neoneo-go/pkg/vm/compiler/emit.go

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package compiler
import (
"bytes"
"encoding/binary"
"errors"
"fmt"
"io"
"math/big"
"github.com/CityOfZion/neo-go/pkg/util"
"github.com/CityOfZion/neo-go/pkg/vm"
)
func emit(w *bytes.Buffer, instr vm.Instruction, b []byte) error {
if err := w.WriteByte(byte(instr)); err != nil {
return err
}
_, err := w.Write(b)
return err
}
func emitOpcode(w io.ByteWriter, instr vm.Instruction) error {
return w.WriteByte(byte(instr))
}
func emitBool(w io.ByteWriter, ok bool) error {
if ok {
return emitOpcode(w, vm.PUSHT)
}
return emitOpcode(w, vm.PUSHF)
}
func emitInt(w *bytes.Buffer, i int64) error {
if i == -1 {
return emitOpcode(w, vm.PUSHM1)
}
if i == 0 {
return emitOpcode(w, vm.PUSHF)
}
if i > 0 && i < 16 {
val := vm.Instruction(int(vm.PUSH1) - 1 + int(i))
return emitOpcode(w, val)
}
bInt := big.NewInt(i)
val := util.ArrayReverse(bInt.Bytes())
return emitBytes(w, val)
}
func emitString(w *bytes.Buffer, s string) error {
return emitBytes(w, []byte(s))
}
func emitBytes(w *bytes.Buffer, b []byte) error {
var (
err error
n = len(b)
)
switch {
case n <= int(vm.PUSHBYTES75):
return emit(w, vm.Instruction(n), b)
case n < 0x100:
err = emit(w, vm.PUSHDATA1, []byte{byte(n)})
case n < 0x10000:
buf := make([]byte, 2)
binary.LittleEndian.PutUint16(buf, uint16(n))
err = emit(w, vm.PUSHDATA2, buf)
default:
buf := make([]byte, 4)
binary.LittleEndian.PutUint32(buf, uint32(n))
err = emit(w, vm.PUSHDATA4, buf)
}
if err != nil {
return err
}
_, err = w.Write(b)
return err
}
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))
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copy(buf[1:], api)
return emit(w, vm.SYSCALL, buf)
}
func emitCall(w *bytes.Buffer, instr vm.Instruction, label int16) error {
return emitJmp(w, instr, label)
}
func emitJmp(w *bytes.Buffer, instr vm.Instruction, label int16) error {
if !isInstrJmp(instr) {
return fmt.Errorf("opcode %s is not a jump or call type", instr)
}
buf := make([]byte, 2)
binary.LittleEndian.PutUint16(buf, uint16(label))
return emit(w, instr, buf)
}
func isInstrJmp(instr vm.Instruction) bool {
if instr == vm.JMP || instr == vm.JMPIFNOT || instr == vm.JMPIF || instr == vm.CALL {
return true
}
return false
}