github.com/ontio/ontology@v1.14.4/vm/neovm/execution_context.go (about)

     1  /*
     2   * Copyright (C) 2018 The ontology Authors
     3   * This file is part of The ontology library.
     4   *
     5   * The ontology is free software: you can redistribute it and/or modify
     6   * it under the terms of the GNU Lesser General Public License as published by
     7   * the Free Software Foundation, either version 3 of the License, or
     8   * (at your option) any later version.
     9   *
    10   * The ontology is distributed in the hope that it will be useful,
    11   * but WITHOUT ANY WARRANTY; without even the implied warranty of
    12   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    13   * GNU Lesser General Public License for more details.
    14   *
    15   * You should have received a copy of the GNU Lesser General Public License
    16   * along with The ontology.  If not, see <http://www.gnu.org/licenses/>.
    17   */
    18  
    19  package neovm
    20  
    21  import (
    22  	"io"
    23  
    24  	"github.com/ontio/ontology/vm/neovm/utils"
    25  )
    26  
    27  type ExecutionContext struct {
    28  	Code               []byte
    29  	OpReader           *utils.VmReader
    30  	InstructionPointer int
    31  	vmFlags            VmFeatureFlag
    32  }
    33  
    34  func NewExecutionContext(code []byte, flag VmFeatureFlag) *ExecutionContext {
    35  	var context ExecutionContext
    36  	context.Code = code
    37  	context.OpReader = utils.NewVmReader(code)
    38  	context.OpReader.AllowEOF = flag.AllowReaderEOF
    39  	context.vmFlags = flag
    40  
    41  	context.InstructionPointer = 0
    42  	return &context
    43  }
    44  
    45  func (ec *ExecutionContext) GetInstructionPointer() int {
    46  	return ec.OpReader.Position()
    47  }
    48  
    49  func (ec *ExecutionContext) SetInstructionPointer(offset int64) error {
    50  	_, err := ec.OpReader.Seek(offset, io.SeekStart)
    51  	return err
    52  }
    53  
    54  func (ec *ExecutionContext) NextInstruction() OpCode {
    55  	return OpCode(ec.Code[ec.OpReader.Position()])
    56  }
    57  
    58  func (self *ExecutionContext) ReadOpCode() (val OpCode, eof bool) {
    59  	code, err := self.OpReader.ReadByte()
    60  	if err != nil {
    61  		eof = true
    62  		return
    63  	}
    64  	val = OpCode(code)
    65  	return val, false
    66  }
    67  
    68  func (ec *ExecutionContext) Clone() *ExecutionContext {
    69  	context := NewExecutionContext(ec.Code, ec.vmFlags)
    70  	context.InstructionPointer = ec.InstructionPointer
    71  	_ = context.SetInstructionPointer(int64(ec.GetInstructionPointer()))
    72  	return context
    73  }