Question #214638 on rohc changed:
https://answers.launchpad.net/rohc/+question/214638
Status: Answered => Open
Carlos is still having a problem:
Hi Didier,
Thank you very much for your answer. It really helped me to understand how to
integrate the standalone feedback mode in my compression test. I am following
the 4-step process you recommend in your message. However, I have some troubles
decompressing packets. The decompressor fails to decompress every packet. An
error message "no profile found for decompression" always displays . Am I
forgetting anyhing? By the way, IP and no compresion modes are only enabled.
Below I include the code lines that initialize both compressor and decompressor.
Best regards,
Carlos
/* Initialize entity's RoHC compressor. Suggestion: set max_cid = 15 */
comp = rohc_alloc_compressor(max_cid, 0, 0, 0);
if(comp == NULL)
{
fprintf(stderr, "cannot create the ROHC compressor\n");
/* manage the error here */
}
/*
* Load selected profiles. List of supported modes below:
rohc_activate_profile(comp, ROHC_PROFILE_UNCOMPRESSED);
/* Uncompressed mode must always be enabled, in case compression is
* not possible */
if(ROHC_profile != ROHC_PROFILE_UNCOMPRESSED)
rohc_activate_profile(comp,ROHC_profile);
/* Set MAX CID */
rohc_c_set_large_cid(comp, 0);
if(max_cid > 15)
{
rohc_c_set_large_cid(comp, 1);
rohc_c_set_max_cid(comp, ROHC_LARGE_CID_MAX);
}
/* set the callback for random numbers */
if(!rohc_comp_set_random_cb(comp, gen_random_num, NULL))
{
fprintf(stderr, "failed to set the callback for random
numbers\n");
}
decomp = rohc_alloc_decompressor(comp);
if(decomp == NULL)
{
fprintf(stderr, "cannot create the ROHC decompressor\n");
/* manage the error here */
}
/* set CID type and MAX_CID for decompressor */
if(max_cid > 15)
{
if(!rohc_decomp_set_cid_type(decomp, ROHC_LARGE_CID))
{
fprintf(stderr, "failed to set CID type to large CIDs
for "
"decompressor\n");
}
if(!rohc_decomp_set_max_cid(decomp, ROHC_LARGE_CID_MAX))
{
fprintf(stderr, "failed to set MAX_CID to %d for "
"decompressor\n", ROHC_LARGE_CID_MAX);
}
}
else
{
if(!rohc_decomp_set_cid_type(decomp, ROHC_SMALL_CID))
{
fprintf(stderr, "failed to set CID type to small CIDs
for "
"decompressor\n");
}
if(!rohc_decomp_set_max_cid(decomp, ROHC_SMALL_CID_MAX))
{
fprintf(stderr, "failed to set MAX_CID to %d for "
"decompressor\n", ROHC_SMALL_CID_MAX);
}
}
Following, the relevant code from the decompressor part:
int ip_size = rohc_decompress(
decomp,
(u8*)(*sdu)->getDataField(),
(*sdu)->get_packet_size(),
ip_packet,
MAXLENGTH
);
/*
* If the packet is not successfully uncompressed, the value of ip_size
* is negative. Manage the error and erase the pdu.
*/
if(ip_size < 0)
{
//TODO: error managing if needed. Have a look at all the
possible negative values of ip_size
//-------------------------------------------------
#ifdef DEBUG
std::cout << "Packet decompression failed. Returned value = "
<< ip_size << std::endl;
#endif
/* Delete the SDU */
delete *sdu;
*sdu = NULL;
return;
}
/* Send feedback to peer compressor */
u8 feedback_buffer[MAXLENGTH];
int feedback_size = rohc_feedback_flush(comp,feedback_buffer,MAXLENGTH);
std::cout << "Feedback size = " << feedback_size << std::endl;
if(feedback_size > 0)
{
Protocol_Packet* interspersed_pdu = new Protocol_Packet();
interspersed_pdu->addDataBytes(feedback_buffer,feedback_size);
/* Create interspersed ROHC feedback packet */
addHeader(interspersed_pdu, PDCP_Control_PDU_interspersed, 0);
//SN deprecated here
/* Deliver to peer */
p_layer->generate_rlc_message(0, this->getRbId(),
interspersed_pdu);
}
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