[FFmpeg-devel] [PATCH] avcodec/dxvenc: Use proper alignment, write endian-independent output

[James Almer]

On 2/26/2024 8:50 PM, Andreas Rheinhardt wrote:
> Fixes the dxv3enc-dxt1 FATE test with UBSan.
> 
> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at outlook.com>
> ---
> I have not actually tested whether the output is actually wrong
> on BE systems. Would be nice if someone could.
> 
>   libavcodec/dxvenc.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/libavcodec/dxvenc.c b/libavcodec/dxvenc.c
> index 1ce2b1d014..3f28fb696a 100644
> --- a/libavcodec/dxvenc.c
> +++ b/libavcodec/dxvenc.c
> @@ -149,7 +149,7 @@ typedef struct DXVEncContext {
>           } else {                                                              \
>               op = 0;                                                           \
>           }                                                                     \
> -        *value |= (op << (state * 2));                                        \
> +        AV_WL32(value, AV_RL32(value) | (op << (state * 2)));                 \
>           state++;                                                              \
>       } while (0)
>   
> @@ -157,7 +157,7 @@ static int dxv_compress_dxt1(AVCodecContext *avctx)
>   {
>       DXVEncContext *ctx = avctx->priv_data;
>       PutByteContext *pbc = &ctx->pbc;
> -    uint32_t *value;
> +    void *value;

You should probably also remove the uint32_t* cast in the above macro.

>       uint32_t color, lut, idx, color_idx, lut_idx, prev_pos, state = 16, pos = 2, op = 0;
>   
>       ht_init(ctx->color_lookback_ht);