Messages in this thread |  | | From | Andreas Dilger <> | Date | Fri, 28 Sep 2001 17:17:41 -0600 | Subject | Re: [PATCH] Big-endian reading/writing cramfs (vs 2.4.10) |
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On Sep 28, 2001 15:54 -0700, Brad Bozarth wrote: > > On Sep 28, 2001 14:58 -0700, Brad wrote: > > > +#define CRAM_SWAB_16(x) ( ( (0x0000FF00 & (x)) >> 8 ) | \ > > > + ( (0x000000FF & (x)) << 8 ) ) > > > > Why not just use the well-defined le16_to_cpu() and le32_to_cpu() macros? > > I did, originally... And it worked in inode.c, but I couldn't get mkcramfs > to compile using those macros. It's outside of __KERNEL__ so I tried > using __cpu_to_le32. The following error occurred:
I didn't realize that the header was also used in user-space. I would still use the le32_to_cpu() style macros in the code, but only define macros of your own if the kernel ones were not defined, using either #ifndef __KERNEL__ or #ifndef le32_to_cpu, or both.
This way, you get the benefit of the fast asm-based instructions in the kernel, and you only use the slow ones in user-space (mkcramfs) where you don't really care.
Cheers, Andreas -- Andreas Dilger \ "If a man ate a pound of pasta and a pound of antipasto, \ would they cancel out, leaving him still hungry?" http://www-mddsp.enel.ucalgary.ca/People/adilger/ -- Dogbert
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