[FFmpeg-devel] [PATCH] cabac: initialize all of ff_h264_cabac_tables programmatically.

[wm4]

On Sat, 30 Aug 2014 18:18:41 +0200
Reimar Döffinger <Reimar.Doeffinger at gmx.de> wrote:

> Moves it from .data to .bss, slightly reducing binary size.
> 
> Signed-off-by: Reimar Döffinger <Reimar.Doeffinger at gmx.de>
> ---
>  libavcodec/cabac.c | 26 ++++----------------------
>  1 file changed, 4 insertions(+), 22 deletions(-)
> 
> diff --git a/libavcodec/cabac.c b/libavcodec/cabac.c
> index 65579d8..803c81c 100644
> --- a/libavcodec/cabac.c
> +++ b/libavcodec/cabac.c
> @@ -32,28 +32,7 @@
>  #include "cabac.h"
>  #include "cabac_functions.h"
>  
> -uint8_t ff_h264_cabac_tables[512 + 4*2*64 + 4*64 + 63] = {
> - 9,8,7,7,6,6,6,6,5,5,5,5,5,5,5,5,
> - 4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,
> - 3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,
> - 3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,
> - 2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
> - 2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
> - 2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
> - 2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
> - 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
> - 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
> - 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
> - 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
> - 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
> - 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
> - 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
> - 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
> - 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
> - 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
> - 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
> - 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
> -};
> +uint8_t ff_h264_cabac_tables[512 + 4*2*64 + 4*64 + 63];
>  
>  static const uint8_t lps_range[64][4]= {
>  {128,176,208,240}, {128,167,197,227}, {128,158,187,216}, {123,150,178,205},
> @@ -143,6 +122,9 @@ void ff_init_cabac_states(void)
>      if (initialized)
>          return;
>  
> +    for (i = 0; i < 512; i++)
> +        ff_h264_norm_shift[i] = i ? 8 - av_log2(i) : 9;
> +
>      for(i=0; i<64; i++){
>          for(j=0; j<4; j++){ //FIXME check if this is worth the 1 shift we save
>              ff_h264_lps_range[j*2*64+2*i+0]=

Doesn't this make library safety issues worse, instead of improving it?