path: root/vm/vm.go

package vm

import (
    "fmt"
    "math/big"

    "github.com/ethereum/go-ethereum/crypto"
    "github.com/ethereum/go-ethereum/ethutil"
    "github.com/ethereum/go-ethereum/state"
)

type Vm struct {
    env Environment

    logTy  byte
    logStr string

    err error
    // For logging
    debug bool

    Dbg Debugger

    BreakPoints []int64
    Stepping    bool
    Fn          string

    Recoverable bool
}

func New(env Environment) *Vm {
    lt := LogTyPretty
    if ethutil.Config.Diff {
        lt = LogTyDiff
    }

    return &Vm{debug: false, env: env, logTy: lt, Recoverable: true}
}

func (self *Vm) Run(me, caller ContextRef, code []byte, value, gas, price *big.Int, callData []byte) (ret []byte, err error) {
    self.env.SetDepth(self.env.Depth() + 1)

    context := NewContext(caller, me, code, gas, price)

    vmlogger.Debugf("(%d) (%x) %x (code=%d) gas: %v (d) %x\n", self.env.Depth(), caller.Address()[:4], context.Address(), len(code), context.Gas, callData)

    if self.Recoverable {
        // Recover from any require exception
        defer func() {
            if r := recover(); r != nil {
                self.Printf(" %v", r).Endl()

                context.UseGas(context.Gas)

                ret = context.Return(nil)

                err = fmt.Errorf("%v", r)

            }
        }()
    }

    if p := Precompiled[string(me.Address())]; p != nil {
        return self.RunPrecompiled(p, callData, context)
    }

    var (
        op OpCode

        destinations        = analyseJumpDests(context.Code)
        mem                 = NewMemory()
        stack               = NewStack()
        pc           uint64 = 0
        step                = 0
        prevStep            = 0
        statedb             = self.env.State()

        jump = func(from uint64, to *big.Int) {
            p := to.Uint64()

            nop := context.GetOp(p)
            if !destinations.Has(p) {
                panic(fmt.Sprintf("invalid jump destination (%v) %v", nop, p))
            }

            self.Printf(" ~> %v", to)
            pc = to.Uint64()

            self.Endl()
        }
    )

    // Don't bother with the execution if there's no code.
    if len(code) == 0 {
        return context.Return(nil), nil
    }

    for {
        prevStep = step
        // The base for all big integer arithmetic
        base := new(big.Int)

        step++
        // Get the memory location of pc
        op = context.GetOp(pc)

        self.Printf("(pc) %-3d -o- %-14s (m) %-4d (s) %-4d ", pc, op.String(), mem.Len(), stack.Len())
        if self.Dbg != nil {
            //self.Dbg.Step(self, op, mem, stack, context)
        }

        newMemSize, gas := self.calculateGasAndSize(context, caller, op, statedb, mem, stack)

        self.Printf("(g) %-3v (%v)", gas, context.Gas)

        if !context.UseGas(gas) {
            self.Endl()

            tmp := new(big.Int).Set(context.Gas)

            context.UseGas(context.Gas)

            return context.Return(nil), OOG(gas, tmp)
        }

        mem.Resize(newMemSize.Uint64())

        switch op {
        // 0x20 range
        case ADD:
            x, y := stack.Popn()
            self.Printf(" %v + %v", y, x)

            base.Add(y, x)

            U256(base)

            self.Printf(" = %v", base)
            // Pop result back on the stack
            stack.Push(base)
        case SUB:
            x, y := stack.Popn()
            self.Printf(" %v - %v", y, x)

            base.Sub(y, x)

            U256(base)

            self.Printf(" = %v", base)
            // Pop result back on the stack
            stack.Push(base)
        case MUL:
            x, y := stack.Popn()
            self.Printf(" %v * %v", y, x)

            base.Mul(y, x)

            U256(base)

            self.Printf(" = %v", base)
            // Pop result back on the stack
            stack.Push(base)
        case DIV:
            x, y := stack.Pop(), stack.Pop()
            self.Printf(" %v / %v", x, y)

            if y.Cmp(ethutil.Big0) != 0 {
                base.Div(x, y)
            }

            U256(base)

            self.Printf(" = %v", base)
            // Pop result back on the stack
            stack.Push(base)
        case SDIV:
            x, y := S256(stack.Pop()), S256(stack.Pop())

            self.Printf(" %v / %v", x, y)

            if y.Cmp(ethutil.Big0) == 0 {
                base.Set(ethutil.Big0)
            } else {
                n := new(big.Int)
                if new(big.Int).Mul(x, y).Cmp(ethutil.Big0) < 0 {
                    n.SetInt64(-1)
                } else {
                    n.SetInt64(1)
                }

                base.Div(x.Abs(x), y.Abs(y)).Mul(base, n)

                U256(base)
            }

            self.Printf(" = %v", base)
            stack.Push(base)
        case MOD:
            x, y := stack.Pop(), stack.Pop()

            self.Printf(" %v %% %v", x, y)

            if y.Cmp(ethutil.Big0) == 0 {
                base.Set(ethutil.Big0)
            } else {
                base.Mod(x, y)
            }

            U256(base)

            self.Printf(" = %v", base)
            stack.Push(base)
        case SMOD:
            x, y := S256(stack.Pop()), S256(stack.Pop())

            self.Printf(" %v %% %v", x, y)

            if y.Cmp(ethutil.Big0) == 0 {
                base.Set(ethutil.Big0)
            } else {
                n := new(big.Int)
                if x.Cmp(ethutil.Big0) < 0 {
                    n.SetInt64(-1)
                } else {
                    n.SetInt64(1)
                }

                base.Mod(x.Abs(x), y.Abs(y)).Mul(base, n)

                U256(base)
            }

            self.Printf(" = %v", base)
            stack.Push(base)

        case EXP:
            x, y := stack.Popn()

            self.Printf(" %v ** %v", y, x)

            base.Exp(y, x, Pow256)

            U256(base)

            self.Printf(" = %v", base)

            stack.Push(base)
        case SIGNEXTEND:
            back := stack.Pop().Uint64()
            if back < 31 {
                bit := uint(back*8 + 7)
                num := stack.Pop()
                mask := new(big.Int).Lsh(ethutil.Big1, bit)
                mask.Sub(mask, ethutil.Big1)
                if ethutil.BitTest(num, int(bit)) {
                    num.Or(num, mask.Not(mask))
                } else {
                    num.And(num, mask)
                }

                num = U256(num)

                self.Printf(" = %v", num)

                stack.Push(num)
            }
        case NOT:
            base.Sub(Pow256, stack.Pop()).Sub(base, ethutil.Big1)

            // Not needed
            base = U256(base)

            stack.Push(base)
        case LT:
            x, y := stack.Popn()
            self.Printf(" %v < %v", y, x)
            // x < y
            if y.Cmp(x) < 0 {
                stack.Push(ethutil.BigTrue)
            } else {
                stack.Push(ethutil.BigFalse)
            }
        case GT:
            x, y := stack.Popn()
            self.Printf(" %v > %v", y, x)

            // x > y
            if y.Cmp(x) > 0 {
                stack.Push(ethutil.BigTrue)
            } else {
                stack.Push(ethutil.BigFalse)
            }

        case SLT:
            y, x := S256(stack.Pop()), S256(stack.Pop())
            self.Printf(" %v < %v", y, x)
            // x < y
            if y.Cmp(S256(x)) < 0 {
                stack.Push(ethutil.BigTrue)
            } else {
                stack.Push(ethutil.BigFalse)
            }
        case SGT:
            y, x := S256(stack.Pop()), S256(stack.Pop())
            self.Printf(" %v > %v", y, x)

            // x > y
            if y.Cmp(x) > 0 {
                stack.Push(ethutil.BigTrue)
            } else {
                stack.Push(ethutil.BigFalse)
            }

        case EQ:
            x, y := stack.Popn()
            self.Printf(" %v == %v", y, x)

            // x == y
            if x.Cmp(y) == 0 {
                stack.Push(ethutil.BigTrue)
            } else {
                stack.Push(ethutil.BigFalse)
            }
        case ISZERO:
            x := stack.Pop()
            if x.Cmp(ethutil.BigFalse) > 0 {
                stack.Push(ethutil.BigFalse)
            } else {
                stack.Push(ethutil.BigTrue)
            }

            // 0x10 range
        case AND:
            x, y := stack.Popn()
            self.Printf(" %v & %v", y, x)

            stack.Push(base.And(y, x))
        case OR:
            x, y := stack.Popn()
            self.Printf(" %v | %v", y, x)

            stack.Push(base.Or(y, x))
        case XOR:
            x, y := stack.Popn()
            self.Printf(" %v ^ %v", y, x)

            stack.Push(base.Xor(y, x))
        case BYTE:
            val, th := stack.Popn()

            if th.Cmp(big.NewInt(32)) < 0 {
                byt := big.NewInt(int64(ethutil.LeftPadBytes(val.Bytes(), 32)[th.Int64()]))

                base.Set(byt)
            } else {
                base.Set(ethutil.BigFalse)
            }

            self.Printf(" => 0x%x", base.Bytes())

            stack.Push(base)
        case ADDMOD:

            x := stack.Pop()
            y := stack.Pop()
            z := stack.Pop()

            add := new(big.Int).Add(x, y)
            if len(z.Bytes()) > 0 { // NOT 0x0
                base.Mod(add, z)

                U256(base)
            }

            self.Printf(" %v + %v %% %v = %v", x, y, z, base)

            stack.Push(base)
        case MULMOD:

            x := stack.Pop()
            y := stack.Pop()
            z := stack.Pop()

            mul := new(big.Int).Mul(x, y)
            if len(z.Bytes()) > 0 { // NOT 0x0
                base.Mod(mul, z)

                U256(base)
            }

            self.Printf(" %v + %v %% %v = %v", x, y, z, base)

            stack.Push(base)

            // 0x20 range
        case SHA3:
            size, offset := stack.Popn()
            data := crypto.Sha3(mem.Get(offset.Int64(), size.Int64()))

            stack.Push(ethutil.BigD(data))

            self.Printf(" => %x", data)
            // 0x30 range
        case ADDRESS:
            stack.Push(ethutil.BigD(context.Address()))

            self.Printf(" => %x", context.Address())
        case BALANCE:

            addr := stack.Pop().Bytes()
            balance := statedb.GetBalance(addr)

            stack.Push(balance)

            self.Printf(" => %v (%x)", balance, addr)
        case ORIGIN:
            origin := self.env.Origin()

            stack.Push(ethutil.BigD(origin))

            self.Printf(" => %x", origin)
        case CALLER:
            caller := context.caller.Address()
            stack.Push(ethutil.BigD(caller))

            self.Printf(" => %x", caller)
        case CALLVALUE:
            stack.Push(value)

            self.Printf(" => %v", value)
        case CALLDATALOAD:
            var (
                offset  = stack.Pop()
                data    = make([]byte, 32)
                lenData = big.NewInt(int64(len(callData)))
            )

            if lenData.Cmp(offset) >= 0 {
                length := new(big.Int).Add(offset, ethutil.Big32)
                length = ethutil.BigMin(length, lenData)

                copy(data, callData[offset.Int64():length.Int64()])
            }

            self.Printf(" => 0x%x", data)

            stack.Push(ethutil.BigD(data))
        case CALLDATASIZE:
            l := int64(len(callData))
            stack.Push(big.NewInt(l))

            self.Printf(" => %d", l)
        case CALLDATACOPY:
            var (
                size = uint64(len(callData))
                mOff = stack.Pop().Uint64()
                cOff = stack.Pop().Uint64()
                l    = stack.Pop().Uint64()
            )

            if cOff > size {
                cOff = 0
                l = 0
            } else if cOff+l > size {
                l = 0
            }

            code := callData[cOff : cOff+l]

            mem.Set(mOff, l, code)

            self.Printf(" => [%v, %v, %v] %x", mOff, cOff, l, callData[cOff:cOff+l])
        case CODESIZE, EXTCODESIZE:
            var code []byte
            if op == EXTCODESIZE {
                addr := stack.Pop().Bytes()

                code = statedb.GetCode(addr)
            } else {
                code = context.Code
            }

            l := big.NewInt(int64(len(code)))
            stack.Push(l)

            self.Printf(" => %d", l)
        case CODECOPY, EXTCODECOPY:
            var code []byte
            if op == EXTCODECOPY {
                code = statedb.GetCode(stack.Pop().Bytes())
            } else {
                code = context.Code
            }
            context := NewContext(nil, nil, code, ethutil.Big0, ethutil.Big0)
            var (
                mOff = stack.Pop().Uint64()
                cOff = stack.Pop().Uint64()
                l    = stack.Pop().Uint64()
            )
            codeCopy := context.GetCode(cOff, l)

            mem.Set(mOff, l, codeCopy)

            self.Printf(" => [%v, %v, %v] %x", mOff, cOff, l, codeCopy)
        case GASPRICE:
            stack.Push(context.Price)

            self.Printf(" => %x", context.Price)

            // 0x40 range
        case BLOCKHASH:
            num := stack.Pop()

            n := new(big.Int).Sub(self.env.BlockNumber(), ethutil.Big257)
            if num.Cmp(n) > 0 && num.Cmp(self.env.BlockNumber()) < 0 {
                stack.Push(ethutil.BigD(self.env.GetHash(num.Uint64())))
            } else {
                stack.Push(ethutil.Big0)
            }

            self.Printf(" => 0x%x", stack.Peek().Bytes())
        case COINBASE:
            coinbase := self.env.Coinbase()

            stack.Push(ethutil.BigD(coinbase))

            self.Printf(" => 0x%x", coinbase)
        case TIMESTAMP:
            time := self.env.Time()

            stack.Push(big.NewInt(time))

            self.Printf(" => 0x%x", time)
        case NUMBER:
            number := self.env.BlockNumber()

            stack.Push(U256(number))

            self.Printf(" => 0x%x", number.Bytes())
        case DIFFICULTY:
            difficulty := self.env.Difficulty()

            stack.Push(difficulty)

            self.Printf(" => 0x%x", difficulty.Bytes())
        case GASLIMIT:
            self.Printf(" => %v", self.env.GasLimit())

            stack.Push(self.env.GasLimit())

            // 0x50 range
        case PUSH1, PUSH2, PUSH3, PUSH4, PUSH5, PUSH6, PUSH7, PUSH8, PUSH9, PUSH10, PUSH11, PUSH12, PUSH13, PUSH14, PUSH15, PUSH16, PUSH17, PUSH18, PUSH19, PUSH20, PUSH21, PUSH22, PUSH23, PUSH24, PUSH25, PUSH26, PUSH27, PUSH28, PUSH29, PUSH30, PUSH31, PUSH32:
            a := uint64(op - PUSH1 + 1)
            byts := context.GetRangeValue(pc+1, a)
            // Push value to stack
            stack.Push(ethutil.BigD(byts))
            pc += a

            step += int(op) - int(PUSH1) + 1

            self.Printf(" => 0x%x", byts)
        case POP:
            stack.Pop()
        case DUP1, DUP2, DUP3, DUP4, DUP5, DUP6, DUP7, DUP8, DUP9, DUP10, DUP11, DUP12, DUP13, DUP14, DUP15, DUP16:
            n := int(op - DUP1 + 1)
            stack.Dupn(n)

            self.Printf(" => [%d] 0x%x", n, stack.Peek().Bytes())
        case SWAP1, SWAP2, SWAP3, SWAP4, SWAP5, SWAP6, SWAP7, SWAP8, SWAP9, SWAP10, SWAP11, SWAP12, SWAP13, SWAP14, SWAP15, SWAP16:
            n := int(op - SWAP1 + 2)
            x, y := stack.Swapn(n)

            self.Printf(" => [%d] %x [0] %x", n, x.Bytes(), y.Bytes())
        case LOG0, LOG1, LOG2, LOG3, LOG4:
            n := int(op - LOG0)
            topics := make([][]byte, n)
            mSize, mStart := stack.Popn()
            for i := 0; i < n; i++ {
                topics[i] = ethutil.LeftPadBytes(stack.Pop().Bytes(), 32)
            }

            data := mem.Get(mStart.Int64(), mSize.Int64())
            log := &Log{context.Address(), topics, data, self.env.BlockNumber().Uint64()}
            self.env.AddLog(log)

            self.Printf(" => %v", log)
        case MLOAD:
            offset := stack.Pop()
            val := ethutil.BigD(mem.Get(offset.Int64(), 32))
            stack.Push(val)

            self.Printf(" => 0x%x", val.Bytes())
        case MSTORE: // Store the value at stack top-1 in to memory at location stack top
            // Pop value of the stack
            val, mStart := stack.Popn()
            mem.Set(mStart.Uint64(), 32, ethutil.BigToBytes(val, 256))

            self.Printf(" => 0x%x", val)
        case MSTORE8:
            off := stack.Pop()
            val := stack.Pop()

            mem.store[off.Int64()] = byte(val.Int64() & 0xff)

            self.Printf(" => [%v] 0x%x", off, val)
        case SLOAD:
            loc := stack.Pop()
            val := ethutil.BigD(statedb.GetState(context.Address(), loc.Bytes()))
            stack.Push(val)

            self.Printf(" {0x%x : 0x%x}", loc.Bytes(), val.Bytes())
        case SSTORE:
            val, loc := stack.Popn()
            statedb.SetState(context.Address(), loc.Bytes(), val)

            self.Printf(" {0x%x : 0x%x}", loc.Bytes(), val.Bytes())
        case JUMP:
            jump(pc, stack.Pop())

            continue
        case JUMPI:
            cond, pos := stack.Popn()

            if cond.Cmp(ethutil.BigTrue) >= 0 {
                jump(pc, pos)

                continue
            }

            self.Printf(" ~> false")

        case JUMPDEST:
        case PC:
            stack.Push(big.NewInt(int64(pc)))
        case MSIZE:
            stack.Push(big.NewInt(int64(mem.Len())))
        case GAS:
            stack.Push(context.Gas)

            self.Printf(" => %x", context.Gas)
            // 0x60 range
        case CREATE:

            var (
                value        = stack.Pop()
                size, offset = stack.Popn()
                input        = mem.Get(offset.Int64(), size.Int64())
                gas          = new(big.Int).Set(context.Gas)
                addr         []byte
            )
            self.Endl()

            context.UseGas(context.Gas)
            ret, suberr, ref := self.env.Create(context, nil, input, gas, price, value)
            if suberr != nil {
                stack.Push(ethutil.BigFalse)

                self.Printf(" (*) 0x0 %v", suberr)
            } else {

                // gas < len(ret) * CreateDataGas == NO_CODE
                dataGas := big.NewInt(int64(len(ret)))
                dataGas.Mul(dataGas, GasCreateByte)
                if context.UseGas(dataGas) {
                    ref.SetCode(ret)
                }
                addr = ref.Address()

                fmt.Printf("CREATE %X\n", addr)
                stack.Push(ethutil.BigD(addr))

            }

            // Debug hook
            if self.Dbg != nil {
                self.Dbg.SetCode(context.Code)
            }
        case CALL, CALLCODE:
            gas := stack.Pop()
            // Pop gas and value of the stack.
            value, addr := stack.Popn()
            value = U256(value)
            // Pop input size and offset
            inSize, inOffset := stack.Popn()
            // Pop return size and offset
            retSize, retOffset := stack.Popn()

            address := ethutil.Address(addr.Bytes())
            self.Printf(" => %x", address).Endl()

            // Get the arguments from the memory
            args := mem.Get(inOffset.Int64(), inSize.Int64())

            var (
                ret []byte
                err error
            )
            if op == CALLCODE {
                ret, err = self.env.CallCode(context, address, args, gas, price, value)
            } else {
                ret, err = self.env.Call(context, address, args, gas, price, value)
            }

            if err != nil {
                stack.Push(ethutil.BigFalse)

                vmlogger.Debugln(err)
            } else {
                stack.Push(ethutil.BigTrue)

                mem.Set(retOffset.Uint64(), retSize.Uint64(), ret)
            }
            self.Printf("resume %x (%v)", context.Address(), context.Gas)

            // Debug hook
            if self.Dbg != nil {
                self.Dbg.SetCode(context.Code)
            }

        case RETURN:
            size, offset := stack.Popn()
            ret := mem.Get(offset.Int64(), size.Int64())

            self.Printf(" => [%v, %v] (%d) 0x%x", offset, size, len(ret), ret).Endl()

            return context.Return(ret), nil
        case SUICIDE:
            receiver := statedb.GetOrNewStateObject(stack.Pop().Bytes())
            balance := statedb.GetBalance(context.Address())

            self.Printf(" => (%x) %v", receiver.Address()[:4], balance)

            receiver.AddBalance(balance)
            statedb.Delete(context.Address())

            fallthrough
        case STOP: // Stop the context
            self.Endl()

            return context.Return(nil), nil
        default:
            vmlogger.Debugf("(pc) %-3v Invalid opcode %x\n", pc, op)

            panic(fmt.Errorf("Invalid opcode %x", op))
        }

        pc++

        self.Endl()

        if self.Dbg != nil {
            for _, instrNo := range self.Dbg.BreakPoints() {
                if pc == uint64(instrNo) {
                    self.Stepping = true

                    if !self.Dbg.BreakHook(prevStep, op, mem, stack, statedb.GetStateObject(context.Address())) {
                        return nil, nil
                    }
                } else if self.Stepping {
                    if !self.Dbg.StepHook(prevStep, op, mem, stack, statedb.GetStateObject(context.Address())) {
                        return nil, nil
                    }
                }
            }
        }

    }
}

func (self *Vm) calculateGasAndSize(context *Context, caller ContextRef, op OpCode, statedb *state.StateDB, mem *Memory, stack *Stack) (*big.Int, *big.Int) {
    gas := new(big.Int)
    addStepGasUsage := func(amount *big.Int) {
        if amount.Cmp(ethutil.Big0) >= 0 {
            gas.Add(gas, amount)
        }
    }

    addStepGasUsage(GasStep)

    var newMemSize *big.Int = ethutil.Big0
    var additionalGas *big.Int = new(big.Int)
    // Stack Check, memory resize & gas phase
    switch op {
    // Stack checks only
    case ISZERO, CALLDATALOAD, POP, JUMP, NOT, EXTCODESIZE, BLOCKHASH: // 1
        stack.require(1)
    case JUMPI, ADD, SUB, DIV, MUL, SDIV, MOD, SMOD, LT, GT, SLT, SGT, EQ, AND, OR, XOR, BYTE, SIGNEXTEND: // 2
        stack.require(2)
    case ADDMOD, MULMOD: // 3
        stack.require(3)
    case SWAP1, SWAP2, SWAP3, SWAP4, SWAP5, SWAP6, SWAP7, SWAP8, SWAP9, SWAP10, SWAP11, SWAP12, SWAP13, SWAP14, SWAP15, SWAP16:
        n := int(op - SWAP1 + 2)
        stack.require(n)
    case DUP1, DUP2, DUP3, DUP4, DUP5, DUP6, DUP7, DUP8, DUP9, DUP10, DUP11, DUP12, DUP13, DUP14, DUP15, DUP16:
        n := int(op - DUP1 + 1)
        stack.require(n)
    case LOG0, LOG1, LOG2, LOG3, LOG4:
        n := int(op - LOG0)
        stack.require(n + 2)

        gas.Set(GasLog)
        addStepGasUsage(new(big.Int).Mul(big.NewInt(int64(n)), GasLog))

        mSize, mStart := stack.Peekn()
        addStepGasUsage(mSize)

        newMemSize = calcMemSize(mStart, mSize)
    case EXP:
        stack.require(2)

        gas.Set(big.NewInt(int64(len(stack.data[stack.Len()-2].Bytes()) + 1)))
    // Gas only
    case STOP:
        gas.Set(ethutil.Big0)
    case SUICIDE:
        stack.require(1)

        gas.Set(ethutil.Big0)
    case SLOAD:
        stack.require(1)

        gas.Set(GasSLoad)
    // Memory resize & Gas
    case SSTORE:
        stack.require(2)

        var mult *big.Int
        y, x := stack.Peekn()
        val := statedb.GetState(context.Address(), x.Bytes())
        if len(val) == 0 && len(y.Bytes()) > 0 {
            // 0 => non 0
            mult = ethutil.Big3
        } else if len(val) > 0 && len(y.Bytes()) == 0 {
            statedb.Refund(self.env.Origin(), GasSStoreRefund)

            mult = ethutil.Big0
        } else {
            // non 0 => non 0 (or 0 => 0)
            mult = ethutil.Big1
        }
        gas.Set(new(big.Int).Mul(mult, GasSStore))
    case BALANCE:
        stack.require(1)
        gas.Set(GasBalance)
    case MSTORE:
        stack.require(2)
        newMemSize = calcMemSize(stack.Peek(), u256(32))
    case MLOAD:
        stack.require(1)

        newMemSize = calcMemSize(stack.Peek(), u256(32))
    case MSTORE8:
        stack.require(2)
        newMemSize = calcMemSize(stack.Peek(), u256(1))
    case RETURN:
        stack.require(2)

        newMemSize = calcMemSize(stack.Peek(), stack.data[stack.Len()-2])
    case SHA3:
        stack.require(2)
        gas.Set(GasSha)
        newMemSize = calcMemSize(stack.Peek(), stack.data[stack.Len()-2])
        additionalGas.Set(stack.data[stack.Len()-2])
    case CALLDATACOPY:
        stack.require(3)

        newMemSize = calcMemSize(stack.Peek(), stack.data[stack.Len()-3])
        additionalGas.Set(stack.data[stack.Len()-3])
    case CODECOPY:
        stack.require(3)

        newMemSize = calcMemSize(stack.Peek(), stack.data[stack.Len()-3])
        additionalGas.Set(stack.data[stack.Len()-3])
    case EXTCODECOPY:
        stack.require(4)

        newMemSize = calcMemSize(stack.data[stack.Len()-2], stack.data[stack.Len()-4])
        additionalGas.Set(stack.data[stack.Len()-4])
    case CALL, CALLCODE:
        stack.require(7)
        gas.Set(GasCall)
        addStepGasUsage(stack.data[stack.Len()-1])

        x := calcMemSize(stack.data[stack.Len()-6], stack.data[stack.Len()-7])
        y := calcMemSize(stack.data[stack.Len()-4], stack.data[stack.Len()-5])

        newMemSize = ethutil.BigMax(x, y)
    case CREATE:
        stack.require(3)
        gas.Set(GasCreate)

        newMemSize = calcMemSize(stack.data[stack.Len()-2], stack.data[stack.Len()-3])
    }

    switch op {
    case CALLDATACOPY, CODECOPY, EXTCODECOPY:
        additionalGas.Add(additionalGas, u256(31))
        additionalGas.Div(additionalGas, u256(32))
        addStepGasUsage(additionalGas)
    case SHA3:
        additionalGas.Add(additionalGas, u256(31))
        additionalGas.Div(additionalGas, u256(32))
        additionalGas.Mul(additionalGas, GasSha3Byte)
        addStepGasUsage(additionalGas)
    }

    if newMemSize.Cmp(ethutil.Big0) > 0 {
        newMemSize.Add(newMemSize, u256(31))
        newMemSize.Div(newMemSize, u256(32))
        newMemSize.Mul(newMemSize, u256(32))

        if newMemSize.Cmp(u256(int64(mem.Len()))) > 0 {
            memGasUsage := new(big.Int).Sub(newMemSize, u256(int64(mem.Len())))
            memGasUsage.Mul(GasMemory, memGasUsage)
            memGasUsage.Div(memGasUsage, u256(32))

            addStepGasUsage(memGasUsage)
        }

    }

    return newMemSize, gas
}

func (self *Vm) RunPrecompiled(p *PrecompiledAccount, callData []byte, context *Context) (ret []byte, err error) {
    gas := p.Gas(len(callData))
    if context.UseGas(gas) {
        ret = p.Call(callData)
        self.Printf("NATIVE_FUNC => %x", ret)
        self.Endl()

        return context.Return(ret), nil
    } else {
        self.Printf("NATIVE_FUNC => failed").Endl()

        tmp := new(big.Int).Set(context.Gas)

        panic(OOG(gas, tmp).Error())
    }
}

func (self *Vm) Printf(format string, v ...interface{}) VirtualMachine {
    if self.debug {
        if self.logTy == LogTyPretty {
            self.logStr += fmt.Sprintf(format, v...)
        }
    }

    return self
}

func (self *Vm) Endl() VirtualMachine {
    if self.debug {
        if self.logTy == LogTyPretty {
            vmlogger.Debugln(self.logStr)
            self.logStr = ""
        }
    }

    return self
}

func (self *Vm) Env() Environment {
    return self.env
}