oh - I get it : the UDH is already encoded correctly using the right DCS
before the call to at2_pdu_encode(), and then at2_pdu_encode() only
needs to translate the bitstream to hex strings, and in the length
computation it computes how many septets are in the already encoded bit
stream - right ?
Oded Arbel
m-Wise Inc.
[EMAIL PROTECTED]
--
Don't ever take a fence down until you know why it was put up.
-- Robert Frost
-----Original Message-----
From: Andreas Fink [mailto:[EMAIL PROTECTED]]
Sent: Sunday, January 13, 2002 6:56 PM
To: Oded Arbel
Cc: [EMAIL PROTECTED]
Subject: Re: A question about PDU encoding in smsc_at2
>Hi list.
>
>I was wandering about this part from smsc_at2.c :
><snip>
> if(octstr_len(msg->sms.udhdata)) {
> if (msg->sms.coding == DC_8BIT || msg->sms.coding == DC_UCS2)
{
> len += octstr_len(msg->sms.udhdata);
> } else {
> /* The reason we branch here is because UDH data length is
>determined
> in septets if we are in GSM coding, otherwise it's in
>octets. Adding 6
> will ensure that for an octet length of 0, we get
septet
>length 0,
> and for octet length 1 we get septet length 2.*/
> len += (((8*octstr_len(msg->sms.udhdata)) + 6)/7);
> }
> }
></snip>
>
>if adds the length of the UDH differently for 7 bit then to 8 bit
>encoding (as per the message coding)
>
><snip>
> /* udh */
> if(octstr_len(msg->sms.udhdata)) {
> pos += at2_encode8bituncompressed(msg->sms.udhdata,
>&pdu[pos]);
> }
></snip>
>
>and then always code the UDH as 8 bit.. is that OK
The final data is always octets (8bit). If the source data is 7 bit,
then its packet into octets of 8 bit. This means if you have 7 bit
data you need 7/8 less the spac on the output.
Take a look at the corresponding ITU spec.
--
Andreas Fink
Fink-Consulting
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