You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: vm.go
    path of file: ./repos/bytom/lib/golang.org/x/net/bpf
    
    the code of the file until where you have to start completion: // Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package bpf

import (
	"errors"
	"fmt"
)

// A VM is an emulated BPF virtual machine.
type VM struct {
	filter []Instruction
}

// NewVM returns a new VM using the input BPF program.
func NewVM(filter []Instruction) (*VM, error) {
	if len(filter) == 0 {
		return nil, errors.New("one or more Instructions must be specified")
	}

	for i, ins := range filter {
		check := len(filter) - (i + 1)
		switch ins := ins.(type) {
		// Check for out-of-bounds jumps in instructions
		case Jump:
			if check <= int(ins.Skip) {
				return nil, fmt.Errorf("cann
    
func (v *VM) Run(in []byte) (int, error) {
	var (
		// Registers of the virtual machine
		regA       uint32
		regX       uint32
		regScratch [16]uint32

		// OK is true if the program should continue processing the next
		// instruction, or false if not, causing the loop to break
		ok = true
	)

	// TODO(mdlayher): implement:
	// - NegateA:
	//   - would require a change from uint32 registers to int32
	//     registers

	// TODO(mdlayher): add interop tests that check signedness of ALU
	// operations against kernel implementation, and make sure Go
	// implementation matches behavior

	for i := 0; i < len(v.filter) && ok; i++ {
		ins := v.filter[i]

		switch ins := ins.(type) {
		case ALUOpConstant:
			regA = aluOpConstant(ins, regA)
		case ALUOpX:
			regA, ok = aluOpX(ins, regA, regX)
		case Jump:
			i += int(ins.Skip)
		case JumpIf:
			jump := jumpIf(ins, regA)
			i += jump
		case LoadAbsolute:
			regA, ok = loadAbsolute(ins, in)
		case LoadConstant:
			regA, regX = loadConstant(ins, regA, regX)
		case LoadExtension:
			regA = loadExtension(ins, in)
		case LoadIndirect:
			regA, ok = loadIndirect(ins, in, regX)
		case LoadMemShift:
			regX, ok = loadMemShift(ins, in)
		case LoadScratch:
			regA, regX = loadScratch(ins, regScratch, regA, regX)
		case RetA:
			return int(regA), nil
		case RetConstant:
			return int(ins.Val), nil
		case StoreScratch:
			regScratch = storeScratch(ins, regScratch, regA, regX)
		case TAX:
			regX = regA
		case TXA:
			regA = regX
		default:
			return 0, fmt.Errorf("unknown Instruction at index %d: %T", i, ins)
		}
	}

	return 0, nil
}