Re: canonical byte swap macros?

[Steve Graegert <graegerts@gmail.com>]

On 7/11/05, Robert P. J. Day <rpjday@mindspring.com> wrote:
> 
>   is there a standard set of byte swap macros/functions for doing
> big/little endian conversion?  i have no interest in re-inventing the
> wheel and i'm sure there's a universally-recognized set of macros for
> this, no?
> 

For quick and dirty solutions I sometimes use one of the following
(not favoured over any other solution, it just work for me):

#define swap_16(x) (((x) & 0x00ff) << 8 | ((x) & 0xff00) >> 8)

#define swap_32(x) \
     ((((x) & 0xff000000) >> 24) | (((x) & 0x00ff0000) >>  8) | \
      (((x) & 0x0000ff00) <<  8) | (((x) & 0x000000ff) << 24))

uint64_t swap_64(uint64_t x) {
    union { 
        uint64_t ll;
        uint32_t l[2]; 
    } w, r;
    w.ll = x;
    r.l[0] = bswap_32 (w.l[1]);
    r.l[1] = bswap_32 (w.l[0]);
    return r.ll;
}


Kind Regards

    \Steve

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Steve Graegert <graegerts@gmail.com> || <http://www.technologies.de/~sg/>
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