Implemented SHL, SHR opcode (#250)

pkg/vm/vm_ops.go

@@ -5,6 +5,8 @@ import "github.com/CityOfZion/neo-go/pkg/vm/stack"
 type stackInfo func(op stack.Instruction, ctx *stack.Context, istack *stack.Invocation, rstack *stack.RandomAccess) (Vmstate, error)
 
 var opFunc = map[stack.Instruction]stackInfo{
+	stack.SHR:         Shr,
+	stack.SHL:         Shl,
 	stack.INC:         Inc,
 	stack.DEC:         Dec,
 	stack.DIV:         Div,

pkg/vm/vm_ops_maths.go

@@ -260,6 +260,46 @@ func popTwoIntegers(ctx *stack.Context) (*stack.Int, *stack.Int, error) {
 	return operandA, operandB, nil
 }
 
+// Shl pops two integers, a and b, off of the stack and pushes an integer to the stack
+// whose value is the b's value shift to the left by a's value bits.
+// Returns an error if either items cannot be casted to an integer
+// or if the left shift operation cannot per performed with the two integer's value.
+func Shl(op stack.Instruction, ctx *stack.Context, istack *stack.Invocation, rstack *stack.RandomAccess) (Vmstate, error) {
+
+	a, b, err := popTwoIntegers(ctx)
+	if err != nil {
+		return FAULT, err
+	}
+	res, err := b.Lsh(a)
+	if err != nil {
+		return FAULT, err
+	}
+
+	ctx.Estack.Push(res)
+
+	return NONE, nil
+}
+
+// Shr pops two integers, a and b, off of the stack and pushes an integer to the stack
+// whose value is the b's value shift to the right by a's value bits.
+// Returns an error if either items cannot be casted to an integer
+// or if the right shift operation cannot per performed with the two integer's value.
+func Shr(op stack.Instruction, ctx *stack.Context, istack *stack.Invocation, rstack *stack.RandomAccess) (Vmstate, error) {
+
+	a, b, err := popTwoIntegers(ctx)
+	if err != nil {
+		return FAULT, err
+	}
+	res, err := b.Rsh(a)
+	if err != nil {
+		return FAULT, err
+	}
+
+	ctx.Estack.Push(res)
+
+	return NONE, nil
+}
+
 func popTwoByteArrays(ctx *stack.Context) (*stack.ByteArray, *stack.ByteArray, error) {
 	// Pop first stack item and cast as byte array
 	ba1, err := ctx.Estack.PopByteArray()

pkg/vm/vm_ops_maths_test.go

@@ -326,3 +326,71 @@ func TestNegateOp(t *testing.T) {
 
 	assert.Equal(t, int64(20), item.Value().Int64())
 }
+
+func TestShlOp(t *testing.T) {
+
+	v := VM{}
+
+	a, err := stack.NewInt(big.NewInt(2))
+	if err != nil {
+		t.Fail()
+	}
+	b, err := stack.NewInt(big.NewInt(3))
+	if err != nil {
+		t.Fail()
+	}
+
+	ctx := stack.NewContext([]byte{})
+	ctx.Estack.Push(a).Push(b)
+
+	// b is the first item pop.
+	// a is the second item pop.
+	// we perform a.Lsh(b) and place
+	// the result on top of the evaluation
+	// stack
+	v.executeOp(stack.SHL, ctx)
+
+	// Stack should have one item
+	assert.Equal(t, 1, ctx.Estack.Len())
+
+	item, err := ctx.Estack.PopInt()
+	if err != nil {
+		t.Fail()
+	}
+
+	assert.Equal(t, int64(16), item.Value().Int64())
+}
+
+func TestShrOp(t *testing.T) {
+
+	v := VM{}
+
+	a, err := stack.NewInt(big.NewInt(10))
+	if err != nil {
+		t.Fail()
+	}
+	b, err := stack.NewInt(big.NewInt(2))
+	if err != nil {
+		t.Fail()
+	}
+
+	ctx := stack.NewContext([]byte{})
+	ctx.Estack.Push(a).Push(b)
+
+	// b is the first item pop.
+	// a is the second item pop.
+	// we perform a.Rsh(b) and place
+	// the result on top of the evaluation
+	// stack
+	v.executeOp(stack.SHR, ctx)
+
+	// Stack should have one item
+	assert.Equal(t, 1, ctx.Estack.Len())
+
+	item, err := ctx.Estack.PopInt()
+	if err != nil {
+		t.Fail()
+	}
+
+	assert.Equal(t, int64(2), item.Value().Int64())
+}