Re: [PATCH V6 13/33] csky: Library functions

[Guo Ren]

On Fri, Sep 28, 2018 at 09:20:30AM -0700, Christoph Hellwig wrote:
> > +unsigned long long notrace __bswapdi2(unsigned long long u)
> > +{
> > +	return (((u) & 0xff00000000000000ull) >> 56) |
> > +	       (((u) & 0x00ff000000000000ull) >> 40) |
> > +	       (((u) & 0x0000ff0000000000ull) >> 24) |
> > +	       (((u) & 0x000000ff00000000ull) >>  8) |
> > +	       (((u) & 0x00000000ff000000ull) <<  8) |
> > +	       (((u) & 0x0000000000ff0000ull) << 24) |
> > +	       (((u) & 0x000000000000ff00ull) << 40) |
> > +	       (((u) & 0x00000000000000ffull) << 56);
> > +}
> 
> How is this any better than using the generic byteswap helpers?
OK.
#include <uapi/linux/swab.h>

unsigned long long notrace __bswapdi2(unsigned long long u)
{
	return ___constant_swab64(u);


> 
> > +unsigned int notrace __bswapsi2(unsigned int u)
> > +{
> > +	return (((u) & 0xff000000) >> 24) |
> > +	       (((u) & 0x00ff0000) >>  8) |
> > +	       (((u) & 0x0000ff00) <<  8) |
> > +	       (((u) & 0x000000ff) << 24);
> > +}
> 
> Same here.
OK.
#include <uapi/linux/swab.h>

unsigned int notrace __bswapsi2(unsigned int u)
{
	return ___constant_swab32(u);
}

Thx
 Guo Ren