class Controller:
def __init__(self):
"""Model of a standard contoller unit demonstrating the Texas 4-step (fetch,decode,execute,store) with methods for each."""
self.R1 = 0 # General purpose register to store final result.
self.R2 = 0 # General purpose register to store file length.
self.R3 = "" # Storage register to store mnemonic from memory.
self.IR = 0 # Instruction register
self.PC = 0 # Program counter/accumulator
self.running = False # Machine state
self.clock = time.time() # Start system clock
self.ALU = ALU() # Arithmetic-logic units
self.MEM = Memory() # System memory
def loader(self, cfile):
"""Load file data into memory prior 4-step and store it into gp register R2."""
io("Loading " + cfile + "...")
self.R2 = self.MEM.loader(cfile)
io("Processed: " + str(self.R2) + " lines.")
io("Machine is running...")
self.running = True
def fetch(self):
"""Fetch next instruction stored in memory using PC address and store it into storage register R3."""
self.R3 = self.MEM.read(self.PC)
io("|FETCH|--> address(" + str(self.PC) + ")")
io(">read(" + str(self.PC) + "->" + self.R3 + ")")
def decode(self):
"""Decode data fetched. Determine if valid value or instruction, bump accumulator, and store in inst register IR."""
self.PC += 1
try:
self.IR = int(self.R3)
self.R3 = "push"
io("\t|DECODE|--> decoding(" + str(self.IR) + ")...")
io("\t>found operand(" + str(self.IR) + ")")
io("\t>valid instruction")
except ValueError:
self.IR = self.R3
io("\t|DECODE|--> decoding(" + self.IR + ")...")
io("\t>found operator(" + self.IR + ")")
io("\t>valid instruction")
def execute(self):
"""Execute instruction fetched from memory and operate/manage stack memory."""
op = self.R3
if op == "push":
io("\t\t|EXECUTE|--> " + op)
io("\t\t>pushed(" + str(self.IR) + ")")
self.MEM.push(self.IR)
else:
op1, op2 = self.MEM.pop()
io("\t\t|EXECUTE|--> " + op + "(" + str(op1) + "," + str(op2) + ")")
io("\t\t>pop <-(" + str(op1) + ")")
io("\t\t>pop <-(" + str(op2) + ")")
self.R1 = self.ALU.operate(op, op1, op2)
io("\t\t>push ->(" + str(self.R1) + ")")
self.MEM.push(self.R1)
def store(self):
"""Store resulting data, output value that is stored in register."""
io("\t\t\t|STORE|--> storing(" + str(self.R1) + ")")
def run(self):
"""Start steppin. Begin the Texas 4-step, calculate/display the total processing time, and display final result."""
while self.running and self.PC < self.R2:
io("=" * 62)
self.fetch()
self.decode()
self.execute()
self.store()
io(
"=" * 62
+ "\nResult:\t"
+ str(self.R1)
+ "\nTime :\t"
+ str(round(time.time() - self.clock, 4))
+ " s\n"
+ "=" * 62
)
