[FFmpeg-devel] [PATCH]lavu/imgutils: Use llabs() for ptrdiff_t

Michael Niedermayer michael at niedermayer.cc
Fri Feb 1 23:58:13 EET 2019


On Fri, Feb 01, 2019 at 10:37:22PM +0100, Carl Eugen Hoyos wrote:
> Hi!
> 
> Attached patch fixes a warning with clang.
> 
> Please comment, Carl Eugen

>  imgutils.c |    4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> d1c5f9eb38d36664164f3df0170eb946b6d4f1cd  0001-lavu-imgutils-Use-llabs-for-ptrdiff_t.patch
> From 5218c47a129a927dd3de781cdd66d2250955b2cb Mon Sep 17 00:00:00 2001
> From: Carl Eugen Hoyos <ceffmpeg at gmail.com>
> Date: Fri, 1 Feb 2019 22:34:51 +0100
> Subject: [PATCH] lavu/imgutils: Use llabs() for ptrdiff_t.
> 
> Fixes a warning with clang:
> libavutil/imgutils.c:314:16: warning: absolute value function 'abs' given an argument of type 'ptrdiff_t' (aka 'long') but has parameter
>       of type 'int' which may cause truncation of value
> ---
>  libavutil/imgutils.c |    4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/libavutil/imgutils.c b/libavutil/imgutils.c
> index afc73e2..82c26c3 100644
> --- a/libavutil/imgutils.c
> +++ b/libavutil/imgutils.c
> @@ -311,8 +311,8 @@ static void image_copy_plane(uint8_t       *dst, ptrdiff_t dst_linesize,
>  {
>      if (!dst || !src)
>          return;
> -    av_assert0(abs(src_linesize) >= bytewidth);
> -    av_assert0(abs(dst_linesize) >= bytewidth);
> +    av_assert0(llabs(src_linesize) >= bytewidth);
> +    av_assert0(llabs(dst_linesize) >= bytewidth);

I think FFABS() is (theoretically) more correct

thx

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Complexity theory is the science of finding the exact solution to an
approximation. Benchmarking OTOH is finding an approximation of the exact
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