def __init__(self, id: int, cacheSz: int, blockSz: int, a: int, bus: Bus,
processor: Processor):
""" Constructor for the class
...
Parameters
----------
id: int
id of the processor
cacheSz: int
size of the cache
blockSz: int
size of the block
a: int
Associativity
bus: Bus
bus object
processor: Processor
processor object
"""
self.id = id
self.num_entries = int(cacheSz / blockSz)
self.entries = [CacheEntry() for i in range(self.num_entries)]
self.cacheSz = cacheSz
self.blockSz = blockSz
self.num_sets = self.num_entries // a
self.num_entries_per_set = self.num_entries // self.num_sets
self.a = a
self.bus = bus
self.processor = processor
self.currentRequestAddr = None
self.currentRequestType = None
self.currentRequestId = None
# Stats related fields
self.cacheAccesses = 0
self.cacheHits = 0
self.cacheMisses = 0
self.numMemBusTransaction = 0
self.numCacheBusTransaction = 0
def snoopBus(self, clock: int):
"""Snoops the bus and updates accordingly
.....
Parameters
----------
clock: int
the clock tick number
Returns
-------
str
Action performed by cache on Snooping
"""
if self.bus.currentData != None:
request = deepcopy(self.bus.currentData)
print(request.addr, request.coreId, request.msg, self.id,
request.response)
# entry_id = self.containsEntry(request.addr)
if request.response or request.msg == 'Flush':
# This is a response to some data request
if request.addr != None and request.id == self.currentRequestId and request.coreId == self.id and request.addr == self.currentRequestAddr:
entry_id = self.containsEntry(request.addr)
if request.responseTime == 0:
self.numCacheBusTransaction += 1
if request.responseTime > 0 or request.msg == 'Flush':
self.numMemBusTransaction += 1
if request.response:
self.bus.currentData = None
if entry_id != -1:
if self.currentRequestType != 'READ':
self.entries[entry_id].state == 'M'
else:
# print(f"Setting the state as E or s for index {entry_id}")
self.entries[
entry_id].state = 'E' if request.responseTime > 0 else 'S'
self.entries[
entry_id].access = clock # Relying on python's mutable objects
else:
newEntry = CacheEntry()
if request.entry != None:
newEntry = request.entry
else:
newEntry.access = clock
newEntry.valid, newEntry.tag, newEntry.index = True, (
request.addr // self.blockSz
) // self.num_sets, (request.addr //
self.blockSz) % self.num_sets
if self.currentRequestType != 'READ':
# print("M must be added")
newEntry.state = 'M'
else:
# print("E or S must be added")
newEntry.state = 'E' if request.responseTime > 0 else 'S'
# print("Adding a new ENTRY!!!!!!!!!!!!!!!!!!!!!!")
self.addEntry(newEntry)
return 'RECV_DATA'
else:
entry_id = self.containsEntry(request.addr)
if entry_id != -1:
entry = self.entries[entry_id]
# State must be M or S
if request.msg == 'BusRd':
if entry.state == 'S' or entry.state == 'E':
entry.access = clock
entry.state = 'S'
request.response = True
self.bus.reply = request
self.bus.reply.entry = entry
self.entries[entry_id] = entry
elif entry.state == 'M':
# writeBackRequest = Request(request.addr, 'Flush', self.id)
self.bus.reply = request
self.bus.reply.msg = 'Flush'
self.bus.reply.responseTime = 0
entry.access = clock
entry.state = 'S'
else:
print("snoopBus: Incorrect state while snooping")
exit()
print(
f'Cache {self.id} performed bus request for msg {request.msg}'
)
return 'BusRd'
elif request.msg == 'BusRdX' and request.coreId != self.id:
# State is either 'M' or 'S or 'E'
entry.valid = False
# print(self.bus.currentData.response)
request.response = True
# print(self.bus.currentData.response)
self.bus.reply = request
self.entries[entry_id] = entry
print(
f'Cache {self.id} performed bus request for msg {request.msg}'
)
return 'BusRdX'
elif request.msg in ['BusRdX'
] and request.coreId == self.id:
pass
elif request.msg == 'BusUpgr' and request.coreId != self.id:
entry.valid = False
request.response = True
self.bus.reply = request
self.entries[entry_id] = entry
print(
f'Cache {self.id} performed bus request for msg {request.msg}'
)
return 'BusUpgr'
elif request.msg == 'BusUpgr' and request.coreId == self.id:
# print(self.bus.currentData.response)
request.response = True
# print(self.bus.currentData.response)
self.bus.reply = request
return 'BusUpgr'
else:
print(
f'Wrong msg {request.msg}, {request.coreId} detected in the bus while snooping by cache {self.id}'
)
return 'UNUSED'