Le 13/01/2011 13:05, Aneesh V a écrit :
What I need is something like below:
#define get_bit_field(nr, start, mask)\ (((nr) & (mask)) >> (start))
#define set_bit_field(nr, start, mask, val)\ (nr) = ((nr) & ~(mask)) | (((val) << (start)) & (mask))
Can these go in a generic header? If so, can I add them to "include/linux/bitops.h"
After some more thought, I am wondering if a *generic* field setting and getting macro is really useful. So far everyone is fine with at most defining field-specific macros.
Is it going to be easy if you have many fields to deal with?
I don't see how the generic macros ease anything. Instead of defining say
#define get_field_F(x) ((x >> F_start) & F_mask) #define set_field_F(x,v) { x = (x ~ F_mask ) | (v << F_start) }
You'd have
#define get_field_F(x) get_bit_field(x, F_start, F_mask) #define set_field_F(x,v) set_bit_field(x, F_start, F_mask, v);
Which does not seem to bring any simplicity to me.
However, I agree that the above may be specific to our needs.
What may be of more generic interest may be something like this with the mask automatically generated: #define get_bit_field(nr, start, end) #define set_bit_field(nr, start, end, val)
However, in our case I am already given the mask and start position for each field (automatically generated from hw database). So, I prefer the former versions.
If that doesn't look useful for generic use I will put them in OMAP specific headers.
Best regards, Aneesh
Amicalement,