VM draft + cli setup (#20)

* updated readme

* added basic cmd.

* added seperate folders for cmd packages.

* Fix netmodes in test + reverse bigint bytes

* glide get deps

README.md

@@ -50,8 +50,9 @@ The project will exist out of the following packages:
 | api           | started | [@anthdm](https://github.com/anthdm) |
 | core          | started | [@anthdm](https://github.com/anthdm) |
 | network       | started | [@anthdm](https://github.com/anthdm) |
+| vm            | started | [@anthdm](https://github.com/anthdm) |
 | smartcontract | started | [@revett](https://github.com/revett) |
-| vm            | started | [@revett](https://github.com/revett) |
+| cli           | started | [@revett](https://github.com/revett) |
 
 # Getting Started 
 

VERSION

@@ -1 +1 @@
-0.8.0
+0.9.0

cli/main.go

@@ -1,43 +1,21 @@
 package main
 
 import (
-	"flag"
-	"strings"
+	"os"
 
-	"github.com/CityOfZion/neo-go/pkg/network"
+	"github.com/CityOfZion/neo-go/cli/server"
+	"github.com/CityOfZion/neo-go/cli/smartcontract"
+	"github.com/urfave/cli"
 )
 
-var (
-	tcp  = flag.Int("tcp", 3000, "port TCP listener will listen on.")
-	seed = flag.String("seed", "", "initial seed servers.")
-	net  = flag.Int("net", 56753, "the mode the server will operate in.")
-	rpc  = flag.Int("rpc", 0, "let this server also respond to rpc calls on this port")
-)
-
-// Simple dirty and quick bootstrapping for the sake of development.
-// e.g run 2 nodes:
-// neoserver -tcp :4000
-// neoserver -tcp :3000 -seed 127.0.0.1:4000
 func main() {
-	flag.Parse()
+	ctl := cli.NewApp()
+	ctl.Name = "neo-go"
 
-	opts := network.StartOpts{
-		Seeds: parseSeeds(*seed),
-		TCP:   *tcp,
-		RPC:   *rpc,
+	ctl.Commands = []cli.Command{
+		server.NewCommand(),
+		smartcontract.NewCommand(),
 	}
 
-	s := network.NewServer(network.NetMode(*net))
-	s.Start(opts)
-}
-
-func parseSeeds(s string) []string {
-	if len(s) == 0 {
-		return nil
-	}
-	seeds := strings.Split(s, ",")
-	if len(seeds) == 0 {
-		return nil
-	}
-	return seeds
+	ctl.Run(os.Args)
 }

cli/server/server.go

@@ -0,0 +1,56 @@
+package server
+
+import (
+	"strings"
+
+	"github.com/CityOfZion/neo-go/pkg/network"
+	"github.com/urfave/cli"
+)
+
+// NewCommand creates a new Node command
+func NewCommand() cli.Command {
+	return cli.Command{
+		Name:   "node",
+		Usage:  "start a NEO node",
+		Action: startServer,
+		Flags: []cli.Flag{
+			cli.IntFlag{Name: "tcp"},
+			cli.IntFlag{Name: "rpc"},
+			cli.StringFlag{Name: "seed"},
+			cli.BoolFlag{Name: "privnet, p"},
+			cli.BoolFlag{Name: "mainnet, m"},
+			cli.BoolFlag{Name: "testnet, t"},
+		},
+	}
+}
+
+func startServer(ctx *cli.Context) error {
+	opts := network.StartOpts{
+		Seeds: parseSeeds(ctx.String("seed")),
+		TCP:   ctx.Int("tcp"),
+		RPC:   ctx.Int("rpc"),
+	}
+
+	net := network.ModePrivNet
+	if ctx.Bool("testnet") {
+		net = network.ModeTestNet
+	}
+	if ctx.Bool("mainnet") {
+		net = network.ModeMainNet
+	}
+
+	s := network.NewServer(net)
+	s.Start(opts)
+	return nil
+}
+
+func parseSeeds(s string) []string {
+	if len(s) == 0 {
+		return nil
+	}
+	seeds := strings.Split(s, ",")
+	if len(seeds) == 0 {
+		return nil
+	}
+	return seeds
+}

cli/smartcontract/smart_contract.go

@@ -0,0 +1,44 @@
+package smartcontract
+
+import (
+	"fmt"
+
+	"github.com/CityOfZion/neo-go/pkg/vm"
+	"github.com/urfave/cli"
+)
+
+// NewCommand returns a new contract command.
+func NewCommand() cli.Command {
+	return cli.Command{
+		Name:  "contract",
+		Usage: "compile - debug - deploy smart contracts",
+		Subcommands: []cli.Command{
+			{
+				Name:   "compile",
+				Usage:  "compile a smart contract to a .avm file",
+				Action: contractCompile,
+			},
+			{
+				Name:   "opdump",
+				Usage:  "dump the opcode of a .go file",
+				Action: contractDumpOpcode,
+			},
+		},
+	}
+}
+
+func contractCompile(ctx *cli.Context) error {
+	fmt.Println("compile")
+	return nil
+}
+
+func contractDumpOpcode(ctx *cli.Context) error {
+	src := ctx.Args()[0]
+
+	c := vm.NewCompiler()
+	if err := c.CompileSource(src); err != nil {
+		return err
+	}
+	c.DumpOpcode()
+	return nil
+}

glide.lock

@@ -1,5 +1,5 @@
-hash: 2b8debf7936e789545da367433ddbf5f0e3bb54658340d6a412970bca25e6335
-updated: 2018-02-05T16:11:44.616743+01:00
+hash: 5cb2fb077aa0e57c788a99f9ded4bf2d421a04f12f6b8436234d12e93f418f36
+updated: 2018-02-09T16:49:32.538502496+01:00
 imports:
 - name: github.com/golang/snappy
   version: 553a641470496b2327abcac10b36396bd98e45c9
@@ -18,4 +18,6 @@ imports:
   - leveldb/storage
   - leveldb/table
   - leveldb/util
+- name: github.com/urfave/cli
+  version: cfb38830724cc34fedffe9a2a29fb54fa9169cd1
 testImports: []

glide.yaml

@@ -1,5 +1,7 @@
 package: github.com/CityOfZion/neo-go
 import:
-  - package: github.com/syndtr/goleveldb/leveldb
-
-
+- package: github.com/syndtr/goleveldb
+  subpackages:
+  - leveldb
+- package: github.com/urfave/cli
+  version: ^1.20.0

pkg/network/message.go

@@ -28,8 +28,8 @@ type NetMode uint32
 // String implements the stringer interface.
 func (n NetMode) String() string {
 	switch n {
-	case ModeDevNet:
-		return "devnet"
+	case ModePrivNet:
+		return "privnet"
 	case ModeTestNet:
 		return "testnet"
 	case ModeMainNet:
@@ -42,8 +42,8 @@ func (n NetMode) String() string {
 // Values used for the magic field, according to the docs.
 const (
 	ModeMainNet NetMode = 0x00746e41 // 7630401
-	ModeTestNet         = 0x74746e41 // 1953787457
-	ModeDevNet          = 56753      // docker privnet
+	ModeTestNet NetMode = 0x74746e41 // 1953787457
+	ModePrivNet NetMode = 56753      // docker privnet
 )
 
 // Message is the complete message send between nodes.

pkg/network/server.go

@@ -105,7 +105,7 @@ func (m protectedHashmap) has(h util.Uint256) bool {
 func NewServer(net NetMode) *Server {
 	logger := log.New(os.Stdout, "[NEO SERVER] :: ", 0)
 
-	if net != ModeTestNet && net != ModeMainNet && net != ModeDevNet {
+	if net != ModeTestNet && net != ModeMainNet && net != ModePrivNet {
 		logger.Fatalf("invalid network mode %d", net)
 	}
 

pkg/network/server_test.go

@@ -9,7 +9,7 @@ import (
 // TODO this should be moved to localPeer test.
 
 func TestHandleVersionFailWrongPort(t *testing.T) {
-	s := NewServer(ModeDevNet)
+	s := NewServer(ModePrivNet)
 	go s.loop()
 
 	p := NewLocalPeer(s)
@@ -21,7 +21,7 @@ func TestHandleVersionFailWrongPort(t *testing.T) {
 }
 
 func TestHandleVersionFailIdenticalNonce(t *testing.T) {
-	s := NewServer(ModeDevNet)
+	s := NewServer(ModePrivNet)
 	go s.loop()
 
 	p := NewLocalPeer(s)
@@ -33,7 +33,7 @@ func TestHandleVersionFailIdenticalNonce(t *testing.T) {
 }
 
 func TestHandleVersion(t *testing.T) {
-	s := NewServer(ModeDevNet)
+	s := NewServer(ModePrivNet)
 	go s.loop()
 
 	p := NewLocalPeer(s)

pkg/util/uint256.go

@@ -23,7 +23,7 @@ func Uint256DecodeFromString(s string) (Uint256, error) {
 		return val, err
 	}
 
-	b = ReverseByteSlice(b)
+	b = ToArrayReverse(b)
 
 	return Uint256DecodeFromBytes(b)
 }
@@ -43,7 +43,8 @@ func Uint256DecodeFromBytes(b []byte) (Uint256, error) {
 	return val, nil
 }
 
-func ReverseByteSlice(b []byte) []byte {
+// ToArrayReverse return a reversed version of the given byte slice.
+func ToArrayReverse(b []byte) []byte {
 	dest := make([]byte, len(b))
 
 	for i, j := 0, len(b)-1; i < j; i, j = i+1, j-1 {

pkg/vm/compiler.go

@@ -0,0 +1,194 @@
+package vm
+
+import (
+	"bytes"
+	"fmt"
+	"go/ast"
+	"go/parser"
+	"go/token"
+	"io"
+	"os"
+	"reflect"
+	"strconv"
+	"strings"
+)
+
+const (
+	outputExt = ".avm"
+)
+
+// Syscalls that have no return value.
+var nonReturnSysCalls = []string{
+	"Notify", "print", "Log", "Put", "Register",
+	"append", "Delete", "SetVotes", "ContractDestroy",
+	"MerkleRoot", "Hash", "PrevHash", "GetHeader"}
+
+// Compiler holds the output buffer of the compiled source.
+type Compiler struct {
+	// Output extension of the file. Default .avm.
+	OutputExt  string
+	sb         *ScriptBuilder
+	curLineNum int
+
+	i       int
+	varList []Variable
+	vars    map[string]Variable
+}
+
+// NewCompiler returns a new compiler ready to compile smartcontracts.
+func NewCompiler() *Compiler {
+	return &Compiler{
+		OutputExt: outputExt,
+		sb:        &ScriptBuilder{new(bytes.Buffer)},
+		vars:      map[string]Variable{},
+		varList:   []Variable{},
+	}
+}
+
+// CompileSource will compile the source file into an avm format.
+func (c *Compiler) CompileSource(src string) error {
+	file, err := os.Open(src)
+	if err != nil {
+		return err
+	}
+	return c.Compile(file)
+}
+
+// Visit implements the ast.Visitor interface.
+func (c *Compiler) Visit(node ast.Node) ast.Visitor {
+	switch t := node.(type) {
+	case *ast.AssignStmt:
+		c.processAssignStmt(t)
+	case *ast.FuncDecl:
+	case *ast.ReturnStmt:
+	}
+	return c
+}
+
+func (c *Compiler) newVariable(k token.Token, i, val string) Variable {
+	v := Variable{
+		kind:  k,
+		ident: i,
+		value: val,
+		pos:   c.i,
+	}
+	c.vars[v.ident] = v
+	c.i++
+	return v
+}
+
+func (c *Compiler) initialize(n OpCode) {
+	// Get the (n) localVars which is basicly the number of args passed in Main
+	// and the number of local Vars in the function body.
+	c.sb.emitPush(n)
+	c.sb.emitPush(OpNewArray)
+	c.sb.emitPush(OpToAltStack)
+}
+
+func (c *Compiler) teardown() {
+	c.sb.emitPush(OpNOP)
+	c.sb.emitPush(OpFromAltStack)
+	c.sb.emitPush(OpDrop)
+	c.sb.emitPush(OpRET)
+}
+
+// Push a variable on to the stack.
+func (c *Compiler) storeLocal(v Variable) {
+	if v.kind == token.INT {
+		val, _ := strconv.Atoi(v.value)
+		c.sb.emitPushInt(int64(val))
+	}
+	if v.kind == token.STRING {
+		val := strings.Replace(v.value, `"`, "", 2)
+		c.sb.emitPushString(val)
+	}
+
+	c.sb.emitPush(OpFromAltStack)
+	c.sb.emitPush(OpDup)
+	c.sb.emitPush(OpToAltStack)
+
+	pos := int64(v.pos)
+
+	c.sb.emitPushInt(pos)
+	c.sb.emitPushInt(2)
+	c.sb.emitPush(OpRoll)
+	c.sb.emitPush(OpSetItem)
+}
+
+func (c *Compiler) loadLocal(ident string) {
+	val, ok := c.vars[ident]
+	if !ok {
+		c.reportError(fmt.Sprintf("local variable %s not found", ident))
+	}
+
+	pos := int64(val.pos)
+
+	c.sb.emitPush(OpFromAltStack)
+	c.sb.emitPush(OpDup)
+	c.sb.emitPush(OpToAltStack)
+
+	// push it's index on the stack
+	c.sb.emitPushInt(pos)
+	c.sb.emitPush(OpPickItem)
+}
+
+// TODO: instead of passing the stmt in to this, put the lhs and rhs in.
+// so we can reuse this.
+func (c *Compiler) processAssignStmt(stmt *ast.AssignStmt) {
+	lhs := stmt.Lhs[0].(*ast.Ident)
+	switch t := stmt.Rhs[0].(type) {
+	case *ast.BasicLit:
+		c.storeLocal(c.newVariable(t.Kind, lhs.Name, t.Value))
+	case *ast.CompositeLit:
+		switch t.Type.(type) {
+		case *ast.StructType:
+			c.reportError("assigning struct literals not yet implemented")
+		case *ast.ArrayType:
+			// for _, expr := range t.Elts {
+			// 	v := expr.(*ast.BasicLit)
+			// 	c.storeLocal(c.newVariable(v.Kind, lhs.Name, v.Value))
+			// }
+		}
+	case *ast.Ident:
+		c.loadLocal(t.Name)
+	case *ast.FuncLit:
+		c.reportError("assigning function literals not yet implemented")
+	default:
+		fmt.Println(reflect.TypeOf(t))
+	}
+}
+
+// Compile will compile from r into an avm format.
+func (c *Compiler) Compile(r io.Reader) error {
+	fset := token.NewFileSet()
+	f, err := parser.ParseFile(fset, "", r, 0)
+	if err != nil {
+		return err
+	}
+
+	c.initialize(OpPush2) // initialize the compiler with n local stack vars.
+	ast.Walk(c, f)        // walk through and process the AST
+	c.teardown()          // done compiling
+
+	return nil
+}
+
+// TODO: More detailed report (lineno, ...)
+func (c *Compiler) reportError(msg string) {
+	fmt.Printf("COMPILER ERROR :: %s\n", msg)
+	os.Exit(1)
+}
+
+// DumpOpcode dumps the current buffer, formatted with index, hex and opcode.
+// Usefull for debugging smartcontracts.
+func (c *Compiler) DumpOpcode() {
+	c.sb.dumpOpcode()
+}
+
+// A Variable can represent any variable in the program.
+type Variable struct {
+	ident string
+	kind  token.Token
+	value string
+	pos   int
+}

pkg/vm/compiler_test.go

@@ -0,0 +1,86 @@
+package vm
+
+import (
+	"strings"
+	"testing"
+)
+
+// opener
+//
+// 0x53 push len arguments
+// 0xc5 open new array
+// 0x6B to alt stack
+//
+// 0x5A the number 10 is pushed on the stack
+// 0x6C put the input onto the main stack remove from alt
+// 0x76 dup the item on top of the stack
+// 0x6B put the item on the alt stack
+// 0x00 put empty array on the stack
+// 0x52 put the number 2 on the stack
+// 0x7A put the item n back on top of the stack
+// 0xC4 set item
+// 0x59 put the number 9 on the stack
+// 0x6C put the input onto the main stack remove from alt stack
+// 0x76 dup the item on top of the stackj
+// 0x6B put the item on the alt stack
+// 0x51 push the number 1 on the stack
+// 0x52 push the number 2 on the stack
+// 0x7A put the item n back on top of the stack
+// 0xC4 set the item
+// 0x62 JMP
+// 0x03 the next 3 bytes is dat pushed on the stack
+// 0x6C put the input ont the main stack remove from alt stack
+// 0x00 put empty array onto the stack
+// 0x02 the next 2 bytes is data pushed on the stack
+// 0xE8 1000 uint16
+// 0x03 1000 uint16
+// 0x6C put the input onto the main stack remove from alt
+// 0x76 dup the item on top of the stack
+// 0x6B put the item on the alt stack
+// 0x52 push the number 2 on the stack
+// 0x52 push the number 2 on the stack
+// 0x7A put the item n back on top of the stack
+// 0xC4 set the item
+// 0x00 empty array is pushed on the stack
+// 0x61 nop
+// 0x6C put the input onto the main stack remove from alt
+// 0x75 removes the top stack item
+// 0x66 return
+
+//
+
+func TestSimpleAssign(t *testing.T) {
+	src := `
+		package NEP5	
+
+		func Main() {
+			x := 10
+			y := 8
+		}
+	`
+
+	c := NewCompiler()
+	if err := c.Compile(strings.NewReader(src)); err != nil {
+		t.Fatal(err)
+	}
+
+	// c.DumpOpcode()
+}
+
+func TestAssignLoadLocal(t *testing.T) {
+	src := `
+		package NEP5	
+
+		func Main() {
+			x := 1
+			y := x
+		}
+	`
+
+	c := NewCompiler()
+	if err := c.Compile(strings.NewReader(src)); err != nil {
+		t.Fatal(err)
+	}
+
+	// c.DumpOpcode()
+}

pkg/vm/opcode.go

@@ -0,0 +1,129 @@
+package vm
+
+// OpCode is an single operational instruction for the GO NEO virtual machine.
+type OpCode byte
+
+// List of supported opcodes.
+const (
+	// Constants
+	OpPush0       OpCode = 0x00 // An empty array of bytes is pushed onto the stack.
+	OpPushF       OpCode = OpPush0
+	OpPushBytes1  OpCode = 0x01 // 0x01-0x4B The next opcode bytes is data to be pushed onto the stack
+	OpPushBytes75 OpCode = 0x4B
+	OpPushData1   OpCode = 0x4C // The next byte contains the number of bytes to be pushed onto the stack.
+	OpPushData2   OpCode = 0x4D // The next two bytes contain the number of bytes to be pushed onto the stack.
+	OpPushData4   OpCode = 0x4E // The next four bytes contain the number of bytes to be pushed onto the stack.
+	OpPushM1      OpCode = 0x4F // The number -1 is pushed onto the stack.
+	OpPush1       OpCode = 0x51
+	OpPushT       OpCode = OpPush1
+	OpPush2       OpCode = 0x52 // The number 2 is pushed onto the stack.
+	OpPush3       OpCode = 0x53 // The number 3 is pushed onto the stack.
+	OpPush4       OpCode = 0x54 // The number 4 is pushed onto the stack.
+	OpPush5       OpCode = 0x55 // The number 5 is pushed onto the stack.
+	OpPush6       OpCode = 0x56 // The number 6 is pushed onto the stack.
+	OpPush7       OpCode = 0x57 // The number 7 is pushed onto the stack.
+	OpPush8       OpCode = 0x58 // The number 8 is pushed onto the stack.
+	OpPush9       OpCode = 0x59 // The number 9 is pushed onto the stack.
+	OpPush10      OpCode = 0x5A // The number 10 is pushed onto the stack.
+	OpPush11      OpCode = 0x5B // The number 11 is pushed onto the stack.
+	OpPush12      OpCode = 0x5C // The number 12 is pushed onto the stack.
+	OpPush13      OpCode = 0x5D // The number 13 is pushed onto the stack.
+	OpPush14      OpCode = 0x5E // The number 14 is pushed onto the stack.
+	OpPush15      OpCode = 0x5F // The number 15 is pushed onto the stack.
+	OpPush16      OpCode = 0x60 // The number 16 is pushed onto the stack.
+
+	// Flow control
+	OpNOP      OpCode = 0x61 // No operation.
+	OpJMP      OpCode = 0x62
+	OpJMPIF    OpCode = 0x63
+	OpJMPIFNOT OpCode = 0x64
+	OpCall     OpCode = 0x65
+	OpRET      OpCode = 0x66
+	OpAppCall  OpCode = 0x67
+	OpSysCall  OpCode = 0x68
+	OpTailCall OpCode = 0x69
+
+	// The stack
+	OpDupFromAltStack OpCode = 0x6A
+	OpToAltStack      OpCode = 0x6B // Puts the input onto the top of the alt stack. Removes it from the main stack.
+	OpFromAltStack    OpCode = 0x6C // Puts the input onto the top of the main stack. Removes it from the alt stack.
+	OpXDrop           OpCode = 0x6D
+	OpXSwap           OpCode = 0x72
+	OpXTuck           OpCode = 0x73
+	OpDepth           OpCode = 0x74 // Puts the number of stack items onto the stack.
+	OpDrop            OpCode = 0x75 // Removes the top stack item.
+	OpDup             OpCode = 0x76 // Duplicates the top stack item.
+	OpNip             OpCode = 0x77 // Removes the second-to-top stack item.
+	OpOver            OpCode = 0x78 // Copies the second-to-top stack item to the top.
+	OpPick            OpCode = 0x79 // The item n back in the stack is copied to the top.
+	OpRoll            OpCode = 0x7A // The item n back in the stack is moved to the top.
+	OpRot             OpCode = 0x7B // The top three items on the stack are rotated to the left.
+	OpSwap            OpCode = 0x7C // The top two items on the stack are swapped.
+	OpTuck            OpCode = 0x7D // The item at the top of the stack is copied and inserted before the second-to-top item.
+
+	// Splice
+	OpCat    OpCode = 0x7E // Concatenates two strings.
+	OpSubStr OpCode = 0x7F // Returns a section of a string.
+	OpLeft   OpCode = 0x80 // Keeps only characters left of the specified point in a string.
+	OpRight  OpCode = 0x81 // Keeps only characters right of the specified point in a string.
+	OpSize   OpCode = 0x82 // Returns the length of the input string.
+
+	// Bitwise logic
+	OpInvert OpCode = 0x83 // Flips all of the bits in the input.
+	OpAnd    OpCode = 0x84 // Boolean and between each bit in the inputs.
+	OpOr     OpCode = 0x85 // Boolean or between each bit in the inputs.
+	OpXor    OpCode = 0x86 // Boolean exclusive or between each bit in the inputs.
+	OpEqual  OpCode = 0x87 // Returns 1 if the inputs are exactly equal, 0 otherwise.
+
+	// Arithmetic
+	// Note: Arithmetic inputs are limited to signed 32-bit integers, but may overflow their output.
+	OpInc         OpCode = 0x8B // 1 is added to the input.
+	OpDec         OpCode = 0x8C // 1 is subtracted from the input.
+	OpSign        OpCode = 0x8D
+	OpNegate      OpCode = 0x8F // The sign of the input is flipped.
+	OpAbs         OpCode = 0x90 // The input is made positive.
+	OpNot         OpCode = 0x91 // If the input is 0 or 1, it is flipped. Otherwise the output will be 0.
+	OpNZ          OpCode = 0x92 // Returns 0 if the input is 0. 1 otherwise.
+	OpAdd         OpCode = 0x93 // a is added to b.
+	OpSub         OpCode = 0x94 // b is subtracted from a.
+	OpMul         OpCode = 0x95 // a is multiplied by b.
+	OpDiv         OpCode = 0x96 // a is divided by b.
+	OpMod         OpCode = 0x97 // Returns the remainder after dividing a by b.
+	OpShl         OpCode = 0x98 // Shifts a left b bits, preserving sign.
+	OpShr         OpCode = 0x99 // Shifts a right b bits, preserving sign.
+	OpBoolAnd     OpCode = 0x9A // If both a and b are not 0, the output is 1. Otherwise 0.
+	OpBoolOr      OpCode = 0x9B // If a or b is not 0, the output is 1. Otherwise 0.
+	OpNumEqual    OpCode = 0x9C // Returns 1 if the numbers are equal, 0 otherwise.
+	OpNumNotEqual OpCode = 0x9E // Returns 1 if the numbers are not equal, 0 otherwise.
+	OpLT          OpCode = 0x9F // Returns 1 if a is less than b, 0 otherwise.
+	OpGT          OpCode = 0xA0 // Returns 1 if a is greater than b, 0 otherwise.
+	OpLTE         OpCode = 0xA1 // Returns 1 if a is less than or equal to b, 0 otherwise.
+	OpGTE         OpCode = 0xA2 // Returns 1 if a is greater than or equal to b, 0 otherwise.
+	OpMin         OpCode = 0xA3 // Returns the smaller of a and b.
+	OpMax         OpCode = 0xA4 // Returns the larger of a and b.
+	OpWithin      OpCode = 0xA5 // Returns 1 if x is within the specified range (left-inclusive), 0 otherwise.
+
+	// Crypto
+	OpSHA1          OpCode = 0xA7 // The input is hashed using SHA-1.
+	OpSHA256        OpCode = 0xA8 // The input is hashed using SHA-256.
+	OpHASH160       OpCode = 0xA9
+	OpHASH256       OpCode = 0xAA
+	OpCheckSig      OpCode = 0xAC
+	OpCheckMultiSig OpCode = 0xAE
+
+	// Array
+	OpArraySize OpCode = 0xC0
+	OpPack      OpCode = 0xC1
+	OpUnpack    OpCode = 0xC2
+	OpPickItem  OpCode = 0xC3
+	OpSetItem   OpCode = 0xC4
+	OpNewArray  OpCode = 0xC5 // Pops size from stack and creates a new array with that size, and pushes the array into the stack
+	OpNewStruct OpCode = 0xC6
+	OpAppend    OpCode = 0xC8
+	OpReverse   OpCode = 0xC9
+	OpRemove    OpCode = 0xCA
+
+	// Exceptions
+	OpThrow      OpCode = 0xF0
+	OpThrowIfNot OpCode = 0xF1
+)

pkg/vm/opcode_string.go

@@ -0,0 +1,118 @@
+// Code generated by "stringer -type=OpCode ./pkg/vm"; DO NOT EDIT.
+
+package vm
+
+import "strconv"
+
+const _OpCode_name = "OpPush0OpPushBytes1OpPushBytes75OpPushData1OpPushData2OpPushData4OpPushM1OpPush1OpPush2OpPush3OpPush4OpPush5OpPush6OpPush7OpPush8OpPush9OpPush10OpPush11OpPush12OpPush13OpPush14OpPush15OpPush16OpNOPOpJMPOpJMPIFOpJMPIFNOTOpCallOpRETOpAppCallOpSysCallOpTailCallOpDupFromAltStackOpToAltStackOpFromAltStackOpXDropOpXSwapOpXTuckOpDepthOpDropOpDupOpNipOpOverOpPickOpRollOpRotOpSwapOpTuckOpCatOpSubStrOpLeftOpRightOpSizeOpInvertOpAndOpOrOpXorOpEqualOpIncOpDecOpSignOpNegateOpAbsOpNotOpNZOpAddOpSubOpMulOpDivOpModOpShlOpShrOpBoolAndOpBoolOrOpNumEqualOpNumNotEqualOpLTOpGTOpLTEOpGTEOpMinOpMaxOpWithinOpSHA1OpSHA256OpHASH160OpHASH256OpCheckSigOpCheckMultiSigOpArraySizeOpPackOpUnpackOpPickItemOpSetItemOpNewArrayOpNewStructOpAppendOpReverseOpRemoveOpThrowOpThrowIfNot"
+
+var _OpCode_map = map[OpCode]string{
+	0:   _OpCode_name[0:7],
+	1:   _OpCode_name[7:19],
+	75:  _OpCode_name[19:32],
+	76:  _OpCode_name[32:43],
+	77:  _OpCode_name[43:54],
+	78:  _OpCode_name[54:65],
+	79:  _OpCode_name[65:73],
+	81:  _OpCode_name[73:80],
+	82:  _OpCode_name[80:87],
+	83:  _OpCode_name[87:94],
+	84:  _OpCode_name[94:101],
+	85:  _OpCode_name[101:108],
+	86:  _OpCode_name[108:115],
+	87:  _OpCode_name[115:122],
+	88:  _OpCode_name[122:129],
+	89:  _OpCode_name[129:136],
+	90:  _OpCode_name[136:144],
+	91:  _OpCode_name[144:152],
+	92:  _OpCode_name[152:160],
+	93:  _OpCode_name[160:168],
+	94:  _OpCode_name[168:176],
+	95:  _OpCode_name[176:184],
+	96:  _OpCode_name[184:192],
+	97:  _OpCode_name[192:197],
+	98:  _OpCode_name[197:202],
+	99:  _OpCode_name[202:209],
+	100: _OpCode_name[209:219],
+	101: _OpCode_name[219:225],
+	102: _OpCode_name[225:230],
+	103: _OpCode_name[230:239],
+	104: _OpCode_name[239:248],
+	105: _OpCode_name[248:258],
+	106: _OpCode_name[258:275],
+	107: _OpCode_name[275:287],
+	108: _OpCode_name[287:301],
+	109: _OpCode_name[301:308],
+	114: _OpCode_name[308:315],
+	115: _OpCode_name[315:322],
+	116: _OpCode_name[322:329],
+	117: _OpCode_name[329:335],
+	118: _OpCode_name[335:340],
+	119: _OpCode_name[340:345],
+	120: _OpCode_name[345:351],
+	121: _OpCode_name[351:357],
+	122: _OpCode_name[357:363],
+	123: _OpCode_name[363:368],
+	124: _OpCode_name[368:374],
+	125: _OpCode_name[374:380],
+	126: _OpCode_name[380:385],
+	127: _OpCode_name[385:393],
+	128: _OpCode_name[393:399],
+	129: _OpCode_name[399:406],
+	130: _OpCode_name[406:412],
+	131: _OpCode_name[412:420],
+	132: _OpCode_name[420:425],
+	133: _OpCode_name[425:429],
+	134: _OpCode_name[429:434],
+	135: _OpCode_name[434:441],
+	139: _OpCode_name[441:446],
+	140: _OpCode_name[446:451],
+	141: _OpCode_name[451:457],
+	143: _OpCode_name[457:465],
+	144: _OpCode_name[465:470],
+	145: _OpCode_name[470:475],
+	146: _OpCode_name[475:479],
+	147: _OpCode_name[479:484],
+	148: _OpCode_name[484:489],
+	149: _OpCode_name[489:494],
+	150: _OpCode_name[494:499],
+	151: _OpCode_name[499:504],
+	152: _OpCode_name[504:509],
+	153: _OpCode_name[509:514],
+	154: _OpCode_name[514:523],
+	155: _OpCode_name[523:531],
+	156: _OpCode_name[531:541],
+	158: _OpCode_name[541:554],
+	159: _OpCode_name[554:558],
+	160: _OpCode_name[558:562],
+	161: _OpCode_name[562:567],
+	162: _OpCode_name[567:572],
+	163: _OpCode_name[572:577],
+	164: _OpCode_name[577:582],
+	165: _OpCode_name[582:590],
+	167: _OpCode_name[590:596],
+	168: _OpCode_name[596:604],
+	169: _OpCode_name[604:613],
+	170: _OpCode_name[613:622],
+	172: _OpCode_name[622:632],
+	174: _OpCode_name[632:647],
+	192: _OpCode_name[647:658],
+	193: _OpCode_name[658:664],
+	194: _OpCode_name[664:672],
+	195: _OpCode_name[672:682],
+	196: _OpCode_name[682:691],
+	197: _OpCode_name[691:701],
+	198: _OpCode_name[701:712],
+	200: _OpCode_name[712:720],
+	201: _OpCode_name[720:729],
+	202: _OpCode_name[729:737],
+	240: _OpCode_name[737:744],
+	241: _OpCode_name[744:756],
+}
+
+func (i OpCode) String() string {
+	if str, ok := _OpCode_map[i]; ok {
+		return str
+	}
+	return "OpCode(" + strconv.FormatInt(int64(i), 10) + ")"
+}

pkg/vm/script_builder.go

@@ -0,0 +1,127 @@
+package vm
+
+import (
+	"bytes"
+	"encoding/binary"
+	"errors"
+	"fmt"
+	"math/big"
+
+	"github.com/CityOfZion/neo-go/pkg/util"
+)
+
+// ScriptBuilder generates bytecode and will write all
+// generated bytecode into its internal buffer.
+type ScriptBuilder struct {
+	buf *bytes.Buffer
+}
+
+func (sb *ScriptBuilder) emit(op OpCode, b []byte) error {
+	if err := sb.buf.WriteByte(byte(op)); err != nil {
+		return err
+	}
+	_, err := sb.buf.Write(b)
+	return err
+}
+
+func (sb *ScriptBuilder) emitPush(op OpCode) error {
+	return sb.buf.WriteByte(byte(op))
+}
+
+func (sb *ScriptBuilder) emitPushBool(b bool) error {
+	if b {
+		return sb.emitPush(OpPushT)
+	}
+	return sb.emitPush(OpPushF)
+}
+
+func (sb *ScriptBuilder) emitPushInt(i int64) error {
+	if i == -1 {
+		return sb.emitPush(OpPushM1)
+	}
+	if i == 0 {
+		return sb.emitPush(OpPushF)
+	}
+	if i > 0 && i < 16 {
+		val := OpCode((int(OpPush1) - 1 + int(i)))
+		return sb.emitPush(val)
+	}
+
+	bInt := big.NewInt(i)
+	val := util.ToArrayReverse(bInt.Bytes())
+	return sb.emitPushArray(val)
+}
+
+func (sb *ScriptBuilder) emitPushArray(b []byte) error {
+	var (
+		err error
+		n   = len(b)
+	)
+
+	if n == 0 {
+		return errors.New("0 bytes given in pushArray")
+	}
+	if n <= int(OpPushBytes75) {
+		return sb.emit(OpCode(n), b)
+	} else if n < 0x100 {
+		err = sb.emit(OpPushData1, []byte{byte(n)})
+	} else if n < 0x10000 {
+		buf := make([]byte, 2)
+		binary.LittleEndian.PutUint16(buf, uint16(n))
+		err = sb.emit(OpPushData2, buf)
+	} else {
+		buf := make([]byte, 4)
+		binary.LittleEndian.PutUint32(buf, uint32(n))
+		err = sb.emit(OpPushData4, buf)
+	}
+	if err != nil {
+		return err
+	}
+	_, err = sb.buf.Write(b)
+	return err
+}
+
+func (sb *ScriptBuilder) emitPushString(str string) error {
+	return sb.emitPushArray([]byte(str))
+}
+
+func (sb *ScriptBuilder) emitSysCall(api string) error {
+	lenAPI := len(api)
+	if lenAPI == 0 {
+		return errors.New("syscall argument cant be 0")
+	}
+	if lenAPI > 252 {
+		return fmt.Errorf("invalid syscall argument: %s", api)
+	}
+
+	bapi := []byte(api)
+	args := make([]byte, lenAPI+1)
+	args[0] = byte(lenAPI)
+	copy(args, bapi[1:])
+	return sb.emit(OpSysCall, args)
+}
+
+func (sb *ScriptBuilder) emitPushCall(scriptHash []byte, tailCall bool) error {
+	if len(scriptHash) != 20 {
+		return errors.New("expected a 20 byte long scriptHash (uint160) for pushCall")
+	}
+	op := OpAppCall
+	if tailCall {
+		op = OpTailCall
+	}
+	return sb.emit(op, scriptHash)
+}
+
+func (sb *ScriptBuilder) emitJump(op OpCode, offset int16) error {
+	if op != OpJMP && op != OpJMPIF && op != OpJMPIFNOT && op != OpCall {
+		return fmt.Errorf("invalid jump opcode: %v", op)
+	}
+	return sb.emit(op, []byte{}) // convert to bits?
+}
+
+func (sb *ScriptBuilder) dumpOpcode() {
+	buf := sb.buf.Bytes()
+	for i := 0; i < len(buf); i++ {
+		fmt.Printf("OPCODE AT INDEX \t %d \t 0x%2x \t %s \n", i, buf[i], OpCode(buf[i]))
+	}
+}

pkg/vm/script_builder_test.go

@@ -0,0 +1,74 @@
+package vm
+
+import (
+	"bytes"
+	"math/big"
+	"testing"
+
+	"github.com/CityOfZion/neo-go/pkg/util"
+)
+
+func TestEmitPush(t *testing.T) {
+	sb := &ScriptBuilder{new(bytes.Buffer)}
+
+	if err := sb.emitPush(OpPush1); err != nil {
+		t.Fatal(err)
+	}
+	if sb.buf.Len() != 1 {
+		t.Fatalf("expect buffer len of 1 got %d", sb.buf.Len())
+	}
+}
+
+func TestEmitPushInt(t *testing.T) {
+	sb := &ScriptBuilder{new(bytes.Buffer)}
+
+	val := -1
+	if err := sb.emitPushInt(int64(val)); err != nil {
+		t.Fatal(err)
+	}
+	if want, have := OpPushM1, OpCode(sb.buf.Bytes()[0]); want != have {
+		t.Fatalf("expected %v got %v", want, have)
+	}
+	val = 0
+	if err := sb.emitPushInt(int64(val)); err != nil {
+		t.Fatal(err)
+	}
+	if want, have := OpPushF, OpCode(sb.buf.Bytes()[1]); want != have {
+		t.Fatalf("expected %v got %v", want, have)
+	}
+	val = 1
+	if err := sb.emitPushInt(int64(val)); err != nil {
+		t.Fatal(err)
+	}
+	if want, have := OpPush1, OpCode(sb.buf.Bytes()[2]); want != have {
+		t.Fatalf("expected %v got %v", want, have)
+	}
+	val = 1000
+	if err := sb.emitPushInt(int64(val)); err != nil {
+		t.Fatal(err)
+	}
+	bInt := big.NewInt(int64(val))
+	if want, have := byte(len(bInt.Bytes())), byte(sb.buf.Bytes()[3]); want != have {
+		t.Fatalf("expected %v got %v", want, have)
+	}
+	want := util.ToArrayReverse(bInt.Bytes()) // reverse
+	have := sb.buf.Bytes()[4:]
+	if bytes.Compare(want, have) != 0 {
+		t.Fatalf("expected %v got %v", want, have)
+	}
+}
+
+func TestEmitPushString(t *testing.T) {
+	sb := &ScriptBuilder{new(bytes.Buffer)}
+	str := "anthdm"
+	if err := sb.emitPushString(str); err != nil {
+		t.Fatal(err)
+	}
+	if want, have := byte(len(str)), sb.buf.Bytes()[0]; want != have {
+		t.Fatalf("expected %v got %v", want, have)
+	}
+	want, have := []byte(str), sb.buf.Bytes()[1:]
+	if bytes.Compare(want, have) != 0 {
+		t.Fatalf("expected %v got %v", want, have)
+	}
+}