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Merge pull request #275 from dauTT/dauTT/vm-XSWAP-XTUCK-DEPTH-DROP-opcode

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VM: Implement XSWAP, XTUCK, DEPTH, DROP opcode

Closes #274, merging as per #283 discussion.
This commit is contained in:
Roman Khimov 2019-08-12 13:05:30 +03:00 committed by GitHub
commit 37d7198877
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4 changed files with 227 additions and 0 deletions
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15
pkg/vm/stack/stack.go
View file

@ -127,6 +127,21 @@ func (ras *RandomAccess) CopyTo(stack *RandomAccess) error {
return nil
}
// Set sets the n-item from the stack
// starting from the top of the stack with the new item.
// the n-item to replace is located at the position "len(stack)-index-1".
func (ras *RandomAccess) Set(index uint16, item Item) error {
stackSize := uint16(len(ras.vals))
if ok := index >= stackSize; ok {
return errors.New("index out of range")
}
n := stackSize - index - 1
ras.vals[n] = item
return nil
}
// Convenience Functions
// PopInt will remove the last stack item that was added

4
pkg/vm/vm_ops.go
View file

@ -5,6 +5,10 @@ import "github.com/CityOfZion/neo-go/pkg/vm/stack"
type stackInfo func(op stack.Instruction, ctx *stack.Context, istack *stack.Invocation, rstack *stack.RandomAccess) (Vmstate, error)
var opFunc = map[stack.Instruction]stackInfo{
stack.DROP: DROP,
stack.DEPTH: DEPTH,
stack.XTUCK: XTUCK,
stack.XSWAP: XSWAP,
stack.XDROP: XDROP,
stack.FROMALTSTACK: FROMALTSTACK,
stack.TOALTSTACK: TOALTSTACK,

81
pkg/vm/vm_ops_stackmani.go
View file

@ -1,6 +1,8 @@
package vm
import (
"math/big"
"github.com/CityOfZion/neo-go/pkg/vm/stack"
)
@ -18,6 +20,35 @@ func PushNBytes(op stack.Instruction, ctx *stack.Context, istack *stack.Invocati
return NONE, nil
}
// XSWAP pops an integer n off of the stack and
// swaps the n-item from the stack starting from
// the top of the stack with the top stack item.
func XSWAP(op stack.Instruction, ctx *stack.Context, istack *stack.Invocation, rstack *stack.RandomAccess) (Vmstate, error) {
n, err := ctx.Estack.PopInt()
if err != nil {
return FAULT, err
}
nItem, err := ctx.Estack.Peek(uint16(n.Value().Int64()))
if err != nil {
return FAULT, err
}
item, err := ctx.Estack.Peek(0)
if err != nil {
return FAULT, err
}
if err := ctx.Estack.Set(uint16(n.Value().Int64()), item); err != nil {
return FAULT, err
}
if err := ctx.Estack.Set(0, nItem); err != nil {
return FAULT, err
}
return NONE, nil
}
// DUPFROMALTSTACK duplicates the item on top of alternative stack and
// puts it on top of evaluation stack.
// Returns an error if the alt stack is empty.
@ -33,6 +64,29 @@ func DUPFROMALTSTACK(op stack.Instruction, ctx *stack.Context, istack *stack.Inv
return NONE, nil
}
// XTUCK pops an integer n off of the stack and
// inserts the top stack item to the position len(stack)-n in the evaluation stack.
func XTUCK(op stack.Instruction, ctx *stack.Context, istack *stack.Invocation, rstack *stack.RandomAccess) (Vmstate, error) {
n, err := ctx.Estack.PopInt()
if err != nil || n.Value().Int64() < 0 {
return FAULT, err
}
item, err := ctx.Estack.Peek(0)
if err != nil {
return FAULT, err
}
ras, err := ctx.Estack.Insert(uint16(n.Value().Int64()), item)
if err != nil {
return FAULT, err
}
ctx.Estack = *ras
return NONE, nil
}
// TOALTSTACK pops an item off of the evaluation stack and
// pushes it on top of the alternative stack.
// Returns an error if the alternative stack is empty.
@ -48,6 +102,20 @@ func TOALTSTACK(op stack.Instruction, ctx *stack.Context, istack *stack.Invocati
return NONE, nil
}
// DEPTH puts the number of stack items onto the stack.
func DEPTH(op stack.Instruction, ctx *stack.Context, istack *stack.Invocation, rstack *stack.RandomAccess) (Vmstate, error) {
l := ctx.Estack.Len()
length, err := stack.NewInt(big.NewInt(int64(l)))
if err != nil {
return FAULT, err
}
ctx.Estack.Push(length)
return NONE, nil
}
// FROMALTSTACK pops an item off of the alternative stack and
// pushes it on top of the evaluation stack.
// Returns an error if the evaluation stack is empty.
@ -63,6 +131,19 @@ func FROMALTSTACK(op stack.Instruction, ctx *stack.Context, istack *stack.Invoca
return NONE, nil
}
// DROP removes the the top stack item.
// Returns error if the operation Pop cannot
// be performed.
func DROP(op stack.Instruction, ctx *stack.Context, istack *stack.Invocation, rstack *stack.RandomAccess) (Vmstate, error) {
_, err := ctx.Estack.Pop()
if err != nil {
return FAULT, err
}
return NONE, nil
}
// XDROP pops an integer n off of the stack and
// removes the n-item from the stack starting from
// the top of the stack.

127
pkg/vm/vm_ops_stackmani_test.go
View file

@ -8,6 +8,133 @@ import (
"github.com/stretchr/testify/assert"
)
func TestXswapOp(t *testing.T) {
v := VM{}
a, err := stack.NewInt(big.NewInt(3))
assert.Nil(t, err)
b, err := stack.NewInt(big.NewInt(6))
assert.Nil(t, err)
c, err := stack.NewInt(big.NewInt(9))
assert.Nil(t, err)
d, err := stack.NewInt(big.NewInt(2))
assert.Nil(t, err)
ctx := stack.NewContext([]byte{})
ctx.Estack.Push(a).Push(b).Push(c).Push(d)
// pop n (= d = 2) from the stack.
// we will swap the n-item which
// is located in position len(stack)-n-1 (= 3-2-1= 0)
// with the top stack item.
// The final stack will be [c,b,a]
v.executeOp(stack.XSWAP, ctx)
// Stack should have three items
assert.Equal(t, 3, ctx.Estack.Len())
itemA, err := ctx.Estack.PopInt()
assert.Nil(t, err)
itemB, err := ctx.Estack.PopInt()
assert.Nil(t, err)
itemC, err := ctx.Estack.PopInt()
assert.Nil(t, err)
assert.Equal(t, int64(3), itemA.Value().Int64())
assert.Equal(t, int64(6), itemB.Value().Int64())
assert.Equal(t, int64(9), itemC.Value().Int64())
}
func TestXTuckOp(t *testing.T) {
v := VM{}
a, err := stack.NewInt(big.NewInt(3))
assert.Nil(t, err)
b, err := stack.NewInt(big.NewInt(6))
assert.Nil(t, err)
c, err := stack.NewInt(big.NewInt(9))
assert.Nil(t, err)
d, err := stack.NewInt(big.NewInt(2))
assert.Nil(t, err)
ctx := stack.NewContext([]byte{})
ctx.Estack.Push(a).Push(b).Push(c).Push(d)
// pop n (= d = 2) from the stack
// and insert the top stack item c
// to the position len(stack)-n (= 3-2 = 1)
// of the stack.The final stack will be [a,c,b,c]
v.executeOp(stack.XTUCK, ctx)
// Stack should have four items
assert.Equal(t, 4, ctx.Estack.Len())
// c
item0, err := ctx.Estack.PopInt()
assert.Nil(t, err)
// b
item1, err := ctx.Estack.PopInt()
assert.Nil(t, err)
// c
item2, err := ctx.Estack.PopInt()
assert.Nil(t, err)
// a
item3, err := ctx.Estack.PopInt()
assert.Nil(t, err)
assert.Equal(t, int64(9), item0.Value().Int64())
assert.Equal(t, int64(6), item1.Value().Int64())
assert.Equal(t, int64(9), item2.Value().Int64())
assert.Equal(t, int64(3), item3.Value().Int64())
}
func TestXDepthOp(t *testing.T) {
v := VM{}
a, err := stack.NewInt(big.NewInt(3))
assert.Nil(t, err)
b, err := stack.NewInt(big.NewInt(6))
assert.Nil(t, err)
ctx := stack.NewContext([]byte{})
ctx.Estack.Push(a).Push(b)
// push integer whose value is len(stack) (2)
// on top of the stack
v.executeOp(stack.DEPTH, ctx)
// Stack should have three items
assert.Equal(t, 3, ctx.Estack.Len())
// len(stack)
item0, err := ctx.Estack.PopInt()
assert.Nil(t, err)
// b
item1, err := ctx.Estack.PopInt()
assert.Nil(t, err)
// a
item2, err := ctx.Estack.PopInt()
assert.Nil(t, err)
assert.Equal(t, int64(2), item0.Value().Int64())
assert.Equal(t, int64(6), item1.Value().Int64())
assert.Equal(t, int64(3), item2.Value().Int64())
}
func TestDupFromAltStackOp(t *testing.T) {
v := VM{}