[FFmpeg-devel] [PATCH v2 8/9] swscale/arm/yuv2rgb: save a few instructions by processing the luma line interleaved

[Benoit Fouet]

Hi,

On 28/03/2016 21:19, Matthieu Bouron wrote:
> ---
>   libswscale/arm/yuv2rgb_neon.S | 88 +++++++++++++++++--------------------------
>   1 file changed, 34 insertions(+), 54 deletions(-)
>
> diff --git a/libswscale/arm/yuv2rgb_neon.S b/libswscale/arm/yuv2rgb_neon.S
> index 124d7d3..6b911c8 100644
> --- a/libswscale/arm/yuv2rgb_neon.S
> +++ b/libswscale/arm/yuv2rgb_neon.S
>
> [...]
>
> @@ -94,25 +67,29 @@
>   .ifc \ofmt,bgra
>       compute_rgba        d8, d7, d6, d9, d12, d11, d10, d13
>   .endif
> +
> +    vzip.8              d6, d10
> +    vzip.8              d7, d11
> +    vzip.8              d8, d12
> +    vzip.8              d9, d13

Adding a comment to explain the resulting interleaving would be nice

>       vst4.8              {q3, q4}, [\dst,:128]!
>       vst4.8              {q5, q6}, [\dst,:128]!
> -
>   .endm
>   
>   .macro process_1l ofmt
> -    compute_premult     d28, d29, d30, d31
> -    vld1.8              {q7}, [r4]!
> -    compute             r2, d14, d15, \ofmt
> +    compute_premult
> +    vld2.8              {d14, d15}, [r4]!
> +    compute             r2, \ofmt
>   .endm
>   
>   .macro process_2l ofmt
> -    compute_premult     d28, d29, d30, d31
> +    compute_premult
>   
> -    vld1.8              {q7}, [r4]!                                    @ first line of luma
> -    compute             r2, d14, d15, \ofmt
> +    vld2.8              {d14, d15}, [r4]!                              @ q7 = Y (interleaved)
> +    compute             r2, \ofmt
>   
> -    vld1.8              {q7}, [r12]!                                   @ second line of luma
> -    compute             r11, d14, d15, \ofmt
> +    vld2.8              {d14, d15}, [r12]!                             @ q7 = Y (interleaved)
> +    compute             r11, \ofmt
>   .endm
>   

What about adding a level of macro here? Something like:
.macro process_1l_internal ofmt src_addr res
     compute_premult
     vld2.8            {d14, d15}, [\src_addr]!
     compute        \res, \ofmt
.endm

(again, the naming could be changed, according to your own taste :-) )

This way, we would get:
.macro process_1l ofmt
     process_1l_internal \ofmt, r4, r2
.endm

.macro process_2l ofmt
     process_1l_internal \ofmt, r4,  r2
     process_1l_internal \ofmt, r12, r11
.endm

-- 
Ben