Now when i encode the H323 message according to X691,i have 6 questions:
(1)As X690 say:
Encoding of an object identifier value
(X*40) + Y
where X is the value of the first object identifier component and Y is the
value of the
second object identifier component.
NOTE �C This packing of the first two object identifier components
recognizes that only
three values are allocated from the root node, and at most 39 subsequent
values from nodes
reached by X = 0 and X = 1
what does "only three values are allocated from the root node" mean?
(2)if i want to encode a IA5String(SIZE(1..128))(FROM (��0123456789No.
*,")),
should i encode the length of the string into 7 bits,and encode every
character into 7 bits
according to X691 26.5.3 say:"For IA5String the range is 0 to 127"?
please tell me is that right??
(3)who could explain this sentence in X691:"If there is a PER-visible size
constraint and an extension marker is present in it".
what is PER-visible size?is that mean like this SIZE(1..128)?
where and what is the extension marker?
(4)how to encode semi-constrained whole number's length?
if need n octets to encode semi-constrained whole number,how to encode
the length n?
should i encode n as LengthDeterminant?
(5)encoding the OCTET STRING tpye
As X691 say:if the OCTET STRING type has lb and ub,then the string length
should
be encoded as constrained whole number
My question is that if the string length is greater than 16K,such as
OCTET STRING(SIZE(1..32768)),lb is 1 and ub is 32768,should i still encode
the OCTET STRING's length as constrained whole number without fragment?
(6)how to encode SEQUENCE OF type's length
if there is a SEQUENCE OF type to be encoded like this:
SEQUENCE OF AliasAddress
In the above example,lb is 0 and ub is unset,is that right??
and if there is only 1 AliasAddress to be encoded,then how to encode the
length?
As X691 say:"preceded by a length determinant equal to "n" components as
a constrained whole number if "ub" is set, and as a semi-constrained whole
number if "ub" is unset. "lb" is as determined above."
should i encode the length(1) as semi-constrained whole number?
if that is true,should the first some bits of encoding look like this:
00000001(the number of octet to encode the length) 00000001(the length)
then following the code of 1 AliasAddress.
it seems wrong,but i don't know how to understand what X691 say.
Who could tell me how to encode this ?
thanks
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