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execution_engine.go
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execution_engine.go
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/*
* Copyright (C) 2018 The DNA Authors
* This file is part of The DNA library.
*
* The DNA is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* The DNA is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with The DNA. If not, see <http://www.gnu.org/licenses/>.
*/
package neovm
import (
"github.com/dnaproject2/DNA/vm/neovm/errors"
)
func NewExecutionEngine() *ExecutionEngine {
var engine ExecutionEngine
engine.EvaluationStack = NewRandAccessStack()
engine.AltStack = NewRandAccessStack()
engine.State = BREAK
engine.OpCode = 0
return &engine
}
type ExecutionEngine struct {
EvaluationStack *RandomAccessStack
AltStack *RandomAccessStack
State VMState
Contexts []*ExecutionContext
Context *ExecutionContext
OpCode OpCode
OpExec OpExec
}
func (this *ExecutionEngine) CurrentContext() *ExecutionContext {
return this.Contexts[len(this.Contexts)-1]
}
func (this *ExecutionEngine) PopContext() {
if len(this.Contexts) != 0 {
this.Contexts = this.Contexts[:len(this.Contexts)-1]
}
if len(this.Contexts) != 0 {
this.Context = this.CurrentContext()
}
}
func (this *ExecutionEngine) PushContext(context *ExecutionContext) {
this.Contexts = append(this.Contexts, context)
this.Context = this.CurrentContext()
}
func (this *ExecutionEngine) Execute() error {
this.State = this.State & (^BREAK)
for {
if this.State == FAULT || this.State == HALT || this.State == BREAK {
break
}
err := this.StepInto()
if err != nil {
return err
}
}
return nil
}
func (this *ExecutionEngine) ExecuteCode() error {
code, err := this.Context.OpReader.ReadByte()
if err != nil {
this.State = FAULT
return err
}
this.OpCode = OpCode(code)
return nil
}
func (this *ExecutionEngine) ValidateOp() error {
opExec := OpExecList[this.OpCode]
if opExec.Name == "" {
return errors.ERR_NOT_SUPPORT_OPCODE
}
this.OpExec = opExec
return nil
}
func (this *ExecutionEngine) StepInto() error {
state, err := this.ExecuteOp()
this.State = state
if err != nil {
return err
}
return nil
}
func (this *ExecutionEngine) ExecuteOp() (VMState, error) {
if this.OpCode >= PUSHBYTES1 && this.OpCode <= PUSHBYTES75 {
bs, err := this.Context.OpReader.ReadBytes(int(this.OpCode))
if err != nil {
return FAULT, err
}
PushData(this, bs)
return NONE, nil
}
if this.OpExec.Validator != nil {
if err := this.OpExec.Validator(this); err != nil {
return FAULT, err
}
}
return this.OpExec.Exec(this)
}