Re: [PATCH] hex <-> int conversion routines.

From: H. Peter Anvin (hpa@zytor.com)
Date: Tue Feb 19 2002 - 15:27:28 EST


Followup to: <200202191902.g1JJ2wx28246@frodo.gams.co.at>
By author: Bernd Petrovitsch <bernd@gams.at>
In newsgroup: linux.dev.kernel
>
> Jakob Kemi <jakob.kemi@telia.com> wrote:
> >> > +static __inline__ char inthex_nibble(int x)
> >> > +{
> >> > + const char* digits = "0123456789abcdef";
> >> > +
> >> > + return digits[x & 0x0f];
> >> > +}
> >>
> >> perhaps better do static const char *digits.
> >GCC doesn't copy const strings, as opposed to other const arrays.
> >So it should be fine as it is. GCC also reuse duplicated strings.
>
> You could also do
> return "0123456789abcdef"[x & 0x0f];
> though some will find it bad, ugly, wrong
> or make a file-global
> static const char digits[] = "0123456789abcdef";
>

Better yet...

extern const char inthex_digits[];
static __inline__ char inthex_nybble(int x)
{
        return inthex_digits[x & 15];
}

(Nibble = small amount of food; nybble = 4 bits. It's a pun on
bite/byte.)

        -hpa

-- 
<hpa@transmeta.com> at work, <hpa@zytor.com> in private!
"Unix gives you enough rope to shoot yourself in the foot."
http://www.zytor.com/~hpa/puzzle.txt	<amsp@zytor.com>
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