From d235e2c6a5788ec4a6cff15a16f56b38a3876a0d Mon Sep 17 00:00:00 2001
From: Determinant <tederminant@gmail.com>
Date: Sun, 28 Jun 2020 14:47:41 -0400
Subject: ...

---
 core/vm/stack.go | 95 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 95 insertions(+)
 create mode 100644 core/vm/stack.go

(limited to 'core/vm/stack.go')

diff --git a/core/vm/stack.go b/core/vm/stack.go
new file mode 100644
index 0000000..4c1b9e8
--- /dev/null
+++ b/core/vm/stack.go
@@ -0,0 +1,95 @@
+// Copyright 2014 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package vm
+
+import (
+	"fmt"
+	"math/big"
+)
+
+// Stack is an object for basic stack operations. Items popped to the stack are
+// expected to be changed and modified. stack does not take care of adding newly
+// initialised objects.
+type Stack struct {
+	data []*big.Int
+}
+
+func newstack() *Stack {
+	return &Stack{data: make([]*big.Int, 0, 1024)}
+}
+
+// Data returns the underlying big.Int array.
+func (st *Stack) Data() []*big.Int {
+	return st.data
+}
+
+func (st *Stack) push(d *big.Int) {
+	// NOTE push limit (1024) is checked in baseCheck
+	//stackItem := new(big.Int).Set(d)
+	//st.data = append(st.data, stackItem)
+	st.data = append(st.data, d)
+}
+func (st *Stack) pushN(ds ...*big.Int) {
+	st.data = append(st.data, ds...)
+}
+
+func (st *Stack) pop() (ret *big.Int) {
+	ret = st.data[len(st.data)-1]
+	st.data = st.data[:len(st.data)-1]
+	return
+}
+
+func (st *Stack) len() int {
+	return len(st.data)
+}
+
+func (st *Stack) swap(n int) {
+	st.data[st.len()-n], st.data[st.len()-1] = st.data[st.len()-1], st.data[st.len()-n]
+}
+
+func (st *Stack) dup(pool *intPool, n int) {
+	st.push(pool.get().Set(st.data[st.len()-n]))
+}
+
+func (st *Stack) peek() *big.Int {
+	return st.data[st.len()-1]
+}
+
+// Back returns the n'th item in stack
+func (st *Stack) Back(n int) *big.Int {
+	return st.data[st.len()-n-1]
+}
+
+func (st *Stack) require(n int) error {
+	if st.len() < n {
+		return fmt.Errorf("stack underflow (%d <=> %d)", len(st.data), n)
+	}
+	return nil
+}
+
+// Print dumps the content of the stack
+func (st *Stack) Print() {
+	fmt.Println("### stack ###")
+	if len(st.data) > 0 {
+		for i, val := range st.data {
+			fmt.Printf("%-3d  %v\n", i, val)
+		}
+	} else {
+		fmt.Println("-- empty --")
+	}
+	fmt.Println("#############")
+}
-- 
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