github.com/phillinzzz/newBsc@v1.1.6/core/vm/stack.go (about)

     1  // Copyright 2014 The go-ethereum Authors
     2  // This file is part of the go-ethereum library.
     3  //
     4  // The go-ethereum library is free software: you can redistribute it and/or modify
     5  // it under the terms of the GNU Lesser General Public License as published by
     6  // the Free Software Foundation, either version 3 of the License, or
     7  // (at your option) any later version.
     8  //
     9  // The go-ethereum library is distributed in the hope that it will be useful,
    10  // but WITHOUT ANY WARRANTY; without even the implied warranty of
    11  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    12  // GNU Lesser General Public License for more details.
    13  //
    14  // You should have received a copy of the GNU Lesser General Public License
    15  // along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
    16  
    17  package vm
    18  
    19  import (
    20  	"fmt"
    21  	"sync"
    22  
    23  	"github.com/holiman/uint256"
    24  )
    25  
    26  var stackPool = sync.Pool{
    27  	New: func() interface{} {
    28  		return &Stack{data: make([]uint256.Int, 0, 16)}
    29  	},
    30  }
    31  
    32  // Stack is an object for basic stack operations. Items popped to the stack are
    33  // expected to be changed and modified. stack does not take care of adding newly
    34  // initialised objects.
    35  type Stack struct {
    36  	data []uint256.Int
    37  }
    38  
    39  func newstack() *Stack {
    40  	return stackPool.Get().(*Stack)
    41  }
    42  
    43  func returnStack(s *Stack) {
    44  	s.data = s.data[:0]
    45  	stackPool.Put(s)
    46  }
    47  
    48  // Data returns the underlying uint256.Int array.
    49  func (st *Stack) Data() []uint256.Int {
    50  	return st.data
    51  }
    52  
    53  func (st *Stack) push(d *uint256.Int) {
    54  	// NOTE push limit (1024) is checked in baseCheck
    55  	st.data = append(st.data, *d)
    56  }
    57  func (st *Stack) pushN(ds ...uint256.Int) {
    58  	// FIXME: Is there a way to pass args by pointers.
    59  	st.data = append(st.data, ds...)
    60  }
    61  
    62  func (st *Stack) pop() (ret uint256.Int) {
    63  	ret = st.data[len(st.data)-1]
    64  	st.data = st.data[:len(st.data)-1]
    65  	return
    66  }
    67  
    68  func (st *Stack) len() int {
    69  	return len(st.data)
    70  }
    71  
    72  func (st *Stack) swap(n int) {
    73  	st.data[st.len()-n], st.data[st.len()-1] = st.data[st.len()-1], st.data[st.len()-n]
    74  }
    75  
    76  func (st *Stack) dup(n int) {
    77  	st.push(&st.data[st.len()-n])
    78  }
    79  
    80  func (st *Stack) peek() *uint256.Int {
    81  	return &st.data[st.len()-1]
    82  }
    83  
    84  // Back returns the n'th item in stack
    85  func (st *Stack) Back(n int) *uint256.Int {
    86  	return &st.data[st.len()-n-1]
    87  }
    88  
    89  // Print dumps the content of the stack
    90  func (st *Stack) Print() {
    91  	fmt.Println("### stack ###")
    92  	if len(st.data) > 0 {
    93  		for i, val := range st.data {
    94  			fmt.Printf("%-3d  %v\n", i, val)
    95  		}
    96  	} else {
    97  		fmt.Println("-- empty --")
    98  	}
    99  	fmt.Println("#############")
   100  }