path: root/core/vm/common.go

// Copyright 2014 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

package vm

import (
    "math"
    "math/big"

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

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

type Type byte

const (
    StdVmTy Type = iota
    JitVmTy
    MaxVmTy

    LogTyPretty byte = 0x1
    LogTyDiff   byte = 0x2
)

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

    U256 = common.U256
    S256 = common.S256

    Zero = common.Big0
    One  = common.Big1

    max = big.NewInt(math.MaxInt64)
)

func NewVm(env Environment) VirtualMachine {
    switch env.VmType() {
    case JitVmTy:
        return NewJitVm(env)
    default:
        glog.V(0).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 *big.Int) []byte {
    dlen := big.NewInt(int64(len(data)))

    s := common.BigMin(start, dlen)
    e := common.BigMin(new(big.Int).Add(s, size), dlen)
    return common.RightPadBytes(data[s.Uint64():e.Uint64()], int(size.Uint64()))
}

func UseGas(gas, amount *big.Int) bool {
    if gas.Cmp(amount) < 0 {
        return false
    }

    // Sub the amount of gas from the remaining
    gas.Sub(gas, amount)
    return true
}