T2: minor fix for 4x4 processing

• correct max number of LDPC segments for T2 processing
• use pointer arithmetics in retrieve_ldpc_enc_op() in T2 lib to optimize loop processing

Comparison of processing time measured in nr_dlsim for LDPC encoding performed by CPU, T2 and T2 with this MR.

testcase	develop (8 cores)	develop with T2	this MR with T2
SNR = 30, MCS = 5, 106 PRBs, 1 layer	184 us	37 us	31 us
SNR = 30, MCS = 15, 106 PRBs, 1 layer	243 us	61 us	48 us
SNR = 30, MCS = 25, 106 PRBs, 1 layer	248 us	89 us	69 us
SNR = 30, MCS = 5, 273 PRBs, 1 layer	256 us	68 us	53 us
SNR = 30, MCS = 15, 273 PRBs, 1 layer	308 us	135 us	101 us
SNR = 30, MCS = 25, 273 PRBs, 1 layer	337 us	202 us	153 us
SNR = 30, MCS = 5, 273 PRBs, 2 layers	334 us	126 us	125 us
SNR = 30, MCS = 15, 273 PRBs, 2 layers	365 us	246 us	181 us
SNR = 30, MCS = 25, 273 PRBs, 2 layers	394 us	386 us	273 us
SNR = 30, MCS = 5, 273 PRBs, 2 layers, 4x4	349 us	131 us	98 us
SNR = 30, MCS = 15, 273 PRBs, 2 layers, 4x4	355 us	250 us	186 us
SNR = 30, MCS = 25, 273 PRBs, 2 layers, 4x4	388 us	377 us	279 us

• Note: tested with develop tag 2024.w47 and t2-fix-4x4 branch, commit ID 2f27839515b0f11606961b3eb53115e6b0e3be25
• test run with this MR: https://jenkins-oai.eurecom.fr/job/RAN-gNB-N300-Timing-Phytest-LDPC/5877/artifact/test_results-RAN-gNB-N300-Timing-Phytest-LDPC.html

added BUILD-ONLY label

OAI RAN-Container-Parent build (11107): passed (https://jenkins-oai.eurecom.fr/job/RAN-Container-Parent/11107/)

added 2 commits

• 0021b696 - Optimize memory usage in decode_offload function
• 0c354dbc - T2: Rework retrieve_ldpc_enc_op()

Compare with previous version

OAI RAN-Container-Parent build (11111): passed (https://jenkins-oai.eurecom.fr/job/RAN-Container-Parent/11111/)

added documentation label

removed BUILD-ONLY label

added 1 commit

• 2f278395 - T2: Rework retrieve_ldpc_enc_op()

Compare with previous version

OAI RAN-Container-Parent build (11154): passed (https://jenkins-oai.eurecom.fr/job/RAN-Container-Parent/11154/)

resolved all threads

requested review from @lthomas

added 5G-NR label

removed documentation label

changed milestone to %REVIEW_CAN_START

changed the description

changed milestone to %REVIEW_COMPLETED_AND_APPROVED

marked this merge request as draft

marked this merge request as ready

OAI RAN-Container-Parent build (11221): failed (https://jenkins-oai.eurecom.fr/job/RAN-Container-Parent/11221/)

List of failing test stages:

• RAN-SA-AW2S-CN5G
• RAN-gNB-N300-Timing-Phytest-LDPC
• RAN-SA-OAIUE-CN5G
• RAN-SA-2x2-Module-CN5G
• RAN-SA-B200-Module-SABOX-Container
• RAN-RF-Sim-Test-5G

mentioned in merge request !2952 (merged)

changed milestone to %OK_TO_BE_MERGED

mentioned in commit a8081914

mentioned in merge request !3134 (merged)

mentioned in commit c942fe43

merged with merge request !3134 (merged)