Introduce jumps

elm.go

@@ -13,10 +13,15 @@ type Operation int
 const (
 	HALT Operation = 0
 	PUSH Operation = 1
-	ADD Operation = 2
+	POP Operation = 2
-	SUB Operation = 3
+	DUP Operation = 3
-	MUL Operation = 4
+	ADD Operation = 4
-	DIV Operation = 5
+	SUB Operation = 5
+	MUL Operation = 6
+	DIV Operation = 7
+	EQ Operation = 8
+	JMP Operation = 9
+	JMPIF Operation = 10
 )
 
 type Inst struct {
@@ -61,33 +66,55 @@ func (m* Machine) Execute() error {
 		m.stack[m.sp] = instr.Operand
 		m.sp++
 		m.ip++
+	case POP:
+		if (m.sp <= 0) {
+			return errors.New("Empty Stack")
+		}
+
+		m.stack[m.sp] = 0
+		m.sp--
+	case DUP:
+		if (m.sp - instr.Operand <= 0) {
+			return errors.New("Stack Underflow")
+		}
+
+		if (m.sp >= STACK_SIZE) {
+            return errors.New("Stack Overflow");
+        }
+
+		if (instr.Operand < 0) {
+			return errors.New("Illegal access")
+		}
+
+		m.stack[m.sp] = m.stack[m.sp - 1 - instr.Operand]
+		m.sp++
 	case ADD:
-		if (len(m.stack) < 2) {
+		if (m.sp < 2) {
-			return errors.New("Stack size is less than required to execute ADD")
+			return errors.New("Stack size is less than required to execute binary operation")
 		}
 		
 		m.stack[m.sp - 2] += m.stack[m.sp - 1];
 		m.sp--
 		m.ip++
 	case SUB:
-		if (len(m.stack) < 2) {
+		if (m.sp < 2) {
-			return errors.New("Stack size is less than required to execute SUB")
+			return errors.New("Stack size is less than required to execute binary operation")
 		}
 
 		m.stack[m.sp - 2] -= m.stack[m.sp - 1];
 		m.sp--
 		m.ip++
 	case MUL:
-		if (len(m.stack) < 2) {
+		if (m.sp < 2) {
-			return errors.New("Stack size is less than required to execute MUL")
+			return errors.New("Stack size is less than required to execute binary operation")
 		}
 
 		m.stack[m.sp - 2] *= m.stack[m.sp - 1];
 		m.sp--
 		m.ip++
 	case DIV:
-		if (len(m.stack) < 2) {
+		if (m.sp < 2) {
-			return errors.New("Stack size is less than required to execute DIV")
+			return errors.New("Stack size is less than required to execute binary operation")
 		}
 
 		if (m.stack[m.sp - 2] == 0 || m.stack[m.sp - 1] == 0) {
@@ -97,6 +124,41 @@ func (m* Machine) Execute() error {
 		m.stack[m.sp - 2] /= m.stack[m.sp - 1];
 		m.sp--
 		m.ip++
+	case EQ:
+		if (m.sp < 2) {
+			return errors.New("Stack size is less than required to execute binary operation")
+		}
+
+		eq := m.stack[m.sp - 1] == m.stack[m.sp - 2]
+		if (eq) {
+			m.stack[m.sp - 2] = 1
+		} else {
+			m.stack[m.sp - 2] = 0
+		}
+
+		m.sp--
+		m.ip++
+	case JMP:
+		if (m.ip < instr.Operand || instr.Operand < 0) {
+			return errors.New("Illegal access")
+		}
+
+		m.ip = instr.Operand
+	case JMPIF:
+		if (m.sp < 1) {
+			return errors.New("Stack Underflow")
+		}
+
+		if (m.ip < instr.Operand || instr.Operand < 0) {
+			return errors.New("Illegal access")
+		}
+		
+		if (m.stack[m.sp - 1] >= 1) {
+			m.sp--
+			m.ip = instr.Operand
+		} else {
+			m.ip++
+		}
 	}
 	return nil
 }
@@ -111,22 +173,32 @@ func (m* Machine) Print() {
 func main() {
 	m := Constructor()
 
+	// m.Push(Inst{Operation: PUSH, Operand: 1})
+	// m.Push(Inst{Operation: PUSH, Operand: 2})
+	// m.Push(Inst{Operation: ADD})
+	// m.Push(Inst{Operation: PUSH, Operand: 2})
+	// m.Push(Inst{Operation: SUB})
+	// m.Push(Inst{Operation: PUSH, Operand: 6})
+	// m.Push(Inst{Operation: MUL})
+	// m.Push(Inst{Operation: PUSH, Operand: 2})
+	// m.Push(Inst{Operation: DIV})
+	// m.Push(Inst{Operation: HALT})
+
+	m.Push(Inst{Operation: PUSH, Operand: 0})
 	m.Push(Inst{Operation: PUSH, Operand: 1})
-	m.Push(Inst{Operation: PUSH, Operand: 2})
 	m.Push(Inst{Operation: ADD})
-	m.Push(Inst{Operation: PUSH, Operand: 2})
+	m.Push(Inst{Operation: JMP, Operand: 1})
-	m.Push(Inst{Operation: SUB})
-	m.Push(Inst{Operation: PUSH, Operand: 6})
-	m.Push(Inst{Operation: MUL})
-	m.Push(Inst{Operation: PUSH, Operand: 2})
-	m.Push(Inst{Operation: DIV})
 	m.Push(Inst{Operation: HALT})
 	
-	for !m.isHalted {
+	stackCounter := 0
+	for !m.isHalted && stackCounter < 69  {
 		m.Print()
 		err := m.Execute()
 		if err != nil {
-			fmt.Fprintf(os.Stderr, "[ERR] %s", err);
+			fmt.Fprintf(os.Stderr, "[ERR] %s\n", err);
-		}
+			os.Exit(1)
+		}
+		stackCounter++
+
 	}
 }