OT - calculating length

[Jerry Windrel]

It seems like you'd do the following:

Take the length and do an integer-divide by 256.  (If your language doesn't
have an integer-divide operator, do a floating-point divide and chop off the
fractional part to get a whole number).  Add 192.  That's your first octet.

Take the length and do an integer-remainder by 256.  (If your language
doesn't have an integer-remainder operator, multiply the result of the
integer-divide above [before you added 192] by 256 and subtract that from
the length.) Add 192.  That's your second octet.

----- Original Message ----- 
From: "Atom 'Smasher'" <atom at suspicious.org>
To: <gnupg-users at gnupg.org>
Sent: Sunday, May 09, 2004 3:38 PM
Subject: OT - calculating length


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> it's been a long time since i had any math classes... can anyone help me
> figure out how to calculate octet lengths as specified in
> rfc2440:4.2.2.2. Two-Octet Lengths
>
> A two-octet Body Length header encodes a length of from 192 to
> 8383 octets.  It is recognized because its first octet is in the
> range 192 to 223.  The body length is equal to:
>
> bodyLen = ((1st_octet - 192) << 8) + (2nd_octet) + 192
>
> so, if i have something that's a certain size, how do i calculate that as
> a two octet representation? how do i verify that it's correct? can someone
> explain that to me in a "dumbed down" way?
>
> thanks...
>
>
>   ...atom
>
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