forked from cerc-io/plugeth
83 lines
2.1 KiB
Go
83 lines
2.1 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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"sync"
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"github.com/holiman/uint256"
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)
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var stackPool = sync.Pool{
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New: func() interface{} {
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return &Stack{data: make([]uint256.Int, 0, 16)}
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},
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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 []uint256.Int
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}
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func newstack() *Stack {
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return stackPool.Get().(*Stack)
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}
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func returnStack(s *Stack) {
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s.data = s.data[:0]
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stackPool.Put(s)
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}
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// Data returns the underlying uint256.Int array.
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func (st *Stack) Data() []uint256.Int {
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return st.data
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}
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func (st *Stack) push(d *uint256.Int) {
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// NOTE push limit (1024) is checked in baseCheck
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st.data = append(st.data, *d)
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}
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func (st *Stack) pop() (ret uint256.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(&st.data[st.len()-n])
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}
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func (st *Stack) peek() *uint256.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) *uint256.Int {
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return &st.data[st.len()-n-1]
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}
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