neoneo-go/pkg/compiler/emit.go

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package compiler
import (
"encoding/binary"
"errors"
"fmt"
"math/big"
"github.com/CityOfZion/neo-go/pkg/io"
"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 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 opcode.Opcode) {
w.WriteBytes([]byte{byte(instr)})
}
// emitBool emits a bool type the given buffer.
func emitBool(w *io.BinWriter, ok bool) {
if ok {
emitOpcode(w, opcode.PUSHT)
return
}
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, opcode.PUSHM1)
return
case i == 0:
emitOpcode(w, opcode.PUSHF)
return
case i > 0 && i < 16:
val := opcode.Opcode(int(opcode.PUSH1) - 1 + int(i))
emitOpcode(w, val)
return
}
bInt := big.NewInt(i)
val := vm.IntToBytes(bInt)
emitBytes(w, val)
}
// emitString emits a string to the given buffer.
func emitString(w *io.BinWriter, s string) {
emitBytes(w, []byte(s))
}
// emitBytes emits a byte array to the given buffer.
func emitBytes(w *io.BinWriter, b []byte) {
n := len(b)
switch {
case n <= int(opcode.PUSHBYTES75):
emit(w, opcode.Opcode(n), b)
return
case n < 0x100:
emit(w, opcode.PUSHDATA1, []byte{byte(n)})
case n < 0x10000:
buf := make([]byte, 2)
binary.LittleEndian.PutUint16(buf, uint16(n))
emit(w, opcode.PUSHDATA2, buf)
default:
buf := make([]byte, 4)
binary.LittleEndian.PutUint32(buf, uint32(n))
emit(w, opcode.PUSHDATA4, buf)
if w.Err != nil {
return
}
}
w.WriteBytes(b)
}
// emitSyscall emits the syscall API to the given buffer.
// Syscall API string cannot be 0.
func emitSyscall(w *io.BinWriter, api string) {
if len(api) == 0 {
w.Err = errors.New("syscall api cannot be of length 0")
return
}
buf := make([]byte, len(api)+1)
buf[0] = byte(len(api))
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copy(buf[1:], api)
emit(w, opcode.SYSCALL, buf)
}
// emitCall emits a call Instruction with label to the given buffer.
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 opcode.Opcode, label int16) {
if !isInstrJmp(instr) {
w.Err = fmt.Errorf("opcode %s is not a jump or call type", instr)
return
}
buf := make([]byte, 2)
binary.LittleEndian.PutUint16(buf, uint16(label))
emit(w, instr, buf)
}
func isInstrJmp(instr opcode.Opcode) bool {
if instr == opcode.JMP || instr == opcode.JMPIFNOT || instr == opcode.JMPIF || instr == opcode.CALL {
return true
}
return false
}