The LDPC coder and decoder are implemented in a shared library, dynamically loaded at run-time using the oai shared library loader. The code loading the LDPC library is in nrLDPC_load.c, in function load_nrLDPClib, which must be called at init time.
By default the function int load_nrLDPClib(void) looks for libldpc.so, this default behavior can be changed using the oai loader configuration options in the configuration file or from the command line as shown below:
loading libldpc_optim8seg.so instead of libldpc.so:
./nr-softmodem -O libconfig:gnb.band78.tm1.106PRB.usrpx300.conf:dbgl5 --loader.ldpc.shlibversion _optim8seg
.......................
[CONFIG] loader.ldpc.shlibversion set to default value ""
[LIBCONFIG] loader.ldpc: 2/2 parameters successfully set, (1 to default value)
[CONFIG] shlibversion set to _optim8seg from command line
[CONFIG] loader.ldpc 1 options set from command line
[LOADER] library libldpc_optim8seg.so successfully loaded
........................
loading libldpc_cl.so instead of libldpc.so:
make ldpc_cl
This command creates the libldpc_cl.so shared library. To perform this build successfully, only the OpenCL header (/usr/include/CL/opencl.h) and library (/usr/lib/x86_64-linux-gnu/libOpenCL.so)are required, they implement OpenCL API support which is not hardware dependent.
Scanning dependencies of target nrLDPC_decoder_kernels_CL
Built target nrLDPC_decoder_kernels_CL
Scanning dependencies of target ldpc_cl
Building C object CMakeFiles/ldpc_cl.dir/usr/local/oai/oai-develop/openairinterface5g/openair1/PHY/CODING/nrLDPC_decoder/nrLDPC_decoder_CL.c.o
In file included from /usr/include/CL/cl.h:32,
from /usr/include/CL/opencl.h:38,
from /usr/local/oai/oai-develop/openairinterface5g/openair1/PHY/CODING/nrLDPC_decoder/nrLDPC_decoder_CL.c:49:
/usr/include/CL/cl_version.h:34:9: note: #pragma message: cl_version.h: CL_TARGET_OPENCL_VERSION is not defined. Defaulting to 220 (OpenCL 2.2)
#pragma message("cl_version.h: CL_TARGET_OPENCL_VERSION is not defined. Defaulting to 220 (OpenCL 2.2)")
^~~~~~~
Building C object CMakeFiles/ldpc_cl.dir/usr/local/oai/oai-develop/openairinterface5g/openair1/PHY/CODING/nrLDPC_encoder/ldpc_encoder_optim8segmulti.c.o
Linking C shared module libldpc_cl.so
Built target ldpc_cl
At runtime, to successfully use hardware acceleration via OpenCL, you need to install vendor specific packages which deliver the required drivers and tools to make use of their GPU (Nvidia, Intel...) , fpga (Xilinx, Intel) or CPU (Intel, AMD, ARM...) through OpenCL.
./nr-softmodem -O libconfig:gnb.band78.sa.fr1.106PRB.usrpb210.conf:dbgl5 --rfsim --rfsimulator.serveraddr server --log_config.gtpu_log_level info --loader.ldpc.shlibversion _cl
------------------------------------------------
[LOADER] library libldpc_cl.so successfully loaded
[HW] Platform 0, OpenCL profile FULL_PROFILE
[HW] Platform 0, OpenCL version OpenCL 2.1 LINUX
[HW] Device 0 is available
[HW] Device 0, type 2 = 0x00000002: cpu
[HW] Device 0, number of Compute Units: 8
[HW] Device 0, max Work Items dimension: 3
[HW] Device 0, max Work Items size for dimension: 0 8192
[HW] Device 0, max Work Items size for dimension: 1 8192
[HW] Device 0, max Work Items size for dimension: 2 8192
[New Thread 0x7fffcc258700 (LWP 3945123)]
[New Thread 0x7fffc3e57700 (LWP 3945124)]
[New Thread 0x7fffcbe57700 (LWP 3945125)]
[New Thread 0x7fffcba56700 (LWP 3945126)]
[New Thread 0x7fffcb254700 (LWP 3945128)]
[New Thread 0x7fffcb655700 (LWP 3945127)]
[New Thread 0x7fffcae53700 (LWP 3945129)]
[HW] Platform 1, OpenCL profile FULL_PROFILE
[HW] Platform 1, OpenCL version OpenCL 2.0 beignet 1.3
[New Thread 0x7fffc965a700 (LWP 3945130)]
[Thread 0x7fffc965a700 (LWP 3945130) exited]
[HW] Device 0 is available
[HW] Device 0, type 4 = 0x00000004: gpu
[HW] Device 0, number of Compute Units: 20
[HW] Device 0, max Work Items dimension: 3
[HW] Device 0, max Work Items size for dimension: 0 512
[HW] Device 0, max Work Items size for dimension: 1 512
[HW] Device 0, max Work Items size for dimension: 2 512
-----------------------------------------------------------------
./nr-uesoftmodem -r 106 --numerology 1 --band 78 -C 3619200000 --rfsim -O libconfig:/usr/local/oai/conf/nrue_sim.conf:dbgl5 --loader.ldpc.shlibversion _cl --log_config.hw_log_level info
............................................................
[CONFIG] shlibversion set to _cl from command line
[CONFIG] loader.ldpc 1 options set from command line
[LOADER] library libldpc_cl.so successfully loaded
[HW] Platform 0, OpenCL profile FULL_PROFILE
[HW] Platform 0, OpenCL version OpenCL 2.1 LINUX
[HW] Device 0 is available
[HW] Device 0, type 2 = 0x00000002: cpu
[HW] Device 0, number of Compute Units: 8
[HW] Device 0, max Work Items dimension: 3
[HW] Device 0, max Work Items size for dimension: 0 8192
[HW] Device 0, max Work Items size for dimension: 1 8192
[HW] Device 0, max Work Items size for dimension: 2 8192
[New Thread 0x7fffecccc700 (LWP 3945413)]
[New Thread 0x7fffec8cb700 (LWP 3945415)]
[New Thread 0x7fffec4ca700 (LWP 3945414)]
[New Thread 0x7fffdf7fd700 (LWP 3945417)]
[New Thread 0x7fffdfbfe700 (LWP 3945418)]
[New Thread 0x7fffdffff700 (LWP 3945416)]
[New Thread 0x7fffd73fc700 (LWP 3945419)]
[HW] Platform 1, OpenCL profile FULL_PROFILE
[HW] Platform 1, OpenCL version OpenCL 2.0 beignet 1.3
[New Thread 0x7fffde105700 (LWP 3945420)]
[Thread 0x7fffde105700 (LWP 3945420) exited]
[HW] Device 0 is available
[HW] Device 0, type 4 = 0x00000004: gpu
[HW] Device 0, number of Compute Units: 20
[HW] Device 0, max Work Items dimension: 3
[HW] Device 0, max Work Items size for dimension: 0 512
[HW] Device 0, max Work Items size for dimension: 1 512
[HW] Device 0, max Work Items size for dimension: 2 512
------------------------------------------------------------
A mechanism to select ldpc implementation is also available in the ldpctest phy simulator via the -voption, which can be used to specify the version of the ldpc shared library to be used.
Loading libldpc_cuda.so, the cuda implementation of the ldpc decoder:
$ ./ldpctest -v _cuda
ldpctest -v _cuda
Initializing random number generator, seed 0
block length 8448:
n_trials 1:
SNR0 -2.000000:
[CONFIG] get parameters from cmdline , debug flags: 0x00400000
[CONFIG] log_config: 2/3 parameters successfully set
[CONFIG] log_config: 53/53 parameters successfully set
[CONFIG] log_config: 53/53 parameters successfully set
[CONFIG] log_config: 16/16 parameters successfully set
[CONFIG] log_config: 16/16 parameters successfully set
log init done
[CONFIG] loader: 2/2 parameters successfully set
[CONFIG] loader.ldpc: 1/2 parameters successfully set
[LOADER] library libldpc_cuda.so successfully loaded
...................................
Loading libldpc_cl.so, the opencl implementation of the ldpc decoder:
make ldpc_cl
$ ./ldpctest -v _cl
Initializing random number generator, seed 0
block length 8448:
n_trials 1:
SNR0 -2.000000:
[CONFIG] get parameters from cmdline , debug flags: 0x00400000
[CONFIG] log_config: 2/3 parameters successfully set
[CONFIG] log_config: 53/53 parameters successfully set
[CONFIG] log_config: 53/53 parameters successfully set
[CONFIG] log_config: 16/16 parameters successfully set
[CONFIG] log_config: 16/16 parameters successfully set
log init done
[CONFIG] loader: 2/2 parameters successfully set
[CONFIG] loader.ldpc: 1/2 parameters successfully set
[LOADER] library libldpc_cl.so successfully loaded
[HW] Platform 0, OpenCL profile FULL_PROFILE
[HW] Platform 0, OpenCL version OpenCL 2.1 LINUX
[HW] Device 0 is available
[HW] Device 0, type 2 = 0x00000002: cpu
[HW] Device 0, number of Compute Units: 8
[HW] Device 0, max Work Items dimension: 3
[HW] Device 0, max Work Items size for dimension: 0 8192
[HW] Device 0, max Work Items size for dimension: 1 8192
[HW] Device 0, max Work Items size for dimension: 2 8192
[HW] Platform 1, OpenCL profile FULL_PROFILE
[HW] Platform 1, OpenCL version OpenCL 2.0 beignet 1.3
[HW] Device 0 is available
[HW] Device 0, type 4 = 0x00000004: gpu
[HW] Device 0, number of Compute Units: 20
[HW] Device 0, max Work Items dimension: 3
[HW] Device 0, max Work Items size for dimension: 0 512
[HW] Device 0, max Work Items size for dimension: 1 512
[HW] Device 0, max Work Items size for dimension: 2 512
................................
Libraries implementing the LDPC algorithms must be named libldpc<_version>.so, they must implement three functions: nrLDPC_initcall nrLDPC_decod and nrLDPC_encod. The prototypes for these functions is defined in nrLDPC_defs.h.
libldpc_cuda.sohas been tested with the ldpctest executable, usage from the softmodem's has to be tested.
libldpc_cl.sois under development.