package vm
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import (
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"fmt"
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. "github.com/tendermint/go-common"
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)
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// Not goroutine safe
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type Stack struct {
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data []Word256
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ptr int
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gas *int64
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err *error
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}
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func NewStack(capacity int, gas *int64, err *error) *Stack {
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return &Stack{
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data: make([]Word256, capacity),
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ptr: 0,
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gas: gas,
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err: err,
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}
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}
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func (st *Stack) useGas(gasToUse int64) {
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if *st.gas > gasToUse {
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*st.gas -= gasToUse
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} else {
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st.setErr(ErrInsufficientGas)
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}
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}
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func (st *Stack) setErr(err error) {
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if *st.err == nil {
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*st.err = err
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}
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}
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func (st *Stack) Push(d Word256) {
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st.useGas(GasStackOp)
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if st.ptr == cap(st.data) {
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st.setErr(ErrDataStackOverflow)
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return
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}
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st.data[st.ptr] = d
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st.ptr++
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}
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// currently only called after Sha3
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func (st *Stack) PushBytes(bz []byte) {
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if len(bz) != 32 {
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PanicSanity("Invalid bytes size: expected 32")
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}
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st.Push(LeftPadWord256(bz))
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}
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func (st *Stack) Push64(i int64) {
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st.Push(Int64ToWord256(i))
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}
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func (st *Stack) Pop() Word256 {
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st.useGas(GasStackOp)
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if st.ptr == 0 {
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st.setErr(ErrDataStackUnderflow)
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return Zero256
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}
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st.ptr--
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return st.data[st.ptr]
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}
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func (st *Stack) PopBytes() []byte {
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return st.Pop().Bytes()
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}
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func (st *Stack) Pop64() int64 {
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d := st.Pop()
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return Int64FromWord256(d)
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}
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func (st *Stack) Len() int {
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return st.ptr
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}
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func (st *Stack) Swap(n int) {
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st.useGas(GasStackOp)
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if st.ptr < n {
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st.setErr(ErrDataStackUnderflow)
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return
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}
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st.data[st.ptr-n], st.data[st.ptr-1] = st.data[st.ptr-1], st.data[st.ptr-n]
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return
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}
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func (st *Stack) Dup(n int) {
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st.useGas(GasStackOp)
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if st.ptr < n {
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st.setErr(ErrDataStackUnderflow)
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return
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}
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st.Push(st.data[st.ptr-n])
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return
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}
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// Not an opcode, costs no gas.
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func (st *Stack) Peek() Word256 {
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if st.ptr == 0 {
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st.setErr(ErrDataStackUnderflow)
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return Zero256
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}
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return st.data[st.ptr-1]
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}
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func (st *Stack) Print(n int) {
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fmt.Println("### stack ###")
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if st.ptr > 0 {
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nn := MinInt(n, st.ptr)
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for j, i := 0, st.ptr-1; i > st.ptr-1-nn; i-- {
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fmt.Printf("%-3d %X\n", j, st.data[i])
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j += 1
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}
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} else {
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fmt.Println("-- empty --")
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}
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fmt.Println("#############")
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}
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