[tremor] Re: [PATCH] eliminate alloca() usage

[Nicolas Pitre]

On Thu, 17 Oct 2002, Michael Smith wrote:

> At 11:40 AM 10/17/02 +0200, you wrote:
> >
> >On 2002-10-17 at 05:38:51 Nicolas Pitre wrote:
> >
> >NP> Anybody with another compiler than GCC please confirm if the attached
> >NP> patch works for you or not.
> >
> >This will only work with GCC, since it is a GCC specific extension. It
> >is definitely not ANSI or ISO C. (Note that I agree that it is a very
> >handy feature, which almost entirely removes the need for an alloca()
> >function.)
> 
> Whilst it was at one time a GCC (and other compilers, though far from all
> of them) extension, it's been part of ANSI C for a few years now. C99
> introduces variable-size automatic arrays, so any compiler that supports
> C99 will work with this. alloca() is more portable in practice, though,
> this was only suggested as an alternative for people without alloca().

The ultimate solution would involve extending that patch by declaring 
constant arrays using the maximum possible size per the Vorbis 
specification.  Since the maximum size must be accomodated to be compliant 
it won't hurt declaring everything that way and be fully portable.

Pushing this idea further all malloc()/free() could be removed the same way 
as well.  This way Tremor would become fully predictable with regard to 
memory usage, eliminating the need for heap memory.

<p>Nicolas

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