⛓ Pull

cpu.py

@@ -0,0 +1,145 @@
+"""CPU functionality."""
+
+import sys
+
+ADD = 0b10100000
+HLT = 0b00000001
+LDI = 0b10000010
+PRN = 0b01000111
+MUL = 0b10100010
+PUSH = 0b01000101
+POP =  0b01000110
+CALL = 0b01010000
+RET = 0b00010001
+CMP = 0b10100111
+JMP = 0b01010100
+JEQ = 0b01010101
+JNE = 0b01010110
+
+class CPU:
+    """Main CPU class."""
+
+    def __init__(self):
+        """Construct a new CPU."""
+
+        # is computer running:
+        self.running = False
+
+        self.ram = [0] * 256
+
+
+        self.reg = [0] * 8
+
+        # Internal Registers
+        self.pc = 0 # Program Counter: address of the currently executing instruction
+        self.mem_add = 0 # Memory Address Register: holds the memory address we're reading or writing
+        # Memory Data Register: holds the value to write or the value just read
+        self.fl = 0b00000000 # Flag Register: holds the current flags status
+        self.SP = 7
+        self.reg[self.SP] = 0xf4  #Register at SP contains f4, most recent key press, last element in stack
+
+    def load(self):
+        """Load a program into memory."""
+        address = 0
+
+        with open(sys.argv[1]) as f:
+            for line in f:
+                l_value = line.split("#")[0].strip()
+                if l_value == '':
+                    continue
+                val = int(l_value, 2)
+                self.ram[address] = val
+                address += 1
+
+
+    def alu(self, op, reg_a, reg_b):
+        """ALU operations."""
+
+        if op == "ADD":
+            self.reg[reg_a] += self.reg[reg_b]
+        #elif op == "SUB": etc
+        elif op == 'MULT':
+            self.reg[reg_a] *= self.reg[reg_b]
+        elif op == "CMP":
+            self.fl = 0b00000000
+            if self.reg[reg_a] == self.reg[reg_b]:
+                self.fl = 0b00000001
+            elif self.reg[reg_a] < self.reg[reg_b]:
+                self.fl = 0b00000100
+            elif self.reg[reg_a] > self.reg[reg_b]:
+                self.fl = 0b00000010
+        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):
+        self.running = True
+        while self.running:
+            ir = self.ram_read(self.pc)  # Instruction register
+            operand_a = self.ram_read(self.pc + 1)
+            operand_b = self.ram_read(self.pc + 2)
+
+            if ir == HLT: 
+                self.running = False
+            elif ir == PRN:
+                print(self.reg[operand_a])
+                self.pc += 2
+            elif ir == LDI:
+                self.reg[operand_a] = operand_b
+                self.pc += 3
+            elif ir == ADD:
+                self.alu(ir, operand_a, operand_b)
+            elif ir == MUL:
+                self.alu("MUL", operand_a, operand_b)
+                self.pc += 3
+            elif ir == PUSH:
+                self.reg[self.SP] -= 1
+                self.ram_write(self.reg[self.SP], self.reg[operand_a])
+                self.pc += 2
+            elif ir == POP:
+                self.trace()
+                self.reg[operand_a] = self.ram[self.reg[self.SP]]
+                self.reg[self.SP] += 1
+                self.pc +=2
+            elif ir == CMP:
+                self.alu("CMP", operand_a, operand_b)
+                print("Comparing")
+            elif ir == JMP:
+                self.pc = self.reg[operand_a]
+            elif ir == JEQ:
+                if self.fl == 1:
+                    self.pc = self.reg[operand_a]
+            elif ir == JNE:
+                if self.fl != 1:
+                    self.pc = self.reg[operand_a]
+            else:
+                print("Help computer; stop all downloading")
+                self.running = False
+
+
+
+
+    def ram_read(self, mem_add):
+        return self.ram[mem_add]
+
+    def ram_write(self, mem_add, value):
+        self.ram[mem_add] = value

ls8.py

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