Re: [PATCH 4/6] Add macros for increasing data alignment

[Eric Wong <normalperson@yhbt.net>]

Måns Rullgård <mans@mansr.com> wrote:
> Eric Wong <normalperson@yhbt.net> writes:
> >  dnl Checks for library functions.
> > -AC_CHECK_FUNCS(strcasecmp strdup popen vsnprintf gettimeofday mkstemp fmemopen aligned_alloc)
> > +AC_CHECK_FUNCS(strcasecmp strdup popen vsnprintf gettimeofday mkstemp fmemopen)
> > +
> > +dnl aligned alloc required for sdm using AVX (32-byte) or SSE2 (16-byte)
> > +AC_CHECK_FUNCS(aligned_alloc)
> > +AS_IF([test "x$ac_cv_func_aligned_alloc" != xyes], [
> > +	AC_CHECK_FUNCS([memalign])
> > +	AS_IF([test "x$ac_cv_func_memalign" != xyes], [
> > +		AC_CHECK_FUNCS([posix_memalign])
> > +	])
> > +])
> 
> Why don't you just add (posix_)memalign to the existing list of
> functions?  It's not an error if some of them don't exist, and you're
> checking the resulting HAVE_ macros in the same order anyway.

I wanted to avoid the overhead of checking redundantly if one
function was already available; but perhaps it's not worth the effort
since `configure' is already slow in other places.

> > +static inline void *sox_aligned_alloc_m(size_t align, size_t size)
> > +{
> > +  void *res = malloc(align + size + sizeof(void *));
> > +  char *aligned = (char *)res + align + sizeof(void *);
> > +
> > +  aligned -= ((size_t)aligned & (align - 1));
> 
> Use uintptr_t rather than size_t there.  Although they are usually the
> same underlying type, there is no such guarantee, especially for systems
> bizarre enough not to have an aligned allocation function.

I wanted to, but I figure systems missing *memalign could also
be missing uintptr_t and stdint.h
Perhaps "unsigned long" is better?

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