120 lines
3.4 KiB
Go
120 lines
3.4 KiB
Go
// Copyright 2014 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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package vm
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import (
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"math"
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"math/big"
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"github.com/ethereum/go-ethereum/common"
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"github.com/ethereum/go-ethereum/params"
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)
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// Type is the VM type accepted by **NewVm**
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type Type byte
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const (
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StdVmTy Type = iota // Default standard VM
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JitVmTy // LLVM JIT VM
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MaxVmTy
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)
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var (
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Pow256 = common.BigPow(2, 256) // Pow256 is 2**256
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U256 = common.U256 // Shortcut to common.U256
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S256 = common.S256 // Shortcut to common.S256
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Zero = common.Big0 // Shortcut to common.Big0
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One = common.Big1 // Shortcut to common.Big1
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max = big.NewInt(math.MaxInt64) // Maximum 64 bit integer
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)
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// calculates the memory size required for a step
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func calcMemSize(off, l *big.Int) *big.Int {
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if l.Cmp(common.Big0) == 0 {
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return common.Big0
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}
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return new(big.Int).Add(off, l)
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}
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// calculates the quadratic gas
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func quadMemGas(mem *Memory, newMemSize, gas *big.Int) {
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if newMemSize.Cmp(common.Big0) > 0 {
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newMemSizeWords := toWordSize(newMemSize)
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newMemSize.Mul(newMemSizeWords, u256(32))
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if newMemSize.Cmp(u256(int64(mem.Len()))) > 0 {
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// be careful reusing variables here when changing.
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// The order has been optimised to reduce allocation
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oldSize := toWordSize(big.NewInt(int64(mem.Len())))
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pow := new(big.Int).Exp(oldSize, common.Big2, Zero)
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linCoef := oldSize.Mul(oldSize, params.MemoryGas)
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quadCoef := new(big.Int).Div(pow, params.QuadCoeffDiv)
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oldTotalFee := new(big.Int).Add(linCoef, quadCoef)
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pow.Exp(newMemSizeWords, common.Big2, Zero)
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linCoef = linCoef.Mul(newMemSizeWords, params.MemoryGas)
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quadCoef = quadCoef.Div(pow, params.QuadCoeffDiv)
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newTotalFee := linCoef.Add(linCoef, quadCoef)
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fee := newTotalFee.Sub(newTotalFee, oldTotalFee)
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gas.Add(gas, fee)
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}
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}
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}
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// Simple helper
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func u256(n int64) *big.Int {
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return big.NewInt(n)
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}
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// Mainly used for print variables and passing to Print*
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func toValue(val *big.Int) interface{} {
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// Let's assume a string on right padded zero's
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b := val.Bytes()
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if b[0] != 0 && b[len(b)-1] == 0x0 && b[len(b)-2] == 0x0 {
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return string(b)
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}
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return val
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}
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// getData returns a slice from the data based on the start and size and pads
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// up to size with zero's. This function is overflow safe.
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func getData(data []byte, start, size *big.Int) []byte {
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dlen := big.NewInt(int64(len(data)))
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s := common.BigMin(start, dlen)
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e := common.BigMin(new(big.Int).Add(s, size), dlen)
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return common.RightPadBytes(data[s.Uint64():e.Uint64()], int(size.Uint64()))
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}
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// useGas attempts to subtract the amount of gas and returns whether it was
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// successful
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func useGas(gas, amount *big.Int) bool {
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if gas.Cmp(amount) < 0 {
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return false
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}
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// Sub the amount of gas from the remaining
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gas.Sub(gas, amount)
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return true
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}
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