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usage of LENGTHTO and UNIT(elements) [message #1853081]

Fri, 17 June 2022 02:15

lou ban

Messages: 17
Registered: June 2020

Junior Member

as the struct in the images

what I do is use noOfPktFillter represent the count of packetFilterList elements,
But whatever I do, the decoded struct show noOfPktFillter := '0000'B, while in the encodedNasMessage, which should be '0010'B

do I has a wrong usage of LENGTHTO and UNIT(elements)?

thanks very much

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[Updated on: Fri, 17 June 2022 02:17]

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Re: usage of LENGTHTO and UNIT(elements) [message #1853084 is a reply to message #1853081]

Fri, 17 June 2022 06:01

Gábor Szalai

Messages: 134
Registered: December 2015

Senior Member

The order of the fields are wrong, Either change the order of the fields in the type definition or apply the FIELDORDER variant.

By default the RAW encoder puts the fields into the octet right to left direction.

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Re: usage of LENGTHTO and UNIT(elements) [message #1853086 is a reply to message #1853084]

Fri, 17 June 2022 06:25

lou ban

Messages: 17
Registered: June 2020

Junior Member

thanks for your reply

But this doesnot work

I have configured this way before

type record TrafficFlowTemplate{
    IEI8_Type        iei    optional,
    Type4Length_Type    iel,
    B3_Type        tftOperationCode,
    B1_Type         eBit,
    B4_Type        noOfPktFilter,
    record of PacketFilter    packetFilterList    optional,
    record of TftParameter    parameterList    optional,
}with{
    variant    (iel)    "LENGTHTO(tftOperationCode, eBit, noOfPktFilter,  packetFilterList, parameterList)"

    variant    (tftOperationCode, eBit, noOfPktFilter)    "FIELDORDER(msb)"

    variant    (parameterList)    "PRESENCE(eBit = '1'B)

    variant (noOfPktFilter)    "LENGTHTO(packetFilterList)"
    variant (noOfpktFilter)    "UNIT(elements)"
}

BUT no matter what the encoded code is, the noOfPktFilter will be decoded as '0000'B, and packetFilterList is omit

it seems the statements

    variant (noOfPktFilter)    "LENGTHTO(packetFilterList)"
    variant (noOfpktFilter)    "UNIT(elements)"

affects the decoding of noOfPktFilter

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Re: usage of LENGTHTO and UNIT(elements) [message #1853088 is a reply to message #1853086]

Fri, 17 June 2022 06:48

Gábor Szalai

Messages: 134
Registered: December 2015

Senior Member

The LENGTHTO and the UNIT can't effect the decoding of the noOfPktFilter field only the packetFilterList. Are the value of the tftOperationCode and eBit correct?

Please change the order of the fields in the type definition.

The FIELDORDER attribute is not transitive, practically it effects only the basic types.

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Re: usage of LENGTHTO and UNIT(elements) [message #1853089 is a reply to message #1853088]

Fri, 17 June 2022 06:54

Gábor Szalai

Messages: 134
Registered: December 2015

Senior Member

If the LinkedEpsBearerId is not "type bit4 LinkedEpsBearerId" it won't be encoded/decoded as you think.

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Re: usage of LENGTHTO and UNIT(elements) [message #1853091 is a reply to message #1853089]

Fri, 17 June 2022 09:17

lou ban

Messages: 17
Registered: June 2020

Junior Member

it still puzzles me

let me show the difference

if I configure as

type record TrafficFlowTemplate{
    IEI8_Type        iei    optional,
    Type4Length_Type    iel,
    B3_Type        tftOperationCode,
    B1_Type         eBit,
    B4_Type        noOfPktFilter,
    record of PacketFilter    packetFilterList    optional,
    record of TftParameter    parameterList    optional,
}with{
    variant    (iel)    "LENGTHTO(tftOperationCode, eBit, noOfPktFilter,  packetFilterList, parameterList)"

    variant    (tftOperationCode, eBit, noOfPktFilter)    "FIELDORDER(msb)"

    variant    (parameterList)    "PRESENCE(eBit = '1'B)

    variant (noOfPktFilter)    "LENGTHTO(packetFilterList)"
    variant (noOfpktFilter)    "UNIT(elements)"
}

then the decoded situation show in decoded_with_UNIT.jpg

if I configure as

type record TrafficFlowTemplate{
    IEI8_Type        iei    optional,
    Type4Length_Type    iel,
    B3_Type        tftOperationCode,
    B1_Type         eBit,
    B4_Type        noOfPktFilter,
    record of PacketFilter    packetFilterList    optional,
    record of TftParameter    parameterList    optional,
}with{
    variant    (iel)    "LENGTHTO(tftOperationCode, eBit, noOfPktFilter,  packetFilterList, parameterList)"

    variant    (tftOperationCode, eBit, noOfPktFilter)    "FIELDORDER(msb)"

    variant    (parameterList)    "PRESENCE(eBit = '1'B)

    // variant (noOfPktFilter)    "LENGTHTO(packetFilterList)"
    // variant (noOfpktFilter)    "UNIT(elements)"
}

then the decoded situation show in decoded_without_UNIT.jpg

there is no other different except the above configuration

you can ignore the decoding of the previous part (outside the red frame), and the LinkedEpsBearerId is 4 bit

and I cannot change the order of the fields, This is explicit in the protocol documentation

Attachment: decoded_with_UNIT.jpg
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Attachment: decoded_without_UNIT.jpg
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Attachment: struct_all.png
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Attachment: struct_epsId.jpg
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Attachment: struct_PacketFilter.jpg
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