Confusion with device driver programming.

[sangharsha]

dear frens,
i am in delima
so if somecan help please do
i gonna be dead soon
what are these lines of codes do in c programming?

1)
#if defined(CONFIG_SMP)
#define MODEVERSIONS
#include <linux/modeversions.h>
#endif

2)
static struct file_operations schar_fops={
read: schar_read,
write: schar_write,
};

can anyone explain this to me? I would be grateful if you provide some useful links too.
thanking in advance

[the_unforgiven]

1.
This is an example of conditional compilation.

The code (the C preprocessor, to be precise) first checks if the macro CONFIG_SMP is defined. If it is defined, then it will go onto executing the following instructions, otherwise they will not be executed. It's much like regular if(){....} block in C, but it is processed by the preprocessor.

So, in this case, if CONFIG_SMP is defined, then the preprocessor will define a macro MODVERSIONS and include linux/modversions.h

2. It defines an object of the type struct file_operations.
It uses the GNU extension of tagged initialization to C structures.
Look under the section of "File Operations" in the following article:
http://lwn.net/Kernel/LDD2/ch03.lwn

[sangharsha]

Thanks a lot........

I will be seeking details, so please forward me any links if you have some..


Thanks again.