[PATCH 2/5] wined3d: Wrap resource->heapMemory into a structure

[Stefan Dösinger]

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Am 2013-08-19 14:34, schrieb Henri Verbeet:
> On 19 August 2013 14:20, Stefan Dösinger
> <stefandoesinger at gmail.com> wrote:
>> Am 2013-08-19 13:53, schrieb Henri Verbeet:
>>> That's actually a bug in what I posted.
>> What's your suggested fix? Allocating size + align + alignment,
>> and adding alignment to mem if mem happens to be already
>> aligned?
>> 
> I think it needs to be "align = max(sizeof(*p), alignment);", but 
> that's actually for the aligned + 1 case.
With some inspiration from _aligned_offset_malloc in msvcrt I came up
with this:

void *wined3d_alloc_resource_mem(SIZE_T size)
{
    void **p;
    SIZE_T align = RESOURCE_ALIGNMENT - 1 + sizeof(*p);
    void *mem;

    if (!(mem = HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY, size +
align)))
        return NULL;

    p = (void **)(((ULONG_PTR)mem + align) & ~(RESOURCE_ALIGNMENT -
1)) - 1;
    *p = mem;

    return ++p;
}

void wined3d_free_resource_mem(void *mem)
{
    void **p = mem;

    if (!mem)
        return;

    HeapFree(GetProcessHeap(), 0, *(--p));
}

I'm not entirely sure about the SIZE_T align = RESOURCE_ALIGNMENT - 1
+ sizeof(*p); line though. Msvcrt doesn't have the - 1, and allocating
size + RESOURCE_ALIGNMENT bytes might be enough. msvcrt allocates the
equivalent of size + RESOURCE_ALIGNMENT + sizeof(void *).

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