89 lines
2.6 KiB
Go
89 lines
2.6 KiB
Go
package decoder
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import (
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"bytes"
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"encoding/binary"
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"encoding/hex"
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"github.com/aceld/zinx/ziface"
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"github.com/aceld/zinx/zlog"
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"math"
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)
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//ffff 01 00999999 000a 68656c6c6f2074657374
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// +---------------+---------------+--------------------+----------------+-------------------
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// | 开始标志 | type | 秒时间戳 | 长度 | 消息体
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// | 0xffff(2byte) | uint8(1byte) | uint32(4byte) | uint16(2byte) | bytes(N byte)
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// +---------------+---------------+--------------------+----------------+-------------------
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const OmcMsgHeaderSize = 9 //表示OMC空包长度
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type OmcDecoder struct {
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StartSign uint16
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MsgType uint8
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TimeStamp uint32
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LenOfBody uint16
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Value []byte
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}
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func NewOmcDecoder() ziface.IDecoder {
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return &OmcDecoder{}
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}
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func (omc *OmcDecoder) GetLengthField() *ziface.LengthField {
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return &ziface.LengthField{
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MaxFrameLength: math.MaxUint16 + 9,
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LengthFieldOffset: 7,
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LengthFieldLength: 2,
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LengthAdjustment: 0,
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InitialBytesToStrip: 0,
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//注意现在默认是大端，使用小端需要指定编码方式
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Order: binary.BigEndian,
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}
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}
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func (omc *OmcDecoder) decode(data []byte) *OmcDecoder {
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ltvData := OmcDecoder{}
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ltvData.StartSign = binary.BigEndian.Uint16(data[0:2])
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ltvData.MsgType = data[2]
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ltvData.TimeStamp = binary.BigEndian.Uint32(data[3:7])
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ltvData.LenOfBody = binary.BigEndian.Uint16(data[7:9])
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//Determine the length of V. (确定V的长度)
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ltvData.Value = make([]byte, ltvData.LenOfBody)
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//5. Get V
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binary.Read(bytes.NewBuffer(data[OmcMsgHeaderSize:OmcMsgHeaderSize+ltvData.LenOfBody]), binary.BigEndian, ltvData.Value)
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return <vData
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}
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func (omc *OmcDecoder) Intercept(chain ziface.IChain) ziface.IcResp {
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//1. Get the IMessage of zinx
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iMessage := chain.GetIMessage()
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if iMessage == nil {
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// Go to the next layer in the chain of responsibility
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return chain.ProceedWithIMessage(iMessage, nil)
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}
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//2. Get Data
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data := iMessage.GetData()
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zlog.Ins().DebugF("omc-RawData size:%d data:%s\n", len(data), hex.EncodeToString(data))
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// (读取的数据不超过包头，直接进入下一层)
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if len(data) < OmcMsgHeaderSize {
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return chain.ProceedWithIMessage(iMessage, nil)
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}
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//4. Decode
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ltvData := omc.decode(data)
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zlog.Ins().DebugF("omc-decode %v", ltvData)
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// (将解码后的数据重新设置到IMessage中, Zinx的Router需要MsgID来寻址)
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iMessage.SetDataLen(uint32(ltvData.LenOfBody))
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iMessage.SetMsgID(uint32(ltvData.MsgType))
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iMessage.SetData(ltvData.Value)
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//6. Pass the decoded data to the next layer.
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// (将解码后的数据进入下一层)
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return chain.ProceedWithIMessage(iMessage, *ltvData)
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}
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