anyone can help me?? my board is LPC1768 and the sensor is BMP180
Rebuild target 'Target 1'
compiling BMP180.c...
compiling I2C.c...
assembling startup_LPC17xx.s...
compiling system_LPC17xx.c...
compiling GPIO_LPC17xx.c...
compiling PIN_LPC17xx.c...
linking...
.\Objects\asdsa.axf: Error: L6218E: Undefined symbol main (referred from __rtentry2.o).
Not enough information to list image symbols.
Finished: 1 information, 0 warning and 1 error messages.
".\Objects\asdsa.axf" - 1 Error(s), 0 Warning(s).
Target not created.
I found the solution is easy, but before going deeper into the solution, keep in mind that C compilation unit (C Compiler and Assembler at least) compiles each pure C source file after resolving necessary pre-processor directives, and generates a relocatable object file as a result of compilation.
After the compilation unit does its job, there is another unit that is responsible for combining individually every source file that is compiled successfully into the relocatable form of one big object file for all. This unit is called Linker and the operation is called Linking
A very important feature in relocatable object file is that what is called variable, function will be noted as symbol so far. The linker has to solve the symbols, defining what is originally defined in an object file, reference what is being used in another to their original object file.
After this motivation, now we can call main() function as main() symbol.
I Found that the problem is because the source file that contains the main() function was not compiled. As a result, there is no a relocatable object file that contains the symbol corresponding to main() function. Hence, the compiler is complaining: you asked me to use (reference) a symbol you guaranteed to be found (defined) in another file but I found no such symbol!
The solution:
For Kiel IDE, to queue a source file for a compilation; you gotta shortlist it in the category "Source Group",by clicking right, either adding new files to group, or existing files to group. It will result in something like the following figure:
Now we have a main function, is turned (defined) to main symbol later, and found by the linker to reference it to whatever use it in any other relocatable object files.
I solved this problem with the following steps;
Delete your old project and create new project
Choose true library from Manage Run Time Environment like so:
Configure "Options for Target" segment. Define symbol USE_STDPERIPH_DRIVER and define project path like so:
Test your configuration. Please write the following code:
#include "stm32f10x.h" // Device header
int main() {
}
I had the same issue. The problem was that the function name in .c file had a different name with the one in the .h file, and I didn't know.
just add your c file (ex: 'main.c') to the source group (ex: 'source group 1') by expanding the target then right click on the source group, choose add existing files to group 'your source group', then choose the main.c file.
http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.faqs/14222.html
This should help.
Just create a dummy main() or main.c file. Linker can't find it in your pjt.
For solution only add this file C to driver folder and translate it,
Solved: This "Target Not Created" Issue was Resolved by the setting of Run Time Environment as shown in below(url) image.https://i.stack.imgur.com/kJ4IL.jpg ( consisting of CMSIS and Device supporting components in Run time environment)
{ compiling TransformFunctions.c...
linking...
Program Size: Code=768 RO-data=320 RW-data=4 ZI-data=612
FromELF: creating hex file...
".\Objects\LPC1768_B_T.axf" - 0 Error(s), 0 Warning(s).
Build Time Elapsed: 00:00:07
}
Related
This is my current workspace. I have the Headers in the same folder with the otp.c but whenever I compile and run it it returns an error telling me that hmac-sha1 is undefined. Hope someone can help me.
Short Background
Including a header file enables you to compile the source file into an object file by declaring the function.
However, to get an executable, you need to link the object files together whereby one function used in one object file may be defined (i.e. implemented) in another object file. When listing the objects for the linker, they must be arranged in order of dependency, e.g if a depends on b the a should appear before b on the command line (in case of circular dependencies please find a post on it).
Solution
The way you run gcc makes it first compile the sources into object files and link them. otp.c requires the function hmac_sha1 is probably in hmac-sha1.c (I am guessing from the header file name) and so you should run:
gcc otp.c hmac-sha1.c -o otp
Note that otp.c depends on hmac-sha1.c hence the order.
I did setup a C project with Eclipse Photon (4.8.0) for developing a program for the ESP-32. I did configure the IDE according to this official setup instructions.
Flashing the ESP-32 works fine. But as soon as I try to include header files from a sub folder, I run into troubles. I have set up a very simple project to illustrate the issue. The project consists of main.c, base/test.h and base/test.c, whereas the test.h and test.c files only contain one function with the signature void function1(void);.
When I try to call function1() in main.c, I get this error in main.c:
Undefined reference to function1()
Please compare to the attached screenshot, where everything is depicted.
How to solve this issue?
This is not a compiler, but rather a linker error.
Note, with #includeing a header file, you only make the external function known to the compiler. You also need to link to the external function during the linking stage. Make sure you include the compiled object file that contains function1 into the link.
Seems like you need to do proper linking.
If you are linking with a library, you need to specify:
The name of the library: Project\Settings\C C++ General\Paths and Symbols\Libraries
Location where the linker should search for this library:
Project\Settings\C C++ General\Paths and Symbols\Library Paths
Important: see Note.
If you are linking with object files, add those to:
Project\Settings\C C++ Build\Settings\Linker\Miscellaneous\Other objects
Note:
If your library name is, for example, libsomething.a, than you need to specify only something as the name; so omit lib prefix and .a suffix.
If your library is not prefixed with lib, then you need to add its name prefixed with :. For example, something.a should be added as :something.a.
I am writing a program using the Contiki operating system.
I have the remote_firmware.c file and a folder called parser with the files parser.h and parser.c where I wrote the method void test(). I included parser.h in remote_firmware.c with:
#include "parser/parser.h"
The Makefile looks like this:
CONTIKI_PROJECT = remote_firmware
all: $(CONTIKI_PROJECT)
#UIP_CONF_IPV6=1
CONTIKI_WITH_RIME = 1
CONTIKI = $(HOME)/contiki
include $(CONTIKI)/Makefile.include
When I try to build this the Error occurs:
undefined reference to 'test'
I am aware that the Makefile needs to know about parser.h, but I do not know how. I tried several solutions which were proposed here but I guess I did something wrong. Maybe somebody of you know what to do?
Thank you a lot.
Where is your source file located? Try adding the source file name to the PROJECT_SOURCEFILES preprocessor variable (i.e PROJECT_SOURCEFILES+=parser.c) and adding the location of the source file to the CONTIKIDIRS preprocessor variable (i.e CONTIKIDIRS+={Directory}).
If parser.c depends on a lot other C files you might want create an C library archive first and then adding the library to your project by adding the name of the library to the TARGET_LIBFILES variable.
The error undefined reference to test is an error from the linker not the compiler. It has nothing to do with including a header file. It means when you linked the executable you didn't include parser.o
I'm pretty new to working with libraries and I'm in the process of trying to understand some specifics regarding static libraries and object files.
Summary
The behavior I'm noticing is that I can link several objects to make an executable with no problem, but if I take an intermediate step of combining those objects into static libraries, I cannot link those static libraries to make an executable without additionally specifying the needed C Run-time library in the link command.
Also, or the record, I'm doing the compiling/linking with Visual Studio 2010 from the command line. More details of the process I'm following are below.
First, let's say I have four source files in a project: main.c, util1.c, util2.c, and util3.c.
What works
I can compile these sources with the following command:cl -c main.c util1.c util2.c util3.cAs a result, I now have four object files: main.obj, util1.obj, util2.obj, and util3.obj. These object files each contain a DEFAULTLIB statement intended to inform the linker that it should additionally check the static C Run-time library libcmt.lib for any unresolved external dependencies in these object files when linking them.
I can create an executable named "app_objs.exe" by linking these objects with the following command:
link -out:app_objs.exe main.obj util1.obj util2.obj util3.obj
As mentioned in step 1, the linker used the runtime library due to the compiler's step of adding a default library statement to the objects.
Where I'm confused
Let's say I want to have an intermediate step of combining these objects into static libraries, and then linking those resulting LIB files to create my executable. First, I can create these libraries with the following commands:
link -lib -out:main.lib main.obj
link -lib -out:util.lib util1.obj util2.obj util3.obj
Now, my original thought was that I could simply link these libraries and have the same executable that I created in step 2 of "What works". I tried the following command and received linker error LNK1561, which states that an entry point needs to be specified:
link -out:app_libs.exe main.lib util.lib
From Microsoft's documentation, it is evident that linking libraries without any object files may require entry points to be specified, so I modified the command to set the subsystem as "console" to specify that the executable in intended to be a console application (which seems to imply certain entry points, thereby resolving that error):link -out:app_libs.exe -subsystem:console main.lib util.libUnfortunately, now I get a linker error stating that mainCRTStartup is an unresolved external symbol. I understand that this is defined in the C runtime library, so I can resolve this issue by manually specifying that I want to link against libcmt.lib, and this gives me a functioning executable:link -out:app_libs.exe -subsystem:console main.lib util.lib libcmt.lib
What I'm not understanding is why the default library info that the compiler placed in each object file couldn't be used to resolve the dependency on libcmt.lib. If I can link object files without explicitly stating I want libcmt.lib, and I created static libraries that are containers for the object files, why can't I link those static libraries without having to explicitly state that I want libcmt.lib? Is this just the way things are, or is there some way I could create the static libraries so that the linker will know to check for unresolved symbols in the runtime library?
Thanks for your help. If I have some fundamentally incorrect ideas here, I'd love suggestions on good references to learn all of this correctly.
Well the answer to your misunderstanding is that .lib files are often a product in themselves, and the compiler can't make those assumptions safely. That's what "external" is for.
If I produce binaries for someone's platform because its users are totally helpless, and they want/need static linkage, I have to give them foo.h and libfoo.lib without tying them to a specific runtime entry point. They may very well have defined their own entry point already for their final product, whether DLL or EXE.
You either want the runtime, or you want your own .obj that contains your entry point. Be warned that declaring and defining mainCRTStartup on your own may mean you're not executing important instructions for the target platform.
I'm using CppUTest to test the C code defined in a fornol.c source file. That file defines the main production main() function.
I also have an AllTests.cpp file that also has a main() function, but that main() is supposed to be used only when running the unit tests.
AllTests.cpp gets compiled to a .o file, whereas fornol.c gets compiled to a libfornol.a archive.
Then CppUTest tries to link everything together, but here is what I get instead:
Linking fornol_tests
cc -o fornol_tests objs/tests/AllTests.o objs/tests/FornolTests.o lib/libfornol.a ../../CppUTest/lib/libCppUTest.a ../../CppUTest/lib/libCppUTestExt.a -lstdc++ -lgcov
lib/libfornol.a(fornol.o): In function `main':
/home/dlindelof/Work/endor/nol/fornol/fornol.c:453: multiple definition of `main'
objs/tests/AllTests.o:/home/dlindelof/Work/endor/nol/fornol/tests/AllTests.cpp:4: first defined here
collect2: ld returned 1 exit status
It looks as if the main() function defined in fornol.c and present in the archive libfornol.a conflicts with the main() defined in AllTests.cpp. But my understanding was that archive/library files are searched only if/when a given symbol hasn't been referenced yet. It should therefore not be a problem to have the same symbol defined more than once, provided all definitions are in archive/library files.
What am I doing wrong here?
You need to remove the main() from AllTests.cpp and put it in its own source file.
When a linker links in a library, it can't split object files in the library; it has to either link or omit each object file in the library as a unit. (I know LLVM is different, but that's another topic.) This is why, if you look at the source for a library like glibc, each function gets its own source file.
So what's happening to you is that the linker needs to pull in an object file (fornol.o) from the library (libfornol.a) to satisfy dependencies, but that object file carries a duplicate symbol with it (main).
It's perfectly okay to put test code in a library (we do this routinely where I work), but keep it in its own source files (we traditionally use main.cc). (This is a better test anyway, because test code should not have access to static-declared symbols.)
A library is supposed not to have a main() function as it is a library.
You should remove that main() from fornol.c and compile it again.
main() is the entry point of an executable file's source code, since a library (especially a static ".a" library) is only pre-compiled source code, you cannot use a main in there.
If you want a main production entry point of your library you could rename the main() in fornol.c to something more explicit and less reserved such as "fornolMain()" for example.
A static library is compiled in your binary executable and thus is not searched only if the symbol is loaded. It is exactly the same as compiling fornol.c and linking fornol.o and your other .o