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avfilter/avfilter: Add numbers of (in|out)pads directly to AVFilter

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Up until now, an AVFilter's lists of input and output AVFilterPads
were terminated by a sentinel and the only way to get the length
of these lists was by using avfilter_pad_count(). This has two
drawbacks: first, sizeof(AVFilterPad) is not negligible
(i.e. 64B on 64bit systems); second, getting the size involves
a function call instead of just reading the data.

This commit therefore changes this. The sentinels are removed and new
private fields nb_inputs and nb_outputs are added to AVFilter that
contain the number of elements of the respective AVFilterPad array.

Given that AVFilter.(in|out)puts are the only arrays of zero-terminated
AVFilterPads an API user has access to (AVFilterContext.(in|out)put_pads
are not zero-terminated and they already have a size field) the argument
to avfilter_pad_count() is always one of these lists, so it just has to
find the filter the list belongs to and read said number. This is slower
than before, but a replacement function that just reads the internal numbers
that users are expected to switch to will be added soon; and furthermore,
avfilter_pad_count() is probably never called in hot loops anyway.

This saves about 49KiB from the binary; notice that these sentinels are
not in .bss despite being zeroed: they are in .data.rel.ro due to the
non-sentinels.

Reviewed-by: Nicolas George <george@nsup.org>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
This commit is contained in:
Andreas Rheinhardt 2021-08-12 13:05:31 +02:00
parent d53d48c799
commit 8be701d9f7
389 changed files with 906 additions and 1696 deletions
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18
libavfilter/avfilter.c
View file

@ -540,14 +540,20 @@ int avfilter_process_command(AVFilterContext *filter, const char *cmd, const cha
int avfilter_pad_count(const AVFilterPad *pads)
{
int count;
const AVFilter *filter;
void *opaque = NULL;
if (!pads)
return 0;
for (count = 0; pads->name; count++)
pads++;
return count;
while (filter = av_filter_iterate(&opaque)) {
if (pads == filter->inputs)
return filter->nb_inputs;
if (pads == filter->outputs)
return filter->nb_outputs;
}
av_assert0(!"AVFilterPad list not from a filter");
}
static const char *default_filter_name(void *filter_ctx)
@ -650,7 +656,7 @@ AVFilterContext *ff_filter_alloc(const AVFilter *filter, const char *inst_name)
goto err;
ret->internal->execute = default_execute;
ret->nb_inputs = avfilter_pad_count(filter->inputs);
ret->nb_inputs = filter->nb_inputs;
if (ret->nb_inputs ) {
ret->input_pads = av_memdup(filter->inputs, ret->nb_inputs * sizeof(*filter->inputs));
if (!ret->input_pads)
@ -660,7 +666,7 @@ AVFilterContext *ff_filter_alloc(const AVFilter *filter, const char *inst_name)
goto err;
}
ret->nb_outputs = avfilter_pad_count(filter->outputs);
ret->nb_outputs = filter->nb_outputs;
if (ret->nb_outputs) {
ret->output_pads = av_memdup(filter->outputs, ret->nb_outputs * sizeof(*filter->outputs));
if (!ret->output_pads)