[FFmpeg-devel] [PATCH 2/2] eval: Allow specifying the variable id.

[Nicolas George]

Le quartidi 4 ventôse, an CCXX, Michael Niedermayer a écrit :
> Signed-off-by: Michael Niedermayer <michaelni at gmx.at>
> ---
>  doc/eval.texi    |    5 +++--
>  libavutil/eval.c |   12 ++++++++----
>  2 files changed, 11 insertions(+), 6 deletions(-)
> 
> diff --git a/doc/eval.texi b/doc/eval.texi
> index b481bfe..c4a8ac5 100644
> --- a/doc/eval.texi
> +++ b/doc/eval.texi
> @@ -107,9 +107,10 @@ the evaluation of @var{y}, return 0 otherwise.
>  Evaluate @var{x}, and if the result is zero return the result of the
>  evaluation of @var{y}, return 0 otherwise.
>  
> - at item taylor(expr, x)
> + at item taylor(expr, x) taylor(expr, x, id)
>  Evaluate a taylor series at x.
> -expr represents the LD(0)-th derivates of f(x) at 0.
> +expr represents the LD(id)-th derivates of f(x) at 0. If id is not specified
> +then 0 is assumed.
>  note, when you have the derivatives at y instead of 0
>  taylor(expr, x-y) can be used
>  When the series does not converge the results are undefined.
> diff --git a/libavutil/eval.c b/libavutil/eval.c
> index d1d2cec..0061e22 100644
> --- a/libavutil/eval.c
> +++ b/libavutil/eval.c
> @@ -184,18 +184,19 @@ static double eval_expr(Parser *p, AVExpr *e)
>          case e_taylor: {
>              double t = 1, d = 0, v;
>              double x = eval_expr(p, e->param[1]);
> +            int id = e->param[2] ? eval_expr(p, e->param[2]) : 0;

av_clip(eval..., 0, VARS - 1)?

>              int i;
> -            double var0 = p->var[0];
> +            double var0 = p->var[id];
>              for(i=0; i<1000; i++) {
>                  double ld = d;
> -                p->var[0] = i;
> +                p->var[id] = i;
>                  v = eval_expr(p, e->param[0]);
>                  d += t*v;
>                  if(ld==d && v)
>                      break;
>                  t *= x / (i+1);
>              }
> -            p->var[0] = var0;
> +            p->var[id] = var0;
>              return d;
>          }
>          default: {
> @@ -523,6 +524,9 @@ static int verify_expr(AVExpr *e)
>          case e_not:
>          case e_random:
>              return verify_expr(e->param[0]);
> +        case e_taylor:
> +            if (e->param[2] && !verify_expr(e->param[2]))
> +                return 0;
>          default: return verify_expr(e->param[0]) && verify_expr(e->param[1]);
>      }
>  }
> @@ -722,7 +726,7 @@ int main(int argc, char **argv)
>          "ifnot(0, 23)",
>          "ifnot(1, NaN) + if(0, 1)",
>          "taylor(1, 1)",
> -        "taylor(eq(mod(ld(0),4),1)-eq(mod(ld(0),4),3), PI/2)",
> +        "taylor(eq(mod(ld(1),4),1)-eq(mod(ld(1),4),3), PI/2, 1)",
>          NULL
>      };

Apart from that, looks right. If you did not apply the original patch yet,
it could be reordered and squashed with it.

Thanks.

Regards,

-- 
  Nicolas George
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