1 files changed, 162 insertions, 0 deletions
diff --git a/vm/stack.go b/vm/stack.go
new file mode 100644
index 000000000..55fdb6d15
--- /dev/null
+++ b/vm/stack.go
@@ -0,0 +1,162 @@
+package vm
+
+import (
+	"fmt"
+	"math"
+	"math/big"
+)
+
+type OpType int
+
+const (
+	tNorm = iota
+	tData
+	tExtro
+	tCrypto
+)
+
+type TxCallback func(opType OpType) bool
+
+// Simple push/pop stack mechanism
+type Stack struct {
+	data []*big.Int
+}
+
+func NewStack() *Stack {
+	return &Stack{}
+}
+
+func (st *Stack) Data() []*big.Int {
+	return st.data
+}
+
+func (st *Stack) Len() int {
+	return len(st.data)
+}
+
+func (st *Stack) Pop() *big.Int {
+	str := st.data[len(st.data)-1]
+
+	copy(st.data[:len(st.data)-1], st.data[:len(st.data)-1])
+	st.data = st.data[:len(st.data)-1]
+
+	return str
+}
+
+func (st *Stack) Popn() (*big.Int, *big.Int) {
+	ints := st.data[len(st.data)-2:]
+
+	copy(st.data[:len(st.data)-2], st.data[:len(st.data)-2])
+	st.data = st.data[:len(st.data)-2]
+
+	return ints[0], ints[1]
+}
+
+func (st *Stack) Peek() *big.Int {
+	str := st.data[len(st.data)-1]
+
+	return str
+}
+
+func (st *Stack) Peekn() (*big.Int, *big.Int) {
+	ints := st.data[len(st.data)-2:]
+
+	return ints[0], ints[1]
+}
+
+func (st *Stack) Swapn(n int) (*big.Int, *big.Int) {
+	st.data[len(st.data)-n], st.data[len(st.data)-1] = st.data[len(st.data)-1], st.data[len(st.data)-n]
+
+	return st.data[len(st.data)-n], st.data[len(st.data)-1]
+}
+
+func (st *Stack) Dupn(n int) *big.Int {
+	st.Push(st.data[len(st.data)-n])
+
+	return st.Peek()
+}
+
+func (st *Stack) Push(d *big.Int) {
+	st.data = append(st.data, new(big.Int).Set(d))
+}
+
+func (st *Stack) Get(amount *big.Int) []*big.Int {
+	// offset + size <= len(data)
+	length := big.NewInt(int64(len(st.data)))
+	if amount.Cmp(length) <= 0 {
+		start := new(big.Int).Sub(length, amount)
+		return st.data[start.Int64():length.Int64()]
+	}
+
+	return nil
+}
+
+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("#############")
+}
+
+type Memory struct {
+	store []byte
+}
+
+func (m *Memory) Set(offset, size int64, value []byte) {
+	totSize := offset + size
+	lenSize := int64(len(m.store) - 1)
+	if totSize > lenSize {
+		// Calculate the diff between the sizes
+		diff := totSize - lenSize
+		if diff > 0 {
+			// Create a new empty slice and append it
+			newSlice := make([]byte, diff-1)
+			// Resize slice
+			m.store = append(m.store, newSlice...)
+		}
+	}
+	copy(m.store[offset:offset+size], value)
+}
+
+func (m *Memory) Resize(size uint64) {
+	if uint64(m.Len()) < size {
+		m.store = append(m.store, make([]byte, size-uint64(m.Len()))...)
+	}
+}
+
+func (m *Memory) Get(offset, size int64) []byte {
+	if len(m.store) > int(offset) {
+		end := int(math.Min(float64(len(m.store)), float64(offset+size)))
+
+		return m.store[offset:end]
+	}
+
+	return nil
+}
+
+func (m *Memory) Len() int {
+	return len(m.store)
+}
+
+func (m *Memory) Data() []byte {
+	return m.store
+}
+
+func (m *Memory) Print() {
+	fmt.Printf("### mem %d bytes ###\n", len(m.store))
+	if len(m.store) > 0 {
+		addr := 0
+		for i := 0; i+32 <= len(m.store); i += 32 {
+			fmt.Printf("%03d: % x\n", addr, m.store[i:i+32])
+			addr++
+		}
+	} else {
+		fmt.Println("-- empty --")
+	}
+	fmt.Println("####################")
+}