neo-go/pkg/vm/emit.go
Anthony De Meulemeester 4bd5b2812e
Optimisations and API changes for smart contracts (#67)
* support VM to pass method and arguments to a script.

* added support for type assertions in smartcontracts.

* added native vm support for print.

* moved VM API packages to vm -> API

* reverted the native Print opcode in favor of runtime.Log

* added support for registering custom interop hooks in the VM.

* Updated README

* Updated compiler with @OPTIMIZE tags

* Moved more tests to VM package.

* optimized and refactored compiler and vm API

* updated README with new smartcontract apis

* bumped version
2018-04-10 11:45:31 +02:00

149 lines
3.6 KiB
Go

package vm
import (
"bytes"
"encoding/binary"
"errors"
"fmt"
"math/big"
"github.com/CityOfZion/neo-go/pkg/util"
)
// Emit a VM Opcode with data to the given buffer.
func Emit(w *bytes.Buffer, op Opcode, b []byte) error {
if err := w.WriteByte(byte(op)); err != nil {
return err
}
_, err := w.Write(b)
return err
}
// EmitOpcode emits a single VM Opcode the given buffer.
func EmitOpcode(w *bytes.Buffer, op Opcode) error {
return w.WriteByte(byte(op))
}
// EmitBool emits a bool type the given buffer.
func EmitBool(w *bytes.Buffer, ok bool) error {
if ok {
return EmitOpcode(w, Opusht)
}
return EmitOpcode(w, Opushf)
}
// EmitInt emits a int type to the given buffer.
func EmitInt(w *bytes.Buffer, i int64) error {
if i == -1 {
return EmitOpcode(w, Opushm1)
}
if i == 0 {
return EmitOpcode(w, Opushf)
}
if i > 0 && i < 16 {
val := Opcode((int(Opush1) - 1 + int(i)))
return EmitOpcode(w, val)
}
bInt := big.NewInt(i)
val := util.ArrayReverse(bInt.Bytes())
return EmitBytes(w, val)
}
// EmitString emits a string to the given buffer.
func EmitString(w *bytes.Buffer, s string) error {
return EmitBytes(w, []byte(s))
}
// EmitBytes emits a byte array to the given buffer.
func EmitBytes(w *bytes.Buffer, b []byte) error {
var (
err error
n = len(b)
)
if n <= int(Opushbytes75) {
return Emit(w, Opcode(n), b)
} else if n < 0x100 {
err = Emit(w, Opushdata1, []byte{byte(n)})
} else if n < 0x10000 {
buf := make([]byte, 2)
binary.LittleEndian.PutUint16(buf, uint16(n))
err = Emit(w, Opushdata2, buf)
} else {
buf := make([]byte, 4)
binary.LittleEndian.PutUint32(buf, uint32(n))
err = Emit(w, Opushdata4, buf)
}
if err != nil {
return err
}
_, err = w.Write(b)
return err
}
// EmitSyscall emits the syscall API to the given buffer.
// Syscall API string cannot be 0.
func EmitSyscall(w *bytes.Buffer, api string) error {
if len(api) == 0 {
return errors.New("syscall api cannot be of length 0")
}
buf := make([]byte, len(api)+1)
buf[0] = byte(len(api))
copy(buf[1:len(buf)], []byte(api))
return Emit(w, Osyscall, buf)
}
// EmitCall emits a call Opcode with label to the given buffer.
func EmitCall(w *bytes.Buffer, op Opcode, label int16) error {
return EmitJmp(w, op, label)
}
// EmitJmp emits a jump Opcode along with label to the given buffer.
func EmitJmp(w *bytes.Buffer, op Opcode, label int16) error {
if !isOpcodeJmp(op) {
return fmt.Errorf("opcode %s is not a jump or call type", op)
}
buf := make([]byte, 2)
binary.LittleEndian.PutUint16(buf, uint16(label))
return Emit(w, op, buf)
}
// 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 := Oappcall
if tailCall {
op = Otailcall
}
return Emit(w, op, scriptHash.Bytes())
}
// EmitAppCallWithOperationAndData emits an appcall with the given operation and data.
func EmitAppCallWithOperationAndData(w *bytes.Buffer, scriptHash util.Uint160, operation string, data []byte) error {
if err := EmitBytes(w, data); err != nil {
return err
}
if err := EmitString(w, operation); err != nil {
return err
}
return EmitAppCall(w, scriptHash, false)
}
// EmitAppCallWithOperation emits an appcall with the given operation.
func EmitAppCallWithOperation(w *bytes.Buffer, scriptHash util.Uint160, operation string) error {
if err := EmitBool(w, false); err != nil {
return err
}
if err := EmitString(w, operation); err != nil {
return err
}
return EmitAppCall(w, scriptHash, false)
}
func isOpcodeJmp(op Opcode) bool {
if op == Ojmp || op == Ojmpifnot || op == Ojmpif || op == Ocall {
return true
}
return false
}