class around the cocotb.triggers.Event class. It provides some additional services such as setting self.callbacks and maintaining the number of waiters.

type_name = 'uvm_event_base'

set_value(key, value)

Sets a value inside this event object and triggers value_changed_event.

Parameters

• key (str) – Member variable name

• value (any) – Value to set for that member variable.

set()

async wait()

async wait_on(delta=False)

Waits for the event to be activated for the first time.

If the event has already been triggered, this task returns immediately. If delta is set, the caller will be forced to wait a single delta #0 before returning. This prevents the caller from returning before previously waiting processes have had a chance to resume.

Once an event has been triggered, it will be remain “on” until the event is UVMEvent.reset.

Parameters

delta (bool) – If True, wait for one zero delay

async wait_off(delta=False)

If the event has already triggered and is “on”, this task waits for the event to be turned “off” via a call to reset.

If the event has not already been triggered, this task returns immediately. If delta is set, the caller will be forced to wait a single delta #0 before returning. This prevents the caller from returning before previously waiting processes have had a chance to resume.

Parameters

delta (bool) – If True, wait for one zero delay

async wait_trigger()

Waits for the event to be triggered.

If one process calls wait_trigger in the same delta as another process calls UVMEvent.trigger, a race condition occurs. If the call to wait occurs before the trigger, this method will return in this delta. If the wait occurs after the trigger, this method will not return until the next trigger, which may never occur and thus cause deadlock.

async wait_ptrigger()

Waits for a persistent trigger of the event. Unlike UVMEvent.wait_trigger, this views the trigger as persistent within a given time-slice and thus avoids certain race conditions. If this method is called after the trigger but within the same time-slice, the caller returns immediately.

get_trigger_time()

Gets the time that this event was last triggered. If the event has not bee triggered, or the event has been reset, then the trigger time will be 0.

Returns

Time when this event was triggered.

Return type

int

is_on()

Indicates whether the event has been triggered since it was last reset.

A return of 1 indicates that the event has triggered.

Returns:

is_off()

Indicates whether the event has been triggered or been reset.

A return of 1 indicates that the event has not been triggered.

Returns:

reset(wakeup=False)

Resets the event to its off state. If wakeup is set, then all processes currently waiting for the event are activated before the reset.

No self.callbacks are called during a reset.

Parameters

wakeup (bool) –

cancel()

Decrements the number of waiters on the event.

This is used if a process that is waiting on an event is disabled or activated by some other means.

get_num_waiters()

Returns the number of processes waiting on the event.

get_type_name() → str

This function returns the type name of the object, which is typically the type identifier enclosed in quotes. It is used for various debugging functions in the library, and it is used by the factory for creating objects.

This function must be defined in every derived class.

A typical implementation is as follows:

Returns

Type name of the object.

Return type

str

class uvm.base.uvm_event.UVMEvent(name='', T=None)

Bases: uvm.base.uvm_event.UVMEventBase

CLASS: UVMEvent

The UVMEvent class is an extension of the abstract UVMEventBase class.

The optional parameter ~T~ allows the user to define a data type which can be passed during an event trigger.

type_name = 'uvm_event'

async wait_trigger_data()

Task: wait_trigger_data

This method calls <uvm_event_base::wait_trigger> followed by get_trigger_data. :returns: Trigger data. :rtype: any

async wait_ptrigger_data(data)

This method calls <uvm_event_base::wait_ptrigger> followed by get_trigger_data.

Parameters

data –

Returns

Data used to trigger this event.

Return type

any

trigger(data=None)

Triggers the event, resuming all waiting processes.

An optional data argument can be supplied with the enable to provide trigger-specific information.

Parameters

data (any) – Data associated with the trigger.

get_trigger_data()

Gets the data, if any, provided by the last call to trigger.

Returns

Data used to trigger this event.

Return type

any

get_type_name()

This function returns the type name of the object, which is typically the type identifier enclosed in quotes. It is used for various debugging functions in the library, and it is used by the factory for creating objects.

This function must be defined in every derived class.

A typical implementation is as follows:

Returns

Type name of the object.

Return type

str

add_callback(cb, append=True)

Registers a callback object, cb, with this event. The callback object may include pre_trigger and post_trigger functionality. If append is set to 1, the default, cb is added to the back of the callback list. Otherwise, cb is placed at the front of the callback list.

Parameters

• cb –

• append (bool) – If True, append to the end. Otherwise insert to front.

delete_callback(cb)

Unregisters the given callback, ~cb~, from this event.

Parameters

cb (UVMCallback) – Callback to delete from this event.

do_print(printer)

The do_print method is the user-definable hook called by print and sprint that allows users to customize what gets printed or sprinted beyond the field information provided by the `uvm_field_* macros, <Utility and Field Macros for Components and Objects>.

The printer argument is the policy object that governs the format and content of the output. To ensure correct print and sprint operation, and to ensure a consistent output format, the printer must be used by all do_print implementations. That is, instead of using ~$display~ or string concatenations directly, a do_print implementation must call through the ~printer’s~ API to add information to be printed or sprinted.

An example implementation of do_print is as follows:

class mytype (UVMObject):
  data_obj data
  int f1
  virtual function void do_print (uvm_printer printer)
    super.do_print(printer)
    printer.print_field_int("f1", f1, $bits(f1), UVM_DEC)
    printer.print_object("data", data)
  endfunction

Then, to print and sprint the object, you could write:

t = mytype()
t.print()
uvm_report_info("Received",t.sprint())

See UVMPrinter for information about the printer API.

Parameters

printer (UVMPrinter) – Printer that is used in printing.