On Wed, 28 November 2001, "Bujji krishna R B" wrote:
>
> Hello,
> I have a doubt regarding the PER encoding of Information Object
> Values.
>
>
> FUNCTION ::= CLASS {
>
> &ArgumentType,
> &ResultType DEFAULT NULL,
> &Errors ERROR NULL,
> &Code INTEGER UNIQUE -- ERROR should be &code
> }
>
> The Above definition of FUNCTION is from the ASN.1 book by Olivier
> Dubission.
>
> funct1 FUNCTION ::= {
> &ArgumentType SEQUENCE {a INTEGER, b INTEGER},
> &ResultType INTEGER,
> &Code 1
> }
>
> funct2 FUNCTION ::= {
> &ArgumentType CHOICE {a INTEGER, b INTEGER},
> &ResultType INTEGER,
> &Code 2
> }
>
> MyFunction{FUNCTION:funct } ::= SEQUENCE { -- ERROR should be Funct
> opcode FUNCTION.&Code({funct}),
> argument FUNCTION.&ArgumentType({funct} {@Opcode})
> }
>
>
> Is it true that argument field in MyFunction is encoded as an OpenType (ie)
> Length encoding followed by the encoding of either SEQUENCE or INTEGER
> depending on Opcode.
Yes, MyFunction is an open type.
>
> So Can I rewrite MyFunction as follows
>
> MyFunction ::= SEQUENCE {
> opcode INTEGER,
> argument OCTET STRING
> }
>
No, I certainly hope not!
Assuming an object-set,
Funct FUNCTION ::= {func1 | func2}
you could re-write two specific instances of MyFunction,
MyFunction-1 ::= SEQUENCE {
code INTEGER(1),
argument SEQUENCE { a INTEGER, b INTEGER }
}
and
MyFunction-2 ::= SEQUENCE {
code INTEGER(2),
argument CHOICE { a INTEGER, b INTEGER }
}
I assume that the compiler will be smart enough to encode such values according to
these re-written types no matter what encoding rules are chosen.
Ladies and Gentlemen of the jury?
Patrick
>
> Thanks
> krishna
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