72 lines
1.2 KiB
Go
72 lines
1.2 KiB
Go
package vm
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import (
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"fmt"
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"math/big"
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)
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func newstack() *stack {
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return &stack{}
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}
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type stack struct {
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data []*big.Int
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ptr int
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}
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func (st *stack) Data() []*big.Int {
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return st.data[:st.ptr]
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}
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func (st *stack) push(d *big.Int) {
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// NOTE push limit (1024) is checked in baseCheck
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stackItem := new(big.Int).Set(d)
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if len(st.data) > st.ptr {
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st.data[st.ptr] = stackItem
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} else {
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st.data = append(st.data, stackItem)
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}
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st.ptr++
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}
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func (st *stack) pop() (ret *big.Int) {
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st.ptr--
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ret = st.data[st.ptr]
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return
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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.data[st.len()-n], st.data[st.len()-1] = st.data[st.len()-1], st.data[st.len()-n]
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}
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func (st *stack) dup(n int) {
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st.push(st.data[st.len()-n])
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}
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func (st *stack) peek() *big.Int {
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return st.data[st.len()-1]
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}
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func (st *stack) require(n int) error {
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if st.len() < n {
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return fmt.Errorf("stack underflow (%d <=> %d)", len(st.data), n)
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}
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return nil
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}
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func (st *stack) Print() {
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fmt.Println("### stack ###")
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if len(st.data) > 0 {
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for i, val := range st.data {
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fmt.Printf("%-3d %v\n", i, val)
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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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