def __init__(self, memory, start_address):
self.memory = memory
self.start_address = start_address
self.register_file = RegisterFile()
self.data_memory_key_fn = lambda: -777
self.data_memory = defaultdict(self.data_memory_key_fn)
self.cycle_count = 0
self.instr_count = 0
self.PC = 0
self.fetch_input_buffer = FetchInputBuffer({
'PC':
self.start_address,
'instr_count':
self.instr_count,
})
self.fetcher_buffer = FetcherBuffer()
self.fetch_stage = FetchStage(self.memory, self.fetch_input_buffer,
self.fetcher_buffer)
self.decoder_buffer = DecoderBuffer()
self.decode_stage = DecodeStage(self.fetcher_buffer,
self.decoder_buffer,
self.register_file)
self.executer_buffer = ExecuterBuffer()
self.execute_stage = ExecuteStage(self.decoder_buffer,
self.executer_buffer)
self.memory_buffer = MemoryBuffer()
self.memory_stage = MemoryStage(self.executer_buffer,
self.memory_buffer, self.data_memory)
self.write_back_stage = WriteBackStage(self.memory_buffer,
self.register_file)
def test_do_operand_forwarding(self):
self.processor.decoder_buffer = DecoderBuffer({'rs': [2, None]})
self.processor.executer_buffer = ExecuterBuffer({'rt': [2, 7]})
self.processor.do_operand_forwarding()
self.assertEqual(self.processor.decoder_buffer.rs, [2, 7])
self.processor.decoder_buffer = DecoderBuffer({'rs': [2, None]})
self.processor.executer_buffer = ExecuterBuffer()
self.processor.memory_buffer = MemoryBuffer({'rd': [2, 9]})
self.processor.do_operand_forwarding()
self.assertEqual(self.processor.decoder_buffer.rs, [2, 9])
def __init__ (self, memory, start_address):
self.memory = memory
self.start_address = start_address
self.register_file = RegisterFile ()
self.data_memory_key_fn = lambda: -777
self.data_memory = defaultdict (self.data_memory_key_fn)
self.cycle_count = 0
self.instr_count = 0
self.PC = 0
self.fetch_input_buffer = FetchInputBuffer({
'PC': self.start_address,
'instr_count': self.instr_count,
})
self.fetcher_buffer = FetcherBuffer()
self.fetch_stage = FetchStage(self.memory,
self.fetch_input_buffer,
self.fetcher_buffer)
self.decoder_buffer = DecoderBuffer()
self.decode_stage = DecodeStage(self.fetcher_buffer,
self.decoder_buffer,
self.register_file)
self.executer_buffer = ExecuterBuffer()
self.execute_stage = ExecuteStage(self.decoder_buffer,
self.executer_buffer)
self.memory_buffer = MemoryBuffer()
self.memory_stage = MemoryStage(self.executer_buffer,
self.memory_buffer,
self.data_memory)
self.write_back_stage = WriteBackStage(
self.memory_buffer,
self.register_file)
def test_execute_I_instruction_BEQ_true(self):
self.register_file[2] = 8
self.register_file[5] = 8
self.set_up_execute_stage('I BEQ R2 R5 4')
expected_branch_PC = self.decoder_buffer.npc + 4 * 4
self.execute_stage.execute_I_instruction()
self.assertFalse(self.execute_stage.is_stalled)
self.assertEqual(self.execute_stage.branch_pc, expected_branch_PC)
self.assertEqual(self.execute_stage.executer_buffer, ExecuterBuffer())
self.assertEqual(self.execute_stage.decoder_buffer, DecoderBuffer())
def test_execute_I_instruction_LW(self):
self.register_file[2] = 8
self.set_up_execute_stage('I LW R2 R5 4')
executer_buffer = ExecuterBuffer({
'instr': self.instr,
'npc': self.decoder_buffer.npc,
'rt': [5, None],
'memaddr': 12,
})
self.execute_stage.execute_I_instruction()
self.assertFalse(self.execute_stage.is_stalled)
self.assertEqual(self.execute_stage.executer_buffer, executer_buffer)
self.assertEqual(self.execute_stage.decoder_buffer, DecoderBuffer())
def test_execute_I_instruction_ADDI(self):
self.register_file[1] = 3
self.set_up_execute_stage('I ADDI R1 R1 1')
executer_buffer = ExecuterBuffer({
'instr':
self.instr,
'npc':
self.decoder_buffer.npc,
'rt': [self.instr.rt, self.register_file[1] + 1],
})
self.execute_stage.execute_I_instruction()
self.assertFalse(self.execute_stage.is_stalled)
self.assertEqual(self.execute_stage.executer_buffer, executer_buffer)
self.assertEqual(self.execute_stage.decoder_buffer, DecoderBuffer())
def get_stage_output(memory, register_file, pc, instr_count, stage_name):
"""Return the output buffer of stage given the initial conditions.
All the stages before stage_name will be executed.
Arguments:
- `memory`:
- `register_file`:
- `pc`:
- `stage_name`:
TODO: Maybe just take the stages as input later.
"""
fetch_input_buffer = FetchInputBuffer({
'PC': pc,
'instr_count': instr_count,
})
fetcher_buffer = FetcherBuffer()
fetch_stage = FetchStage(memory, fetch_input_buffer, fetcher_buffer)
fetch_stage.fetch_instruction()
if stage_name == 'fetch':
return fetch_stage.fetcher_buffer
decode_stage = DecodeStage(fetch_stage.fetcher_buffer, DecoderBuffer(),
register_file)
decode_stage.decode_instruction()
if stage_name == 'decode':
return decode_stage.decoder_buffer
execute_stage = ExecuteStage(decode_stage.decoder_buffer,
ExecuterBuffer())
execute_stage.execute()
if stage_name == 'execute':
return execute_stage.executer_buffer
data_memory_key_fn = lambda: -1
data_memory = defaultdict(data_memory_key_fn)
memory_stage = MemoryStage(execute_stage.executer_buffer,
MemoryBuffer(), data_memory)
memory_stage.do_memory_operation()
if stage_name == 'memory':
return memory_stage.memory_buffer
def test_execute_R_instruction(self):
self.register_file[1] = 3
self.register_file[2] = 7
self.set_up_execute_stage('R ADD R1 R2 R3')
executer_buffer = ExecuterBuffer({
'instr':
self.instr,
'npc':
self.decoder_buffer.npc,
'rd':
[self.instr.rd, self.register_file[1] + self.register_file[2]],
})
self.execute_stage.execute_R_instruction()
self.assertFalse(self.execute_stage.is_stalled)
self.assertEqual(self.execute_stage.executer_buffer, executer_buffer)
self.assertEqual(self.execute_stage.decoder_buffer, DecoderBuffer())
def test_execute_I_instruction_BEQ_false(self):
self.register_file[2] = 8
self.register_file[5] = 7
self.set_up_execute_stage('I BEQ R2 R5 4')
expected_branch_PC = self.decoder_buffer.npc
self.execute_stage.executer_buffer = ExecuterBuffer({'foo': 123})
self.execute_stage.execute_I_instruction()
self.assertFalse(self.execute_stage.is_stalled)
print 'self.decoder_buffer: ', self.decoder_buffer
self.assertEqual(self.execute_stage.branch_pc, expected_branch_PC)
# NOTE: You need different instances of ExecuterBuffers, else,
# just one instance gets modified and the two references will
# turn out to be equal.
self.assertEqual(
self.execute_stage.executer_buffer, ExecuterBuffer({'foo': 123}),
"execute_stage shouldn't modify its executer_buffer after a BEQ")
self.assertEqual(self.execute_stage.decoder_buffer, DecoderBuffer())
def test_execute_cycles_BEQ_true(self):
instruction_list = [
'I BEQ R2 R5 4',
'R ADD R1 R2 R3',
'R ADD R1 R2 R3',
'R ADD R2 R0 R1',
'R ADD R3 R0 R2',
'J J 3',
'I ADDI R9 R9 999',
]
instruction_list = [
instruction_string.split()
for instruction_string in instruction_list
]
memory = Memory.Memory(instruction_list)
processor = Processor.Processor(memory, 0)
processor.execute_cycles(3)
self.assertEqual(processor.execute_stage.branch_pc, 20)
self.assertEqual(processor.fetch_stage.fetch_input_buffer.PC, 20)
self.assertEqual(processor.executer_buffer, ExecuterBuffer())
self.assertEqual(processor.decoder_buffer, DecoderBuffer())
self.assertEqual(processor.fetcher_buffer, FetcherBuffer())
class Processor (object):
def __init__ (self, memory, start_address):
self.memory = memory
self.start_address = start_address
self.register_file = RegisterFile ()
self.data_memory_key_fn = lambda: -777
self.data_memory = defaultdict (self.data_memory_key_fn)
self.cycle_count = 0
self.instr_count = 0
self.PC = 0
self.fetch_input_buffer = FetchInputBuffer({
'PC': self.start_address,
'instr_count': self.instr_count,
})
self.fetcher_buffer = FetcherBuffer()
self.fetch_stage = FetchStage(self.memory,
self.fetch_input_buffer,
self.fetcher_buffer)
self.decoder_buffer = DecoderBuffer()
self.decode_stage = DecodeStage(self.fetcher_buffer,
self.decoder_buffer,
self.register_file)
self.executer_buffer = ExecuterBuffer()
self.execute_stage = ExecuteStage(self.decoder_buffer,
self.executer_buffer)
self.memory_buffer = MemoryBuffer()
self.memory_stage = MemoryStage(self.executer_buffer,
self.memory_buffer,
self.data_memory)
self.write_back_stage = WriteBackStage(
self.memory_buffer,
self.register_file)
def print_buffers (self):
print "PC:", self.fetch_stage.fetch_input_buffer
print 'fetch_stage.fetch_input_buffer:'
print self.fetch_stage.fetch_input_buffer
print 'fetch_stage.fetcher_buffer:'
print self.fetch_stage.fetcher_buffer
print
print 'decode_stage.fetcher_buffer:'
print self.decode_stage.fetcher_buffer
print 'decode_stage.decoder_buffer:'
print self.decode_stage.decoder_buffer
print
print 'execute_stage.decoder_buffer:'
print self.execute_stage.decoder_buffer
print 'execute_stage.executer_buffer:'
print self.execute_stage.executer_buffer
print
print 'memory_stage.executer_buffer:'
print self.memory_stage.executer_buffer
print 'memory_stage.memory_buffer:'
print self.memory_stage.memory_buffer
print
print 'write_back_stage.memory_buffer:'
print self.write_back_stage.memory_buffer
# def get_all_curr_data(self):
# """Return dict of all data in the Processor at the moment.
# """
# # TODO: It gives 'Can't pickle instancemethod object' error
# # when I have self.data_memory too.
# curr_data_dict = {
# 'fetcher_buffer': self.fetcher_buffer,
# 'decoder_buffer': self.decoder_buffer,
# 'executer_buffer': self.executer_buffer,
# 'memory_buffer': self.memory_buffer,
# 'decoder_stalled': self.decoder_stalled,
# 'executer_stalled': self.executer_stalled,
# 'mem_stalled': self.mem_stalled,
# 'reg_writer_stalled': self.reg_writer_stalled,
# 'memory': self.memory,
# 'start_address': self.start_address,
# 'register_file': self.register_file,
# 'PC': self.PC,
# 'IR': self.IR,
# 'NPC': self.NPC,
# 'cycle_count': self.cycle_count,
# 'instr_count': self.instr_count,
# }
# return curr_data_dict
# @staticmethod
# def save_cycle_data(cycle_data_list, cycle_data_file_name = default_data_file_name):
# """Pickle and save cycle_data_list.
# Arguments:
# - `cycle_data_list`:
# """
# with open(cycle_data_file_name, 'w') as f:
# pickle.dump(cycle_data_list, f)
# print 'Wrote cycle_data_list to {0}'.format(cycle_data_file_name)
# @staticmethod
# def read_saved_data(cycle_data_file_name = default_data_file_name):
# """Return cycle data list saved in cycle_data_file_name.
# Arguments:
# - `cycle_data_file_name`:
# """
# cycle_data_list = []
# with open(cycle_data_file_name, 'rb') as f:
# cycle_data_list = pickle.load(f)
# print 'Read cycle_data_list from {0}'.format(cycle_data_file_name)
# return cycle_data_list
# TODO: Be careful. In reality, the stages are executed in reverse
# order.
@staticmethod
def get_stage_output(memory, register_file, pc, instr_count,
stage_name):
"""Return the output buffer of stage given the initial conditions.
All the stages before stage_name will be executed.
Arguments:
- `memory`:
- `register_file`:
- `pc`:
- `stage_name`:
TODO: Maybe just take the stages as input later.
"""
fetch_input_buffer = FetchInputBuffer({
'PC': pc,
'instr_count': instr_count,
})
fetcher_buffer = FetcherBuffer()
fetch_stage = FetchStage(memory, fetch_input_buffer, fetcher_buffer)
fetch_stage.fetch_instruction()
if stage_name == 'fetch':
return fetch_stage.fetcher_buffer
decode_stage = DecodeStage(fetch_stage.fetcher_buffer,
DecoderBuffer(),
register_file)
decode_stage.decode_instruction()
if stage_name == 'decode':
return decode_stage.decoder_buffer
execute_stage = ExecuteStage(decode_stage.decoder_buffer,
ExecuterBuffer())
execute_stage.execute()
if stage_name == 'execute':
return execute_stage.executer_buffer
data_memory_key_fn = lambda: -1
data_memory = defaultdict (data_memory_key_fn)
memory_stage = MemoryStage(execute_stage.executer_buffer,
MemoryBuffer(),
data_memory)
memory_stage.do_memory_operation()
if stage_name == 'memory':
return memory_stage.memory_buffer
def do_operand_forwarding(self, ):
"""Forward operands if possible.
"""
# TODO: Be careful about this... check if it is an output reg
# value or an input reg value... (Does that make sense?)
# MEM stage
for operand_label in ['rt']:
if (self.executer_buffer[operand_label] is not None
and self.executer_buffer[operand_label][1] is None):
reg_label = self.executer_buffer[operand_label][0]
mem_forward_val = self.memory_buffer.get_reg_val(reg_label)
print 'mem_forward_val: ', mem_forward_val
self.executer_buffer[operand_label][1] = mem_forward_val
# ALU
for operand_label in ['rs', 'rt']:
if (self.decoder_buffer[operand_label] is not None
and self.decoder_buffer[operand_label][1] is None):
reg_label = self.decoder_buffer[operand_label][0]
exec_forward_val = self.executer_buffer.get_reg_val(reg_label)
mem_forward_val = self.memory_buffer.get_reg_val(reg_label)
# Note: exec_forward_val or mem_forward_val won't work
# cos 0 or None => None
forward_val = exec_forward_val if exec_forward_val is not None \
else mem_forward_val
self.decoder_buffer[operand_label][1] = forward_val
def are_instructions_in_flight(self, ):
"""Return True iff there exist instructions in-flight.
TODO: Check if any registers are dirty.
"""
any_non_empty_buffers = not all(buff.is_empty() for buff in
[self.memory_stage.memory_buffer,
self.execute_stage.executer_buffer,
self.decode_stage.decoder_buffer,
self.fetch_stage.fetcher_buffer])
any_stalls = any(stage.is_stalled for stage in [self.decode_stage,
self.execute_stage,
self.memory_stage])
valid_PC_coming_up = self.fetch_stage.is_valid_PC()
# valid_PC_coming_up = False
return any_non_empty_buffers or any_stalls or valid_PC_coming_up
def execute_one_cycle(self, ):
"""Execute one cycle of the Processor.
TODO: Make it such that the stages SHARE the buffer (ie. have
a reference to the same buffer) instead of having copies named
FetcherBuffer, etc.
"""
self.do_operand_forwarding()
self.write_back_stage.write_back()
self.memory_stage.do_memory_operation()
self.execute_stage.execute(self.memory_stage.is_stalled)
self.decode_stage.decode_instruction(self.execute_stage.is_stalled)
self.fetch_stage.fetch_instruction(self.decode_stage.is_stalled)
# self.write_back_stage.memory_buffer = self.memory_stage.memory_buffer
# if not self.memory_stage.is_stalled:
# self.memory_stage.executer_buffer = self.execute_stage.executer_buffer
# if (not self.execute_stage.is_stalled
# and not self.decode_stage.has_jumped):
# self.execute_stage.decoder_buffer = self.decode_stage.decoder_buffer
# # TODO: What is this for?
# if not self.decode_stage.is_stalled and not self.execute_stage.branch_pc is not None:
# self.decode_stage.fetcher_buffer = self.fetch_stage.fetcher_buffer
if (self.memory_stage.is_stalled or
self.execute_stage.is_stalled or
self.decode_stage.is_stalled):
print 'STALL'
print 'self.memory_stage.is_stalled, self.execute_stage.is_stalled, self.decode_stage.is_stalled: \n', [self.memory_stage.is_stalled,
self.execute_stage.is_stalled,
self.decode_stage.is_stalled]
if self.execute_stage.branch_pc is not None:
self.decode_stage.undo_dirties(self.execute_stage.is_stalled)
print 'self.register_file: ', self.register_file
self.decoder_buffer.clear()
self.fetcher_buffer.clear()
# TODO: Can there be a jump PC from Decode and a branch PC
# from Execute at the end of the same cycle?
if self.decode_stage.has_jumped:
# Pass on PC value from decoder_buffer to fetcher_buffer in
# case of a jump.
self.fetch_stage.fetch_input_buffer.PC = self.decode_stage.jump_pc
elif self.execute_stage.branch_pc is not None:
self.fetch_stage.fetch_input_buffer.PC = self.execute_stage.branch_pc
def execute_cycles(self, num_cycles = None):
"""Execute num_cycles cycles of the Processor (if possible).
Else, execute till the program terminates.
"""
self.cycle_count = 0
print 'self.memory: ', self.memory
while True:
self.cycle_count += 1
print '\n'
print 'Beginning of Cycle #' + str(self.cycle_count)
print '=' * 12
print '[self.decode_stage, self.execute_stage, self.memory_stage]: ', [
stage.is_stalled
for stage in [self.decode_stage, self.memory_stage, self.execute_stage]]
self.print_buffers ()
print self.register_file
self.execute_one_cycle()
if not self.are_instructions_in_flight() or (
num_cycles is not None and self.cycle_count == num_cycles):
break
print '\nAt the end'
print '=' * 12
self.print_buffers ()
print self.register_file
def start(self, cycle_data_file_name = default_data_file_name):
"""Start execution of instructions from the start_address.
"""
self.instruction_address = self.start_address
self.execute_cycles()
def getCPI (self):
return (1.0 * self.cycle_count) / self.fetch_stage.fetch_input_buffer.instr_count
class Processor(object):
def __init__(self, memory, start_address):
self.memory = memory
self.start_address = start_address
self.register_file = RegisterFile()
self.data_memory_key_fn = lambda: -777
self.data_memory = defaultdict(self.data_memory_key_fn)
self.cycle_count = 0
self.instr_count = 0
self.PC = 0
self.fetch_input_buffer = FetchInputBuffer({
'PC':
self.start_address,
'instr_count':
self.instr_count,
})
self.fetcher_buffer = FetcherBuffer()
self.fetch_stage = FetchStage(self.memory, self.fetch_input_buffer,
self.fetcher_buffer)
self.decoder_buffer = DecoderBuffer()
self.decode_stage = DecodeStage(self.fetcher_buffer,
self.decoder_buffer,
self.register_file)
self.executer_buffer = ExecuterBuffer()
self.execute_stage = ExecuteStage(self.decoder_buffer,
self.executer_buffer)
self.memory_buffer = MemoryBuffer()
self.memory_stage = MemoryStage(self.executer_buffer,
self.memory_buffer, self.data_memory)
self.write_back_stage = WriteBackStage(self.memory_buffer,
self.register_file)
def print_buffers(self):
print "PC:", self.fetch_stage.fetch_input_buffer
print 'fetch_stage.fetch_input_buffer:'
print self.fetch_stage.fetch_input_buffer
print 'fetch_stage.fetcher_buffer:'
print self.fetch_stage.fetcher_buffer
print
print 'decode_stage.fetcher_buffer:'
print self.decode_stage.fetcher_buffer
print 'decode_stage.decoder_buffer:'
print self.decode_stage.decoder_buffer
print
print 'execute_stage.decoder_buffer:'
print self.execute_stage.decoder_buffer
print 'execute_stage.executer_buffer:'
print self.execute_stage.executer_buffer
print
print 'memory_stage.executer_buffer:'
print self.memory_stage.executer_buffer
print 'memory_stage.memory_buffer:'
print self.memory_stage.memory_buffer
print
print 'write_back_stage.memory_buffer:'
print self.write_back_stage.memory_buffer
# def get_all_curr_data(self):
# """Return dict of all data in the Processor at the moment.
# """
# # TODO: It gives 'Can't pickle instancemethod object' error
# # when I have self.data_memory too.
# curr_data_dict = {
# 'fetcher_buffer': self.fetcher_buffer,
# 'decoder_buffer': self.decoder_buffer,
# 'executer_buffer': self.executer_buffer,
# 'memory_buffer': self.memory_buffer,
# 'decoder_stalled': self.decoder_stalled,
# 'executer_stalled': self.executer_stalled,
# 'mem_stalled': self.mem_stalled,
# 'reg_writer_stalled': self.reg_writer_stalled,
# 'memory': self.memory,
# 'start_address': self.start_address,
# 'register_file': self.register_file,
# 'PC': self.PC,
# 'IR': self.IR,
# 'NPC': self.NPC,
# 'cycle_count': self.cycle_count,
# 'instr_count': self.instr_count,
# }
# return curr_data_dict
# @staticmethod
# def save_cycle_data(cycle_data_list, cycle_data_file_name = default_data_file_name):
# """Pickle and save cycle_data_list.
# Arguments:
# - `cycle_data_list`:
# """
# with open(cycle_data_file_name, 'w') as f:
# pickle.dump(cycle_data_list, f)
# print 'Wrote cycle_data_list to {0}'.format(cycle_data_file_name)
# @staticmethod
# def read_saved_data(cycle_data_file_name = default_data_file_name):
# """Return cycle data list saved in cycle_data_file_name.
# Arguments:
# - `cycle_data_file_name`:
# """
# cycle_data_list = []
# with open(cycle_data_file_name, 'rb') as f:
# cycle_data_list = pickle.load(f)
# print 'Read cycle_data_list from {0}'.format(cycle_data_file_name)
# return cycle_data_list
# TODO: Be careful. In reality, the stages are executed in reverse
# order.
@staticmethod
def get_stage_output(memory, register_file, pc, instr_count, stage_name):
"""Return the output buffer of stage given the initial conditions.
All the stages before stage_name will be executed.
Arguments:
- `memory`:
- `register_file`:
- `pc`:
- `stage_name`:
TODO: Maybe just take the stages as input later.
"""
fetch_input_buffer = FetchInputBuffer({
'PC': pc,
'instr_count': instr_count,
})
fetcher_buffer = FetcherBuffer()
fetch_stage = FetchStage(memory, fetch_input_buffer, fetcher_buffer)
fetch_stage.fetch_instruction()
if stage_name == 'fetch':
return fetch_stage.fetcher_buffer
decode_stage = DecodeStage(fetch_stage.fetcher_buffer, DecoderBuffer(),
register_file)
decode_stage.decode_instruction()
if stage_name == 'decode':
return decode_stage.decoder_buffer
execute_stage = ExecuteStage(decode_stage.decoder_buffer,
ExecuterBuffer())
execute_stage.execute()
if stage_name == 'execute':
return execute_stage.executer_buffer
data_memory_key_fn = lambda: -1
data_memory = defaultdict(data_memory_key_fn)
memory_stage = MemoryStage(execute_stage.executer_buffer,
MemoryBuffer(), data_memory)
memory_stage.do_memory_operation()
if stage_name == 'memory':
return memory_stage.memory_buffer
def do_operand_forwarding(self, ):
"""Forward operands if possible.
"""
# TODO: Be careful about this... check if it is an output reg
# value or an input reg value... (Does that make sense?)
# MEM stage
for operand_label in ['rt']:
if (self.executer_buffer[operand_label] is not None
and self.executer_buffer[operand_label][1] is None):
reg_label = self.executer_buffer[operand_label][0]
mem_forward_val = self.memory_buffer.get_reg_val(reg_label)
print 'mem_forward_val: ', mem_forward_val
self.executer_buffer[operand_label][1] = mem_forward_val
# ALU
for operand_label in ['rs', 'rt']:
if (self.decoder_buffer[operand_label] is not None
and self.decoder_buffer[operand_label][1] is None):
reg_label = self.decoder_buffer[operand_label][0]
exec_forward_val = self.executer_buffer.get_reg_val(reg_label)
mem_forward_val = self.memory_buffer.get_reg_val(reg_label)
# Note: exec_forward_val or mem_forward_val won't work
# cos 0 or None => None
forward_val = exec_forward_val if exec_forward_val is not None \
else mem_forward_val
self.decoder_buffer[operand_label][1] = forward_val
def are_instructions_in_flight(self, ):
"""Return True iff there exist instructions in-flight.
TODO: Check if any registers are dirty.
"""
any_non_empty_buffers = not all(buff.is_empty() for buff in [
self.memory_stage.memory_buffer,
self.execute_stage.executer_buffer,
self.decode_stage.decoder_buffer, self.fetch_stage.fetcher_buffer
])
any_stalls = any(
stage.is_stalled for stage in
[self.decode_stage, self.execute_stage, self.memory_stage])
valid_PC_coming_up = self.fetch_stage.is_valid_PC()
# valid_PC_coming_up = False
return any_non_empty_buffers or any_stalls or valid_PC_coming_up
def execute_one_cycle(self, ):
"""Execute one cycle of the Processor.
TODO: Make it such that the stages SHARE the buffer (ie. have
a reference to the same buffer) instead of having copies named
FetcherBuffer, etc.
"""
self.do_operand_forwarding()
self.write_back_stage.write_back()
self.memory_stage.do_memory_operation()
self.execute_stage.execute(self.memory_stage.is_stalled)
self.decode_stage.decode_instruction(self.execute_stage.is_stalled)
self.fetch_stage.fetch_instruction(self.decode_stage.is_stalled)
# self.write_back_stage.memory_buffer = self.memory_stage.memory_buffer
# if not self.memory_stage.is_stalled:
# self.memory_stage.executer_buffer = self.execute_stage.executer_buffer
# if (not self.execute_stage.is_stalled
# and not self.decode_stage.has_jumped):
# self.execute_stage.decoder_buffer = self.decode_stage.decoder_buffer
# # TODO: What is this for?
# if not self.decode_stage.is_stalled and not self.execute_stage.branch_pc is not None:
# self.decode_stage.fetcher_buffer = self.fetch_stage.fetcher_buffer
if (self.memory_stage.is_stalled or self.execute_stage.is_stalled
or self.decode_stage.is_stalled):
print 'STALL'
print 'self.memory_stage.is_stalled, self.execute_stage.is_stalled, self.decode_stage.is_stalled: \n', [
self.memory_stage.is_stalled, self.execute_stage.is_stalled,
self.decode_stage.is_stalled
]
if self.execute_stage.branch_pc is not None:
self.decode_stage.undo_dirties(self.execute_stage.is_stalled)
print 'self.register_file: ', self.register_file
self.decoder_buffer.clear()
self.fetcher_buffer.clear()
# TODO: Can there be a jump PC from Decode and a branch PC
# from Execute at the end of the same cycle?
if self.decode_stage.has_jumped:
# Pass on PC value from decoder_buffer to fetcher_buffer in
# case of a jump.
self.fetch_stage.fetch_input_buffer.PC = self.decode_stage.jump_pc
elif self.execute_stage.branch_pc is not None:
self.fetch_stage.fetch_input_buffer.PC = self.execute_stage.branch_pc
def execute_cycles(self, num_cycles=None):
"""Execute num_cycles cycles of the Processor (if possible).
Else, execute till the program terminates.
"""
self.cycle_count = 0
print 'self.memory: ', self.memory
while True:
self.cycle_count += 1
print '\n'
print 'Beginning of Cycle #' + str(self.cycle_count)
print '=' * 12
print '[self.decode_stage, self.execute_stage, self.memory_stage]: ', [
stage.is_stalled for stage in
[self.decode_stage, self.memory_stage, self.execute_stage]
]
self.print_buffers()
print self.register_file
self.execute_one_cycle()
if not self.are_instructions_in_flight() or (
num_cycles is not None and self.cycle_count == num_cycles):
break
print '\nAt the end'
print '=' * 12
self.print_buffers()
print self.register_file
def start(self, cycle_data_file_name=default_data_file_name):
"""Start execution of instructions from the start_address.
"""
self.instruction_address = self.start_address
self.execute_cycles()
def getCPI(self):
return (1.0 * self.cycle_count
) / self.fetch_stage.fetch_input_buffer.instr_count