forked from TrueCloudLab/neoneo-go
72 lines
1.9 KiB
Go
72 lines
1.9 KiB
Go
package vm
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import (
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"fmt"
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"github.com/CityOfZion/neo-go/pkg/vm/stack"
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)
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// VM represents an instance of a Neo Virtual Machine
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type VM struct {
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// ResultStack contains the results of
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// the last evaluation stack before the program terminated
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ResultStack stack.RandomAccess
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// InvocationStack contains all of the contexts
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// loaded into the vm
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InvocationStack stack.Invocation
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state Vmstate
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}
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// NewVM will:
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// Set the state of the VM to NONE
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// instantiate a script as a new context
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// Push the Context to the Invocation stack
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func NewVM(script []byte) *VM {
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ctx := stack.NewContext(script)
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v := &VM{
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state: NONE,
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}
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v.InvocationStack.Push(ctx)
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return v
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}
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// Run loops over the current context by continuously stepping.
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// Run breaks; once step returns an error or any state that is not NONE
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func (v *VM) Run() (Vmstate, error) {
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for {
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state, err := v.step()
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if err != nil || state != NONE {
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return state, err
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}
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}
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}
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// step will read `one` opcode from the script in the current context
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// Then excute that opcode
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func (v *VM) step() (Vmstate, error) {
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// Get Current Context
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ctx, err := v.InvocationStack.CurrentContext()
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if err != nil {
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return FAULT, err
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}
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// Read Opcode from context
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op, _ := ctx.Next() // The only error that can occur from this, is if the pointer goes over the pointer
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// In the NEO-VM specs, this is ignored and we return the RET opcode
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// Execute OpCode
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state, err := v.executeOp(stack.Instruction(op), ctx)
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if err != nil {
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return FAULT, err
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}
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return state, nil
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}
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// ExecuteOp will execute one opcode on a given context.
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// If the opcode is not registered, then an unknown opcode error will be returned
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func (v *VM) executeOp(op stack.Instruction, ctx *stack.Context) (Vmstate, error) {
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//Find function which handles that specific opcode
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handleOp, ok := opFunc[op]
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if !ok {
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return FAULT, fmt.Errorf("unknown opcode entered %v", op)
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}
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return handleOp(op, ctx, &v.InvocationStack, &v.ResultStack)
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}
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