go-ethereum/vm/common.go

package vm

import (
	"math"
	"math/big"

	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/logger"
)

var vmlogger = logger.NewLogger("VM")

// Global Debug flag indicating Debug VM (full logging)
var Debug bool

type Type byte

const (
	StdVmTy Type = iota
	JitVmTy
	MaxVmTy

	MaxCallDepth = 1025

	LogTyPretty byte = 0x1
	LogTyDiff   byte = 0x2
)

var (
	Pow256 = common.BigPow(2, 256)

	U256 = common.U256
	S256 = common.S256

	Zero = common.Big0

	max = big.NewInt(math.MaxInt64)
)

func NewVm(env Environment) VirtualMachine {
	switch env.VmType() {
	case JitVmTy:
		return NewJitVm(env)
	default:
		vmlogger.Infoln("unsupported vm type %d", env.VmType())
		fallthrough
	case StdVmTy:
		return New(env)
	}
}

func calcMemSize(off, l *big.Int) *big.Int {
	if l.Cmp(common.Big0) == 0 {
		return common.Big0
	}

	return new(big.Int).Add(off, l)
}

// Simple helper
func u256(n int64) *big.Int {
	return big.NewInt(n)
}

// Mainly used for print variables and passing to Print*
func toValue(val *big.Int) interface{} {
	// Let's assume a string on right padded zero's
	b := val.Bytes()
	if b[0] != 0 && b[len(b)-1] == 0x0 && b[len(b)-2] == 0x0 {
		return string(b)
	}

	return val
}

func getData(data []byte, start, size uint64) []byte {
	x := uint64(math.Min(float64(start), float64(len(data))))
	y := uint64(math.Min(float64(x+size), float64(len(data))))

	return common.RightPadBytes(data[x:y], int(size))
}