Andrew haberman

cpu.py

@@ -0,0 +1,154 @@
+"""CPU functionality."""
+
+import sys
+
+class CPU:
+    """Main CPU class."""
+
+    def __init__(self):
+        """Construct a new CPU."""
+        self.ram = [0] * 256
+        self.reg = [0] * 8 
+        self.sp = 7
+        self.reg[self.sp] = 0xF4
+        self.pc = 0
+        self.ir = 0
+        self.fl = 6
+        self.op_table = {
+                        0b10000010 : self.ldi, 
+                        0b01000111 : self.prn, 
+                        0b10100010 : self.mult,
+                        0b00000001 : self.hlt,
+                        0b01000101 : self.push,
+                        0b01000110 : self.pop,
+                        0b01010000 : self.call, 
+                        0b00010001 : self.ret,
+                        0b10100000 : self.add, 
+                        0b01010110 : self.jne,
+                        0b01010100 : self.jmp,
+                        0b01010101 : self.jeq, 
+                        0b10100111 : self.cmpp}
+
+    def load(self):
+        """Load a program into memory."""
+
+        address = 0
+
+        file = open('sctest.ls8',  "r")
+        for line in file.readlines():
+            try:
+                x = line[:line.index("#")]
+            except ValueError:
+                x = line
+
+            try: 
+                y = int(x, 2)
+                self.ram[address] = y
+            except ValueError:
+                continue
+            address+=1
+
+    def ldi(self, op_a, op_b):
+        self.reg[op_a] = op_b
+
+    def mult(self, op_a, op_b):
+        self.reg[op_a] = self.reg[op_a] * self.reg[op_b]
+
+    # Push the value in the given register on the stack.
+    def push(self, op_a, op_b):        
+        self.reg[self.sp] -= 1
+        self.ram[self.reg[self.sp]] = self.reg[op_a]
+
+    # Pop the value at the top of the stack into the given register.
+    def pop(self, op_a, op_b):
+        self.reg[op_a] = self.ram[self.reg[self.sp]]
+        self.reg[self.sp] += 1
+
+    # Sets the PC to the register value
+    def call(self, op_a, op_b):
+        self.reg[self.sp] -= 1
+        self.ram[self.reg[self.sp]] = self.pc + 2
+        self.pc = self.reg[op_a]
+        return True
+
+    def ret(self, op_a, op_b):
+        self.pop(op_a, 0)
+        self.pc = self.reg[op_a]
+        return True
+
+    def add(self, op_a, op_b):
+        self.reg[op_a] = self.reg[op_a] + self.reg[op_b]
+
+    def cmpp(self, op_a, op_b):
+        value_a = self.reg[op_a]
+        value_b = self.reg[op_b]
+
+        if value_a == value_b:
+            self.reg[self.fl] = 1
+        elif value_a > value_b:
+            self.reg[self.fl] = 2
+        else:
+            self.reg[self.fl] = 4
+
+
+    def jne(self, op_a, op_b):
+        value = self.reg[self.fl]
+        if value == 2 or value == 4:
+            return self.jmp(op_a, 0)
+
+    def jmp(self, op_a, op_b):
+        self.pc = self.reg[op_a]
+        return True
+
+    def jeq(self, op_a, op_b):
+        if self.reg[self.fl] == 1:
+            return self.jmp(op_a, 0)
+
+    def ram_read(self, address):
+        return self.ram[address]
+
+    def ram_write(self, value, address):
+        self.ram[address] = value
+
+    def prn(self, op_a, op_b):
+        print(self.reg[op_a])
+
+    def hlt(self, op_a, op_b):
+        sys.exit()
+
+    def alu(self, op, reg_a, reg_b):
+        """ALU operations."""
+        if op == "ADD":
+            self.reg[reg_a] += self.reg[reg_b]
+        else:
+            raise Exception("Unsupported ALU operation")
+
+    def trace(self):
+        """
+        Handy function to print out the CPU state. You might want to call this
+        from run() if you need help debugging.
+        """
+        print(f"TRACE: %02X | %02X %02X %02X |" % (
+            self.pc,
+            #self.fl,
+            #self.ie,
+            self.ram_read(self.pc),
+            self.ram_read(self.pc + 1),
+            self.ram_read(self.pc + 2)
+        ), end='')
+
+        for i in range(8):
+            print(" %02X" % self.reg[i], end='')
+
+        print()
+
+    def run(self):
+        """Run the CPU."""
+        while True:
+            self.ir = self.ram[self.pc]
+            op_a = self.ram[self.pc + 1]
+            op_b = self.ram[self.pc + 2]
+
+            willJump = self.op_table[self.ir](op_a, op_b)
+            if not willJump:
+                self.pc += (self.ir >> 6) + 1

ls8.py

@@ -0,0 +1,11 @@
+#!/usr/bin/env python3
+
+"""Main."""
+
+import sys
+from cpu import *
+
+cpu = CPU()
+
+cpu.load()
+cpu.run()