Method internal_memalign

libCacheSim/dataStructure/sparsepp/spp_dlalloc.h:3328–3407

}

void* malloc_state::internal_memalign(size_t alignment, size_t bytes)
{
    void* mem = 0;
    if (alignment < MIN_CHUNK_SIZE) // must be at least a minimum chunk size
        alignment = MIN_CHUNK_SIZE;
    if ((alignment & (alignment - 1)) != 0)
    {
        // Ensure a power of 2
        size_t a = SPP_MALLOC_ALIGNMENT << 1;
        while (a < alignment)
            a <<= 1;
        alignment = a;
    }
    if (bytes >= MAX_REQUEST - alignment)
        SPP_MALLOC_FAILURE_ACTION;
    else
    {
        size_t nb = request2size(bytes);
        size_t req = nb + alignment + MIN_CHUNK_SIZE - CHUNK_OVERHEAD;
        mem = internal_malloc(req);
        if (mem != 0)
        {
            mchunkptr p = mem2chunk(mem);
            if ((((size_t)(mem)) & (alignment - 1)) != 0)
            {
                // misaligned
                /*
                  Find an aligned spot inside chunk.  Since we need to give
                  back leading space in a chunk of at least MIN_CHUNK_SIZE, if
                  the first calculation places us at a spot with less than
                  MIN_CHUNK_SIZE leader, we can move to the next aligned spot.
                  We've allocated enough total room so that this is always
                  possible.
                */
                char* br = (char*)mem2chunk((void *)(((size_t)((char*)mem + alignment - 1)) &
                                                     -alignment));
                char* pos = ((size_t)(br - (char*)(p)) >= MIN_CHUNK_SIZE) ?
                            br : br + alignment;
                mchunkptr newp = (mchunkptr)pos;
                size_t leadsize = pos - (char*)(p);
                size_t newsize = p->chunksize() - leadsize;

                if (p->is_mmapped())
                {
                    // For mmapped chunks, just adjust offset
                    newp->_prev_foot = p->_prev_foot + leadsize;
                    newp->_head = newsize;
                }
                else
                {
                    // Otherwise, give back leader, use the rest
                    set_inuse(newp, newsize);
                    set_inuse(p, leadsize);
                    dispose_chunk(p, leadsize);
                }
                p = newp;
            }