[CMake] nasm and cmake

[Brad King]

Prakash Punnoor wrote:
> could someone be so nice and give an example of how to get nasm files
> compiled and linked to c objects? I searched the list and found two
> short threads not actually solving this. Some sort of instructions were
> given, but no concrete example - and till now I failed to get it running
> using latest cmake in linux.

This should work in CMake 2.0:

---------------------------------------------------------
PROJECT(FOO C)
FIND_PROGRAM(NASM_EXECUTABLE nasm)
SET(ASM_OBJECTS)
FOREACH(src myasm1 myasm2)
   SET(ASM_SOURCE ${CMAKE_CURRENT_SOURCE_DIR}/${src}.asm)
   SET(ASM_OBJECT ${CMAKE_CURRENT_BINARY_DIR}/${src}.o)
   SET(ASM_OBJECTS ${ASM_OBJECTS} ${ASM_OBJECT})
   ADD_CUSTOM_COMMAND(
     OUTPUT ${ASM_OBJECT}
     COMMAND ${NASM_EXECUTABLE}
     ARGS    -o ${ASM_OBJECT} ${ASM_SOURCE}
     DEPENDS ${ASM_SOURCE}
     )
ENDFOREACH(src)
ADD_EXECUTABLE(bar bar.c ${ASM_OBJECTS})
---------------------------------------------------------

...but it looks like there is a bug in CMake 2.2 that prevents it from 
working.  I'll get this fixed for the next patch release.

> Why can't cmake just have the possibility
> to define a rule for a certain extension? As far as I understood for the
> custom command you have to add every source file, which isn't very
> convenient.

CMake 2.2 supports custom language definitions, so you might be able to
define an "ASM" language.  Unfortunately this support is new and not yet
documented.  Look in the CMake/Modules directory for
CMakeCXXInformation.cmake and similar files.  If you create your own
CMakeASMInformation.cmake and related files and put them somewhere in
CMAKE_MODULE_PATH then you can define your own language.  Then just do

PROJECT(my_c_and_asm_project C ASM)

and the support for the ASM language will be loaded.  Then you could 
just include .asm sources as any other.  I have not tried doing this though.

-Brad