I'm using the PSOPT package (http://www.psopt.org/) on my research. Instead of using the Makefile that comes within the package, I'm trying to create my own makefile using CMake.
In the default Makefile some Fortran object files are called, more specifically,
FLIBS = -lm -lf2c -llapack -lf77blas -lcblas
How can I insert and link these Fortran libraries in my CMakeLists.txt?
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I want to create a static library libmylib.a from mylib.c/.h and link it to a project to use this library in bootloader code using the arm-none-eabi-gcc cross compiler in ubuntu 20.04 LTS.
I have an electronic engineering background, so I'm kind of new in this compiler and linker stuff.
What I know:
I've been searching about this, and found out that '.a' are just packed '.o' files, and that's it. You can do it using ar in linux. I don't know how to manage the dependencies for this '.a' file, for example, or how to link it to the project.
What I want to know:
I really want to understand how it works, to compile and generate the bin, elf or hex files using these static libraries for arm using the arm-none-eabi-gcc cross compiler (found some for linux), but I don't know how to search for this properly, how to learn it in a linear way. If you guys could help me on this I would be really grateful.
First you create your library objects. Let us say that you have a foo function written in foo.c, then you do:
arm-none-eabi-gcc -c foo.c
The -c options tells the compiler to stop after assembling and no go further.
Then you need to create the .a file
arm-none-eabi-ar -rc libfoo.a foo.o
this command creates a static library called libfoo.a
At the end you compile your main with:
arm-none-eabi-gcc -L. -lfoo main.c -o main
Note that in -l flag we don put "lib" and ".a", those are automagically added. The -L. flag tells gcc to look into the current folder for library files.
I am compiling a third-part software, with mpif90, that in my case is the mpi version of gcc. The package comes with a makefile. After compiling the object files, the makefile creates the archive with ar, but this fails because there are not input object files. In effect I tried to compile by hand the object files (.o) with
mpif90 -lmkl_gf -lmkl_intel_thread -lmkl_core -liomp5 -lpthread -lm -openmp -O3 -DMPI -c a.f90
and the a.o is not created, a .mod file is created instead. I don't have much experience with fortran, and I am a bit puzzled, because the -c flag should create an object, shouldn' it?
I have verified that gfortran does create the object file if I remove the flag openmp
Notes:
mpif90 -v
gcc version 4.4.3
OS : Ubuntu 10.04.4 LTS
I changed the flag openmp to fopenmp
http://gcc.gnu.org/onlinedocs/gfortran/OpenMP.html
In case anyone comes across this question in the future ... the flags used by the OP are specific to the intel fortran compiler while it seems the mpif90 wrapper is using the gfortran compiler. The proper flag to use OpenMP with gfortran is -fopenmp and the library is -lgomp. It is possible to use the intel library with a different vendors compiler, but its easiest to stick with one vendor.
Will libraries in a makefile still be added to compilation when not specified in the preprocessor directives of the containing source files? The makefile in question is listed below, I refer lF77 and lI77 to the unspecified libraries. Thanks.
makefile:
composite: maincomp.c screenio.c cscreens.c turbine.c stat.c decide.c file.c\
sys.c dummy.c util.c cglobal.h composite.h cscreens.h f2c.h\
maincomp.h screenio.h turbine.h util.h makefile gcc maincomp.c screenio.c cscreens.c turbine.c stat.c decide.c util.c\
file.c dummy.c sys.c -I/usr/5include -L/home/boltoj/f2c/libF77\
-lF77 -L/home/boltoj/f2c/libI77 -lI77 -L/usr/5lib -lcurses -lm\
-o composite -g
Linker only links in libraries that resolve unresolved symbols. In other words, if a library doesn't provide any symbols an object file needs, that library doesn't get linked in.
For a test I have written a code of matrix multiplication in C(cuda) and compiled it using nvcc to create shared library using following command.
nvcc -c MatMul.cu -o libmatmul.so
Then i wrote a OpenCV code in C and tried to compile with following command.
gcc ImgMul.c `pkg-config --cflags --libs opencv` -L. -L/usr/local/cuda/lib64 -I/usr/local/cuda/include -I. -lmatmul -lcudart -o ImgMul
and I am getting following error.
gputest.c:(.text+0x3f): undefined reference to `matmul'
Could anyone tell me how to include cuda libraries while compiling a code in gcc.
OS: Ubuntu
gcc : 4.4.0
The first point to make is that
nvcc -c MatMul.cu -o libmatmul.so
does not make a shared library, it just compiles to an object file. Shared libraries and object files are not at all the same thing.
That aside, the reason for the symbol not found error is C++ name mangling. Host code in CUDA source files is compiled using the host C++ compiler, not C. So symbol names in the host code emitted by the compiler are subject to name mangling. To get around this, the easiest way is to declare functions which you wish to call from plain C code using the extern "C" declarator (see here for a reasonable overview of the perils of C/C++ interoperability).
I'm trying to generate a python wrapper for a C++ library that I am putting together. I have just come across SWIG and am trying to use this in conjunction with distutils. I'm modifying someone elses code, so odd errors were to be expected but this one is just confusing.
I've managed to generate a c++ wrapper file with SWIG and am now attempting to run a modified version of setup.py in order to install the wrapper (which itself may or may not work, but I'll cross that bridge when it comes to it.) When doing this compiler errors pop up about inability to include header files. Specifically - string, ostream, sstream, map and vector. All of which are standard libraries, included as "include ".
The code itself compiles, but in trying to create a wrapper this way it does not.
I'm not entirely sure what information is relevant to this but this is how the extension is made:
## Extension definition
import os
wrapsrc = './project_rewrite_wrap.c'
incdir_src = os.path.abspath('../include/project')
incdir_build = os.path.abspath('../include/project')
libdir = os.path.abspath('../lib')
ext = Extension('_project_rewrite',
[wrapsrc],
include_dirs=[incdir_src, incdir_build],
library_dirs=[libdir, os.path.join(libdir,'.libs')],
libraries=['ProjectMain'])
The gcc command that is run is:
gcc -pthread -fno-strict-aliasing -DNDEBUG -g -fwrapv -O2 -Wall -Wstrict-prototypes -fPIC -I/home/ben/Project/rewrite/include/Project -I/home/ben/Project/rewrite/include/Project -I/usr/include/python2.6 -c ./project_rewrite_wrap.c -o build/temp.linux-i686-2.6/./project_rewrite_wrap.o
Which results in errors such as:
./project_rewrite_wrap.c:2696:18: error: string: No such file or directory
Any thoughts would be greatly appreciated, thanks.
You are compiling C code - the headers you mention are part of C++, not C. To compile as C++ code, use the g++ driver instead of gcc, and give the source files a .cpp extension instead of .c.