RE: aligned_alloc c11 function

["Terry Moore" <tmm%mcci.com@localhost>]

Hi,

One small thing.

I don't understand why we're doing this calculation as a while():

	  /*
         * Adjust alignment to satisfy posix_memalign,
         * larger alignments satisfy smaller alignments.
         */
        while (alignment < sizeof (void *)) {
                alignment <<= 1;
        }

We know alignment is a power of two, therefore the result of this is a
constant and could be done as an if() with a 
pre-computed constant:

	if (alignment < MIN_ALIGNMENT)
		alignment = MIN_ALIGNMENT;

where MIN_ALIGNMENT is the smallest power of 2 not less than sizeof(void*).
(On all real platforms, MIN_ALIGNMENT == sizeof(void *) but a purist might
want to use compile-time log2 macros to compute MIN_ALIGNMENT.)

I feel that writing a while() in this context is bad style as it implies
that some iterative computation is being done. It's not at all an iterative
calculation, in fact.

--Terry

> -----Original Message-----
> From: tech-userlevel-owner%NetBSD.org@localhost [mailto:tech-userlevel-
> owner%NetBSD.org@localhost] On Behalf Of Niclas Rosenvik
> Sent: Saturday, October 31, 2015 5:01
> To: tech-userlevel%netbsd.org@localhost
> Subject: Re: aligned_alloc c11 function
> 
> Hi everyone, here is the second take on aligned_alloc, I have incorporated
> the changes suggested by Christos and Robert Elz.
> 
> Ok to commit?
> 
> Regards,
> Niclas Rosenvik
> 
>