The idea is to make LDPC iteration accounting more standard from a C coding perspective by making two changes:
1. Now the iteration counter starts at 0 for the first iteration and goes up to max_ldpc_iterations - 1 for the last iteration.
If it is equal to max_ldpc_iterations, it means that decoding failed.
2. A chain of useless returns in the UE DLSCH decoding call chain was removed.
The logs of `./nr_ulsim -n100 -m19 -s12 -S12 -z2 -L4` were showing that sometimes the decoding of one segment was failing while the CRC check succeeded.
This was happening because the iteration counter `numIter` was not properly managed so that when the last iteration was successful to decode the segment
still `numIter` at the exit was equal to `numMaxIter` plus 1 so that decoding was considered to have failed.
In other words the last iteration if it occured was always wasted.
This commit offers to solve this problem by simply moving the iteration counter increment at the end of the iteration loop
while remaining careful at fixing the tests relying on this counter.
More complex implementations will be achieved using the new reworked interface
- t_nrLDPC_dec_params: remove F, Qm, rv and perCB
- encoder_implemparams_t: remove Qm, Tbslbrm, G, rv and perCB
Fix error reported by the T2 card when running nr_dlsim with 4 DL layers.
Error can be reproduced by running:
./nr_dlsim -n100 -s30 -e25 -b273 -R273 -x4 -z4 -y4 -P --ldpc_offload.dpdk_dev 41:00.0 -c
So far we set NR_LDPC_MAX_NUM_CB to 72, which is sufficient for max 2 DL layers.
Set max possible number of LDPC segments based on the max number of layers
and max number of DLSCH segments (currently it is 144).
- Introduced command line and configuration options to set up PCI address, CPU cores used by DPDK, and DPDK file prefix for T2 offload.
- Made the dpdk_dev parameter (for setting the PCI address of the T2) mandatory.
- Configure dpdk_dev in the CI test cases.
- Replaced bbdev TEST_ASSERTs with the OAI macro AssertFatal() to harmonize error handling.
- Removed unused functions and macros from nrLDPC_offload.h.
- Reworked nrLDPC_decoder_offload.c to process all segments in a TB with a single call to LDPCdecoder() or LDPCencoder().
- Perform CRC checks on the T2.
- Modified nr_ulsch_decoding (gNB decoder) to:
- Count processed segments.
- Properly perform CRC checks.
- Created a constant NR_LDPC_MAX_NUM_CB to define the maximum number of codeblocks.
- Conditional library loading:
- On gNB: Load ldpc_t2 library if offload is enabled using the --ldpc-offload-enable flag.
- On UE: Load both ldpc_t2 and ldpc libraries since only encoder offload is supported.
- General cleanup of nrLDPC_decoder_offload.c for improved readability and maintainability.
- Modified the structure of LDPC encoder/decoder/offload parameters:
- Introduced a structure for code block (CB) related parameters.
- Removed parameter E from the encoder and offload parameter structures for clarity.
- Replaced E with perCB->E_cb in the UE encoder code.
- Rate matching performed by card
- Due to rate matching on card, small TBs are encoded correctly, so the
limitation of encoding small TBs in CPU can be lifted (all TBs encoded
on T2), see a later commits
Testing on Neoverse N1 (Ampere 3GHz). Tested only on a subset of phy-simulators.
- Changes:
- use SIMDE consistently
- adaptations of LDPC decoder generator for ARMv8 performance
- SIMDe modifications of Intel CRC to allow for aarch64 build.
optimizations for 128-bit to improve performance of LDPC encode/decode
on aarch64 (Neoverse 1)
- added BG2 files for 128-bit ldpc encoder (aarch64)
- testing on Xeon
- testing on x86
- minor changes to build/run on x86
- change in crc.h after returning to aarch64
- removed some warning in ldpc decoder generator for x86_64
- char
- Delete irrelevant constants
- Correctly declare variables
- Define stdbool for all architectures
- Remove definition of _MM_SHUFFLE and use SIMDE_MM_SHUFFLE
- Remove commented code
- Fix CMakeLists.txt
- Include SIMDE avx2 functions in tools_defs.h
The CI compiles the physims using Asan. This in turn compiles Asan into
the LDPC decoder generator files. Since they are run during build, there
are two options:
1) trigger the build using capability SYS_PTRACE to allow running asan
when executing the generators.
2) disable asan in the generators.
The first option seems not feasible, as the compilation of the ldpctest
does not succeed (in fact, for a reason I don't understand, ninja seems
to trigger linking and is then blocked indefinitely). Therefore, this
commit simple disables asan in the generators.
The files openair1/PHY/CODING/nrLDPC_cnProc.h and
openair1/PHY/CODING/nrLDPC_decoder/nrLDPC_cnProc.h have the same name,
and also the same include guard/define. This commit renames the define
in the latter to prevent this name clash.
Romain Beurdouche