vm/common.go


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

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