[FFmpeg-devel] [PATCHv2 1/3] avutil/eval: separate AVExpr state to a new AVExprState struct
Michael Niedermayer
michael at niedermayer.cc
Wed Jan 1 14:30:10 EET 2020
On Mon, Dec 30, 2019 at 11:23:40PM +0100, Marton Balint wrote:
> Also add helper functions to allocate and free such a struct, and make it
> usable by providing a new av_eval_expr2 function for which you can specify a
> custom AVExprState.
>
> Signed-off-by: Marton Balint <cus at passwd.hu>
> ---
> doc/APIchanges | 4 ++++
> libavutil/eval.c | 36 +++++++++++++++++++++++++-----------
> libavutil/eval.h | 41 +++++++++++++++++++++++++++++++++++++++++
> libavutil/version.h | 2 +-
> 4 files changed, 71 insertions(+), 12 deletions(-)
>
> diff --git a/doc/APIchanges b/doc/APIchanges
> index 3c24dc6fbc..d0b33bda02 100644
> --- a/doc/APIchanges
> +++ b/doc/APIchanges
> @@ -15,6 +15,10 @@ libavutil: 2017-10-21
>
> API changes, most recent first:
>
> +2020-01-xx - xxxxxxxxxx - lavu 56.39.100 - eval.h
> + Add AVExprState struct and av_expr_eval2, av_expr_state_alloc,
> + av_expr_state_free functions
> +
> 2019-12-27 - xxxxxxxxxx - lavu 56.38.100 - eval.h
> Add av_expr_count_func().
>
> diff --git a/libavutil/eval.c b/libavutil/eval.c
> index d527f6a9d0..4619d0fba0 100644
> --- a/libavutil/eval.c
> +++ b/libavutil/eval.c
> @@ -53,7 +53,6 @@ typedef struct Parser {
> void *opaque;
> int log_offset;
> void *log_ctx;
> -#define VARS 10
> double *var;
> } Parser;
>
> @@ -173,7 +172,7 @@ struct AVExpr {
> double (*func2)(void *, double, double);
> } a;
> struct AVExpr *param[3];
> - double *var;
> + AVExprState *state;
> };
>
> static double etime(double v)
> @@ -191,7 +190,7 @@ static double eval_expr(Parser *p, AVExpr *e)
> case e_func2: return e->value * e->a.func2(p->opaque, eval_expr(p, e->param[0]), eval_expr(p, e->param[1]));
> case e_squish: return 1/(1+exp(4*eval_expr(p, e->param[0])));
> case e_gauss: { double d = eval_expr(p, e->param[0]); return exp(-d*d/2)/sqrt(2*M_PI); }
> - case e_ld: return e->value * p->var[av_clip(eval_expr(p, e->param[0]), 0, VARS-1)];
> + case e_ld: return e->value * p->var[av_clip(eval_expr(p, e->param[0]), 0, AV_EXPR_STATE_NB_VARS-1)];
> case e_isnan: return e->value * !!isnan(eval_expr(p, e->param[0]));
> case e_isinf: return e->value * !!isinf(eval_expr(p, e->param[0]));
> case e_floor: return e->value * floor(eval_expr(p, e->param[0]));
> @@ -230,7 +229,7 @@ static double eval_expr(Parser *p, AVExpr *e)
> return x;
> }
> case e_random:{
> - int idx= av_clip(eval_expr(p, e->param[0]), 0, VARS-1);
> + int idx= av_clip(eval_expr(p, e->param[0]), 0, AV_EXPR_STATE_NB_VARS-1);
> uint64_t r= isnan(p->var[idx]) ? 0 : p->var[idx];
> r= r*1664525+1013904223;
> p->var[idx]= r;
> @@ -245,7 +244,7 @@ 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] ? av_clip(eval_expr(p, e->param[2]), 0, VARS-1) : 0;
> + int id = e->param[2] ? av_clip(eval_expr(p, e->param[2]), 0, AV_EXPR_STATE_NB_VARS-1) : 0;
> int i;
> double var0 = p->var[id];
> for(i=0; i<1000; i++) {
> @@ -320,7 +319,7 @@ static double eval_expr(Parser *p, AVExpr *e)
> case e_div: return e->value * ((!CONFIG_FTRAPV || d2 ) ? (d / d2) : d * INFINITY);
> case e_add: return e->value * (d + d2);
> case e_last:return e->value * d2;
> - case e_st : return e->value * (p->var[av_clip(d, 0, VARS-1)]= d2);
> + case e_st : return e->value * (p->var[av_clip(d, 0, AV_EXPR_STATE_NB_VARS-1)]= d2);
> case e_hypot:return e->value * hypot(d, d2);
> case e_atan2:return e->value * atan2(d, d2);
> case e_bitand: return isnan(d) || isnan(d2) ? NAN : e->value * ((long int)d & (long int)d2);
> @@ -333,13 +332,23 @@ static double eval_expr(Parser *p, AVExpr *e)
>
> static int parse_expr(AVExpr **e, Parser *p);
>
> +AVExprState *av_expr_state_alloc(void)
> +{
> + return av_mallocz(sizeof(AVExprState));
> +}
> +
> +void av_expr_state_free(AVExprState **ps)
> +{
> + av_freep(ps);
> +}
> +
> void av_expr_free(AVExpr *e)
> {
> if (!e) return;
> av_expr_free(e->param[0]);
> av_expr_free(e->param[1]);
> av_expr_free(e->param[2]);
> - av_freep(&e->var);
> + av_expr_state_free(&e->state);
> av_freep(&e);
> }
>
> @@ -724,8 +733,8 @@ int av_expr_parse(AVExpr **expr, const char *s,
> ret = AVERROR(EINVAL);
> goto end;
> }
> - e->var= av_mallocz(sizeof(double) *VARS);
> - if (!e->var) {
> + e->state = av_expr_state_alloc();
> + if (!e->state) {
> ret = AVERROR(ENOMEM);
> goto end;
> }
> @@ -763,16 +772,21 @@ int av_expr_count_func(AVExpr *e, unsigned *counter, int size, int arg)
> return expr_count(e, counter, size, ((int[]){e_const, e_func1, e_func2})[arg]);
> }
>
> -double av_expr_eval(AVExpr *e, const double *const_values, void *opaque)
> +double av_expr_eval2(AVExpr *e, AVExprState *s, const double *const_values, void *opaque)
> {
> Parser p = { 0 };
> - p.var= e->var;
> + p.var = s ? s->vars : e->state->vars;
>
> p.const_values = const_values;
> p.opaque = opaque;
> return eval_expr(&p, e);
> }
>
> +double av_expr_eval(AVExpr *e, const double *const_values, void *opaque)
> +{
> + return av_expr_eval2(e, NULL, const_values, opaque);
> +}
> +
> int av_expr_parse_and_eval(double *d, const char *s,
> const char * const *const_names, const double *const_values,
> const char * const *func1_names, double (* const *funcs1)(void *, double),
> diff --git a/libavutil/eval.h b/libavutil/eval.h
> index 068c62cdab..d5b34e54e8 100644
> --- a/libavutil/eval.h
> +++ b/libavutil/eval.h
> @@ -30,6 +30,21 @@
>
> typedef struct AVExpr AVExpr;
>
> +/**
> + * This structure stores a state used by the expression evaluator.
> + * It must be allocated and freed with its proper allocation functions.
> + *
> + * @see av_expr_state_alloc()
> + * @see av_expr_state_free()
> + */
> +typedef struct AVExprState {
> +#define AV_EXPR_STATE_NB_VARS 10
This would make the NB_VARS part of the public API and it would
not be changeable easily, theres nothing here that says it cannot be used
by the user
[...]
--
Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
I know you won't believe me, but the highest form of Human Excellence is
to question oneself and others. -- Socrates
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