Merge pull request #538 from nspcc-dev/opcode-and-related

To use opcode definitions you have to import whole vm package that you might not care about at all. So this moves opcodes to their own package under vm, fixes and deduplicate related code and moves compiler package up one level.
2019-12-03 19:31:11 +03:00 · 2019-12-03 19:31:11 +03:00 · e002d7b40c
commit e002d7b40c
parent bb5aba8f95 852e6a335b
35 changed files with 1309 additions and 1315 deletions
--- a/.gitignore
+++ b/.gitignore
@ -28,9 +28,6 @@ bin/
 *~
 TAGS

-# anthdm todolists
-/pkg/vm/compiler/todo.md
-
 # leveldb 
 chains/
 chain/
--- a/cli/smartcontract/smart_contract.go
+++ b/cli/smartcontract/smart_contract.go
@ -11,13 +11,13 @@ import (
 	"os"
 	"path/filepath"

+	"github.com/CityOfZion/neo-go/pkg/compiler"
 	"github.com/CityOfZion/neo-go/pkg/crypto/hash"
 	"github.com/CityOfZion/neo-go/pkg/crypto/keys"
 	"github.com/CityOfZion/neo-go/pkg/rpc"
 	"github.com/CityOfZion/neo-go/pkg/smartcontract"
 	"github.com/CityOfZion/neo-go/pkg/util"
 	"github.com/CityOfZion/neo-go/pkg/vm"
-	"github.com/CityOfZion/neo-go/pkg/vm/compiler"
 	"github.com/go-yaml/yaml"
 	"github.com/pkg/errors"
 	"github.com/urfave/cli"
--- a/docs/cli.md
+++ b/docs/cli.md
@ -166,7 +166,7 @@ INDEX    OPCODE    DESC
 ```

 In depth documentation about the **neo-go** compiler and smart contract examples can be found inside 
-the [compiler package](https://github.com/nspcc-dev/neo-go/tree/master/pkg/vm/compiler).
+the [compiler package](https://github.com/nspcc-dev/neo-go/tree/master/pkg/compiler).

 ## VM run
 To run VM use
@ -182,10 +182,8 @@ There is a small subset of commands:
 - `ops` -- show the opcodes of currently loaded contract
 - `run` -- executes currently loaded contract

-More details can be found in
- [vm package]([compiler package](https://github.com/nspcc-dev/neo-go/tree/master/pkg/vm/compiler))
 ## Wallet operations

 - `./bin/neo-go wallet create -p newWallet` to create new wallet in the path `newWallet`
 - `./bin/neo-go wallet open -p newWallet` to open created wallet in the path `newWallet`
- `./bin/neo-go wallet create -p newWallet -a` to create new account
+- `./bin/neo-go wallet create -p newWallet -a` to create new account
--- a/pkg/vm/compiler/analysis.go
+++ b/pkg/vm/compiler/analysis.go
--- a/pkg/vm/compiler/codegen.go
+++ b/pkg/vm/compiler/codegen.go
@ -13,7 +13,7 @@ import (

 	"github.com/CityOfZion/neo-go/pkg/crypto"
 	"github.com/CityOfZion/neo-go/pkg/io"
-	"github.com/CityOfZion/neo-go/pkg/vm"
+	"github.com/CityOfZion/neo-go/pkg/vm/opcode"
 )

 // The identifier of the entry function. Default set to Main.
@ -95,13 +95,13 @@ func (c *codegen) emitLoadLocal(name string) {
 }

 func (c *codegen) emitLoadLocalPos(pos int) {
-	emitOpcode(c.prog.BinWriter, vm.DUPFROMALTSTACK)
+	emitOpcode(c.prog.BinWriter, opcode.DUPFROMALTSTACK)
 	emitInt(c.prog.BinWriter, int64(pos))
-	emitOpcode(c.prog.BinWriter, vm.PICKITEM)
+	emitOpcode(c.prog.BinWriter, opcode.PICKITEM)
 }

 func (c *codegen) emitStoreLocal(pos int) {
-	emitOpcode(c.prog.BinWriter, vm.DUPFROMALTSTACK)
+	emitOpcode(c.prog.BinWriter, opcode.DUPFROMALTSTACK)

 	if pos < 0 {
 		c.prog.Err = fmt.Errorf("invalid position to store local: %d", pos)
@ -110,19 +110,19 @@ func (c *codegen) emitStoreLocal(pos int) {

 	emitInt(c.prog.BinWriter, int64(pos))
 	emitInt(c.prog.BinWriter, 2)
-	emitOpcode(c.prog.BinWriter, vm.ROLL)
-	emitOpcode(c.prog.BinWriter, vm.SETITEM)
+	emitOpcode(c.prog.BinWriter, opcode.ROLL)
+	emitOpcode(c.prog.BinWriter, opcode.SETITEM)
 }

 func (c *codegen) emitLoadField(i int) {
 	emitInt(c.prog.BinWriter, int64(i))
-	emitOpcode(c.prog.BinWriter, vm.PICKITEM)
+	emitOpcode(c.prog.BinWriter, opcode.PICKITEM)
 }

 func (c *codegen) emitStoreStructField(i int) {
 	emitInt(c.prog.BinWriter, int64(i))
-	emitOpcode(c.prog.BinWriter, vm.ROT)
-	emitOpcode(c.prog.BinWriter, vm.SETITEM)
+	emitOpcode(c.prog.BinWriter, opcode.ROT)
+	emitOpcode(c.prog.BinWriter, opcode.SETITEM)
 }

 // convertGlobals traverses the AST and only converts global declarations.
@ -163,8 +163,8 @@ func (c *codegen) convertFuncDecl(file ast.Node, decl *ast.FuncDecl) {
 	// All globals copied into the scope of the function need to be added
 	// to the stack size of the function.
 	emitInt(c.prog.BinWriter, f.stackSize()+countGlobals(file))
-	emitOpcode(c.prog.BinWriter, vm.NEWARRAY)
-	emitOpcode(c.prog.BinWriter, vm.TOALTSTACK)
+	emitOpcode(c.prog.BinWriter, opcode.NEWARRAY)
+	emitOpcode(c.prog.BinWriter, opcode.TOALTSTACK)

 	// We need to handle methods, which in Go, is just syntactic sugar.
 	// The method receiver will be passed in as first argument.
@ -202,9 +202,9 @@ func (c *codegen) convertFuncDecl(file ast.Node, decl *ast.FuncDecl) {

 	// If this function returns the void (no return stmt) we will cleanup its junk on the stack.
 	if !hasReturnStmt(decl) {
-		emitOpcode(c.prog.BinWriter, vm.FROMALTSTACK)
-		emitOpcode(c.prog.BinWriter, vm.DROP)
-		emitOpcode(c.prog.BinWriter, vm.RET)
+		emitOpcode(c.prog.BinWriter, opcode.FROMALTSTACK)
+		emitOpcode(c.prog.BinWriter, opcode.DROP)
+		emitOpcode(c.prog.BinWriter, opcode.RET)
 	}
 }

@ -295,9 +295,9 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {
 			ast.Walk(c, n.Results[0])
 		}

-		emitOpcode(c.prog.BinWriter, vm.FROMALTSTACK)
-		emitOpcode(c.prog.BinWriter, vm.DROP) // Cleanup the stack.
-		emitOpcode(c.prog.BinWriter, vm.RET)
+		emitOpcode(c.prog.BinWriter, opcode.FROMALTSTACK)
+		emitOpcode(c.prog.BinWriter, opcode.DROP) // Cleanup the stack.
+		emitOpcode(c.prog.BinWriter, opcode.RET)
 		return nil

 	case *ast.IfStmt:
@ -307,13 +307,13 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {

 		if n.Cond != nil {
 			ast.Walk(c, n.Cond)
-			emitJmp(c.prog.BinWriter, vm.JMPIFNOT, int16(lElse))
+			emitJmp(c.prog.BinWriter, opcode.JMPIFNOT, int16(lElse))
 		}

 		c.setLabel(lIf)
 		ast.Walk(c, n.Body)
 		if n.Else != nil {
-			emitJmp(c.prog.BinWriter, vm.JMP, int16(lElseEnd))
+			emitJmp(c.prog.BinWriter, opcode.JMP, int16(lElseEnd))
 		}

 		c.setLabel(lElse)
@ -359,7 +359,7 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {
 				c.emitLoadConst(c.typeInfo.Types[n.Elts[i]])
 			}
 			emitInt(c.prog.BinWriter, int64(ln))
-			emitOpcode(c.prog.BinWriter, vm.PACK)
+			emitOpcode(c.prog.BinWriter, opcode.PACK)
 			return nil
 		}

@ -374,13 +374,13 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {
 		switch n.Op {
 		case token.LAND:
 			ast.Walk(c, n.X)
-			emitJmp(c.prog.BinWriter, vm.JMPIFNOT, int16(len(c.l)-1))
+			emitJmp(c.prog.BinWriter, opcode.JMPIFNOT, int16(len(c.l)-1))
 			ast.Walk(c, n.Y)
 			return nil

 		case token.LOR:
 			ast.Walk(c, n.X)
-			emitJmp(c.prog.BinWriter, vm.JMPIF, int16(len(c.l)-3))
+			emitJmp(c.prog.BinWriter, opcode.JMPIF, int16(len(c.l)-3))
 			ast.Walk(c, n.Y)
 			return nil

@ -405,24 +405,24 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {
 			case n.Op == token.ADD:
 				// VM has separate opcodes for number and string concatenation
 				if isStringType(tinfo.Type) {
-					emitOpcode(c.prog.BinWriter, vm.CAT)
+					emitOpcode(c.prog.BinWriter, opcode.CAT)
 				} else {
-					emitOpcode(c.prog.BinWriter, vm.ADD)
+					emitOpcode(c.prog.BinWriter, opcode.ADD)
 				}
 			case n.Op == token.EQL:
 				// VM has separate opcodes for number and string equality
 				if isStringType(c.typeInfo.Types[n.X].Type) {
-					emitOpcode(c.prog.BinWriter, vm.EQUAL)
+					emitOpcode(c.prog.BinWriter, opcode.EQUAL)
 				} else {
-					emitOpcode(c.prog.BinWriter, vm.NUMEQUAL)
+					emitOpcode(c.prog.BinWriter, opcode.NUMEQUAL)
 				}
 			case n.Op == token.NEQ:
 				// VM has separate opcodes for number and string equality
 				if isStringType(c.typeInfo.Types[n.X].Type) {
-					emitOpcode(c.prog.BinWriter, vm.EQUAL)
-					emitOpcode(c.prog.BinWriter, vm.NOT)
+					emitOpcode(c.prog.BinWriter, opcode.EQUAL)
+					emitOpcode(c.prog.BinWriter, opcode.NOT)
 				} else {
-					emitOpcode(c.prog.BinWriter, vm.NUMNOTEQUAL)
+					emitOpcode(c.prog.BinWriter, opcode.NUMNOTEQUAL)
 				}
 			default:
 				c.convertToken(n.Op)
@ -478,14 +478,14 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {
 		// Do not swap for builtin functions.
 		if !isBuiltin {
 			if numArgs == 2 {
-				emitOpcode(c.prog.BinWriter, vm.SWAP)
+				emitOpcode(c.prog.BinWriter, opcode.SWAP)
 			} else if numArgs == 3 {
 				emitInt(c.prog.BinWriter, 2)
-				emitOpcode(c.prog.BinWriter, vm.XSWAP)
+				emitOpcode(c.prog.BinWriter, opcode.XSWAP)
 			} else {
 				for i := 1; i < numArgs; i++ {
 					emitInt(c.prog.BinWriter, int64(i))
-					emitOpcode(c.prog.BinWriter, vm.ROLL)
+					emitOpcode(c.prog.BinWriter, opcode.ROLL)
 				}
 			}
 		}
@ -499,7 +499,7 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {
 		case isSyscall(f):
 			c.convertSyscall(f.selector.Name, f.name)
 		default:
-			emitCall(c.prog.BinWriter, vm.CALL, int16(f.label))
+			emitCall(c.prog.BinWriter, opcode.CALL, int16(f.label))
 		}

 		return nil
@ -529,11 +529,11 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {
 		case token.ADD:
 			// +10 == 10, no need to do anything in this case
 		case token.SUB:
-			emitOpcode(c.prog.BinWriter, vm.NEGATE)
+			emitOpcode(c.prog.BinWriter, opcode.NEGATE)
 		case token.NOT:
-			emitOpcode(c.prog.BinWriter, vm.NOT)
+			emitOpcode(c.prog.BinWriter, opcode.NOT)
 		case token.XOR:
-			emitOpcode(c.prog.BinWriter, vm.INVERT)
+			emitOpcode(c.prog.BinWriter, opcode.INVERT)
 		default:
 			c.prog.Err = fmt.Errorf("invalid unary operator: %s", n.Op)
 			return nil
@ -565,7 +565,7 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {
 			c.emitLoadField(int(val))
 		default:
 			ast.Walk(c, n.Index)
-			emitOpcode(c.prog.BinWriter, vm.PICKITEM) // just pickitem here
+			emitOpcode(c.prog.BinWriter, opcode.PICKITEM) // just pickitem here
 		}
 		return nil

@ -583,14 +583,14 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {
 		ast.Walk(c, n.Cond)

 		// Jump if the condition is false
-		emitJmp(c.prog.BinWriter, vm.JMPIFNOT, int16(fend))
+		emitJmp(c.prog.BinWriter, opcode.JMPIFNOT, int16(fend))

 		// Walk body followed by the iterator (post stmt).
 		ast.Walk(c, n.Body)
 		ast.Walk(c, n.Post)

 		// Jump back to condition.
-		emitJmp(c.prog.BinWriter, vm.JMP, int16(fstart))
+		emitJmp(c.prog.BinWriter, opcode.JMP, int16(fstart))
 		c.setLabel(fend)

 		return nil
@ -616,7 +616,7 @@ func (c *codegen) convertSyscall(api, name string) {

 	// This NOP instruction is basically not needed, but if we do, we have a
 	// one to one matching avm file with neo-python which is very nice for debugging.
-	emitOpcode(c.prog.BinWriter, vm.NOP)
+	emitOpcode(c.prog.BinWriter, opcode.NOP)
 }

 func (c *codegen) convertBuiltin(expr *ast.CallExpr) {
@ -633,32 +633,32 @@ func (c *codegen) convertBuiltin(expr *ast.CallExpr) {
 		arg := expr.Args[0]
 		typ := c.typeInfo.Types[arg].Type
 		if isStringType(typ) {
-			emitOpcode(c.prog.BinWriter, vm.SIZE)
+			emitOpcode(c.prog.BinWriter, opcode.SIZE)
 		} else {
-			emitOpcode(c.prog.BinWriter, vm.ARRAYSIZE)
+			emitOpcode(c.prog.BinWriter, opcode.ARRAYSIZE)
 		}
 	case "append":
 		arg := expr.Args[0]
 		typ := c.typeInfo.Types[arg].Type
 		if isByteArrayType(typ) {
-			emitOpcode(c.prog.BinWriter, vm.CAT)
+			emitOpcode(c.prog.BinWriter, opcode.CAT)
 		} else {
-			emitOpcode(c.prog.BinWriter, vm.SWAP)
-			emitOpcode(c.prog.BinWriter, vm.DUP)
-			emitOpcode(c.prog.BinWriter, vm.PUSH2)
-			emitOpcode(c.prog.BinWriter, vm.XSWAP)
-			emitOpcode(c.prog.BinWriter, vm.APPEND)
+			emitOpcode(c.prog.BinWriter, opcode.SWAP)
+			emitOpcode(c.prog.BinWriter, opcode.DUP)
+			emitOpcode(c.prog.BinWriter, opcode.PUSH2)
+			emitOpcode(c.prog.BinWriter, opcode.XSWAP)
+			emitOpcode(c.prog.BinWriter, opcode.APPEND)
 		}
 	case "SHA256":
-		emitOpcode(c.prog.BinWriter, vm.SHA256)
+		emitOpcode(c.prog.BinWriter, opcode.SHA256)
 	case "SHA1":
-		emitOpcode(c.prog.BinWriter, vm.SHA1)
+		emitOpcode(c.prog.BinWriter, opcode.SHA1)
 	case "Hash256":
-		emitOpcode(c.prog.BinWriter, vm.HASH256)
+		emitOpcode(c.prog.BinWriter, opcode.HASH256)
 	case "Hash160":
-		emitOpcode(c.prog.BinWriter, vm.HASH160)
+		emitOpcode(c.prog.BinWriter, opcode.HASH160)
 	case "Equals":
-		emitOpcode(c.prog.BinWriter, vm.EQUAL)
+		emitOpcode(c.prog.BinWriter, opcode.EQUAL)
 	case "FromAddress":
 		// We can be sure that this is a ast.BasicLit just containing a simple
 		// address string. Note that the string returned from calling Value will
@ -694,10 +694,10 @@ func (c *codegen) convertStruct(lit *ast.CompositeLit) {
 		return
 	}

-	emitOpcode(c.prog.BinWriter, vm.NOP)
+	emitOpcode(c.prog.BinWriter, opcode.NOP)
 	emitInt(c.prog.BinWriter, int64(strct.NumFields()))
-	emitOpcode(c.prog.BinWriter, vm.NEWSTRUCT)
-	emitOpcode(c.prog.BinWriter, vm.TOALTSTACK)
+	emitOpcode(c.prog.BinWriter, opcode.NEWSTRUCT)
+	emitOpcode(c.prog.BinWriter, opcode.TOALTSTACK)

 	// We need to locally store all the fields, even if they are not initialized.
 	// We will initialize all fields to their "zero" value.
@ -730,55 +730,55 @@ func (c *codegen) convertStruct(lit *ast.CompositeLit) {
 		c.emitLoadConst(typeAndVal)
 		c.emitStoreLocal(i)
 	}
-	emitOpcode(c.prog.BinWriter, vm.FROMALTSTACK)
+	emitOpcode(c.prog.BinWriter, opcode.FROMALTSTACK)
 }

 func (c *codegen) convertToken(tok token.Token) {
 	switch tok {
 	case token.ADD_ASSIGN:
-		emitOpcode(c.prog.BinWriter, vm.ADD)
+		emitOpcode(c.prog.BinWriter, opcode.ADD)
 	case token.SUB_ASSIGN:
-		emitOpcode(c.prog.BinWriter, vm.SUB)
+		emitOpcode(c.prog.BinWriter, opcode.SUB)
 	case token.MUL_ASSIGN:
-		emitOpcode(c.prog.BinWriter, vm.MUL)
+		emitOpcode(c.prog.BinWriter, opcode.MUL)
 	case token.QUO_ASSIGN:
-		emitOpcode(c.prog.BinWriter, vm.DIV)
+		emitOpcode(c.prog.BinWriter, opcode.DIV)
 	case token.ADD:
-		emitOpcode(c.prog.BinWriter, vm.ADD)
+		emitOpcode(c.prog.BinWriter, opcode.ADD)
 	case token.SUB:
-		emitOpcode(c.prog.BinWriter, vm.SUB)
+		emitOpcode(c.prog.BinWriter, opcode.SUB)
 	case token.MUL:
-		emitOpcode(c.prog.BinWriter, vm.MUL)
+		emitOpcode(c.prog.BinWriter, opcode.MUL)
 	case token.QUO:
-		emitOpcode(c.prog.BinWriter, vm.DIV)
+		emitOpcode(c.prog.BinWriter, opcode.DIV)
 	case token.LSS:
-		emitOpcode(c.prog.BinWriter, vm.LT)
+		emitOpcode(c.prog.BinWriter, opcode.LT)
 	case token.LEQ:
-		emitOpcode(c.prog.BinWriter, vm.LTE)
+		emitOpcode(c.prog.BinWriter, opcode.LTE)
 	case token.GTR:
-		emitOpcode(c.prog.BinWriter, vm.GT)
+		emitOpcode(c.prog.BinWriter, opcode.GT)
 	case token.GEQ:
-		emitOpcode(c.prog.BinWriter, vm.GTE)
+		emitOpcode(c.prog.BinWriter, opcode.GTE)
 	case token.EQL:
-		emitOpcode(c.prog.BinWriter, vm.NUMEQUAL)
+		emitOpcode(c.prog.BinWriter, opcode.NUMEQUAL)
 	case token.NEQ:
-		emitOpcode(c.prog.BinWriter, vm.NUMNOTEQUAL)
+		emitOpcode(c.prog.BinWriter, opcode.NUMNOTEQUAL)
 	case token.DEC:
-		emitOpcode(c.prog.BinWriter, vm.DEC)
+		emitOpcode(c.prog.BinWriter, opcode.DEC)
 	case token.INC:
-		emitOpcode(c.prog.BinWriter, vm.INC)
+		emitOpcode(c.prog.BinWriter, opcode.INC)
 	case token.NOT:
-		emitOpcode(c.prog.BinWriter, vm.NOT)
+		emitOpcode(c.prog.BinWriter, opcode.NOT)
 	case token.AND:
-		emitOpcode(c.prog.BinWriter, vm.AND)
+		emitOpcode(c.prog.BinWriter, opcode.AND)
 	case token.OR:
-		emitOpcode(c.prog.BinWriter, vm.OR)
+		emitOpcode(c.prog.BinWriter, opcode.OR)
 	case token.SHL:
-		emitOpcode(c.prog.BinWriter, vm.SHL)
+		emitOpcode(c.prog.BinWriter, opcode.SHL)
 	case token.SHR:
-		emitOpcode(c.prog.BinWriter, vm.SHR)
+		emitOpcode(c.prog.BinWriter, opcode.SHR)
 	case token.XOR:
-		emitOpcode(c.prog.BinWriter, vm.XOR)
+		emitOpcode(c.prog.BinWriter, opcode.XOR)
 	default:
 		c.prog.Err = fmt.Errorf("compiler could not convert token: %s", tok)
 		return
@ -869,8 +869,8 @@ func (c *codegen) resolveFuncDecls(f *ast.File) {
 func (c *codegen) writeJumps(b []byte) {
 	for i, op := range b {
 		j := i + 1
-		switch vm.Instruction(op) {
-		case vm.JMP, vm.JMPIFNOT, vm.JMPIF, vm.CALL:
+		switch opcode.Opcode(op) {
+		case opcode.JMP, opcode.JMPIFNOT, opcode.JMPIF, opcode.CALL:
 			index := int16(binary.LittleEndian.Uint16(b[j : j+2]))
 			if int(index) > len(c.l) || int(index) < 0 {
 				continue
--- a/pkg/vm/compiler/compiler.go
+++ b/pkg/vm/compiler/compiler.go
--- a/pkg/vm/compiler/compiler_test.go
+++ b/pkg/vm/compiler/compiler_test.go
@ -6,10 +6,10 @@ import (
 	"path"
 	"testing"

-	"github.com/CityOfZion/neo-go/pkg/vm/compiler"
+	"github.com/CityOfZion/neo-go/pkg/compiler"
 )

-const examplePath = "../../../examples"
+const examplePath = "../../examples"

 func TestExamplesFolder(t *testing.T) {
 	infos, err := ioutil.ReadDir(examplePath)
--- a/pkg/vm/compiler/emit.go
+++ b/pkg/vm/compiler/emit.go
@ -8,40 +8,40 @@ import (

 	"github.com/CityOfZion/neo-go/pkg/io"
 	"github.com/CityOfZion/neo-go/pkg/util"
-	"github.com/CityOfZion/neo-go/pkg/vm"
+	"github.com/CityOfZion/neo-go/pkg/vm/opcode"
 )

 // emit a VM Instruction with data to the given buffer.
-func emit(w *io.BinWriter, instr vm.Instruction, b []byte) {
+func emit(w *io.BinWriter, instr opcode.Opcode, b []byte) {
 	emitOpcode(w, instr)
 	w.WriteBytes(b)
 }

 // emitOpcode emits a single VM Instruction the given buffer.
-func emitOpcode(w *io.BinWriter, instr vm.Instruction) {
+func emitOpcode(w *io.BinWriter, instr opcode.Opcode) {
 	w.WriteLE(byte(instr))
 }

 // emitBool emits a bool type the given buffer.
 func emitBool(w *io.BinWriter, ok bool) {
 	if ok {
-		emitOpcode(w, vm.PUSHT)
+		emitOpcode(w, opcode.PUSHT)
 		return
 	}
-	emitOpcode(w, vm.PUSHF)
+	emitOpcode(w, opcode.PUSHF)
 }

 // emitInt emits a int type to the given buffer.
 func emitInt(w *io.BinWriter, i int64) {
 	switch {
 	case i == -1:
-		emitOpcode(w, vm.PUSHM1)
+		emitOpcode(w, opcode.PUSHM1)
 		return
 	case i == 0:
-		emitOpcode(w, vm.PUSHF)
+		emitOpcode(w, opcode.PUSHF)
 		return
 	case i > 0 && i < 16:
-		val := vm.Instruction(int(vm.PUSH1) - 1 + int(i))
+		val := opcode.Opcode(int(opcode.PUSH1) - 1 + int(i))
 		emitOpcode(w, val)
 		return
 	}
@ -61,19 +61,19 @@ func emitBytes(w *io.BinWriter, b []byte) {
 	n := len(b)

 	switch {
-	case n <= int(vm.PUSHBYTES75):
-		emit(w, vm.Instruction(n), b)
+	case n <= int(opcode.PUSHBYTES75):
+		emit(w, opcode.Opcode(n), b)
 		return
 	case n < 0x100:
-		emit(w, vm.PUSHDATA1, []byte{byte(n)})
+		emit(w, opcode.PUSHDATA1, []byte{byte(n)})
 	case n < 0x10000:
 		buf := make([]byte, 2)
 		binary.LittleEndian.PutUint16(buf, uint16(n))
-		emit(w, vm.PUSHDATA2, buf)
+		emit(w, opcode.PUSHDATA2, buf)
 	default:
 		buf := make([]byte, 4)
 		binary.LittleEndian.PutUint32(buf, uint32(n))
-		emit(w, vm.PUSHDATA4, buf)
+		emit(w, opcode.PUSHDATA4, buf)
 		if w.Err != nil {
 			return
 		}
@ -92,16 +92,16 @@ func emitSyscall(w *io.BinWriter, api string) {
 	buf := make([]byte, len(api)+1)
 	buf[0] = byte(len(api))
 	copy(buf[1:], api)
-	emit(w, vm.SYSCALL, buf)
+	emit(w, opcode.SYSCALL, buf)
 }

 // emitCall emits a call Instruction with label to the given buffer.
-func emitCall(w *io.BinWriter, instr vm.Instruction, label int16) {
+func emitCall(w *io.BinWriter, instr opcode.Opcode, label int16) {
 	emitJmp(w, instr, label)
 }

 // emitJmp emits a jump Instruction along with label to the given buffer.
-func emitJmp(w *io.BinWriter, instr vm.Instruction, label int16) {
+func emitJmp(w *io.BinWriter, instr opcode.Opcode, label int16) {
 	if !isInstrJmp(instr) {
 		w.Err = fmt.Errorf("opcode %s is not a jump or call type", instr)
 		return
@ -111,8 +111,8 @@ func emitJmp(w *io.BinWriter, instr vm.Instruction, label int16) {
 	emit(w, instr, buf)
 }

-func isInstrJmp(instr vm.Instruction) bool {
-	if instr == vm.JMP || instr == vm.JMPIFNOT || instr == vm.JMPIF || instr == vm.CALL {
+func isInstrJmp(instr opcode.Opcode) bool {
+	if instr == opcode.JMP || instr == opcode.JMPIFNOT || instr == opcode.JMPIF || instr == opcode.CALL {
 		return true
 	}
 	return false
--- a/pkg/vm/compiler/func_scope.go
+++ b/pkg/vm/compiler/func_scope.go
--- a/pkg/vm/compiler/syscall.go
+++ b/pkg/vm/compiler/syscall.go
--- a/pkg/consensus/consensus.go
+++ b/pkg/consensus/consensus.go
@ -12,7 +12,7 @@ import (
 	"github.com/CityOfZion/neo-go/pkg/crypto/keys"
 	"github.com/CityOfZion/neo-go/pkg/smartcontract"
 	"github.com/CityOfZion/neo-go/pkg/util"
-	"github.com/CityOfZion/neo-go/pkg/vm"
+	"github.com/CityOfZion/neo-go/pkg/vm/opcode"
 	"github.com/CityOfZion/neo-go/pkg/wallet"
 	"github.com/nspcc-dev/dbft"
 	"github.com/nspcc-dev/dbft/block"
@ -283,7 +283,7 @@ func (s *service) getBlockWitness(b *core.Block) *transaction.Witness {
 	var invoc []byte
 	for i, j := 0, 0; i < len(pubs) && j < m; i++ {
 		if sig, ok := sigs[pubs[i]]; ok {
-			invoc = append(invoc, byte(vm.PUSHBYTES64))
+			invoc = append(invoc, byte(opcode.PUSHBYTES64))
 			invoc = append(invoc, sig...)
 			j++
 		}
--- a/pkg/consensus/payload.go
+++ b/pkg/consensus/payload.go
@ -7,9 +7,9 @@ import (
 	"github.com/CityOfZion/neo-go/pkg/core/transaction"
 	"github.com/CityOfZion/neo-go/pkg/crypto/hash"
 	"github.com/CityOfZion/neo-go/pkg/io"
-	"github.com/CityOfZion/neo-go/pkg/smartcontract"
 	"github.com/CityOfZion/neo-go/pkg/util"
 	"github.com/CityOfZion/neo-go/pkg/vm"
+	"github.com/CityOfZion/neo-go/pkg/vm/opcode"
 	"github.com/nspcc-dev/dbft/payload"
 	"github.com/pkg/errors"
 )
@ -188,13 +188,8 @@ func (p *Payload) Sign(key *privateKey) error {
 		return err
 	}

-	verif, err := smartcontract.CreateSignatureRedeemScript(key.PublicKey())
-	if err != nil {
-		return err
-	}
-
-	p.Witness.InvocationScript = append([]byte{byte(vm.PUSHBYTES64)}, sig...)
-	p.Witness.VerificationScript = verif
+	p.Witness.InvocationScript = append([]byte{byte(opcode.PUSHBYTES64)}, sig...)
+	p.Witness.VerificationScript = key.PublicKey().GetVerificationScript()

 	return nil
 }
--- a/pkg/core/helper_test.go
+++ b/pkg/core/helper_test.go
@ -15,6 +15,7 @@ import (
 	"github.com/CityOfZion/neo-go/pkg/io"
 	"github.com/CityOfZion/neo-go/pkg/smartcontract"
 	"github.com/CityOfZion/neo-go/pkg/util"
+	"github.com/CityOfZion/neo-go/pkg/vm/opcode"
 	"github.com/stretchr/testify/require"
 )

@ -84,8 +85,7 @@ func newBlock(index uint32, txs ...*transaction.Transaction) *Block {
 		if err != nil || len(sig) != 64 {
 			panic(err)
 		}
-		// 0x40 is PUSHBYTES64
-		invScript = append(invScript, 0x40)
+		invScript = append(invScript, byte(opcode.PUSHBYTES64))
 		invScript = append(invScript, sig...)
 	}
 	b.Script.InvocationScript = invScript
--- a/pkg/core/interop_system.go
+++ b/pkg/core/interop_system.go
@ -8,7 +8,6 @@ import (
 	"github.com/CityOfZion/neo-go/pkg/core/transaction"
 	"github.com/CityOfZion/neo-go/pkg/crypto/hash"
 	"github.com/CityOfZion/neo-go/pkg/crypto/keys"
-	"github.com/CityOfZion/neo-go/pkg/smartcontract"
 	"github.com/CityOfZion/neo-go/pkg/util"
 	"github.com/CityOfZion/neo-go/pkg/vm"
 	gherr "github.com/pkg/errors"
@ -309,11 +308,7 @@ func (ic *interopContext) checkHashedWitness(hash util.Uint160) (bool, error) {
 // checkKeyedWitness checks hash of signature check contract with a given public
 // key against current list of script hashes for verifying in the interop context.
 func (ic *interopContext) checkKeyedWitness(key *keys.PublicKey) (bool, error) {
-	script, err := smartcontract.CreateSignatureRedeemScript(key)
-	if err != nil {
-		return false, gherr.Wrap(err, "failed to create signature script for a key")
-	}
-	return ic.checkHashedWitness(hash.Hash160(script))
+	return ic.checkHashedWitness(hash.Hash160(key.GetVerificationScript()))
 }

 // runtimeCheckWitness checks witnesses.
--- a/pkg/core/util.go
+++ b/pkg/core/util.go
@ -9,7 +9,7 @@ import (
 	"github.com/CityOfZion/neo-go/pkg/crypto/keys"
 	"github.com/CityOfZion/neo-go/pkg/smartcontract"
 	"github.com/CityOfZion/neo-go/pkg/util"
-	"github.com/CityOfZion/neo-go/pkg/vm"
+	"github.com/CityOfZion/neo-go/pkg/vm/opcode"
 )

 // createGenesisBlock creates a genesis block based on the given configuration.
@ -33,7 +33,7 @@ func createGenesisBlock(cfg config.ProtocolConfiguration) (*Block, error) {
 		NextConsensus: nextConsensus,
 		Script: &transaction.Witness{
 			InvocationScript:   []byte{},
-			VerificationScript: []byte{byte(vm.PUSHT)},
+			VerificationScript: []byte{byte(opcode.PUSHT)},
 		},
 	}

@ -77,7 +77,7 @@ func createGenesisBlock(cfg config.ProtocolConfiguration) (*Block, error) {
 				Scripts: []*transaction.Witness{
 					{
 						InvocationScript:   []byte{},
-						VerificationScript: []byte{byte(vm.PUSHT)},
+						VerificationScript: []byte{byte(opcode.PUSHT)},
 					},
 				},
 			},
@ -92,7 +92,7 @@ func createGenesisBlock(cfg config.ProtocolConfiguration) (*Block, error) {
 }

 func governingTokenTX() *transaction.Transaction {
-	admin := hash.Hash160([]byte{byte(vm.PUSHT)})
+	admin := hash.Hash160([]byte{byte(opcode.PUSHT)})
 	registerTX := &transaction.RegisterTX{
 		AssetType: transaction.GoverningToken,
 		Name:      "[{\"lang\":\"zh-CN\",\"name\":\"小蚁股\"},{\"lang\":\"en\",\"name\":\"AntShare\"}]",
@ -115,7 +115,7 @@ func governingTokenTX() *transaction.Transaction {
 }

 func utilityTokenTX() *transaction.Transaction {
-	admin := hash.Hash160([]byte{byte(vm.PUSHF)})
+	admin := hash.Hash160([]byte{byte(opcode.PUSHF)})
 	registerTX := &transaction.RegisterTX{
 		AssetType: transaction.UtilityToken,
 		Name:      "[{\"lang\":\"zh-CN\",\"name\":\"小蚁币\"},{\"lang\":\"en\",\"name\":\"AntCoin\"}]",
--- a/pkg/crypto/keys/publickey.go
+++ b/pkg/crypto/keys/publickey.go
@ -12,6 +12,7 @@ import (
 	"github.com/CityOfZion/neo-go/pkg/crypto"
 	"github.com/CityOfZion/neo-go/pkg/crypto/hash"
 	"github.com/CityOfZion/neo-go/pkg/io"
+	"github.com/CityOfZion/neo-go/pkg/vm/opcode"
 	"github.com/pkg/errors"
 )

@ -222,13 +223,19 @@ func (p *PublicKey) EncodeBinary(w *io.BinWriter) {
 	w.WriteBytes(p.Bytes())
 }

+// GetVerificationScript returns NEO VM bytecode with CHECKSIG command for the
+// public key.
+func (p *PublicKey) GetVerificationScript() []byte {
+	b := p.Bytes()
+	b = append([]byte{byte(opcode.PUSHBYTES33)}, b...)
+	b = append(b, byte(opcode.CHECKSIG))
+
+	return b
+}
+
 // Signature returns a NEO-specific hash of the key.
 func (p *PublicKey) Signature() []byte {
-	b := p.Bytes()
-	b = append([]byte{0x21}, b...)
-	b = append(b, 0xAC)
-
-	sig := hash.Hash160(b)
+	sig := hash.Hash160(p.GetVerificationScript())

 	return sig.Bytes()
 }
--- a/pkg/crypto/keys/wif.go
+++ b/pkg/crypto/keys/wif.go
@ -90,19 +90,3 @@ func WIFDecode(wif string, version byte) (*WIF, error) {
 	w.Compressed = true
 	return w, nil
 }
-
-// GetVerificationScript returns NEO VM bytecode with checksig command for the public key.
-func (wif WIF) GetVerificationScript() []byte {
-	const (
-		pushbytes33 = 0x21
-		checksig    = 0xac
-	)
-	var (
-		vScript []byte
-		pubkey  *PublicKey
-	)
-	pubkey = wif.PrivateKey.PublicKey()
-	vScript = append([]byte{pushbytes33}, pubkey.Bytes()...)
-	vScript = append(vScript, checksig)
-	return vScript
-}
--- a/pkg/rpc/txBuilder.go
+++ b/pkg/rpc/txBuilder.go
@ -13,6 +13,7 @@ import (
 	"github.com/CityOfZion/neo-go/pkg/smartcontract"
 	"github.com/CityOfZion/neo-go/pkg/util"
 	"github.com/CityOfZion/neo-go/pkg/vm"
+	"github.com/CityOfZion/neo-go/pkg/vm/opcode"
 	errs "github.com/pkg/errors"
 )

@ -85,7 +86,7 @@ func SignTx(tx *transaction.Transaction, wif *keys.WIF) error {
 	if witness.InvocationScript, err = GetInvocationScript(tx, wif); err != nil {
 		return errs.Wrap(err, "failed to create invocation script")
 	}
-	witness.VerificationScript = wif.GetVerificationScript()
+	witness.VerificationScript = wif.PrivateKey.PublicKey().GetVerificationScript()
 	tx.Scripts = append(tx.Scripts, &witness)
 	tx.Hash()

@ -94,9 +95,6 @@ func SignTx(tx *transaction.Transaction, wif *keys.WIF) error {

 // GetInvocationScript returns NEO VM script containing transaction signature.
 func GetInvocationScript(tx *transaction.Transaction, wif *keys.WIF) ([]byte, error) {
-	const (
-		pushbytes64 = 0x40
-	)
 	var (
 		err       error
 		buf       = io.NewBufBinWriter()
@ -111,7 +109,7 @@ func GetInvocationScript(tx *transaction.Transaction, wif *keys.WIF) ([]byte, er
 	if err != nil {
 		return nil, errs.Wrap(err, "Failed ti sign transaction with private key")
 	}
-	return append([]byte{pushbytes64}, signature...), nil
+	return append([]byte{byte(opcode.PUSHBYTES64)}, signature...), nil
 }

 // CreateDeploymentScript returns a script that deploys given smart contract
@ -281,7 +279,7 @@ func CreateFunctionInvocationScript(contract util.Uint160, params Params) ([]byt
 			if err != nil {
 				return nil, err
 			}
-			err = vm.EmitOpcode(script, vm.PACK)
+			err = vm.EmitOpcode(script, opcode.PACK)
 			if err != nil {
 				return nil, err
 			}
--- a/pkg/smartcontract/contract.go
+++ b/pkg/smartcontract/contract.go
@ -7,23 +7,9 @@ import (

 	"github.com/CityOfZion/neo-go/pkg/crypto/keys"
 	"github.com/CityOfZion/neo-go/pkg/vm"
+	"github.com/CityOfZion/neo-go/pkg/vm/opcode"
 )

-// CreateSignatureRedeemScript creates a check signature script runnable by VM.
-func CreateSignatureRedeemScript(key *keys.PublicKey) ([]byte, error) {
-	buf := new(bytes.Buffer)
-	err := vm.EmitBytes(buf, key.Bytes())
-	if err != nil {
-		return nil, err
-	}
-	err = vm.EmitOpcode(buf, vm.CHECKSIG)
-	if err != nil {
-		return nil, err
-	}
-
-	return buf.Bytes(), nil
-}
-
 // CreateMultiSigRedeemScript creates a script runnable by the VM.
 func CreateMultiSigRedeemScript(m int, publicKeys keys.PublicKeys) ([]byte, error) {
 	if m <= 1 {
@ -49,7 +35,7 @@ func CreateMultiSigRedeemScript(m int, publicKeys keys.PublicKeys) ([]byte, erro
 	if err := vm.EmitInt(buf, int64(len(publicKeys))); err != nil {
 		return nil, err
 	}
-	if err := vm.EmitOpcode(buf, vm.CHECKMULTISIG); err != nil {
+	if err := vm.EmitOpcode(buf, opcode.CHECKMULTISIG); err != nil {
 		return nil, err
 	}

--- a/pkg/smartcontract/contract_test.go
+++ b/pkg/smartcontract/contract_test.go
@ -5,7 +5,7 @@ import (

 	"github.com/CityOfZion/neo-go/pkg/crypto/keys"
 	"github.com/CityOfZion/neo-go/pkg/io"
-	"github.com/CityOfZion/neo-go/pkg/vm"
+	"github.com/CityOfZion/neo-go/pkg/vm/opcode"
 	"github.com/stretchr/testify/assert"
 )

@ -24,7 +24,7 @@ func TestCreateMultiSigRedeemScript(t *testing.T) {
 	br := io.NewBinReaderFromBuf(out)
 	var b uint8
 	br.ReadLE(&b)
-	assert.Equal(t, vm.PUSH3, vm.Instruction(b))
+	assert.Equal(t, opcode.PUSH3, opcode.Opcode(b))

 	for i := 0; i < len(validators); i++ {
 		bb := br.ReadBytes()
@ -35,7 +35,7 @@ func TestCreateMultiSigRedeemScript(t *testing.T) {
 	}

 	br.ReadLE(&b)
-	assert.Equal(t, vm.PUSH3, vm.Instruction(b))
+	assert.Equal(t, opcode.PUSH3, opcode.Opcode(b))
 	br.ReadLE(&b)
-	assert.Equal(t, vm.CHECKMULTISIG, vm.Instruction(b))
+	assert.Equal(t, opcode.CHECKMULTISIG, opcode.Opcode(b))
 }
--- a/pkg/vm/cli/cli.go
+++ b/pkg/vm/cli/cli.go
@ -10,8 +10,8 @@ import (
 	"strconv"
 	"strings"

+	"github.com/CityOfZion/neo-go/pkg/compiler"
 	"github.com/CityOfZion/neo-go/pkg/vm"
-	"github.com/CityOfZion/neo-go/pkg/vm/compiler"
 	"gopkg.in/abiosoft/ishell.v2"
 )

--- a/pkg/vm/context.go
+++ b/pkg/vm/context.go
@ -4,6 +4,7 @@ import (
 	"errors"

 	"github.com/CityOfZion/neo-go/pkg/io"
+	"github.com/CityOfZion/neo-go/pkg/vm/opcode"
 )

 // Context represents the current execution context of the VM.
@ -42,31 +43,31 @@ func NewContext(b []byte) *Context {
 // Next returns the next instruction to execute with its parameter if any. After
 // its invocation the instruction pointer points to the instruction being
 // returned.
-func (c *Context) Next() (Instruction, []byte, error) {
+func (c *Context) Next() (opcode.Opcode, []byte, error) {
 	c.ip = c.nextip
 	if c.ip >= len(c.prog) {
-		return RET, nil, nil
+		return opcode.RET, nil, nil
 	}
 	r := io.NewBinReaderFromBuf(c.prog[c.ip:])

 	var instrbyte byte
 	r.ReadLE(&instrbyte)
-	instr := Instruction(instrbyte)
+	instr := opcode.Opcode(instrbyte)
 	c.nextip++

 	var numtoread int
 	switch instr {
-	case PUSHDATA1, SYSCALL:
+	case opcode.PUSHDATA1, opcode.SYSCALL:
 		var n byte
 		r.ReadLE(&n)
 		numtoread = int(n)
 		c.nextip++
-	case PUSHDATA2:
+	case opcode.PUSHDATA2:
 		var n uint16
 		r.ReadLE(&n)
 		numtoread = int(n)
 		c.nextip += 2
-	case PUSHDATA4:
+	case opcode.PUSHDATA4:
 		var n uint32
 		r.ReadLE(&n)
 		if n > MaxItemSize {
@ -74,16 +75,16 @@ func (c *Context) Next() (Instruction, []byte, error) {
 		}
 		numtoread = int(n)
 		c.nextip += 4
-	case JMP, JMPIF, JMPIFNOT, CALL, CALLED, CALLEDT:
+	case opcode.JMP, opcode.JMPIF, opcode.JMPIFNOT, opcode.CALL, opcode.CALLED, opcode.CALLEDT:
 		numtoread = 2
-	case CALLI:
+	case opcode.CALLI:
 		numtoread = 4
-	case APPCALL, TAILCALL:
+	case opcode.APPCALL, opcode.TAILCALL:
 		numtoread = 20
-	case CALLE, CALLET:
+	case opcode.CALLE, opcode.CALLET:
 		numtoread = 22
 	default:
-		if instr >= PUSHBYTES1 && instr <= PUSHBYTES75 {
+		if instr >= opcode.PUSHBYTES1 && instr <= opcode.PUSHBYTES75 {
 			numtoread = int(instr)
 		} else {
 			// No parameters, can just return.
@ -112,8 +113,8 @@ func (c *Context) LenInstr() int {
 }

 // CurrInstr returns the current instruction and opcode.
-func (c *Context) CurrInstr() (int, Instruction) {
-	return c.ip, Instruction(c.prog[c.ip])
+func (c *Context) CurrInstr() (int, opcode.Opcode) {
+	return c.ip, opcode.Opcode(c.prog[c.ip])
 }

 // Copy returns an new exact copy of c.
--- a/pkg/vm/contract_checks.go
+++ b/pkg/vm/contract_checks.go
@ -2,18 +2,22 @@ package vm

 import (
 	"encoding/binary"
+
+	"github.com/CityOfZion/neo-go/pkg/vm/opcode"
 )

-func getNumOfThingsFromInstr(instr Instruction, param []byte) (int, bool) {
+func getNumOfThingsFromInstr(instr opcode.Opcode, param []byte) (int, bool) {
 	var nthings int

 	switch instr {
-	case PUSH1, PUSH2, PUSH3, PUSH4, PUSH5, PUSH6, PUSH7, PUSH8,
-		PUSH9, PUSH10, PUSH11, PUSH12, PUSH13, PUSH14, PUSH15, PUSH16:
-		nthings = int(instr-PUSH1) + 1
-	case PUSHBYTES1:
+	case opcode.PUSH1, opcode.PUSH2, opcode.PUSH3, opcode.PUSH4,
+		opcode.PUSH5, opcode.PUSH6, opcode.PUSH7, opcode.PUSH8,
+		opcode.PUSH9, opcode.PUSH10, opcode.PUSH11, opcode.PUSH12,
+		opcode.PUSH13, opcode.PUSH14, opcode.PUSH15, opcode.PUSH16:
+		nthings = int(instr-opcode.PUSH1) + 1
+	case opcode.PUSHBYTES1:
 		nthings = int(param[0])
-	case PUSHBYTES2:
+	case opcode.PUSHBYTES2:
 		nthings = int(binary.LittleEndian.Uint16(param))
 	default:
 		return 0, false
@ -43,7 +47,7 @@ func IsMultiSigContract(script []byte) bool {
 		if err != nil {
 			return false
 		}
-		if instr != PUSHBYTES33 {
+		if instr != opcode.PUSHBYTES33 {
 			break
 		}
 		nkeys++
@ -62,11 +66,11 @@ func IsMultiSigContract(script []byte) bool {
 		return false
 	}
 	instr, _, err = ctx.Next()
-	if err != nil || instr != CHECKMULTISIG {
+	if err != nil || instr != opcode.CHECKMULTISIG {
 		return false
 	}
 	instr, _, err = ctx.Next()
-	if err != nil || instr != RET || ctx.ip != len(script) {
+	if err != nil || instr != opcode.RET || ctx.ip != len(script) {
 		return false
 	}
 	return true
@ -77,15 +81,15 @@ func IsMultiSigContract(script []byte) bool {
 func IsSignatureContract(script []byte) bool {
 	ctx := NewContext(script)
 	instr, _, err := ctx.Next()
-	if err != nil || instr != PUSHBYTES33 {
+	if err != nil || instr != opcode.PUSHBYTES33 {
 		return false
 	}
 	instr, _, err = ctx.Next()
-	if err != nil || instr != CHECKSIG {
+	if err != nil || instr != opcode.CHECKSIG {
 		return false
 	}
 	instr, _, err = ctx.Next()
-	if err != nil || instr != RET || ctx.ip != len(script) {
+	if err != nil || instr != opcode.RET || ctx.ip != len(script) {
 		return false
 	}
 	return true
--- a/pkg/vm/contract_checks_test.go
+++ b/pkg/vm/contract_checks_test.go
@ -3,225 +3,226 @@ package vm
 import (
 	"testing"

+	"github.com/CityOfZion/neo-go/pkg/vm/opcode"
 	"github.com/stretchr/testify/assert"
 )

 func TestIsSignatureContractGood(t *testing.T) {
 	prog := make([]byte, 35)
-	prog[0] = byte(PUSHBYTES33)
-	prog[34] = byte(CHECKSIG)
+	prog[0] = byte(opcode.PUSHBYTES33)
+	prog[34] = byte(opcode.CHECKSIG)
 	assert.Equal(t, true, IsSignatureContract(prog))
 	assert.Equal(t, true, IsStandardContract(prog))
 }

 func TestIsSignatureContractBadNoCheckSig(t *testing.T) {
 	prog := make([]byte, 34)
-	prog[0] = byte(PUSHBYTES33)
+	prog[0] = byte(opcode.PUSHBYTES33)
 	assert.Equal(t, false, IsSignatureContract(prog))
 	assert.Equal(t, false, IsStandardContract(prog))
 }

 func TestIsSignatureContractBadNoCheckSig2(t *testing.T) {
 	prog := make([]byte, 35)
-	prog[0] = byte(PUSHBYTES33)
-	prog[34] = byte(CHECKMULTISIG)
+	prog[0] = byte(opcode.PUSHBYTES33)
+	prog[34] = byte(opcode.CHECKMULTISIG)
 	assert.Equal(t, false, IsSignatureContract(prog))
 }

 func TestIsSignatureContractBadWrongPush(t *testing.T) {
 	prog := make([]byte, 35)
-	prog[0] = byte(PUSHBYTES32)
-	prog[33] = byte(NOP)
-	prog[34] = byte(CHECKSIG)
+	prog[0] = byte(opcode.PUSHBYTES32)
+	prog[33] = byte(opcode.NOP)
+	prog[34] = byte(opcode.CHECKSIG)
 	assert.Equal(t, false, IsSignatureContract(prog))
 }

 func TestIsSignatureContractBadWrongInstr(t *testing.T) {
 	prog := make([]byte, 30)
-	prog[0] = byte(PUSHBYTES33)
+	prog[0] = byte(opcode.PUSHBYTES33)
 	assert.Equal(t, false, IsSignatureContract(prog))
 }

 func TestIsSignatureContractBadExcessiveInstr(t *testing.T) {
 	prog := make([]byte, 36)
-	prog[0] = byte(PUSHBYTES33)
-	prog[34] = byte(CHECKSIG)
-	prog[35] = byte(RET)
+	prog[0] = byte(opcode.PUSHBYTES33)
+	prog[34] = byte(opcode.CHECKSIG)
+	prog[35] = byte(opcode.RET)
 	assert.Equal(t, false, IsSignatureContract(prog))
 }

 func TestIsMultiSigContractGood(t *testing.T) {
 	prog := make([]byte, 71)
-	prog[0] = byte(PUSH2)
-	prog[1] = byte(PUSHBYTES33)
-	prog[35] = byte(PUSHBYTES33)
-	prog[69] = byte(PUSH2)
-	prog[70] = byte(CHECKMULTISIG)
+	prog[0] = byte(opcode.PUSH2)
+	prog[1] = byte(opcode.PUSHBYTES33)
+	prog[35] = byte(opcode.PUSHBYTES33)
+	prog[69] = byte(opcode.PUSH2)
+	prog[70] = byte(opcode.CHECKMULTISIG)
 	assert.Equal(t, true, IsMultiSigContract(prog))
 	assert.Equal(t, true, IsStandardContract(prog))
 }

 func TestIsMultiSigContractGoodPushBytes1(t *testing.T) {
 	prog := make([]byte, 73)
-	prog[0] = byte(PUSHBYTES1)
+	prog[0] = byte(opcode.PUSHBYTES1)
 	prog[1] = 2
-	prog[2] = byte(PUSHBYTES33)
-	prog[36] = byte(PUSHBYTES33)
-	prog[70] = byte(PUSHBYTES1)
+	prog[2] = byte(opcode.PUSHBYTES33)
+	prog[36] = byte(opcode.PUSHBYTES33)
+	prog[70] = byte(opcode.PUSHBYTES1)
 	prog[71] = 2
-	prog[72] = byte(CHECKMULTISIG)
+	prog[72] = byte(opcode.CHECKMULTISIG)
 	assert.Equal(t, true, IsMultiSigContract(prog))
 }

 func TestIsMultiSigContractGoodPushBytes2(t *testing.T) {
 	prog := make([]byte, 75)
-	prog[0] = byte(PUSHBYTES2)
+	prog[0] = byte(opcode.PUSHBYTES2)
 	prog[1] = 2
-	prog[3] = byte(PUSHBYTES33)
-	prog[37] = byte(PUSHBYTES33)
-	prog[71] = byte(PUSHBYTES2)
+	prog[3] = byte(opcode.PUSHBYTES33)
+	prog[37] = byte(opcode.PUSHBYTES33)
+	prog[71] = byte(opcode.PUSHBYTES2)
 	prog[72] = 2
-	prog[74] = byte(CHECKMULTISIG)
+	prog[74] = byte(opcode.CHECKMULTISIG)
 	assert.Equal(t, true, IsMultiSigContract(prog))
 }

 func TestIsMultiSigContractBadNSigs1(t *testing.T) {
 	prog := make([]byte, 71)
-	prog[0] = byte(PUSH0)
-	prog[1] = byte(PUSHBYTES33)
-	prog[35] = byte(PUSHBYTES33)
-	prog[69] = byte(PUSH2)
-	prog[70] = byte(CHECKMULTISIG)
+	prog[0] = byte(opcode.PUSH0)
+	prog[1] = byte(opcode.PUSHBYTES33)
+	prog[35] = byte(opcode.PUSHBYTES33)
+	prog[69] = byte(opcode.PUSH2)
+	prog[70] = byte(opcode.CHECKMULTISIG)
 	assert.Equal(t, false, IsMultiSigContract(prog))
 	assert.Equal(t, false, IsStandardContract(prog))
 }

 func TestIsMultiSigContractBadNSigs2(t *testing.T) {
 	prog := make([]byte, 73)
-	prog[0] = byte(PUSHBYTES2)
+	prog[0] = byte(opcode.PUSHBYTES2)
 	prog[1] = 0xff
 	prog[2] = 0xff
-	prog[3] = byte(PUSHBYTES33)
-	prog[37] = byte(PUSHBYTES33)
-	prog[71] = byte(PUSH2)
-	prog[72] = byte(CHECKMULTISIG)
+	prog[3] = byte(opcode.PUSHBYTES33)
+	prog[37] = byte(opcode.PUSHBYTES33)
+	prog[71] = byte(opcode.PUSH2)
+	prog[72] = byte(opcode.CHECKMULTISIG)
 	assert.Equal(t, false, IsMultiSigContract(prog))
 }

 func TestIsMultiSigContractBadNSigs3(t *testing.T) {
 	prog := make([]byte, 71)
-	prog[0] = byte(PUSH5)
-	prog[1] = byte(PUSHBYTES33)
-	prog[35] = byte(PUSHBYTES33)
-	prog[69] = byte(PUSH2)
-	prog[70] = byte(CHECKMULTISIG)
+	prog[0] = byte(opcode.PUSH5)
+	prog[1] = byte(opcode.PUSHBYTES33)
+	prog[35] = byte(opcode.PUSHBYTES33)
+	prog[69] = byte(opcode.PUSH2)
+	prog[70] = byte(opcode.CHECKMULTISIG)
 	assert.Equal(t, false, IsMultiSigContract(prog))
 }

 func TestIsMultiSigContractBadExcessiveNOP1(t *testing.T) {
 	prog := make([]byte, 72)
-	prog[0] = byte(PUSH2)
-	prog[1] = byte(NOP)
-	prog[2] = byte(PUSHBYTES33)
-	prog[36] = byte(PUSHBYTES33)
-	prog[70] = byte(PUSH2)
-	prog[71] = byte(CHECKMULTISIG)
+	prog[0] = byte(opcode.PUSH2)
+	prog[1] = byte(opcode.NOP)
+	prog[2] = byte(opcode.PUSHBYTES33)
+	prog[36] = byte(opcode.PUSHBYTES33)
+	prog[70] = byte(opcode.PUSH2)
+	prog[71] = byte(opcode.CHECKMULTISIG)
 	assert.Equal(t, false, IsMultiSigContract(prog))
 }

 func TestIsMultiSigContractBadExcessiveNOP2(t *testing.T) {
 	prog := make([]byte, 72)
-	prog[0] = byte(PUSH2)
-	prog[1] = byte(PUSHBYTES33)
-	prog[35] = byte(NOP)
-	prog[36] = byte(PUSHBYTES33)
-	prog[70] = byte(PUSH2)
-	prog[71] = byte(CHECKMULTISIG)
+	prog[0] = byte(opcode.PUSH2)
+	prog[1] = byte(opcode.PUSHBYTES33)
+	prog[35] = byte(opcode.NOP)
+	prog[36] = byte(opcode.PUSHBYTES33)
+	prog[70] = byte(opcode.PUSH2)
+	prog[71] = byte(opcode.CHECKMULTISIG)
 	assert.Equal(t, false, IsMultiSigContract(prog))
 }

 func TestIsMultiSigContractBadExcessiveNOP3(t *testing.T) {
 	prog := make([]byte, 72)
-	prog[0] = byte(PUSH2)
-	prog[1] = byte(PUSHBYTES33)
-	prog[35] = byte(PUSHBYTES33)
-	prog[69] = byte(NOP)
-	prog[70] = byte(PUSH2)
-	prog[71] = byte(CHECKMULTISIG)
+	prog[0] = byte(opcode.PUSH2)
+	prog[1] = byte(opcode.PUSHBYTES33)
+	prog[35] = byte(opcode.PUSHBYTES33)
+	prog[69] = byte(opcode.NOP)
+	prog[70] = byte(opcode.PUSH2)
+	prog[71] = byte(opcode.CHECKMULTISIG)
 	assert.Equal(t, false, IsMultiSigContract(prog))
 }

 func TestIsMultiSigContractBadExcessiveNOP4(t *testing.T) {
 	prog := make([]byte, 72)
-	prog[0] = byte(PUSH2)
-	prog[1] = byte(PUSHBYTES33)
-	prog[35] = byte(PUSHBYTES33)
-	prog[69] = byte(PUSH2)
-	prog[70] = byte(NOP)
-	prog[71] = byte(CHECKMULTISIG)
+	prog[0] = byte(opcode.PUSH2)
+	prog[1] = byte(opcode.PUSHBYTES33)
+	prog[35] = byte(opcode.PUSHBYTES33)
+	prog[69] = byte(opcode.PUSH2)
+	prog[70] = byte(opcode.NOP)
+	prog[71] = byte(opcode.CHECKMULTISIG)
 	assert.Equal(t, false, IsMultiSigContract(prog))
 }

 func TestIsMultiSigContractBadExcessiveNOP5(t *testing.T) {
 	prog := make([]byte, 72)
-	prog[0] = byte(PUSH2)
-	prog[1] = byte(PUSHBYTES33)
-	prog[35] = byte(PUSHBYTES33)
-	prog[69] = byte(PUSH2)
-	prog[70] = byte(CHECKMULTISIG)
-	prog[71] = byte(NOP)
+	prog[0] = byte(opcode.PUSH2)
+	prog[1] = byte(opcode.PUSHBYTES33)
+	prog[35] = byte(opcode.PUSHBYTES33)
+	prog[69] = byte(opcode.PUSH2)
+	prog[70] = byte(opcode.CHECKMULTISIG)
+	prog[71] = byte(opcode.NOP)
 	assert.Equal(t, false, IsMultiSigContract(prog))
 }

 func TestIsMultiSigContractBadNKeys1(t *testing.T) {
 	prog := make([]byte, 71)
-	prog[0] = byte(PUSH2)
-	prog[1] = byte(PUSHBYTES33)
-	prog[35] = byte(PUSHBYTES33)
-	prog[69] = byte(PUSH3)
-	prog[70] = byte(CHECKMULTISIG)
+	prog[0] = byte(opcode.PUSH2)
+	prog[1] = byte(opcode.PUSHBYTES33)
+	prog[35] = byte(opcode.PUSHBYTES33)
+	prog[69] = byte(opcode.PUSH3)
+	prog[70] = byte(opcode.CHECKMULTISIG)
 	assert.Equal(t, false, IsMultiSigContract(prog))
 }

 func TestIsMultiSigContractBadNKeys2(t *testing.T) {
 	prog := make([]byte, 1)
-	prog[0] = byte(PUSH10)
+	prog[0] = byte(opcode.PUSH10)
 	key := make([]byte, 33)
 	var asize = uint16(MaxArraySize + 1)
 	for i := 0; i < int(asize); i++ {
-		prog = append(prog, byte(PUSHBYTES33))
+		prog = append(prog, byte(opcode.PUSHBYTES33))
 		prog = append(prog, key...)
 	}
-	prog = append(prog, byte(PUSHBYTES2), byte(asize&0xff), byte((asize<<8)&0xff), byte(CHECKMULTISIG))
+	prog = append(prog, byte(opcode.PUSHBYTES2), byte(asize&0xff), byte((asize<<8)&0xff), byte(opcode.CHECKMULTISIG))
 	assert.Equal(t, false, IsMultiSigContract(prog))
 }

 func TestIsMultiSigContractBadRead1(t *testing.T) {
 	prog := make([]byte, 71)
-	prog[0] = byte(PUSHBYTES75)
-	prog[1] = byte(PUSHBYTES33)
-	prog[35] = byte(PUSHBYTES33)
-	prog[69] = byte(PUSH2)
-	prog[70] = byte(CHECKMULTISIG)
+	prog[0] = byte(opcode.PUSHBYTES75)
+	prog[1] = byte(opcode.PUSHBYTES33)
+	prog[35] = byte(opcode.PUSHBYTES33)
+	prog[69] = byte(opcode.PUSH2)
+	prog[70] = byte(opcode.CHECKMULTISIG)
 	assert.Equal(t, false, IsMultiSigContract(prog))
 }

 func TestIsMultiSigContractBadRead2(t *testing.T) {
 	prog := make([]byte, 71)
-	prog[0] = byte(PUSH2)
-	prog[1] = byte(PUSHBYTES33)
-	prog[35] = byte(PUSHBYTES75)
-	prog[69] = byte(PUSH2)
-	prog[70] = byte(CHECKMULTISIG)
+	prog[0] = byte(opcode.PUSH2)
+	prog[1] = byte(opcode.PUSHBYTES33)
+	prog[35] = byte(opcode.PUSHBYTES75)
+	prog[69] = byte(opcode.PUSH2)
+	prog[70] = byte(opcode.CHECKMULTISIG)
 	assert.Equal(t, false, IsMultiSigContract(prog))
 }

 func TestIsMultiSigContractBadRead3(t *testing.T) {
 	prog := make([]byte, 71)
-	prog[0] = byte(PUSH2)
-	prog[1] = byte(PUSHBYTES33)
-	prog[35] = byte(PUSHBYTES33)
-	prog[69] = byte(PUSH2)
-	prog[70] = byte(PUSHBYTES1)
+	prog[0] = byte(opcode.PUSH2)
+	prog[1] = byte(opcode.PUSHBYTES33)
+	prog[35] = byte(opcode.PUSHBYTES33)
+	prog[69] = byte(opcode.PUSH2)
+	prog[70] = byte(opcode.PUSHBYTES1)
 	assert.Equal(t, false, IsMultiSigContract(prog))
 }
--- a/pkg/vm/emit.go
+++ b/pkg/vm/emit.go
@ -9,10 +9,11 @@ import (
 	"math/big"

 	"github.com/CityOfZion/neo-go/pkg/util"
+	"github.com/CityOfZion/neo-go/pkg/vm/opcode"
 )

 // Emit a VM Instruction with data to the given buffer.
-func Emit(w *bytes.Buffer, op Instruction, b []byte) error {
+func Emit(w *bytes.Buffer, op opcode.Opcode, b []byte) error {
 	if err := w.WriteByte(byte(op)); err != nil {
 		return err
 	}
@ -21,28 +22,28 @@ func Emit(w *bytes.Buffer, op Instruction, b []byte) error {
 }

 // EmitOpcode emits a single VM Instruction the given buffer.
-func EmitOpcode(w io.ByteWriter, op Instruction) error {
+func EmitOpcode(w io.ByteWriter, op opcode.Opcode) error {
 	return w.WriteByte(byte(op))
 }

 // EmitBool emits a bool type the given buffer.
 func EmitBool(w io.ByteWriter, ok bool) error {
 	if ok {
-		return EmitOpcode(w, PUSHT)
+		return EmitOpcode(w, opcode.PUSHT)
 	}
-	return EmitOpcode(w, PUSHF)
+	return EmitOpcode(w, opcode.PUSHF)
 }

 // EmitInt emits a int type to the given buffer.
 func EmitInt(w *bytes.Buffer, i int64) error {
 	if i == -1 {
-		return EmitOpcode(w, PUSHM1)
+		return EmitOpcode(w, opcode.PUSHM1)
 	}
 	if i == 0 {
-		return EmitOpcode(w, PUSHF)
+		return EmitOpcode(w, opcode.PUSHF)
 	}
 	if i > 0 && i < 16 {
-		val := Instruction(int(PUSH1) - 1 + int(i))
+		val := opcode.Opcode(int(opcode.PUSH1) - 1 + int(i))
 		return EmitOpcode(w, val)
 	}

@ -63,18 +64,18 @@ func EmitBytes(w *bytes.Buffer, b []byte) error {
 		n   = len(b)
 	)

-	if n <= int(PUSHBYTES75) {
-		return Emit(w, Instruction(n), b)
+	if n <= int(opcode.PUSHBYTES75) {
+		return Emit(w, opcode.Opcode(n), b)
 	} else if n < 0x100 {
-		err = Emit(w, PUSHDATA1, []byte{byte(n)})
+		err = Emit(w, opcode.PUSHDATA1, []byte{byte(n)})
 	} else if n < 0x10000 {
 		buf := make([]byte, 2)
 		binary.LittleEndian.PutUint16(buf, uint16(n))
-		err = Emit(w, PUSHDATA2, buf)
+		err = Emit(w, opcode.PUSHDATA2, buf)
 	} else {
 		buf := make([]byte, 4)
 		binary.LittleEndian.PutUint32(buf, uint32(n))
-		err = Emit(w, PUSHDATA4, buf)
+		err = Emit(w, opcode.PUSHDATA4, buf)
 	}
 	if err != nil {
 		return err
@ -92,16 +93,16 @@ func EmitSyscall(w *bytes.Buffer, api string) error {
 	buf := make([]byte, len(api)+1)
 	buf[0] = byte(len(api))
 	copy(buf[1:], api)
-	return Emit(w, SYSCALL, buf)
+	return Emit(w, opcode.SYSCALL, buf)
 }

 // EmitCall emits a call Instruction with label to the given buffer.
-func EmitCall(w *bytes.Buffer, op Instruction, label int16) error {
+func EmitCall(w *bytes.Buffer, op opcode.Opcode, label int16) error {
 	return EmitJmp(w, op, label)
 }

 // EmitJmp emits a jump Instruction along with label to the given buffer.
-func EmitJmp(w *bytes.Buffer, op Instruction, label int16) error {
+func EmitJmp(w *bytes.Buffer, op opcode.Opcode, label int16) error {
 	if !isInstructionJmp(op) {
 		return fmt.Errorf("opcode %s is not a jump or call type", op.String())
 	}
@ -113,9 +114,9 @@ func EmitJmp(w *bytes.Buffer, op Instruction, label int16) error {
 // EmitAppCall emits an appcall, if tailCall is true, tailCall opcode will be
 // emitted instead.
 func EmitAppCall(w *bytes.Buffer, scriptHash util.Uint160, tailCall bool) error {
-	op := APPCALL
+	op := opcode.APPCALL
 	if tailCall {
-		op = TAILCALL
+		op = opcode.TAILCALL
 	}
 	return Emit(w, op, scriptHash.Bytes())
 }
@ -142,8 +143,8 @@ func EmitAppCallWithOperation(w *bytes.Buffer, scriptHash util.Uint160, operatio
 	return EmitAppCall(w, scriptHash, false)
 }

-func isInstructionJmp(op Instruction) bool {
-	if op == JMP || op == JMPIFNOT || op == JMPIF || op == CALL {
+func isInstructionJmp(op opcode.Opcode) bool {
+	if op == opcode.JMP || op == opcode.JMPIFNOT || op == opcode.JMPIF || op == opcode.CALL {
 		return true
 	}
 	return false
--- a/pkg/vm/emit_test.go
+++ b/pkg/vm/emit_test.go
@ -5,13 +5,14 @@ import (
 	"encoding/binary"
 	"testing"

+	"github.com/CityOfZion/neo-go/pkg/vm/opcode"
 	"github.com/stretchr/testify/assert"
 )

 func TestEmitInt(t *testing.T) {
 	buf := new(bytes.Buffer)
 	EmitInt(buf, 10)
-	assert.Equal(t, Instruction(buf.Bytes()[0]), PUSH10)
+	assert.Equal(t, opcode.Opcode(buf.Bytes()[0]), opcode.PUSH10)
 	buf.Reset()
 	EmitInt(buf, 100)
 	assert.Equal(t, buf.Bytes()[0], uint8(1))
@ -26,8 +27,8 @@ func TestEmitBool(t *testing.T) {
 	buf := new(bytes.Buffer)
 	EmitBool(buf, true)
 	EmitBool(buf, false)
-	assert.Equal(t, Instruction(buf.Bytes()[0]), PUSH1)
-	assert.Equal(t, Instruction(buf.Bytes()[1]), PUSH0)
+	assert.Equal(t, opcode.Opcode(buf.Bytes()[0]), opcode.PUSH1)
+	assert.Equal(t, opcode.Opcode(buf.Bytes()[1]), opcode.PUSH0)
 }

 func TestEmitString(t *testing.T) {
@ -48,7 +49,7 @@ func TestEmitSyscall(t *testing.T) {
 	buf := new(bytes.Buffer)
 	for _, syscall := range syscalls {
 		EmitSyscall(buf, syscall)
-		assert.Equal(t, Instruction(buf.Bytes()[0]), SYSCALL)
+		assert.Equal(t, opcode.Opcode(buf.Bytes()[0]), opcode.SYSCALL)
 		assert.Equal(t, buf.Bytes()[1], uint8(len(syscall)))
 		assert.Equal(t, buf.Bytes()[2:], []byte(syscall))
 		buf.Reset()
@ -57,8 +58,8 @@ func TestEmitSyscall(t *testing.T) {

 func TestEmitCall(t *testing.T) {
 	buf := new(bytes.Buffer)
-	EmitCall(buf, JMP, 100)
-	assert.Equal(t, Instruction(buf.Bytes()[0]), JMP)
+	EmitCall(buf, opcode.JMP, 100)
+	assert.Equal(t, opcode.Opcode(buf.Bytes()[0]), opcode.JMP)
 	label := binary.LittleEndian.Uint16(buf.Bytes()[1:3])
 	assert.Equal(t, label, uint16(100))
 }
--- a/pkg/vm/instruction_string.go
+++ b/pkg/vm/instruction_string.go
@ -1,393 +0,0 @@
-// Code generated by "stringer -type=Instruction"; DO NOT EDIT.
-
-package vm
-
-import "strconv"
-
-func _() {
-	// An "invalid array index" compiler error signifies that the constant values have changed.
-	// Re-run the stringer command to generate them again.
-	var x [1]struct{}
-	_ = x[PUSH0-0]
-	_ = x[PUSHF-0]
-	_ = x[PUSHBYTES1-1]
-	_ = x[PUSHBYTES2-2]
-	_ = x[PUSHBYTES3-3]
-	_ = x[PUSHBYTES4-4]
-	_ = x[PUSHBYTES5-5]
-	_ = x[PUSHBYTES6-6]
-	_ = x[PUSHBYTES7-7]
-	_ = x[PUSHBYTES8-8]
-	_ = x[PUSHBYTES9-9]
-	_ = x[PUSHBYTES10-10]
-	_ = x[PUSHBYTES11-11]
-	_ = x[PUSHBYTES12-12]
-	_ = x[PUSHBYTES13-13]
-	_ = x[PUSHBYTES14-14]
-	_ = x[PUSHBYTES15-15]
-	_ = x[PUSHBYTES16-16]
-	_ = x[PUSHBYTES17-17]
-	_ = x[PUSHBYTES18-18]
-	_ = x[PUSHBYTES19-19]
-	_ = x[PUSHBYTES20-20]
-	_ = x[PUSHBYTES21-21]
-	_ = x[PUSHBYTES22-22]
-	_ = x[PUSHBYTES23-23]
-	_ = x[PUSHBYTES24-24]
-	_ = x[PUSHBYTES25-25]
-	_ = x[PUSHBYTES26-26]
-	_ = x[PUSHBYTES27-27]
-	_ = x[PUSHBYTES28-28]
-	_ = x[PUSHBYTES29-29]
-	_ = x[PUSHBYTES30-30]
-	_ = x[PUSHBYTES31-31]
-	_ = x[PUSHBYTES32-32]
-	_ = x[PUSHBYTES33-33]
-	_ = x[PUSHBYTES34-34]
-	_ = x[PUSHBYTES35-35]
-	_ = x[PUSHBYTES36-36]
-	_ = x[PUSHBYTES37-37]
-	_ = x[PUSHBYTES38-38]
-	_ = x[PUSHBYTES39-39]
-	_ = x[PUSHBYTES40-40]
-	_ = x[PUSHBYTES41-41]
-	_ = x[PUSHBYTES42-42]
-	_ = x[PUSHBYTES43-43]
-	_ = x[PUSHBYTES44-44]
-	_ = x[PUSHBYTES45-45]
-	_ = x[PUSHBYTES46-46]
-	_ = x[PUSHBYTES47-47]
-	_ = x[PUSHBYTES48-48]
-	_ = x[PUSHBYTES49-49]
-	_ = x[PUSHBYTES50-50]
-	_ = x[PUSHBYTES51-51]
-	_ = x[PUSHBYTES52-52]
-	_ = x[PUSHBYTES53-53]
-	_ = x[PUSHBYTES54-54]
-	_ = x[PUSHBYTES55-55]
-	_ = x[PUSHBYTES56-56]
-	_ = x[PUSHBYTES57-57]
-	_ = x[PUSHBYTES58-58]
-	_ = x[PUSHBYTES59-59]
-	_ = x[PUSHBYTES60-60]
-	_ = x[PUSHBYTES61-61]
-	_ = x[PUSHBYTES62-62]
-	_ = x[PUSHBYTES63-63]
-	_ = x[PUSHBYTES64-64]
-	_ = x[PUSHBYTES65-65]
-	_ = x[PUSHBYTES66-66]
-	_ = x[PUSHBYTES67-67]
-	_ = x[PUSHBYTES68-68]
-	_ = x[PUSHBYTES69-69]
-	_ = x[PUSHBYTES70-70]
-	_ = x[PUSHBYTES71-71]
-	_ = x[PUSHBYTES72-72]
-	_ = x[PUSHBYTES73-73]
-	_ = x[PUSHBYTES74-74]
-	_ = x[PUSHBYTES75-75]
-	_ = x[PUSHDATA1-76]
-	_ = x[PUSHDATA2-77]
-	_ = x[PUSHDATA4-78]
-	_ = x[PUSHM1-79]
-	_ = x[PUSH1-81]
-	_ = x[PUSHT-81]
-	_ = x[PUSH2-82]
-	_ = x[PUSH3-83]
-	_ = x[PUSH4-84]
-	_ = x[PUSH5-85]
-	_ = x[PUSH6-86]
-	_ = x[PUSH7-87]
-	_ = x[PUSH8-88]
-	_ = x[PUSH9-89]
-	_ = x[PUSH10-90]
-	_ = x[PUSH11-91]
-	_ = x[PUSH12-92]
-	_ = x[PUSH13-93]
-	_ = x[PUSH14-94]
-	_ = x[PUSH15-95]
-	_ = x[PUSH16-96]
-	_ = x[NOP-97]
-	_ = x[JMP-98]
-	_ = x[JMPIF-99]
-	_ = x[JMPIFNOT-100]
-	_ = x[CALL-101]
-	_ = x[RET-102]
-	_ = x[APPCALL-103]
-	_ = x[SYSCALL-104]
-	_ = x[TAILCALL-105]
-	_ = x[DUPFROMALTSTACK-106]
-	_ = x[TOALTSTACK-107]
-	_ = x[FROMALTSTACK-108]
-	_ = x[XDROP-109]
-	_ = x[XSWAP-114]
-	_ = x[XTUCK-115]
-	_ = x[DEPTH-116]
-	_ = x[DROP-117]
-	_ = x[DUP-118]
-	_ = x[NIP-119]
-	_ = x[OVER-120]
-	_ = x[PICK-121]
-	_ = x[ROLL-122]
-	_ = x[ROT-123]
-	_ = x[SWAP-124]
-	_ = x[TUCK-125]
-	_ = x[CAT-126]
-	_ = x[SUBSTR-127]
-	_ = x[LEFT-128]
-	_ = x[RIGHT-129]
-	_ = x[SIZE-130]
-	_ = x[INVERT-131]
-	_ = x[AND-132]
-	_ = x[OR-133]
-	_ = x[XOR-134]
-	_ = x[EQUAL-135]
-	_ = x[INC-139]
-	_ = x[DEC-140]
-	_ = x[SIGN-141]
-	_ = x[NEGATE-143]
-	_ = x[ABS-144]
-	_ = x[NOT-145]
-	_ = x[NZ-146]
-	_ = x[ADD-147]
-	_ = x[SUB-148]
-	_ = x[MUL-149]
-	_ = x[DIV-150]
-	_ = x[MOD-151]
-	_ = x[SHL-152]
-	_ = x[SHR-153]
-	_ = x[BOOLAND-154]
-	_ = x[BOOLOR-155]
-	_ = x[NUMEQUAL-156]
-	_ = x[NUMNOTEQUAL-158]
-	_ = x[LT-159]
-	_ = x[GT-160]
-	_ = x[LTE-161]
-	_ = x[GTE-162]
-	_ = x[MIN-163]
-	_ = x[MAX-164]
-	_ = x[WITHIN-165]
-	_ = x[SHA1-167]
-	_ = x[SHA256-168]
-	_ = x[HASH160-169]
-	_ = x[HASH256-170]
-	_ = x[CHECKSIG-172]
-	_ = x[VERIFY-173]
-	_ = x[CHECKMULTISIG-174]
-	_ = x[ARRAYSIZE-192]
-	_ = x[PACK-193]
-	_ = x[UNPACK-194]
-	_ = x[PICKITEM-195]
-	_ = x[SETITEM-196]
-	_ = x[NEWARRAY-197]
-	_ = x[NEWSTRUCT-198]
-	_ = x[NEWMAP-199]
-	_ = x[APPEND-200]
-	_ = x[REVERSE-201]
-	_ = x[REMOVE-202]
-	_ = x[HASKEY-203]
-	_ = x[KEYS-204]
-	_ = x[VALUES-205]
-	_ = x[CALLI-224]
-	_ = x[CALLE-225]
-	_ = x[CALLED-226]
-	_ = x[CALLET-227]
-	_ = x[CALLEDT-228]
-	_ = x[THROW-240]
-	_ = x[THROWIFNOT-241]
-}
-
-const _Instruction_name = "PUSH0PUSHBYTES1PUSHBYTES2PUSHBYTES3PUSHBYTES4PUSHBYTES5PUSHBYTES6PUSHBYTES7PUSHBYTES8PUSHBYTES9PUSHBYTES10PUSHBYTES11PUSHBYTES12PUSHBYTES13PUSHBYTES14PUSHBYTES15PUSHBYTES16PUSHBYTES17PUSHBYTES18PUSHBYTES19PUSHBYTES20PUSHBYTES21PUSHBYTES22PUSHBYTES23PUSHBYTES24PUSHBYTES25PUSHBYTES26PUSHBYTES27PUSHBYTES28PUSHBYTES29PUSHBYTES30PUSHBYTES31PUSHBYTES32PUSHBYTES33PUSHBYTES34PUSHBYTES35PUSHBYTES36PUSHBYTES37PUSHBYTES38PUSHBYTES39PUSHBYTES40PUSHBYTES41PUSHBYTES42PUSHBYTES43PUSHBYTES44PUSHBYTES45PUSHBYTES46PUSHBYTES47PUSHBYTES48PUSHBYTES49PUSHBYTES50PUSHBYTES51PUSHBYTES52PUSHBYTES53PUSHBYTES54PUSHBYTES55PUSHBYTES56PUSHBYTES57PUSHBYTES58PUSHBYTES59PUSHBYTES60PUSHBYTES61PUSHBYTES62PUSHBYTES63PUSHBYTES64PUSHBYTES65PUSHBYTES66PUSHBYTES67PUSHBYTES68PUSHBYTES69PUSHBYTES70PUSHBYTES71PUSHBYTES72PUSHBYTES73PUSHBYTES74PUSHBYTES75PUSHDATA1PUSHDATA2PUSHDATA4PUSHM1PUSH1PUSH2PUSH3PUSH4PUSH5PUSH6PUSH7PUSH8PUSH9PUSH10PUSH11PUSH12PUSH13PUSH14PUSH15PUSH16NOPJMPJMPIFJMPIFNOTCALLRETAPPCALLSYSCALLTAILCALLDUPFROMALTSTACKTOALTSTACKFROMALTSTACKXDROPXSWAPXTUCKDEPTHDROPDUPNIPOVERPICKROLLROTSWAPTUCKCATSUBSTRLEFTRIGHTSIZEINVERTANDORXOREQUALINCDECSIGNNEGATEABSNOTNZADDSUBMULDIVMODSHLSHRBOOLANDBOOLORNUMEQUALNUMNOTEQUALLTGTLTEGTEMINMAXWITHINSHA1SHA256HASH160HASH256CHECKSIGVERIFYCHECKMULTISIGARRAYSIZEPACKUNPACKPICKITEMSETITEMNEWARRAYNEWSTRUCTNEWMAPAPPENDREVERSEREMOVEHASKEYKEYSVALUESCALLICALLECALLEDCALLETCALLEDTTHROWTHROWIFNOT"
-
-var _Instruction_map = map[Instruction]string{
-	0:   _Instruction_name[0:5],
-	1:   _Instruction_name[5:15],
-	2:   _Instruction_name[15:25],
-	3:   _Instruction_name[25:35],
-	4:   _Instruction_name[35:45],
-	5:   _Instruction_name[45:55],
-	6:   _Instruction_name[55:65],
-	7:   _Instruction_name[65:75],
-	8:   _Instruction_name[75:85],
-	9:   _Instruction_name[85:95],
-	10:  _Instruction_name[95:106],
-	11:  _Instruction_name[106:117],
-	12:  _Instruction_name[117:128],
-	13:  _Instruction_name[128:139],
-	14:  _Instruction_name[139:150],
-	15:  _Instruction_name[150:161],
-	16:  _Instruction_name[161:172],
-	17:  _Instruction_name[172:183],
-	18:  _Instruction_name[183:194],
-	19:  _Instruction_name[194:205],
-	20:  _Instruction_name[205:216],
-	21:  _Instruction_name[216:227],
-	22:  _Instruction_name[227:238],
-	23:  _Instruction_name[238:249],
-	24:  _Instruction_name[249:260],
-	25:  _Instruction_name[260:271],
-	26:  _Instruction_name[271:282],
-	27:  _Instruction_name[282:293],
-	28:  _Instruction_name[293:304],
-	29:  _Instruction_name[304:315],
-	30:  _Instruction_name[315:326],
-	31:  _Instruction_name[326:337],
-	32:  _Instruction_name[337:348],
-	33:  _Instruction_name[348:359],
-	34:  _Instruction_name[359:370],
-	35:  _Instruction_name[370:381],
-	36:  _Instruction_name[381:392],
-	37:  _Instruction_name[392:403],
-	38:  _Instruction_name[403:414],
-	39:  _Instruction_name[414:425],
-	40:  _Instruction_name[425:436],
-	41:  _Instruction_name[436:447],
-	42:  _Instruction_name[447:458],
-	43:  _Instruction_name[458:469],
-	44:  _Instruction_name[469:480],
-	45:  _Instruction_name[480:491],
-	46:  _Instruction_name[491:502],
-	47:  _Instruction_name[502:513],
-	48:  _Instruction_name[513:524],
-	49:  _Instruction_name[524:535],
-	50:  _Instruction_name[535:546],
-	51:  _Instruction_name[546:557],
-	52:  _Instruction_name[557:568],
-	53:  _Instruction_name[568:579],
-	54:  _Instruction_name[579:590],
-	55:  _Instruction_name[590:601],
-	56:  _Instruction_name[601:612],
-	57:  _Instruction_name[612:623],
-	58:  _Instruction_name[623:634],
-	59:  _Instruction_name[634:645],
-	60:  _Instruction_name[645:656],
-	61:  _Instruction_name[656:667],
-	62:  _Instruction_name[667:678],
-	63:  _Instruction_name[678:689],
-	64:  _Instruction_name[689:700],
-	65:  _Instruction_name[700:711],
-	66:  _Instruction_name[711:722],
-	67:  _Instruction_name[722:733],
-	68:  _Instruction_name[733:744],
-	69:  _Instruction_name[744:755],
-	70:  _Instruction_name[755:766],
-	71:  _Instruction_name[766:777],
-	72:  _Instruction_name[777:788],
-	73:  _Instruction_name[788:799],
-	74:  _Instruction_name[799:810],
-	75:  _Instruction_name[810:821],
-	76:  _Instruction_name[821:830],
-	77:  _Instruction_name[830:839],
-	78:  _Instruction_name[839:848],
-	79:  _Instruction_name[848:854],
-	81:  _Instruction_name[854:859],
-	82:  _Instruction_name[859:864],
-	83:  _Instruction_name[864:869],
-	84:  _Instruction_name[869:874],
-	85:  _Instruction_name[874:879],
-	86:  _Instruction_name[879:884],
-	87:  _Instruction_name[884:889],
-	88:  _Instruction_name[889:894],
-	89:  _Instruction_name[894:899],
-	90:  _Instruction_name[899:905],
-	91:  _Instruction_name[905:911],
-	92:  _Instruction_name[911:917],
-	93:  _Instruction_name[917:923],
-	94:  _Instruction_name[923:929],
-	95:  _Instruction_name[929:935],
-	96:  _Instruction_name[935:941],
-	97:  _Instruction_name[941:944],
-	98:  _Instruction_name[944:947],
-	99:  _Instruction_name[947:952],
-	100: _Instruction_name[952:960],
-	101: _Instruction_name[960:964],
-	102: _Instruction_name[964:967],
-	103: _Instruction_name[967:974],
-	104: _Instruction_name[974:981],
-	105: _Instruction_name[981:989],
-	106: _Instruction_name[989:1004],
-	107: _Instruction_name[1004:1014],
-	108: _Instruction_name[1014:1026],
-	109: _Instruction_name[1026:1031],
-	114: _Instruction_name[1031:1036],
-	115: _Instruction_name[1036:1041],
-	116: _Instruction_name[1041:1046],
-	117: _Instruction_name[1046:1050],
-	118: _Instruction_name[1050:1053],
-	119: _Instruction_name[1053:1056],
-	120: _Instruction_name[1056:1060],
-	121: _Instruction_name[1060:1064],
-	122: _Instruction_name[1064:1068],
-	123: _Instruction_name[1068:1071],
-	124: _Instruction_name[1071:1075],
-	125: _Instruction_name[1075:1079],
-	126: _Instruction_name[1079:1082],
-	127: _Instruction_name[1082:1088],
-	128: _Instruction_name[1088:1092],
-	129: _Instruction_name[1092:1097],
-	130: _Instruction_name[1097:1101],
-	131: _Instruction_name[1101:1107],
-	132: _Instruction_name[1107:1110],
-	133: _Instruction_name[1110:1112],
-	134: _Instruction_name[1112:1115],
-	135: _Instruction_name[1115:1120],
-	139: _Instruction_name[1120:1123],
-	140: _Instruction_name[1123:1126],
-	141: _Instruction_name[1126:1130],
-	143: _Instruction_name[1130:1136],
-	144: _Instruction_name[1136:1139],
-	145: _Instruction_name[1139:1142],
-	146: _Instruction_name[1142:1144],
-	147: _Instruction_name[1144:1147],
-	148: _Instruction_name[1147:1150],
-	149: _Instruction_name[1150:1153],
-	150: _Instruction_name[1153:1156],
-	151: _Instruction_name[1156:1159],
-	152: _Instruction_name[1159:1162],
-	153: _Instruction_name[1162:1165],
-	154: _Instruction_name[1165:1172],
-	155: _Instruction_name[1172:1178],
-	156: _Instruction_name[1178:1186],
-	158: _Instruction_name[1186:1197],
-	159: _Instruction_name[1197:1199],
-	160: _Instruction_name[1199:1201],
-	161: _Instruction_name[1201:1204],
-	162: _Instruction_name[1204:1207],
-	163: _Instruction_name[1207:1210],
-	164: _Instruction_name[1210:1213],
-	165: _Instruction_name[1213:1219],
-	167: _Instruction_name[1219:1223],
-	168: _Instruction_name[1223:1229],
-	169: _Instruction_name[1229:1236],
-	170: _Instruction_name[1236:1243],
-	172: _Instruction_name[1243:1251],
-	173: _Instruction_name[1251:1257],
-	174: _Instruction_name[1257:1270],
-	192: _Instruction_name[1270:1279],
-	193: _Instruction_name[1279:1283],
-	194: _Instruction_name[1283:1289],
-	195: _Instruction_name[1289:1297],
-	196: _Instruction_name[1297:1304],
-	197: _Instruction_name[1304:1312],
-	198: _Instruction_name[1312:1321],
-	199: _Instruction_name[1321:1327],
-	200: _Instruction_name[1327:1333],
-	201: _Instruction_name[1333:1340],
-	202: _Instruction_name[1340:1346],
-	203: _Instruction_name[1346:1352],
-	204: _Instruction_name[1352:1356],
-	205: _Instruction_name[1356:1362],
-	224: _Instruction_name[1362:1367],
-	225: _Instruction_name[1367:1372],
-	226: _Instruction_name[1372:1378],
-	227: _Instruction_name[1378:1384],
-	228: _Instruction_name[1384:1391],
-	240: _Instruction_name[1391:1396],
-	241: _Instruction_name[1396:1406],
-}
-
-func (i Instruction) String() string {
-	if str, ok := _Instruction_map[i]; ok {
-		return str
-	}
-	return "Instruction(" + strconv.FormatInt(int64(i), 10) + ")"
-}
--- a/pkg/vm/instructions.go
+++ b/pkg/vm/instructions.go
@ -1,215 +0,0 @@
-package vm
-
-//go:generate stringer -type=Instruction
-
-// Instruction represents an single operation for the NEO virtual machine.
-type Instruction byte
-
-// Viable list of supported instruction constants.
-const (
-	// Constants
-	PUSH0       Instruction = 0x00
-	PUSHF       Instruction = PUSH0
-	PUSHBYTES1  Instruction = 0x01
-	PUSHBYTES2  Instruction = 0x02
-	PUSHBYTES3  Instruction = 0x03
-	PUSHBYTES4  Instruction = 0x04
-	PUSHBYTES5  Instruction = 0x05
-	PUSHBYTES6  Instruction = 0x06
-	PUSHBYTES7  Instruction = 0x07
-	PUSHBYTES8  Instruction = 0x08
-	PUSHBYTES9  Instruction = 0x09
-	PUSHBYTES10 Instruction = 0x0A
-	PUSHBYTES11 Instruction = 0x0B
-	PUSHBYTES12 Instruction = 0x0C
-	PUSHBYTES13 Instruction = 0x0D
-	PUSHBYTES14 Instruction = 0x0E
-	PUSHBYTES15 Instruction = 0x0F
-	PUSHBYTES16 Instruction = 0x10
-	PUSHBYTES17 Instruction = 0x11
-	PUSHBYTES18 Instruction = 0x12
-	PUSHBYTES19 Instruction = 0x13
-	PUSHBYTES20 Instruction = 0x14
-	PUSHBYTES21 Instruction = 0x15
-	PUSHBYTES22 Instruction = 0x16
-	PUSHBYTES23 Instruction = 0x17
-	PUSHBYTES24 Instruction = 0x18
-	PUSHBYTES25 Instruction = 0x19
-	PUSHBYTES26 Instruction = 0x1A
-	PUSHBYTES27 Instruction = 0x1B
-	PUSHBYTES28 Instruction = 0x1C
-	PUSHBYTES29 Instruction = 0x1D
-	PUSHBYTES30 Instruction = 0x1E
-	PUSHBYTES31 Instruction = 0x1F
-	PUSHBYTES32 Instruction = 0x20
-	PUSHBYTES33 Instruction = 0x21
-	PUSHBYTES34 Instruction = 0x22
-	PUSHBYTES35 Instruction = 0x23
-	PUSHBYTES36 Instruction = 0x24
-	PUSHBYTES37 Instruction = 0x25
-	PUSHBYTES38 Instruction = 0x26
-	PUSHBYTES39 Instruction = 0x27
-	PUSHBYTES40 Instruction = 0x28
-	PUSHBYTES41 Instruction = 0x29
-	PUSHBYTES42 Instruction = 0x2A
-	PUSHBYTES43 Instruction = 0x2B
-	PUSHBYTES44 Instruction = 0x2C
-	PUSHBYTES45 Instruction = 0x2D
-	PUSHBYTES46 Instruction = 0x2E
-	PUSHBYTES47 Instruction = 0x2F
-	PUSHBYTES48 Instruction = 0x30
-	PUSHBYTES49 Instruction = 0x31
-	PUSHBYTES50 Instruction = 0x32
-	PUSHBYTES51 Instruction = 0x33
-	PUSHBYTES52 Instruction = 0x34
-	PUSHBYTES53 Instruction = 0x35
-	PUSHBYTES54 Instruction = 0x36
-	PUSHBYTES55 Instruction = 0x37
-	PUSHBYTES56 Instruction = 0x38
-	PUSHBYTES57 Instruction = 0x39
-	PUSHBYTES58 Instruction = 0x3A
-	PUSHBYTES59 Instruction = 0x3B
-	PUSHBYTES60 Instruction = 0x3C
-	PUSHBYTES61 Instruction = 0x3D
-	PUSHBYTES62 Instruction = 0x3E
-	PUSHBYTES63 Instruction = 0x3F
-	PUSHBYTES64 Instruction = 0x40
-	PUSHBYTES65 Instruction = 0x41
-	PUSHBYTES66 Instruction = 0x42
-	PUSHBYTES67 Instruction = 0x43
-	PUSHBYTES68 Instruction = 0x44
-	PUSHBYTES69 Instruction = 0x45
-	PUSHBYTES70 Instruction = 0x46
-	PUSHBYTES71 Instruction = 0x47
-	PUSHBYTES72 Instruction = 0x48
-	PUSHBYTES73 Instruction = 0x49
-	PUSHBYTES74 Instruction = 0x4A
-	PUSHBYTES75 Instruction = 0x4B
-	PUSHDATA1   Instruction = 0x4C
-	PUSHDATA2   Instruction = 0x4D
-	PUSHDATA4   Instruction = 0x4E
-	PUSHM1      Instruction = 0x4F
-	PUSH1       Instruction = 0x51
-	PUSHT       Instruction = PUSH1
-	PUSH2       Instruction = 0x52
-	PUSH3       Instruction = 0x53
-	PUSH4       Instruction = 0x54
-	PUSH5       Instruction = 0x55
-	PUSH6       Instruction = 0x56
-	PUSH7       Instruction = 0x57
-	PUSH8       Instruction = 0x58
-	PUSH9       Instruction = 0x59
-	PUSH10      Instruction = 0x5A
-	PUSH11      Instruction = 0x5B
-	PUSH12      Instruction = 0x5C
-	PUSH13      Instruction = 0x5D
-	PUSH14      Instruction = 0x5E
-	PUSH15      Instruction = 0x5F
-	PUSH16      Instruction = 0x60
-
-	// Flow control
-	NOP      Instruction = 0x61
-	JMP      Instruction = 0x62
-	JMPIF    Instruction = 0x63
-	JMPIFNOT Instruction = 0x64
-	CALL     Instruction = 0x65
-	RET      Instruction = 0x66
-	APPCALL  Instruction = 0x67
-	SYSCALL  Instruction = 0x68
-	TAILCALL Instruction = 0x69
-
-	// Stack
-	DUPFROMALTSTACK Instruction = 0x6A
-	TOALTSTACK      Instruction = 0x6B
-	FROMALTSTACK    Instruction = 0x6C
-	XDROP           Instruction = 0x6D
-	XSWAP           Instruction = 0x72
-	XTUCK           Instruction = 0x73
-	DEPTH           Instruction = 0x74
-	DROP            Instruction = 0x75
-	DUP             Instruction = 0x76
-	NIP             Instruction = 0x77
-	OVER            Instruction = 0x78
-	PICK            Instruction = 0x79
-	ROLL            Instruction = 0x7A
-	ROT             Instruction = 0x7B
-	SWAP            Instruction = 0x7C
-	TUCK            Instruction = 0x7D
-
-	// Splice
-	CAT    Instruction = 0x7E
-	SUBSTR Instruction = 0x7F
-	LEFT   Instruction = 0x80
-	RIGHT  Instruction = 0x81
-	SIZE   Instruction = 0x82
-
-	// Bitwise logic
-	INVERT Instruction = 0x83
-	AND    Instruction = 0x84
-	OR     Instruction = 0x85
-	XOR    Instruction = 0x86
-	EQUAL  Instruction = 0x87
-
-	// Arithmetic
-	INC         Instruction = 0x8B
-	DEC         Instruction = 0x8C
-	SIGN        Instruction = 0x8D
-	NEGATE      Instruction = 0x8F
-	ABS         Instruction = 0x90
-	NOT         Instruction = 0x91
-	NZ          Instruction = 0x92
-	ADD         Instruction = 0x93
-	SUB         Instruction = 0x94
-	MUL         Instruction = 0x95
-	DIV         Instruction = 0x96
-	MOD         Instruction = 0x97
-	SHL         Instruction = 0x98
-	SHR         Instruction = 0x99
-	BOOLAND     Instruction = 0x9A
-	BOOLOR      Instruction = 0x9B
-	NUMEQUAL    Instruction = 0x9C
-	NUMNOTEQUAL Instruction = 0x9E
-	LT          Instruction = 0x9F
-	GT          Instruction = 0xA0
-	LTE         Instruction = 0xA1
-	GTE         Instruction = 0xA2
-	MIN         Instruction = 0xA3
-	MAX         Instruction = 0xA4
-	WITHIN      Instruction = 0xA5
-
-	// Crypto
-	SHA1          Instruction = 0xA7
-	SHA256        Instruction = 0xA8
-	HASH160       Instruction = 0xA9
-	HASH256       Instruction = 0xAA
-	CHECKSIG      Instruction = 0xAC
-	VERIFY        Instruction = 0xAD
-	CHECKMULTISIG Instruction = 0xAE
-
-	// Advanced data structures (arrays, structures, maps)
-	ARRAYSIZE Instruction = 0xC0
-	PACK      Instruction = 0xC1
-	UNPACK    Instruction = 0xC2
-	PICKITEM  Instruction = 0xC3
-	SETITEM   Instruction = 0xC4
-	NEWARRAY  Instruction = 0xC5
-	NEWSTRUCT Instruction = 0xC6
-	NEWMAP    Instruction = 0xC7
-	APPEND    Instruction = 0xC8
-	REVERSE   Instruction = 0xC9
-	REMOVE    Instruction = 0xCA
-	HASKEY    Instruction = 0xCB
-	KEYS      Instruction = 0xCC
-	VALUES    Instruction = 0xCD
-
-	// Stack isolation
-	CALLI   Instruction = 0xE0
-	CALLE   Instruction = 0xE1
-	CALLED  Instruction = 0xE2
-	CALLET  Instruction = 0xE3
-	CALLEDT Instruction = 0xE4
-
-	// Exceptions
-	THROW      Instruction = 0xF0
-	THROWIFNOT Instruction = 0xF1
-)
--- a/pkg/vm/json_test.go
+++ b/pkg/vm/json_test.go
@ -15,6 +15,7 @@ import (

 	"github.com/CityOfZion/neo-go/pkg/crypto/hash"
 	"github.com/CityOfZion/neo-go/pkg/util"
+	"github.com/CityOfZion/neo-go/pkg/vm/opcode"
 	"github.com/stretchr/testify/require"
 )

@ -154,7 +155,7 @@ func testFile(t *testing.T, filename string) {
 							ctx := vm.istack.Peek(i).Value().(*Context)
 							if ctx.nextip < len(ctx.prog) {
 								require.Equal(t, s.InstructionPointer, ctx.nextip)
-								require.Equal(t, s.Instruction, Instruction(ctx.prog[ctx.nextip]).String())
+								require.Equal(t, s.Instruction, opcode.Opcode(ctx.prog[ctx.nextip]).String())
 							}
 							compareStacks(t, s.EStack, vm.estack)
 							compareStacks(t, s.AStack, vm.astack)
--- a/pkg/vm/opcode/opcode.go
+++ b/pkg/vm/opcode/opcode.go
@ -0,0 +1,215 @@
+package opcode
+
+//go:generate stringer -type=Opcode
+
+// Opcode represents a single operation code for the NEO virtual machine.
+type Opcode byte
+
+// Viable list of supported instruction constants.
+const (
+	// Constants
+	PUSH0       Opcode = 0x00
+	PUSHF       Opcode = PUSH0
+	PUSHBYTES1  Opcode = 0x01
+	PUSHBYTES2  Opcode = 0x02
+	PUSHBYTES3  Opcode = 0x03
+	PUSHBYTES4  Opcode = 0x04
+	PUSHBYTES5  Opcode = 0x05
+	PUSHBYTES6  Opcode = 0x06
+	PUSHBYTES7  Opcode = 0x07
+	PUSHBYTES8  Opcode = 0x08
+	PUSHBYTES9  Opcode = 0x09
+	PUSHBYTES10 Opcode = 0x0A
+	PUSHBYTES11 Opcode = 0x0B
+	PUSHBYTES12 Opcode = 0x0C
+	PUSHBYTES13 Opcode = 0x0D
+	PUSHBYTES14 Opcode = 0x0E
+	PUSHBYTES15 Opcode = 0x0F
+	PUSHBYTES16 Opcode = 0x10
+	PUSHBYTES17 Opcode = 0x11
+	PUSHBYTES18 Opcode = 0x12
+	PUSHBYTES19 Opcode = 0x13
+	PUSHBYTES20 Opcode = 0x14
+	PUSHBYTES21 Opcode = 0x15
+	PUSHBYTES22 Opcode = 0x16
+	PUSHBYTES23 Opcode = 0x17
+	PUSHBYTES24 Opcode = 0x18
+	PUSHBYTES25 Opcode = 0x19
+	PUSHBYTES26 Opcode = 0x1A
+	PUSHBYTES27 Opcode = 0x1B
+	PUSHBYTES28 Opcode = 0x1C
+	PUSHBYTES29 Opcode = 0x1D
+	PUSHBYTES30 Opcode = 0x1E
+	PUSHBYTES31 Opcode = 0x1F
+	PUSHBYTES32 Opcode = 0x20
+	PUSHBYTES33 Opcode = 0x21
+	PUSHBYTES34 Opcode = 0x22
+	PUSHBYTES35 Opcode = 0x23
+	PUSHBYTES36 Opcode = 0x24
+	PUSHBYTES37 Opcode = 0x25
+	PUSHBYTES38 Opcode = 0x26
+	PUSHBYTES39 Opcode = 0x27
+	PUSHBYTES40 Opcode = 0x28
+	PUSHBYTES41 Opcode = 0x29
+	PUSHBYTES42 Opcode = 0x2A
+	PUSHBYTES43 Opcode = 0x2B
+	PUSHBYTES44 Opcode = 0x2C
+	PUSHBYTES45 Opcode = 0x2D
+	PUSHBYTES46 Opcode = 0x2E
+	PUSHBYTES47 Opcode = 0x2F
+	PUSHBYTES48 Opcode = 0x30
+	PUSHBYTES49 Opcode = 0x31
+	PUSHBYTES50 Opcode = 0x32
+	PUSHBYTES51 Opcode = 0x33
+	PUSHBYTES52 Opcode = 0x34
+	PUSHBYTES53 Opcode = 0x35
+	PUSHBYTES54 Opcode = 0x36
+	PUSHBYTES55 Opcode = 0x37
+	PUSHBYTES56 Opcode = 0x38
+	PUSHBYTES57 Opcode = 0x39
+	PUSHBYTES58 Opcode = 0x3A
+	PUSHBYTES59 Opcode = 0x3B
+	PUSHBYTES60 Opcode = 0x3C
+	PUSHBYTES61 Opcode = 0x3D
+	PUSHBYTES62 Opcode = 0x3E
+	PUSHBYTES63 Opcode = 0x3F
+	PUSHBYTES64 Opcode = 0x40
+	PUSHBYTES65 Opcode = 0x41
+	PUSHBYTES66 Opcode = 0x42
+	PUSHBYTES67 Opcode = 0x43
+	PUSHBYTES68 Opcode = 0x44
+	PUSHBYTES69 Opcode = 0x45
+	PUSHBYTES70 Opcode = 0x46
+	PUSHBYTES71 Opcode = 0x47
+	PUSHBYTES72 Opcode = 0x48
+	PUSHBYTES73 Opcode = 0x49
+	PUSHBYTES74 Opcode = 0x4A
+	PUSHBYTES75 Opcode = 0x4B
+	PUSHDATA1   Opcode = 0x4C
+	PUSHDATA2   Opcode = 0x4D
+	PUSHDATA4   Opcode = 0x4E
+	PUSHM1      Opcode = 0x4F
+	PUSH1       Opcode = 0x51
+	PUSHT       Opcode = PUSH1
+	PUSH2       Opcode = 0x52
+	PUSH3       Opcode = 0x53
+	PUSH4       Opcode = 0x54
+	PUSH5       Opcode = 0x55
+	PUSH6       Opcode = 0x56
+	PUSH7       Opcode = 0x57
+	PUSH8       Opcode = 0x58
+	PUSH9       Opcode = 0x59
+	PUSH10      Opcode = 0x5A
+	PUSH11      Opcode = 0x5B
+	PUSH12      Opcode = 0x5C
+	PUSH13      Opcode = 0x5D
+	PUSH14      Opcode = 0x5E
+	PUSH15      Opcode = 0x5F
+	PUSH16      Opcode = 0x60
+
+	// Flow control
+	NOP      Opcode = 0x61
+	JMP      Opcode = 0x62
+	JMPIF    Opcode = 0x63
+	JMPIFNOT Opcode = 0x64
+	CALL     Opcode = 0x65
+	RET      Opcode = 0x66
+	APPCALL  Opcode = 0x67
+	SYSCALL  Opcode = 0x68
+	TAILCALL Opcode = 0x69
+
+	// Stack
+	DUPFROMALTSTACK Opcode = 0x6A
+	TOALTSTACK      Opcode = 0x6B
+	FROMALTSTACK    Opcode = 0x6C
+	XDROP           Opcode = 0x6D
+	XSWAP           Opcode = 0x72
+	XTUCK           Opcode = 0x73
+	DEPTH           Opcode = 0x74
+	DROP            Opcode = 0x75
+	DUP             Opcode = 0x76
+	NIP             Opcode = 0x77
+	OVER            Opcode = 0x78
+	PICK            Opcode = 0x79
+	ROLL            Opcode = 0x7A
+	ROT             Opcode = 0x7B
+	SWAP            Opcode = 0x7C
+	TUCK            Opcode = 0x7D
+
+	// Splice
+	CAT    Opcode = 0x7E
+	SUBSTR Opcode = 0x7F
+	LEFT   Opcode = 0x80
+	RIGHT  Opcode = 0x81
+	SIZE   Opcode = 0x82
+
+	// Bitwise logic
+	INVERT Opcode = 0x83
+	AND    Opcode = 0x84
+	OR     Opcode = 0x85
+	XOR    Opcode = 0x86
+	EQUAL  Opcode = 0x87
+
+	// Arithmetic
+	INC         Opcode = 0x8B
+	DEC         Opcode = 0x8C
+	SIGN        Opcode = 0x8D
+	NEGATE      Opcode = 0x8F
+	ABS         Opcode = 0x90
+	NOT         Opcode = 0x91
+	NZ          Opcode = 0x92
+	ADD         Opcode = 0x93
+	SUB         Opcode = 0x94
+	MUL         Opcode = 0x95
+	DIV         Opcode = 0x96
+	MOD         Opcode = 0x97
+	SHL         Opcode = 0x98
+	SHR         Opcode = 0x99
+	BOOLAND     Opcode = 0x9A
+	BOOLOR      Opcode = 0x9B
+	NUMEQUAL    Opcode = 0x9C
+	NUMNOTEQUAL Opcode = 0x9E
+	LT          Opcode = 0x9F
+	GT          Opcode = 0xA0
+	LTE         Opcode = 0xA1
+	GTE         Opcode = 0xA2
+	MIN         Opcode = 0xA3
+	MAX         Opcode = 0xA4
+	WITHIN      Opcode = 0xA5
+
+	// Crypto
+	SHA1          Opcode = 0xA7
+	SHA256        Opcode = 0xA8
+	HASH160       Opcode = 0xA9
+	HASH256       Opcode = 0xAA
+	CHECKSIG      Opcode = 0xAC
+	VERIFY        Opcode = 0xAD
+	CHECKMULTISIG Opcode = 0xAE
+
+	// Advanced data structures (arrays, structures, maps)
+	ARRAYSIZE Opcode = 0xC0
+	PACK      Opcode = 0xC1
+	UNPACK    Opcode = 0xC2
+	PICKITEM  Opcode = 0xC3
+	SETITEM   Opcode = 0xC4
+	NEWARRAY  Opcode = 0xC5
+	NEWSTRUCT Opcode = 0xC6
+	NEWMAP    Opcode = 0xC7
+	APPEND    Opcode = 0xC8
+	REVERSE   Opcode = 0xC9
+	REMOVE    Opcode = 0xCA
+	HASKEY    Opcode = 0xCB
+	KEYS      Opcode = 0xCC
+	VALUES    Opcode = 0xCD
+
+	// Stack isolation
+	CALLI   Opcode = 0xE0
+	CALLE   Opcode = 0xE1
+	CALLED  Opcode = 0xE2
+	CALLET  Opcode = 0xE3
+	CALLEDT Opcode = 0xE4
+
+	// Exceptions
+	THROW      Opcode = 0xF0
+	THROWIFNOT Opcode = 0xF1
+)
--- a/pkg/vm/opcode/opcode_string.go
+++ b/pkg/vm/opcode/opcode_string.go
@ -0,0 +1,393 @@
+// Code generated by "stringer -type=Opcode"; DO NOT EDIT.
+
+package opcode
+
+import "strconv"
+
+func _() {
+	// An "invalid array index" compiler error signifies that the constant values have changed.
+	// Re-run the stringer command to generate them again.
+	var x [1]struct{}
+	_ = x[PUSH0-0]
+	_ = x[PUSHF-0]
+	_ = x[PUSHBYTES1-1]
+	_ = x[PUSHBYTES2-2]
+	_ = x[PUSHBYTES3-3]
+	_ = x[PUSHBYTES4-4]
+	_ = x[PUSHBYTES5-5]
+	_ = x[PUSHBYTES6-6]
+	_ = x[PUSHBYTES7-7]
+	_ = x[PUSHBYTES8-8]
+	_ = x[PUSHBYTES9-9]
+	_ = x[PUSHBYTES10-10]
+	_ = x[PUSHBYTES11-11]
+	_ = x[PUSHBYTES12-12]
+	_ = x[PUSHBYTES13-13]
+	_ = x[PUSHBYTES14-14]
+	_ = x[PUSHBYTES15-15]
+	_ = x[PUSHBYTES16-16]
+	_ = x[PUSHBYTES17-17]
+	_ = x[PUSHBYTES18-18]
+	_ = x[PUSHBYTES19-19]
+	_ = x[PUSHBYTES20-20]
+	_ = x[PUSHBYTES21-21]
+	_ = x[PUSHBYTES22-22]
+	_ = x[PUSHBYTES23-23]
+	_ = x[PUSHBYTES24-24]
+	_ = x[PUSHBYTES25-25]
+	_ = x[PUSHBYTES26-26]
+	_ = x[PUSHBYTES27-27]
+	_ = x[PUSHBYTES28-28]
+	_ = x[PUSHBYTES29-29]
+	_ = x[PUSHBYTES30-30]
+	_ = x[PUSHBYTES31-31]
+	_ = x[PUSHBYTES32-32]
+	_ = x[PUSHBYTES33-33]
+	_ = x[PUSHBYTES34-34]
+	_ = x[PUSHBYTES35-35]
+	_ = x[PUSHBYTES36-36]
+	_ = x[PUSHBYTES37-37]
+	_ = x[PUSHBYTES38-38]
+	_ = x[PUSHBYTES39-39]
+	_ = x[PUSHBYTES40-40]
+	_ = x[PUSHBYTES41-41]
+	_ = x[PUSHBYTES42-42]
+	_ = x[PUSHBYTES43-43]
+	_ = x[PUSHBYTES44-44]
+	_ = x[PUSHBYTES45-45]
+	_ = x[PUSHBYTES46-46]
+	_ = x[PUSHBYTES47-47]
+	_ = x[PUSHBYTES48-48]
+	_ = x[PUSHBYTES49-49]
+	_ = x[PUSHBYTES50-50]
+	_ = x[PUSHBYTES51-51]
+	_ = x[PUSHBYTES52-52]
+	_ = x[PUSHBYTES53-53]
+	_ = x[PUSHBYTES54-54]
+	_ = x[PUSHBYTES55-55]
+	_ = x[PUSHBYTES56-56]
+	_ = x[PUSHBYTES57-57]
+	_ = x[PUSHBYTES58-58]
+	_ = x[PUSHBYTES59-59]
+	_ = x[PUSHBYTES60-60]
+	_ = x[PUSHBYTES61-61]
+	_ = x[PUSHBYTES62-62]
+	_ = x[PUSHBYTES63-63]
+	_ = x[PUSHBYTES64-64]
+	_ = x[PUSHBYTES65-65]
+	_ = x[PUSHBYTES66-66]
+	_ = x[PUSHBYTES67-67]
+	_ = x[PUSHBYTES68-68]
+	_ = x[PUSHBYTES69-69]
+	_ = x[PUSHBYTES70-70]
+	_ = x[PUSHBYTES71-71]
+	_ = x[PUSHBYTES72-72]
+	_ = x[PUSHBYTES73-73]
+	_ = x[PUSHBYTES74-74]
+	_ = x[PUSHBYTES75-75]
+	_ = x[PUSHDATA1-76]
+	_ = x[PUSHDATA2-77]
+	_ = x[PUSHDATA4-78]
+	_ = x[PUSHM1-79]
+	_ = x[PUSH1-81]
+	_ = x[PUSHT-81]
+	_ = x[PUSH2-82]
+	_ = x[PUSH3-83]
+	_ = x[PUSH4-84]
+	_ = x[PUSH5-85]
+	_ = x[PUSH6-86]
+	_ = x[PUSH7-87]
+	_ = x[PUSH8-88]
+	_ = x[PUSH9-89]
+	_ = x[PUSH10-90]
+	_ = x[PUSH11-91]
+	_ = x[PUSH12-92]
+	_ = x[PUSH13-93]
+	_ = x[PUSH14-94]
+	_ = x[PUSH15-95]
+	_ = x[PUSH16-96]
+	_ = x[NOP-97]
+	_ = x[JMP-98]
+	_ = x[JMPIF-99]
+	_ = x[JMPIFNOT-100]
+	_ = x[CALL-101]
+	_ = x[RET-102]
+	_ = x[APPCALL-103]
+	_ = x[SYSCALL-104]
+	_ = x[TAILCALL-105]
+	_ = x[DUPFROMALTSTACK-106]
+	_ = x[TOALTSTACK-107]
+	_ = x[FROMALTSTACK-108]
+	_ = x[XDROP-109]
+	_ = x[XSWAP-114]
+	_ = x[XTUCK-115]
+	_ = x[DEPTH-116]
+	_ = x[DROP-117]
+	_ = x[DUP-118]
+	_ = x[NIP-119]
+	_ = x[OVER-120]
+	_ = x[PICK-121]
+	_ = x[ROLL-122]
+	_ = x[ROT-123]
+	_ = x[SWAP-124]
+	_ = x[TUCK-125]
+	_ = x[CAT-126]
+	_ = x[SUBSTR-127]
+	_ = x[LEFT-128]
+	_ = x[RIGHT-129]
+	_ = x[SIZE-130]
+	_ = x[INVERT-131]
+	_ = x[AND-132]
+	_ = x[OR-133]
+	_ = x[XOR-134]
+	_ = x[EQUAL-135]
+	_ = x[INC-139]
+	_ = x[DEC-140]
+	_ = x[SIGN-141]
+	_ = x[NEGATE-143]
+	_ = x[ABS-144]
+	_ = x[NOT-145]
+	_ = x[NZ-146]
+	_ = x[ADD-147]
+	_ = x[SUB-148]
+	_ = x[MUL-149]
+	_ = x[DIV-150]
+	_ = x[MOD-151]
+	_ = x[SHL-152]
+	_ = x[SHR-153]
+	_ = x[BOOLAND-154]
+	_ = x[BOOLOR-155]
+	_ = x[NUMEQUAL-156]
+	_ = x[NUMNOTEQUAL-158]
+	_ = x[LT-159]
+	_ = x[GT-160]
+	_ = x[LTE-161]
+	_ = x[GTE-162]
+	_ = x[MIN-163]
+	_ = x[MAX-164]
+	_ = x[WITHIN-165]
+	_ = x[SHA1-167]
+	_ = x[SHA256-168]
+	_ = x[HASH160-169]
+	_ = x[HASH256-170]
+	_ = x[CHECKSIG-172]
+	_ = x[VERIFY-173]
+	_ = x[CHECKMULTISIG-174]
+	_ = x[ARRAYSIZE-192]
+	_ = x[PACK-193]
+	_ = x[UNPACK-194]
+	_ = x[PICKITEM-195]
+	_ = x[SETITEM-196]
+	_ = x[NEWARRAY-197]
+	_ = x[NEWSTRUCT-198]
+	_ = x[NEWMAP-199]
+	_ = x[APPEND-200]
+	_ = x[REVERSE-201]
+	_ = x[REMOVE-202]
+	_ = x[HASKEY-203]
+	_ = x[KEYS-204]
+	_ = x[VALUES-205]
+	_ = x[CALLI-224]
+	_ = x[CALLE-225]
+	_ = x[CALLED-226]
+	_ = x[CALLET-227]
+	_ = x[CALLEDT-228]
+	_ = x[THROW-240]
+	_ = x[THROWIFNOT-241]
+}
+
+const _Opcode_name = "PUSH0PUSHBYTES1PUSHBYTES2PUSHBYTES3PUSHBYTES4PUSHBYTES5PUSHBYTES6PUSHBYTES7PUSHBYTES8PUSHBYTES9PUSHBYTES10PUSHBYTES11PUSHBYTES12PUSHBYTES13PUSHBYTES14PUSHBYTES15PUSHBYTES16PUSHBYTES17PUSHBYTES18PUSHBYTES19PUSHBYTES20PUSHBYTES21PUSHBYTES22PUSHBYTES23PUSHBYTES24PUSHBYTES25PUSHBYTES26PUSHBYTES27PUSHBYTES28PUSHBYTES29PUSHBYTES30PUSHBYTES31PUSHBYTES32PUSHBYTES33PUSHBYTES34PUSHBYTES35PUSHBYTES36PUSHBYTES37PUSHBYTES38PUSHBYTES39PUSHBYTES40PUSHBYTES41PUSHBYTES42PUSHBYTES43PUSHBYTES44PUSHBYTES45PUSHBYTES46PUSHBYTES47PUSHBYTES48PUSHBYTES49PUSHBYTES50PUSHBYTES51PUSHBYTES52PUSHBYTES53PUSHBYTES54PUSHBYTES55PUSHBYTES56PUSHBYTES57PUSHBYTES58PUSHBYTES59PUSHBYTES60PUSHBYTES61PUSHBYTES62PUSHBYTES63PUSHBYTES64PUSHBYTES65PUSHBYTES66PUSHBYTES67PUSHBYTES68PUSHBYTES69PUSHBYTES70PUSHBYTES71PUSHBYTES72PUSHBYTES73PUSHBYTES74PUSHBYTES75PUSHDATA1PUSHDATA2PUSHDATA4PUSHM1PUSH1PUSH2PUSH3PUSH4PUSH5PUSH6PUSH7PUSH8PUSH9PUSH10PUSH11PUSH12PUSH13PUSH14PUSH15PUSH16NOPJMPJMPIFJMPIFNOTCALLRETAPPCALLSYSCALLTAILCALLDUPFROMALTSTACKTOALTSTACKFROMALTSTACKXDROPXSWAPXTUCKDEPTHDROPDUPNIPOVERPICKROLLROTSWAPTUCKCATSUBSTRLEFTRIGHTSIZEINVERTANDORXOREQUALINCDECSIGNNEGATEABSNOTNZADDSUBMULDIVMODSHLSHRBOOLANDBOOLORNUMEQUALNUMNOTEQUALLTGTLTEGTEMINMAXWITHINSHA1SHA256HASH160HASH256CHECKSIGVERIFYCHECKMULTISIGARRAYSIZEPACKUNPACKPICKITEMSETITEMNEWARRAYNEWSTRUCTNEWMAPAPPENDREVERSEREMOVEHASKEYKEYSVALUESCALLICALLECALLEDCALLETCALLEDTTHROWTHROWIFNOT"
+
+var _Opcode_map = map[Opcode]string{
+	0:   _Opcode_name[0:5],
+	1:   _Opcode_name[5:15],
+	2:   _Opcode_name[15:25],
+	3:   _Opcode_name[25:35],
+	4:   _Opcode_name[35:45],
+	5:   _Opcode_name[45:55],
+	6:   _Opcode_name[55:65],
+	7:   _Opcode_name[65:75],
+	8:   _Opcode_name[75:85],
+	9:   _Opcode_name[85:95],
+	10:  _Opcode_name[95:106],
+	11:  _Opcode_name[106:117],
+	12:  _Opcode_name[117:128],
+	13:  _Opcode_name[128:139],
+	14:  _Opcode_name[139:150],
+	15:  _Opcode_name[150:161],
+	16:  _Opcode_name[161:172],
+	17:  _Opcode_name[172:183],
+	18:  _Opcode_name[183:194],
+	19:  _Opcode_name[194:205],
+	20:  _Opcode_name[205:216],
+	21:  _Opcode_name[216:227],
+	22:  _Opcode_name[227:238],
+	23:  _Opcode_name[238:249],
+	24:  _Opcode_name[249:260],
+	25:  _Opcode_name[260:271],
+	26:  _Opcode_name[271:282],
+	27:  _Opcode_name[282:293],
+	28:  _Opcode_name[293:304],
+	29:  _Opcode_name[304:315],
+	30:  _Opcode_name[315:326],
+	31:  _Opcode_name[326:337],
+	32:  _Opcode_name[337:348],
+	33:  _Opcode_name[348:359],
+	34:  _Opcode_name[359:370],
+	35:  _Opcode_name[370:381],
+	36:  _Opcode_name[381:392],
+	37:  _Opcode_name[392:403],
+	38:  _Opcode_name[403:414],
+	39:  _Opcode_name[414:425],
+	40:  _Opcode_name[425:436],
+	41:  _Opcode_name[436:447],
+	42:  _Opcode_name[447:458],
+	43:  _Opcode_name[458:469],
+	44:  _Opcode_name[469:480],
+	45:  _Opcode_name[480:491],
+	46:  _Opcode_name[491:502],
+	47:  _Opcode_name[502:513],
+	48:  _Opcode_name[513:524],
+	49:  _Opcode_name[524:535],
+	50:  _Opcode_name[535:546],
+	51:  _Opcode_name[546:557],
+	52:  _Opcode_name[557:568],
+	53:  _Opcode_name[568:579],
+	54:  _Opcode_name[579:590],
+	55:  _Opcode_name[590:601],
+	56:  _Opcode_name[601:612],
+	57:  _Opcode_name[612:623],
+	58:  _Opcode_name[623:634],
+	59:  _Opcode_name[634:645],
+	60:  _Opcode_name[645:656],
+	61:  _Opcode_name[656:667],
+	62:  _Opcode_name[667:678],
+	63:  _Opcode_name[678:689],
+	64:  _Opcode_name[689:700],
+	65:  _Opcode_name[700:711],
+	66:  _Opcode_name[711:722],
+	67:  _Opcode_name[722:733],
+	68:  _Opcode_name[733:744],
+	69:  _Opcode_name[744:755],
+	70:  _Opcode_name[755:766],
+	71:  _Opcode_name[766:777],
+	72:  _Opcode_name[777:788],
+	73:  _Opcode_name[788:799],
+	74:  _Opcode_name[799:810],
+	75:  _Opcode_name[810:821],
+	76:  _Opcode_name[821:830],
+	77:  _Opcode_name[830:839],
+	78:  _Opcode_name[839:848],
+	79:  _Opcode_name[848:854],
+	81:  _Opcode_name[854:859],
+	82:  _Opcode_name[859:864],
+	83:  _Opcode_name[864:869],
+	84:  _Opcode_name[869:874],
+	85:  _Opcode_name[874:879],
+	86:  _Opcode_name[879:884],
+	87:  _Opcode_name[884:889],
+	88:  _Opcode_name[889:894],
+	89:  _Opcode_name[894:899],
+	90:  _Opcode_name[899:905],
+	91:  _Opcode_name[905:911],
+	92:  _Opcode_name[911:917],
+	93:  _Opcode_name[917:923],
+	94:  _Opcode_name[923:929],
+	95:  _Opcode_name[929:935],
+	96:  _Opcode_name[935:941],
+	97:  _Opcode_name[941:944],
+	98:  _Opcode_name[944:947],
+	99:  _Opcode_name[947:952],
+	100: _Opcode_name[952:960],
+	101: _Opcode_name[960:964],
+	102: _Opcode_name[964:967],
+	103: _Opcode_name[967:974],
+	104: _Opcode_name[974:981],
+	105: _Opcode_name[981:989],
+	106: _Opcode_name[989:1004],
+	107: _Opcode_name[1004:1014],
+	108: _Opcode_name[1014:1026],
+	109: _Opcode_name[1026:1031],
+	114: _Opcode_name[1031:1036],
+	115: _Opcode_name[1036:1041],
+	116: _Opcode_name[1041:1046],
+	117: _Opcode_name[1046:1050],
+	118: _Opcode_name[1050:1053],
+	119: _Opcode_name[1053:1056],
+	120: _Opcode_name[1056:1060],
+	121: _Opcode_name[1060:1064],
+	122: _Opcode_name[1064:1068],
+	123: _Opcode_name[1068:1071],
+	124: _Opcode_name[1071:1075],
+	125: _Opcode_name[1075:1079],
+	126: _Opcode_name[1079:1082],
+	127: _Opcode_name[1082:1088],
+	128: _Opcode_name[1088:1092],
+	129: _Opcode_name[1092:1097],
+	130: _Opcode_name[1097:1101],
+	131: _Opcode_name[1101:1107],
+	132: _Opcode_name[1107:1110],
+	133: _Opcode_name[1110:1112],
+	134: _Opcode_name[1112:1115],
+	135: _Opcode_name[1115:1120],
+	139: _Opcode_name[1120:1123],
+	140: _Opcode_name[1123:1126],
+	141: _Opcode_name[1126:1130],
+	143: _Opcode_name[1130:1136],
+	144: _Opcode_name[1136:1139],
+	145: _Opcode_name[1139:1142],
+	146: _Opcode_name[1142:1144],
+	147: _Opcode_name[1144:1147],
+	148: _Opcode_name[1147:1150],
+	149: _Opcode_name[1150:1153],
+	150: _Opcode_name[1153:1156],
+	151: _Opcode_name[1156:1159],
+	152: _Opcode_name[1159:1162],
+	153: _Opcode_name[1162:1165],
+	154: _Opcode_name[1165:1172],
+	155: _Opcode_name[1172:1178],
+	156: _Opcode_name[1178:1186],
+	158: _Opcode_name[1186:1197],
+	159: _Opcode_name[1197:1199],
+	160: _Opcode_name[1199:1201],
+	161: _Opcode_name[1201:1204],
+	162: _Opcode_name[1204:1207],
+	163: _Opcode_name[1207:1210],
+	164: _Opcode_name[1210:1213],
+	165: _Opcode_name[1213:1219],
+	167: _Opcode_name[1219:1223],
+	168: _Opcode_name[1223:1229],
+	169: _Opcode_name[1229:1236],
+	170: _Opcode_name[1236:1243],
+	172: _Opcode_name[1243:1251],
+	173: _Opcode_name[1251:1257],
+	174: _Opcode_name[1257:1270],
+	192: _Opcode_name[1270:1279],
+	193: _Opcode_name[1279:1283],
+	194: _Opcode_name[1283:1289],
+	195: _Opcode_name[1289:1297],
+	196: _Opcode_name[1297:1304],
+	197: _Opcode_name[1304:1312],
+	198: _Opcode_name[1312:1321],
+	199: _Opcode_name[1321:1327],
+	200: _Opcode_name[1327:1333],
+	201: _Opcode_name[1333:1340],
+	202: _Opcode_name[1340:1346],
+	203: _Opcode_name[1346:1352],
+	204: _Opcode_name[1352:1356],
+	205: _Opcode_name[1356:1362],
+	224: _Opcode_name[1362:1367],
+	225: _Opcode_name[1367:1372],
+	226: _Opcode_name[1372:1378],
+	227: _Opcode_name[1378:1384],
+	228: _Opcode_name[1384:1391],
+	240: _Opcode_name[1391:1396],
+	241: _Opcode_name[1396:1406],
+}
+
+func (i Opcode) String() string {
+	if str, ok := _Opcode_map[i]; ok {
+		return str
+	}
+	return "Opcode(" + strconv.FormatInt(int64(i), 10) + ")"
+}
--- a/pkg/vm/opcode/opcode_test.go
+++ b/pkg/vm/opcode/opcode_test.go
@ -0,0 +1,20 @@
+package opcode
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+// Nothing more to test here, really.
+func TestStringer(t *testing.T) {
+	tests := map[Opcode]string{
+		ADD:        "ADD",
+		SUB:        "SUB",
+		THROWIFNOT: "THROWIFNOT",
+		0xff:       "Opcode(255)",
+	}
+	for o, s := range tests {
+		assert.Equal(t, s, o.String())
+	}
+}
--- a/pkg/vm/tests/vm_test.go
+++ b/pkg/vm/tests/vm_test.go
@ -5,8 +5,8 @@ import (
 	"strings"
 	"testing"

+	"github.com/CityOfZion/neo-go/pkg/compiler"
 	"github.com/CityOfZion/neo-go/pkg/vm"
-	"github.com/CityOfZion/neo-go/pkg/vm/compiler"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
--- a/pkg/vm/vm.go
+++ b/pkg/vm/vm.go
@ -14,12 +14,13 @@ import (
 	"github.com/CityOfZion/neo-go/pkg/crypto/hash"
 	"github.com/CityOfZion/neo-go/pkg/crypto/keys"
 	"github.com/CityOfZion/neo-go/pkg/util"
+	"github.com/CityOfZion/neo-go/pkg/vm/opcode"
 	"github.com/pkg/errors"
 )

 type errorAtInstruct struct {
 	ip  int
-	op  Instruction
+	op  opcode.Opcode
 	err interface{}
 }

@ -27,7 +28,7 @@ func (e *errorAtInstruct) Error() string {
 	return fmt.Sprintf("error encountered at instruction %d (%s): %s", e.ip, e.op, e.err)
 }

-func newError(ip int, op Instruction, err interface{}) *errorAtInstruct {
+func newError(ip int, op opcode.Opcode, err interface{}) *errorAtInstruct {
 	return &errorAtInstruct{ip: ip, op: op, err: err}
 }

@ -175,12 +176,12 @@ func (v *VM) PrintOps() {
 		var desc = ""
 		if parameter != nil {
 			switch instr {
-			case JMP, JMPIF, JMPIFNOT, CALL:
+			case opcode.JMP, opcode.JMPIF, opcode.JMPIFNOT, opcode.CALL:
 				offset := int16(binary.LittleEndian.Uint16(parameter))
 				desc = fmt.Sprintf("%d (%d/%x)", ctx.ip+int(offset), offset, parameter)
-			case SYSCALL:
+			case opcode.SYSCALL:
 				desc = fmt.Sprintf("%q", parameter)
-			case APPCALL, TAILCALL:
+			case opcode.APPCALL, opcode.TAILCALL:
 				desc = fmt.Sprintf("%x", parameter)
 			default:
 				if utf8.Valid(parameter) {
@ -447,7 +448,7 @@ func (v *VM) SetScriptGetter(gs func(util.Uint160) []byte) {
 }

 // execute performs an instruction cycle in the VM. Acting on the instruction (opcode).
-func (v *VM) execute(ctx *Context, op Instruction, parameter []byte) (err error) {
+func (v *VM) execute(ctx *Context, op opcode.Opcode, parameter []byte) (err error) {
 	// Instead of polluting the whole VM logic with error handling, we will recover
 	// each panic at a central point, putting the VM in a fault state and setting error.
 	defer func() {
@ -460,44 +461,46 @@ func (v *VM) execute(ctx *Context, op Instruction, parameter []byte) (err error)
 		}
 	}()

-	if op >= PUSHBYTES1 && op <= PUSHBYTES75 {
+	if op >= opcode.PUSHBYTES1 && op <= opcode.PUSHBYTES75 {
 		v.estack.PushVal(parameter)
 		return
 	}

 	switch op {
-	case PUSHM1, PUSH1, PUSH2, PUSH3, PUSH4, PUSH5,
-		PUSH6, PUSH7, PUSH8, PUSH9, PUSH10, PUSH11,
-		PUSH12, PUSH13, PUSH14, PUSH15, PUSH16:
-		val := int(op) - int(PUSH1) + 1
+	case opcode.PUSHM1, opcode.PUSH1, opcode.PUSH2, opcode.PUSH3,
+		opcode.PUSH4, opcode.PUSH5, opcode.PUSH6, opcode.PUSH7,
+		opcode.PUSH8, opcode.PUSH9, opcode.PUSH10, opcode.PUSH11,
+		opcode.PUSH12, opcode.PUSH13, opcode.PUSH14, opcode.PUSH15,
+		opcode.PUSH16:
+		val := int(op) - int(opcode.PUSH1) + 1
 		v.estack.PushVal(val)

-	case PUSH0:
+	case opcode.PUSH0:
 		v.estack.PushVal([]byte{})

-	case PUSHDATA1, PUSHDATA2, PUSHDATA4:
+	case opcode.PUSHDATA1, opcode.PUSHDATA2, opcode.PUSHDATA4:
 		v.estack.PushVal(parameter)

 	// Stack operations.
-	case TOALTSTACK:
+	case opcode.TOALTSTACK:
 		v.astack.Push(v.estack.Pop())

-	case FROMALTSTACK:
+	case opcode.FROMALTSTACK:
 		v.estack.Push(v.astack.Pop())

-	case DUPFROMALTSTACK:
+	case opcode.DUPFROMALTSTACK:
 		v.estack.Push(v.astack.Dup(0))

-	case DUP:
+	case opcode.DUP:
 		v.estack.Push(v.estack.Dup(0))

-	case SWAP:
+	case opcode.SWAP:
 		a := v.estack.Pop()
 		b := v.estack.Pop()
 		v.estack.Push(a)
 		v.estack.Push(b)

-	case TUCK:
+	case opcode.TUCK:
 		a := v.estack.Dup(0)
 		if a == nil {
 			panic("no top-level element found")
@ -507,7 +510,7 @@ func (v *VM) execute(ctx *Context, op Instruction, parameter []byte) (err error)
 		}
 		v.estack.InsertAt(a, 2)

-	case CAT:
+	case opcode.CAT:
 		b := v.estack.Pop().Bytes()
 		a := v.estack.Pop().Bytes()
 		if l := len(a) + len(b); l > MaxItemSize {
@ -516,7 +519,7 @@ func (v *VM) execute(ctx *Context, op Instruction, parameter []byte) (err error)
 		ab := append(a, b...)
 		v.estack.PushVal(ab)

-	case SUBSTR:
+	case opcode.SUBSTR:
 		l := int(v.estack.Pop().BigInt().Int64())
 		if l < 0 {
 			panic("negative length")
@ -538,7 +541,7 @@ func (v *VM) execute(ctx *Context, op Instruction, parameter []byte) (err error)
 		}
 		v.estack.PushVal(s[o:last])

-	case LEFT:
+	case opcode.LEFT:
 		l := int(v.estack.Pop().BigInt().Int64())
 		if l < 0 {
 			panic("negative length")
@ -549,7 +552,7 @@ func (v *VM) execute(ctx *Context, op Instruction, parameter []byte) (err error)
 		}
 		v.estack.PushVal(s[:l])

-	case RIGHT:
+	case opcode.RIGHT:
 		l := int(v.estack.Pop().BigInt().Int64())
 		if l < 0 {
 			panic("negative length")
@ -557,7 +560,7 @@ func (v *VM) execute(ctx *Context, op Instruction, parameter []byte) (err error)
 		s := v.estack.Pop().Bytes()
 		v.estack.PushVal(s[len(s)-l:])

-	case XDROP:
+	case opcode.XDROP:
 		n := int(v.estack.Pop().BigInt().Int64())
 		if n < 0 {
 			panic("invalid length")
@ -567,7 +570,7 @@ func (v *VM) execute(ctx *Context, op Instruction, parameter []byte) (err error)
 			panic("bad index")
 		}

-	case XSWAP:
+	case opcode.XSWAP:
 		n := int(v.estack.Pop().BigInt().Int64())
 		if n < 0 {
 			panic("XSWAP: invalid length")
@ -583,7 +586,7 @@ func (v *VM) execute(ctx *Context, op Instruction, parameter []byte) (err error)
 			b.value = aval
 		}

-	case XTUCK:
+	case opcode.XTUCK:
 		n := int(v.estack.Pop().BigInt().Int64())
 		if n <= 0 {
 			panic("XTUCK: invalid length")
@ -597,30 +600,30 @@ func (v *VM) execute(ctx *Context, op Instruction, parameter []byte) (err error)
 		}
 		v.estack.InsertAt(a, n)

-	case ROT:
+	case opcode.ROT:
 		e := v.estack.RemoveAt(2)
 		if e == nil {
 			panic("no top-level element found")
 		}
 		v.estack.Push(e)

-	case DEPTH:
+	case opcode.DEPTH:
 		v.estack.PushVal(v.estack.Len())

-	case NIP:
+	case opcode.NIP:
 		elem := v.estack.RemoveAt(1)
 		if elem == nil {
 			panic("no second element found")
 		}

-	case OVER:
+	case opcode.OVER:
 		a := v.estack.Peek(1)
 		if a == nil {
 			panic("no second element found")
 		}
 		v.estack.Push(a)

-	case PICK:
+	case opcode.PICK:
 		n := int(v.estack.Pop().BigInt().Int64())
 		if n < 0 {
 			panic("negative stack item returned")
@ -631,7 +634,7 @@ func (v *VM) execute(ctx *Context, op Instruction, parameter []byte) (err error)
 		}
 		v.estack.Push(a)

-	case ROLL:
+	case opcode.ROLL:
 		n := int(v.estack.Pop().BigInt().Int64())
 		if n < 0 {
 			panic("negative stack item returned")
@ -644,13 +647,13 @@ func (v *VM) execute(ctx *Context, op Instruction, parameter []byte) (err error)
 			v.estack.Push(e)
 		}

-	case DROP:
+	case opcode.DROP:
 		if v.estack.Len() < 1 {
 			panic("stack is too small")
 		}
 		v.estack.Pop()

-	case EQUAL:
+	case opcode.EQUAL:
 		b := v.estack.Pop()
 		if b == nil {
 			panic("no top-level element found")
@ -673,28 +676,28 @@ func (v *VM) execute(ctx *Context, op Instruction, parameter []byte) (err error)
 		v.estack.PushVal(reflect.DeepEqual(a, b))

 	// Bit operations.
-	case INVERT:
+	case opcode.INVERT:
 		// inplace
 		a := v.estack.Peek(0).BigInt()
 		a.Not(a)

-	case AND:
+	case opcode.AND:
 		b := v.estack.Pop().BigInt()
 		a := v.estack.Pop().BigInt()
 		v.estack.PushVal(new(big.Int).And(b, a))

-	case OR:
+	case opcode.OR:
 		b := v.estack.Pop().BigInt()
 		a := v.estack.Pop().BigInt()
 		v.estack.PushVal(new(big.Int).Or(b, a))

-	case XOR:
+	case opcode.XOR:
 		b := v.estack.Pop().BigInt()
 		a := v.estack.Pop().BigInt()
 		v.estack.PushVal(new(big.Int).Xor(b, a))

 	// Numeric operations.
-	case ADD:
+	case opcode.ADD:
 		a := v.estack.Pop().BigInt()
 		v.checkBigIntSize(a)
 		b := v.estack.Pop().BigInt()
@ -704,7 +707,7 @@ func (v *VM) execute(ctx *Context, op Instruction, parameter []byte) (err error)
 		v.checkBigIntSize(c)
 		v.estack.PushVal(c)

-	case SUB:
+	case opcode.SUB:
 		b := v.estack.Pop().BigInt()
 		v.checkBigIntSize(b)
 		a := v.estack.Pop().BigInt()
@ -714,7 +717,7 @@ func (v *VM) execute(ctx *Context, op Instruction, parameter []byte) (err error)
 		v.checkBigIntSize(c)
 		v.estack.PushVal(c)

-	case DIV:
+	case opcode.DIV:
 		b := v.estack.Pop().BigInt()
 		v.checkBigIntSize(b)
 		a := v.estack.Pop().BigInt()
@ -722,7 +725,7 @@ func (v *VM) execute(ctx *Context, op Instruction, parameter []byte) (err error)

 		v.estack.PushVal(new(big.Int).Div(a, b))

-	case MUL:
+	case opcode.MUL:
 		a := v.estack.Pop().BigInt()
 		v.checkBigIntSize(a)
 		b := v.estack.Pop().BigInt()
@ -732,7 +735,7 @@ func (v *VM) execute(ctx *Context, op Instruction, parameter []byte) (err error)
 		v.checkBigIntSize(c)
 		v.estack.PushVal(c)

-	case MOD:
+	case opcode.MOD:
 		b := v.estack.Pop().BigInt()
 		v.checkBigIntSize(b)
 		a := v.estack.Pop().BigInt()
@ -740,7 +743,7 @@ func (v *VM) execute(ctx *Context, op Instruction, parameter []byte) (err error)

 		v.estack.PushVal(new(big.Int).Mod(a, b))

-	case SHL, SHR:
+	case opcode.SHL, opcode.SHR:
 		b := v.estack.Pop().BigInt().Int64()
 		if b == 0 {
 			return
@ -751,7 +754,7 @@ func (v *VM) execute(ctx *Context, op Instruction, parameter []byte) (err error)
 		v.checkBigIntSize(a)

 		var item big.Int
-		if op == SHL {
+		if op == opcode.SHL {
 			item.Lsh(a, uint(b))
 		} else {
 			item.Rsh(a, uint(b))
@ -760,47 +763,47 @@ func (v *VM) execute(ctx *Context, op Instruction, parameter []byte) (err error)
 		v.checkBigIntSize(&item)
 		v.estack.PushVal(&item)

-	case BOOLAND:
+	case opcode.BOOLAND:
 		b := v.estack.Pop().Bool()
 		a := v.estack.Pop().Bool()
 		v.estack.PushVal(a && b)

-	case BOOLOR:
+	case opcode.BOOLOR:
 		b := v.estack.Pop().Bool()
 		a := v.estack.Pop().Bool()
 		v.estack.PushVal(a || b)

-	case NUMEQUAL:
+	case opcode.NUMEQUAL:
 		b := v.estack.Pop().BigInt()
 		a := v.estack.Pop().BigInt()
 		v.estack.PushVal(a.Cmp(b) == 0)

-	case NUMNOTEQUAL:
+	case opcode.NUMNOTEQUAL:
 		b := v.estack.Pop().BigInt()
 		a := v.estack.Pop().BigInt()
 		v.estack.PushVal(a.Cmp(b) != 0)

-	case LT:
+	case opcode.LT:
 		b := v.estack.Pop().BigInt()
 		a := v.estack.Pop().BigInt()
 		v.estack.PushVal(a.Cmp(b) == -1)

-	case GT:
+	case opcode.GT:
 		b := v.estack.Pop().BigInt()
 		a := v.estack.Pop().BigInt()
 		v.estack.PushVal(a.Cmp(b) == 1)

-	case LTE:
+	case opcode.LTE:
 		b := v.estack.Pop().BigInt()
 		a := v.estack.Pop().BigInt()
 		v.estack.PushVal(a.Cmp(b) <= 0)

-	case GTE:
+	case opcode.GTE:
 		b := v.estack.Pop().BigInt()
 		a := v.estack.Pop().BigInt()
 		v.estack.PushVal(a.Cmp(b) >= 0)

-	case MIN:
+	case opcode.MIN:
 		b := v.estack.Pop().BigInt()
 		a := v.estack.Pop().BigInt()
 		val := a
@ -809,7 +812,7 @@ func (v *VM) execute(ctx *Context, op Instruction, parameter []byte) (err error)
 		}
 		v.estack.PushVal(val)

-	case MAX:
+	case opcode.MAX:
 		b := v.estack.Pop().BigInt()
 		a := v.estack.Pop().BigInt()
 		val := a
@ -818,46 +821,46 @@ func (v *VM) execute(ctx *Context, op Instruction, parameter []byte) (err error)
 		}
 		v.estack.PushVal(val)

-	case WITHIN:
+	case opcode.WITHIN:
 		b := v.estack.Pop().BigInt()
 		a := v.estack.Pop().BigInt()
 		x := v.estack.Pop().BigInt()
 		v.estack.PushVal(a.Cmp(x) <= 0 && x.Cmp(b) == -1)

-	case INC:
+	case opcode.INC:
 		x := v.estack.Pop().BigInt()
 		a := new(big.Int).Add(x, big.NewInt(1))
 		v.checkBigIntSize(a)
 		v.estack.PushVal(a)

-	case DEC:
+	case opcode.DEC:
 		x := v.estack.Pop().BigInt()
 		a := new(big.Int).Sub(x, big.NewInt(1))
 		v.checkBigIntSize(a)
 		v.estack.PushVal(a)

-	case SIGN:
+	case opcode.SIGN:
 		x := v.estack.Pop().BigInt()
 		v.estack.PushVal(x.Sign())

-	case NEGATE:
+	case opcode.NEGATE:
 		x := v.estack.Pop().BigInt()
 		v.estack.PushVal(x.Neg(x))

-	case ABS:
+	case opcode.ABS:
 		x := v.estack.Pop().BigInt()
 		v.estack.PushVal(x.Abs(x))

-	case NOT:
+	case opcode.NOT:
 		x := v.estack.Pop().Bool()
 		v.estack.PushVal(!x)

-	case NZ:
+	case opcode.NZ:
 		x := v.estack.Pop().BigInt()
 		v.estack.PushVal(x.Cmp(big.NewInt(0)) != 0)

 	// Object operations.
-	case NEWARRAY:
+	case opcode.NEWARRAY:
 		item := v.estack.Pop()
 		switch t := item.value.(type) {
 		case *StructItem:
@ -875,7 +878,7 @@ func (v *VM) execute(ctx *Context, op Instruction, parameter []byte) (err error)
 			v.estack.PushVal(&ArrayItem{items})
 		}

-	case NEWSTRUCT:
+	case opcode.NEWSTRUCT:
 		item := v.estack.Pop()
 		switch t := item.value.(type) {
 		case *ArrayItem:
@ -893,7 +896,7 @@ func (v *VM) execute(ctx *Context, op Instruction, parameter []byte) (err error)
 			v.estack.PushVal(&StructItem{items})
 		}

-	case APPEND:
+	case opcode.APPEND:
 		itemElem := v.estack.Pop()
 		arrElem := v.estack.Pop()

@ -920,7 +923,7 @@ func (v *VM) execute(ctx *Context, op Instruction, parameter []byte) (err error)

 		v.estack.updateSizeAdd(val)

-	case PACK:
+	case opcode.PACK:
 		n := int(v.estack.Pop().BigInt().Int64())
 		if n < 0 || n > v.estack.Len() || n > MaxArraySize {
 			panic("OPACK: invalid length")
@ -933,7 +936,7 @@ func (v *VM) execute(ctx *Context, op Instruction, parameter []byte) (err error)

 		v.estack.PushVal(items)

-	case UNPACK:
+	case opcode.UNPACK:
 		a := v.estack.Pop().Array()
 		l := len(a)
 		for i := l - 1; i >= 0; i-- {
@ -941,7 +944,7 @@ func (v *VM) execute(ctx *Context, op Instruction, parameter []byte) (err error)
 		}
 		v.estack.PushVal(l)

-	case PICKITEM:
+	case opcode.PICKITEM:
 		key := v.estack.Pop()
 		validateMapKey(key)

@ -972,7 +975,7 @@ func (v *VM) execute(ctx *Context, op Instruction, parameter []byte) (err error)
 			v.estack.PushVal(int(item))
 		}

-	case SETITEM:
+	case opcode.SETITEM:
 		item := v.estack.Pop().value
 		key := v.estack.Pop()
 		validateMapKey(key)
@ -1003,14 +1006,14 @@ func (v *VM) execute(ctx *Context, op Instruction, parameter []byte) (err error)
 			panic(fmt.Sprintf("SETITEM: invalid item type %s", t))
 		}

-	case REVERSE:
+	case opcode.REVERSE:
 		a := v.estack.Pop().Array()
 		if len(a) > 1 {
 			for i, j := 0, len(a)-1; i <= j; i, j = i+1, j-1 {
 				a[i], a[j] = a[j], a[i]
 			}
 		}
-	case REMOVE:
+	case opcode.REMOVE:
 		key := v.estack.Pop()
 		validateMapKey(key)

@ -1043,7 +1046,7 @@ func (v *VM) execute(ctx *Context, op Instruction, parameter []byte) (err error)
 			panic("REMOVE: invalid type")
 		}

-	case ARRAYSIZE:
+	case opcode.ARRAYSIZE:
 		elem := v.estack.Pop()
 		// Cause there is no native (byte) item type here, hence we need to check
 		// the type of the item for array size operations.
@ -1056,12 +1059,12 @@ func (v *VM) execute(ctx *Context, op Instruction, parameter []byte) (err error)
 			v.estack.PushVal(len(elem.Bytes()))
 		}

-	case SIZE:
+	case opcode.SIZE:
 		elem := v.estack.Pop()
 		arr := elem.Bytes()
 		v.estack.PushVal(len(arr))

-	case JMP, JMPIF, JMPIFNOT:
+	case opcode.JMP, opcode.JMPIF, opcode.JMPIFNOT:
 		var (
 			rOffset = int16(binary.LittleEndian.Uint16(parameter))
 			offset  = ctx.ip + int(rOffset)
@ -1070,9 +1073,9 @@ func (v *VM) execute(ctx *Context, op Instruction, parameter []byte) (err error)
 			panic(fmt.Sprintf("JMP: invalid offset %d ip at %d", offset, ctx.ip))
 		}
 		cond := true
-		if op > JMP {
+		if op > opcode.JMP {
 			cond = v.estack.Pop().Bool()
-			if op == JMPIFNOT {
+			if op == opcode.JMPIFNOT {
 				cond = !cond
 			}
 		}
@ -1080,18 +1083,18 @@ func (v *VM) execute(ctx *Context, op Instruction, parameter []byte) (err error)
 			ctx.nextip = offset
 		}

-	case CALL:
+	case opcode.CALL:
 		v.checkInvocationStackSize()

 		newCtx := ctx.Copy()
 		newCtx.rvcount = -1
 		v.istack.PushVal(newCtx)
-		err = v.execute(v.Context(), JMP, parameter)
+		err = v.execute(v.Context(), opcode.JMP, parameter)
 		if err != nil {
 			return
 		}

-	case SYSCALL:
+	case opcode.SYSCALL:
 		ifunc, ok := v.interop[string(parameter)]
 		if !ok {
 			panic(fmt.Sprintf("interop hook (%q) not registered", parameter))
@ -1100,12 +1103,12 @@ func (v *VM) execute(ctx *Context, op Instruction, parameter []byte) (err error)
 			panic(fmt.Sprintf("failed to invoke syscall: %s", err))
 		}

-	case APPCALL, TAILCALL:
+	case opcode.APPCALL, opcode.TAILCALL:
 		if v.getScript == nil {
 			panic("no getScript callback is set up")
 		}

-		if op == APPCALL {
+		if op == opcode.APPCALL {
 			v.checkInvocationStackSize()
 		}

@ -1119,13 +1122,13 @@ func (v *VM) execute(ctx *Context, op Instruction, parameter []byte) (err error)
 			panic("could not find script")
 		}

-		if op == TAILCALL {
+		if op == opcode.TAILCALL {
 			_ = v.istack.Pop()
 		}

 		v.LoadScript(script)

-	case RET:
+	case opcode.RET:
 		oldCtx := v.istack.Pop().Value().(*Context)
 		rvcount := oldCtx.rvcount
 		oldEstack := v.estack
@ -1151,12 +1154,12 @@ func (v *VM) execute(ctx *Context, op Instruction, parameter []byte) (err error)
 			v.astack = v.Context().astack
 		}

-	case CHECKSIG, VERIFY:
+	case opcode.CHECKSIG, opcode.VERIFY:
 		var hashToCheck []byte

 		keyb := v.estack.Pop().Bytes()
 		signature := v.estack.Pop().Bytes()
-		if op == CHECKSIG {
+		if op == opcode.CHECKSIG {
 			if v.checkhash == nil {
 				panic("VM is not set up properly for signature checks")
 			}
@ -1173,7 +1176,7 @@ func (v *VM) execute(ctx *Context, op Instruction, parameter []byte) (err error)
 		res := pkey.Verify(signature, hashToCheck)
 		v.estack.PushVal(res)

-	case CHECKMULTISIG:
+	case opcode.CHECKMULTISIG:
 		pkeys, err := v.estack.popSigElements()
 		if err != nil {
 			panic(fmt.Sprintf("wrong parameters: %s", err.Error()))
@ -1214,10 +1217,10 @@ func (v *VM) execute(ctx *Context, op Instruction, parameter []byte) (err error)
 		}
 		v.estack.PushVal(sigok)

-	case NEWMAP:
+	case opcode.NEWMAP:
 		v.estack.Push(&Element{value: NewMapItem()})

-	case KEYS:
+	case opcode.KEYS:
 		item := v.estack.Pop()
 		if item == nil {
 			panic("no argument")
@ -1234,7 +1237,7 @@ func (v *VM) execute(ctx *Context, op Instruction, parameter []byte) (err error)
 		}
 		v.estack.PushVal(arr)

-	case VALUES:
+	case opcode.VALUES:
 		item := v.estack.Pop()
 		if item == nil {
 			panic("no argument")
@ -1259,7 +1262,7 @@ func (v *VM) execute(ctx *Context, op Instruction, parameter []byte) (err error)

 		v.estack.PushVal(arr)

-	case HASKEY:
+	case opcode.HASKEY:
 		key := v.estack.Pop()
 		validateMapKey(key)

@ -1281,31 +1284,31 @@ func (v *VM) execute(ctx *Context, op Instruction, parameter []byte) (err error)
 		}

 	// Cryptographic operations.
-	case SHA1:
+	case opcode.SHA1:
 		b := v.estack.Pop().Bytes()
 		sha := sha1.New()
 		sha.Write(b)
 		v.estack.PushVal(sha.Sum(nil))

-	case SHA256:
+	case opcode.SHA256:
 		b := v.estack.Pop().Bytes()
 		v.estack.PushVal(hash.Sha256(b).Bytes())

-	case HASH160:
+	case opcode.HASH160:
 		b := v.estack.Pop().Bytes()
 		v.estack.PushVal(hash.Hash160(b).Bytes())

-	case HASH256:
+	case opcode.HASH256:
 		b := v.estack.Pop().Bytes()
 		v.estack.PushVal(hash.DoubleSha256(b).Bytes())

-	case NOP:
+	case opcode.NOP:
 		// unlucky ^^

-	case CALLI, CALLE, CALLED, CALLET, CALLEDT:
+	case opcode.CALLI, opcode.CALLE, opcode.CALLED, opcode.CALLET, opcode.CALLEDT:
 		var (
-			tailCall    = (op == CALLET || op == CALLEDT)
-			hashOnStack = (op == CALLED || op == CALLEDT)
+			tailCall    = (op == opcode.CALLET || op == opcode.CALLEDT)
+			hashOnStack = (op == opcode.CALLED || op == opcode.CALLEDT)
 			addElement  int
 			newCtx      *Context
 		)
@ -1327,7 +1330,7 @@ func (v *VM) execute(ctx *Context, op Instruction, parameter []byte) (err error)
 			v.checkInvocationStackSize()
 		}

-		if op == CALLI {
+		if op == opcode.CALLI {
 			newCtx = ctx.Copy()
 		} else {
 			var hashBytes []byte
@ -1362,17 +1365,17 @@ func (v *VM) execute(ctx *Context, op Instruction, parameter []byte) (err error)
 		v.istack.PushVal(newCtx)
 		v.estack = newCtx.estack
 		v.astack = newCtx.astack
-		if op == CALLI {
-			err = v.execute(v.Context(), JMP, parameter[2:])
+		if op == opcode.CALLI {
+			err = v.execute(v.Context(), opcode.JMP, parameter[2:])
 			if err != nil {
 				return
 			}
 		}

-	case THROW:
+	case opcode.THROW:
 		panic("THROW")

-	case THROWIFNOT:
+	case opcode.THROWIFNOT:
 		if !v.estack.Pop().Bool() {
 			panic("THROWIFNOT")
 		}
--- a/pkg/vm/vm_test.go
+++ b/pkg/vm/vm_test.go