litex/examples/sim/abstract_transactions_wb.py

82 lines
2.2 KiB
Python

from random import Random
from migen.fhdl.std import *
from migen.bus.transactions import *
from migen.bus import wishbone
from migen.sim.generic import run_simulation
# Our bus master.
# Python generators let us program bus transactions in an elegant sequential style.
def my_generator():
prng = Random(92837)
# Write to the first addresses.
for x in range(10):
t = TWrite(x, 2*x)
yield t
print("Wrote in " + str(t.latency) + " cycle(s)")
# Insert some dead cycles to simulate bus inactivity.
for delay in range(prng.randrange(0, 3)):
yield None
# Read from the first addresses.
for x in range(10):
t = TRead(x)
yield t
print("Read " + str(t.data) + " in " + str(t.latency) + " cycle(s)")
for delay in range(prng.randrange(0, 3)):
yield None
# Our bus slave.
class MyModelWB(wishbone.TargetModel):
def __init__(self):
self.prng = Random(763627)
def read(self, address):
return address + 4
def can_ack(self, bus):
# Simulate variable latency.
return self.prng.randrange(0, 2)
class TB(Module):
def __init__(self):
# The "wishbone.Initiator" library component runs our generator
# and manipulates the bus signals accordingly.
self.submodules.master = wishbone.Initiator(my_generator())
# The "wishbone.Target" library component examines the bus signals
# and calls into our model object.
self.submodules.slave = wishbone.Target(MyModelWB())
# The "wishbone.Tap" library component examines the bus at the slave port
# and displays the transactions on the console (<TRead...>/<TWrite...>).
self.submodules.tap = wishbone.Tap(self.slave.bus)
# Connect the master to the slave.
self.submodules.intercon = wishbone.InterconnectPointToPoint(self.master.bus, self.slave.bus)
if __name__ == "__main__":
run_simulation(TB())
# Output:
# <TWrite adr:0x0 dat:0x0>
# Wrote in 0 cycle(s)
# <TWrite adr:0x1 dat:0x2>
# Wrote in 0 cycle(s)
# <TWrite adr:0x2 dat:0x4>
# Wrote in 0 cycle(s)
# <TWrite adr:0x3 dat:0x6>
# Wrote in 1 cycle(s)
# <TWrite adr:0x4 dat:0x8>
# Wrote in 1 cycle(s)
# <TWrite adr:0x5 dat:0xa>
# Wrote in 2 cycle(s)
# ...
# <TRead adr:0x0 dat:0x4>
# Read 4 in 2 cycle(s)
# <TRead adr:0x1 dat:0x5>
# Read 5 in 2 cycle(s)
# <TRead adr:0x2 dat:0x6>
# Read 6 in 1 cycle(s)
# <TRead adr:0x3 dat:0x7>
# Read 7 in 1 cycle(s)
# ...