Re: [FFmpeg-devel] [PATCH 1/4] fftools/textformat: narrow variable scopes

[Marvin Scholz <epirat07-at-gmail.com@ffmpeg.org>]

On 12 Jun 2025, at 18:10, softworkz . wrote:

>> -----Original Message-----
>> From: ffmpeg-devel <ffmpeg-devel-bounces@ffmpeg.org> On Behalf Of
>> Marvin Scholz
>> Sent: Donnerstag, 12. Juni 2025 13:25
>> To: FFmpeg development discussions and patches <ffmpeg-
>> devel@ffmpeg.org>
>> Subject: Re: [FFmpeg-devel] [PATCH 1/4] fftools/textformat: narrow
>> variable scopes
>>
>>
>>
>> On 12 Jun 2025, at 4:26, softworkz . wrote:
>>
>>> Hi Marvin,
>>>
>>>> -----Original Message-----
>>>> From: ffmpeg-devel <ffmpeg-devel-bounces@ffmpeg.org> On Behalf
>> Of
>>>> Marvin Scholz
>>>> Sent: Mittwoch, 11. Juni 2025 22:42
>>>> To: ffmpeg-devel@ffmpeg.org
>>>> Subject: [FFmpeg-devel] [PATCH 1/4] fftools/textformat: narrow
>>>> variable scopes
>>>>
>>>> ---
>>>>  fftools/textformat/avtextformat.c | 15 ++++++---------
>>>>  1 file changed, 6 insertions(+), 9 deletions(-)
>>>>
>>>> diff --git a/fftools/textformat/avtextformat.c
>>>> b/fftools/textformat/avtextformat.c
>>>> index 14779e6f0c..f1811abb1c 100644
>>>> --- a/fftools/textformat/avtextformat.c
>>>> +++ b/fftools/textformat/avtextformat.c
>>>> @@ -101,7 +101,6 @@ static void bprint_bytes(AVBPrint *bp, const
>>>> uint8_t *ubuf, size_t ubuf_size)
>>>>  int avtext_context_close(AVTextFormatContext **ptctx)
>>>>  {
>>>>      AVTextFormatContext *tctx = *ptctx;
>>>> -    int i;
>>>>      int ret = 0;
>>>>
>>>>      if (!tctx)
>>>> @@ -117,7 +116,7 @@ int avtext_context_close(AVTextFormatContext
>>>> **ptctx)
>>>>          if (tctx->formatter->priv_class)
>>>>              av_opt_free(tctx->priv);
>>>>      }
>>>> -    for (i = 0; i < SECTION_MAX_NB_LEVELS; i++)
>>>> +    for (int i = 0; i < SECTION_MAX_NB_LEVELS; i++)
>>>>          av_bprint_finalize(&tctx->section_pbuf[i], NULL);
>>>>      av_freep(&tctx->priv);
>>>>      av_opt_free(tctx);
>>>> @@ -130,7 +129,7 @@ int avtext_context_open(AVTextFormatContext
>>>> **ptctx, const AVTextFormatter *form
>>>>                          const AVTextFormatSection *sections,
>> int
>>>> nb_sections, AVTextFormatOptions options, char *show_data_hash)
>>>>  {
>>>>      AVTextFormatContext *tctx;
>>>> -    int i, ret = 0;
>>>> +    int ret = 0;
>>>>
>>>>      av_assert0(ptctx && formatter);
>>>>
>>>> @@ -202,7 +201,7 @@ int avtext_context_open(AVTextFormatContext
>>>> **ptctx, const AVTextFormatter *form
>>>>              if (ret == AVERROR(EINVAL)) {
>>>>                  const char *n;
>>>>                  av_log(NULL, AV_LOG_ERROR, "Unknown hash
>> algorithm
>>>> '%s'\nKnown algorithms:", show_data_hash);
>>>> -                for (i = 0; (n = av_hash_names(i)); i++)
>>>> +                for (unsigned i = 0; (n = av_hash_names(i));
>> i++)
>>>>                      av_log(NULL, AV_LOG_ERROR, " %s", n);
>>>>                  av_log(NULL, AV_LOG_ERROR, "\n");
>>>>              }
>>>> @@ -525,13 +524,13 @@ void avtext_print_data(AVTextFormatContext
>>>> *tctx, const char *key,
>>>>  {
>>>>      AVBPrint bp;
>>>>      unsigned offset = 0;
>>>> -    int l, i;
>>>> +    int i;
>>>>
>>>>      av_bprint_init(&bp, 0, AV_BPRINT_SIZE_UNLIMITED);
>>>>      av_bprintf(&bp, "\n");
>>>>      while (size) {
>>>>          av_bprintf(&bp, "%08x: ", offset);
>>>> -        l = FFMIN(size, 16);
>>>> +        int l = FFMIN(size, 16);
>>>>          for (i = 0; i < l; i++) {
>>>>              av_bprintf(&bp, "%02x", data[i]);
>>>>              if (i & 1)
>>>> @@ -571,7 +570,6 @@ void
>> avtext_print_integers(AVTextFormatContext
>>>> *tctx, const char *key,
>>>>  {
>>>>      AVBPrint bp;
>>>>      unsigned offset = 0;
>>>> -    int l, i;
>>>>
>>>>      if (!key || !data || !format || columns <= 0 || bytes <= 0)
>>>>          return;
>>>> @@ -580,8 +578,7 @@ void
>> avtext_print_integers(AVTextFormatContext
>>>> *tctx, const char *key,
>>>>      av_bprintf(&bp, "\n");
>>>>      while (size) {
>>>>          av_bprintf(&bp, "%08x: ", offset);
>>>> -        l = FFMIN(size, columns);
>>>> -        for (i = 0; i < l; i++) {
>>>> +        for (int i = 0, l = FFMIN(size, columns); i < l; i++) {
>>>
>>> You are changing behavior here because size is changed inside the
>> loop.
>>> The pre-evaluation into l is intentional.
>>>
>>
>> I fail to see how I change anything here though? It is still just
>> assigned before
>> the loop runs, just that l is scoped narrower?
>
> This is the original code:
>
>         l = FFMIN(size, columns);
>         for (i = 0; i < l; i++) {
>             if      (bytes == 1) av_bprintf(&bp, format, *data);
>             else if (bytes == 2) av_bprintf(&bp, format, AV_RN16(data));
>             else if (bytes == 4) av_bprintf(&bp, format, AV_RN32(data));
>             data += bytes;
>             size--;
>         }
>
> See the size-- ?
>

I see that but again I fail to see how this changes anything.
I am not changing that l is assigned before the loop runs, just
narrow the scope to the loop.

See: https://godbolt.org/z/c3hGKfne4

>
> Thanks
> sw
>
>
>
>
>
>
>
> _______________________________________________
> ffmpeg-devel mailing list
> ffmpeg-devel@ffmpeg.org
> https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>
> To unsubscribe, visit link above, or email
> ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe".
_______________________________________________
ffmpeg-devel mailing list
ffmpeg-devel@ffmpeg.org
https://ffmpeg.org/mailman/listinfo/ffmpeg-devel

To unsubscribe, visit link above, or email
ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe".