[Mesa-dev] [PATCH v2 27/64] gallium/util: add new util_dynarray_{shrink, delete} helpers

[Marek Olšák]

On Thu, Jun 8, 2017 at 12:26 PM, Samuel Pitoiset
<samuel.pitoiset at gmail.com> wrote:
>
>
> On 06/07/2017 06:21 PM, Nicolai Hähnle wrote:
>>
>> On 30.05.2017 22:35, Samuel Pitoiset wrote:
>>>
>>> These helpers will be used for handling dynamic arrays of resident
>>> texture/image handles.
>>>
>>> Signed-off-by: Samuel Pitoiset <samuel.pitoiset at gmail.com>
>>> ---
>>>   src/gallium/auxiliary/util/u_dynarray.h | 20 ++++++++++++++++++++
>>>   1 file changed, 20 insertions(+)
>>>
>>> diff --git a/src/gallium/auxiliary/util/u_dynarray.h
>>> b/src/gallium/auxiliary/util/u_dynarray.h
>>> index 7b7a093d82..d6f3d5c901 100644
>>> --- a/src/gallium/auxiliary/util/u_dynarray.h
>>> +++ b/src/gallium/auxiliary/util/u_dynarray.h
>>> @@ -109,6 +109,26 @@ util_dynarray_trim(struct util_dynarray *buf)
>>>   #define util_dynarray_element(buf, type, idx) ((type*)(buf)->data +
>>> (idx))
>>>   #define util_dynarray_begin(buf) ((buf)->data)
>>>   #define util_dynarray_end(buf) ((void*)util_dynarray_element((buf),
>>> char, (buf)->size))
>>> +#define util_dynarray_shrink(buf, type, begin, end)
>>> \
>>> +   do {
>>> \
>>> +      void *__begin = util_dynarray_element((buf), type, (begin));
>>> \
>>> +      void *__end = util_dynarray_element((buf), type, (end));
>>> \
>>> +      if ((end) * sizeof(type) < (buf)->size)
>>> \
>>> +         memmove(__begin, __end, (buf)->size - ((end) * sizeof(type)));
>>> \
>>> +      (buf)->size = (buf)->size - ((end) - (begin)) * sizeof(type);
>>> \
>>> +   } while (0)
>>> +#define util_dynarray_delete(buf, type, v)                           \
>>> +   do {                                                              \
>>> +      unsigned num_elements = (buf)->size / sizeof(type);            \
>>> +      unsigned i;                                                    \
>>> +      for (i = 0; i < num_elements; i++) {                           \
>>> +         type __v = *util_dynarray_element((buf), type, (i));        \
>>> +         if (v == __v) {                                             \
>>> +            util_dynarray_shrink((buf), type, i, i + 1);             \
>>> +            break;                                                   \
>>> +         }                                                           \
>>> +      }                                                              \
>>> +   } while (0)
>>
>>
>> Does the order of elements matter? If not, it would be better to just copy
>> the last element into the gap that is left by the deleted element.
>
>
> It doesn't matter, at least not for bindless handles.
>
>>
>> Might be wise to rename the macro to util_dynarray_delete_unordered to
>> avoid future confusion.

I think Nicolai meant that the "util_dynarray_delete_unordered" name
be used for the case when it copies the last element to the gap.

Marek