[FFmpeg-devel] [PATCH] postproc/postprocess_template: Fix left shift of negative numbers

[FFmpeg-devel] [PATCH] postproc/postprocess_template: Fix left shift of negative numbers

[Andreas Rheinhardt]

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Patch attached.

- Andreas

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From 54ceac12363b666ad8005f282f6f9f08b6334b21 Mon Sep 17 00:00:00 2001
From: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
Date: Wed, 30 Apr 2025 20:30:53 +0200
Subject: [PATCH] postproc/postprocess_template: Fix left shift of negative
 numbers

Affects the blocktest test tool.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
---
 libpostproc/postprocess_template.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/libpostproc/postprocess_template.c b/libpostproc/postprocess_template.c
index 0531e39477..fd8a4760af 100644
--- a/libpostproc/postprocess_template.c
+++ b/libpostproc/postprocess_template.c
@@ -1060,8 +1060,8 @@ DERING_CORE((%0, %1, 8)       ,(%%FF_REGd, %1, 4),%%mm2,%%mm4,%%mm0,%%mm3,%%mm5,
         if(src[stride*y + 8] > avg) t+= 256;
         if(!rightborder && src[stride*y + 9] > avg) t+= 512;
 
-        t |= (~t)<<16;
-        t &= (t<<1) & (t>>1);
+        t |= (~t) * (1 << 16);
+        t &= (t * 2) & (t>>1);
         s[y] = t;
     }
 
-- 
2.45.2


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Re: [FFmpeg-devel] [PATCH] postproc/postprocess_template: Fix left shift of negative numbers

[Michael Niedermayer]

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On Wed, Apr 30, 2025 at 08:36:01PM +0200, Andreas Rheinhardt wrote:
> Patch attached.
> 
> - Andreas

>  postprocess_template.c |    4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 805bee95b493f276f7802afbd7180c0f096ea52a  0001-postproc-postprocess_template-Fix-left-shift-of-nega.patch
> From 54ceac12363b666ad8005f282f6f9f08b6334b21 Mon Sep 17 00:00:00 2001
> From: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
> Date: Wed, 30 Apr 2025 20:30:53 +0200
> Subject: [PATCH] postproc/postprocess_template: Fix left shift of negative
>  numbers
> 
> Affects the blocktest test tool.
> 
> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
> ---
>  libpostproc/postprocess_template.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/libpostproc/postprocess_template.c b/libpostproc/postprocess_template.c
> index 0531e39477..fd8a4760af 100644
> --- a/libpostproc/postprocess_template.c
> +++ b/libpostproc/postprocess_template.c
> @@ -1060,8 +1060,8 @@ DERING_CORE((%0, %1, 8)       ,(%%FF_REGd, %1, 4),%%mm2,%%mm4,%%mm0,%%mm3,%%mm5,
>          if(src[stride*y + 8] > avg) t+= 256;
>          if(!rightborder && src[stride*y + 9] > avg) t+= 512;
>  
> -        t |= (~t)<<16;
> -        t &= (t<<1) & (t>>1);
> +        t |= (~t) * (1 << 16);
> +        t &= (t * 2) & (t>>1);
>          s[y] = t;

making t unsigned instead would keep the code more symmetric

thx

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Democracy is the form of government in which you can choose your dictator

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