path: root/core/vm/stack.go

package vm

import (
    "fmt"
    "math/big"
)

const maxStack = 1024

func newStack() *stack {
    return &stack{}
}

type stack struct {
    data []*big.Int
    ptr  int
}

func (st *stack) push(d *big.Int) {
    // NOTE push limit (1024) is checked in baseCheck
    stackItem := new(big.Int).Set(d)
    if len(st.data) > st.ptr {
        st.data[st.ptr] = stackItem
    } else {
        st.data = append(st.data, stackItem)
    }
    st.ptr++
}

func (st *stack) pop() (ret *big.Int) {
    st.ptr--
    ret = st.data[st.ptr]
    return
}

func (st *stack) len() int {
    return st.ptr
}

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(n int) {
    st.push(st.data[st.len()-n])
}

func (st *stack) peek() *big.Int {
    return st.data[st.len()-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
}

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("#############")
}