[FFmpeg-devel] [PATCH] [libavutil] Add saturated add/sub operations for int64_t.

[Michael Niedermayer]

On Fri, May 01, 2020 at 11:42:43AM -0700, Dale Curtis wrote:
> On Fri, May 1, 2020 at 10:57 AM Carl Eugen Hoyos <ceffmpeg at gmail.com> wrote:
> 
> > Could you confirm that you attached the wrong patch?
> >
> 
> No, I sent the patches without completing the rebase. Sorry.
> 
> - dale

>  common.h |   36 ++++++++++++++++++++++++++++++++++++
>  1 file changed, 36 insertions(+)
> f5567ae046c0c2d4ac9053611457b9d9045b6ccb  sat_math_v4.patch
> From 06c20d84e3bf0f56bcba63ef8e74812e796f3ffe Mon Sep 17 00:00:00 2001
> From: Dale Curtis <dalecurtis at chromium.org>
> Date: Thu, 30 Apr 2020 15:16:31 -0700
> Subject: [PATCH 1/2] Add saturated add/sub operations for int64_t.
> 
> Many places are using their own custom code for handling overflow
> around timestamps or other int64_t values. There are enough of these
> now that having some common saturated math functions seems sound.
> 
> Signed-off-by: Dale Curtis <dalecurtis at chromium.org>
> ---
>  libavutil/common.h | 36 ++++++++++++++++++++++++++++++++++++
>  1 file changed, 36 insertions(+)
> 
> diff --git a/libavutil/common.h b/libavutil/common.h
> index 142ff9abe7..11907e5ba7 100644
> --- a/libavutil/common.h
> +++ b/libavutil/common.h
> @@ -291,6 +291,36 @@ static av_always_inline int av_sat_dsub32_c(int a, int b)
>      return av_sat_sub32(a, av_sat_add32(b, b));
>  }
>  
> +/**
> + * Add two signed 64-bit values with saturation.
> + *
> + * @param  a one value
> + * @param  b another value
> + * @return sum with signed saturation
> + */
> +static av_always_inline int64_t av_sat_add64_c(int64_t a, int64_t b) {
> +  if (b >= 0 && a >= INT64_MAX - b)
> +    return INT64_MAX;
> +  if (b <= 0 && a <= INT64_MIN - b)
> +    return INT64_MIN;
> +  return a + b;
> +}
> +
> +/**
> + * Subtract two signed 64-bit values with saturation.
> + *
> + * @param  a one value
> + * @param  b another value
> + * @return difference with signed saturation
> + */
> +static av_always_inline int64_t av_sat_sub64_c(int64_t a, int64_t b) {
> +  if (b <= 0 && a >= INT64_MAX + b) {
> +    return INT64_MAX;
> +  if (b >= 0 && a <= INT64_MIN + b) {
> +    return INT64_MIN;

the { are not paired with }
this will not build

indention level also does not match the rest of the code

Thanks


[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Does the universe only have a finite lifespan? No, its going to go on
forever, its just that you wont like living in it. -- Hiranya Peiri
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