bbc4ea4ae8
The run loop, which previously contained custom opcode executes have been removed and has been simplified to a few checks. Each operation consists of 4 elements: execution function, gas cost function, stack validation function and memory size function. The execution function implements the operation's runtime behaviour, the gas cost function implements the operation gas costs function and greatly depends on the memory and stack, the stack validation function validates the stack and makes sure that enough items can be popped off and pushed on and the memory size function calculates the memory required for the operation and returns it. This commit also allows the EVM to go unmetered. This is helpful for offline operations such as contract calls.
94 lines
2.3 KiB
Go
94 lines
2.3 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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"fmt"
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"math/big"
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)
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// stack is an object for basic stack operations. Items popped to the stack are
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// expected to be changed and modified. stack does not take care of adding newly
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// initialised objects.
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type Stack struct {
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data []*big.Int
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}
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func newstack() *Stack {
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return &Stack{}
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}
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func (st *Stack) Data() []*big.Int {
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return st.data
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}
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func (st *Stack) push(d *big.Int) {
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// NOTE push limit (1024) is checked in baseCheck
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//stackItem := new(big.Int).Set(d)
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//st.data = append(st.data, stackItem)
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st.data = append(st.data, d)
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}
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func (st *Stack) pushN(ds ...*big.Int) {
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st.data = append(st.data, ds...)
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}
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func (st *Stack) pop() (ret *big.Int) {
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ret = st.data[len(st.data)-1]
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st.data = st.data[:len(st.data)-1]
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return
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}
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func (st *Stack) len() int {
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return len(st.data)
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}
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func (st *Stack) swap(n int) {
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st.data[st.len()-n], st.data[st.len()-1] = st.data[st.len()-1], st.data[st.len()-n]
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}
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func (st *Stack) dup(n int) {
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st.push(new(big.Int).Set(st.data[st.len()-n]))
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}
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func (st *Stack) peek() *big.Int {
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return st.data[st.len()-1]
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}
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// Back returns the n'th item in stack
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func (st *Stack) Back(n int) *big.Int {
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return st.data[st.len()-n-1]
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}
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func (st *Stack) require(n int) error {
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if st.len() < n {
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return fmt.Errorf("stack underflow (%d <=> %d)", len(st.data), n)
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}
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return nil
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}
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func (st *Stack) Print() {
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fmt.Println("### stack ###")
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if len(st.data) > 0 {
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for i, val := range st.data {
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fmt.Printf("%-3d %v\n", i, val)
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}
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} else {
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fmt.Println("-- empty --")
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}
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fmt.Println("#############")
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}
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