Compiling Assembly (.S) file alongside iPhone proj

问题:

In my iPhone project, I have an assembly file named arm_asm_stub.S, which contains a method I need to call from another file in my project called main.c. When I don't #include the file at the top of my main.c file, I get no build errors, but I do get the linker error:

Undefined symbols for architecture armv7:
  "_execute_arm_translate", referenced from:
      _iphone_main in main.o

However, when I attempt to #include the file at the top of main.c, Xcode uses Clang to compile arm_asm_stub.S and so I get a bunch of errors, ones that don't appear when I don't #include the file such as:

unknown type name 'ldr'
expected identifier or '('
use of undeclared identifier 'sp'

How can Xcode compile this one file separately than the rest of the project?

回答1:

You should just add the .S file to your project and the build system will automatically assemble it. Be careful with the symbols though. All C functions have an underscore prepended to them by the compiler, so your assembly language routine label needs an underscore at the front for C code to be able to call it.