On Mon, 12 Aug 2013 15:28:06 -0700 Andy Lutomirski <luto@xxxxxxxxxxxxxx> wrote: > > +#define _mfrob(v,r,m,l) ((((v) >> (r)) & (m)) << (l)) > > +#define __frob(v,r,l) (((v) >> (r)) << (l)) > > + > > #ifdef CONFIG_MEM_SOFT_DIRTY > > > > If I'm understanding this right, the idea is to take the bits in the > range a..b of v and stick them at c..d, where a-b == c-d. Would it > make sense to change this to look something like > > #define __frob(v, inmsb, inlsb, outlsb) ((v >> inlsb) & ((1<<(inmsb - > inlsb + 1)-1) << outlsb) > > For extra fun, there could be an __unfrob macro that takes the same > inmsg, inlsb, outlsb parameters but undoes it so that it's (more) > clear that the operations that are supposed to be inverses are indeed > inverses. hm, I seem to remember writing drivers/net/ethernet/3com/3c59x.c:BFINS() and BFEXT() shortly after the invention of the electronic computer. I'm kinda surprised that we don't already have something like this in kernel.h or somewhere - there's surely a ton of code which does such things. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>