Re: Make STL containers allocate aligned memory

From:
Maxim Yegorushkin <maxim.yegorushkin@gmail.com>
Newsgroups:
comp.lang.c++
Date:
Wed, 26 Nov 2008 09:32:47 -0800 (PST)
Message-ID:
<034838c9-c8ef-4547-bb80-8bec074f79b5@c1g2000yqg.googlegroups.com>
On Nov 26, 5:03 pm, Maxim Yegorushkin <maxim.yegorush...@gmail.com>
wrote:

On Nov 26, 4:42 pm, zr <zvir...@gmail.com> wrote:

I need to use STL containers that allocate aligned memory.


Why?

My compiler provides an aligned_malloc routine.


It is probably provided by a library shipped with the compiler, not by
compiler itself.

How can this be accomplished?


Something like this:

#include <memory>
#include <stdexcept>

template<class T, size_t alignment>
struct aligned_allocator : std::allocator<T>
{
    template<class U>
    struct rebind { typedef aligned_allocator<U, alignment> other; };

    typedef std::allocator<T> base;

    typedef typename base::pointer pointer;
    typedef typename base::size_type size_type;

    pointer allocate(size_type n)
    {
        if(pointer p = (pointer)aligned_malloc(n, alignment))
            return p;
        throw std::bad_alloc("aligned_allocator");
    }

    pointer allocate(size_type n, void const*)
    {
        return this->allocate(n);
    }

    void deallocate(pointer p, size_type)
    {
        aligned_free(p);
    }

};


Usage is:

    typedef std::vector<X, aligned_allocator<X, required_alignment> >
VecX;

--
Max

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