On Wed, Jan 01, 2020 at 05:40:33PM +0100, Marton Balint wrote: > > > On Wed, 1 Jan 2020, Michael Niedermayer wrote: > > >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 <c...@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 > > I assumed it is OK as long as you only increase this. If you are adding > other fields, then you are of course locked to 10 vars. What do you propose > instead?
Well, AV_EXPR_STATE_NB_VARS should not be a value in a public header which does not contain a comment saying that it must not be used outside libavutil also the question is, can this struct be made opaque for the user ? if so we can change it in any way in the future, including making it non opaque if needed Thanks [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB Those who are too smart to engage in politics are punished by being governed by those who are dumber. -- Plato
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