On Sun, Dec 29, 2019 at 04:46:12PM +0100, Marton Balint wrote: > > > On Sun, 29 Dec 2019, Michael Niedermayer wrote: > > >On Sat, Dec 28, 2019 at 03:46:23PM +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 | 3 +++ > >> libavutil/eval.c | 31 +++++++++++++++++++++++++------ > >> libavutil/eval.h | 27 +++++++++++++++++++++++++++ > >> libavutil/version.h | 2 +- > >> 4 files changed, 56 insertions(+), 7 deletions(-) > >> > >>diff --git a/doc/APIchanges b/doc/APIchanges > >>index 3c24dc6fbc..e4ad364ed9 100644 > >>--- a/doc/APIchanges > >>+++ b/doc/APIchanges > >>@@ -15,6 +15,9 @@ libavutil: 2017-10-21 > >> > >> API changes, most recent first: > >> > >>+2020-01-xx - xxxxxxxxxx - lavu 56.39.100 - eval.h > >>+ Add av_expr_eval2, av_expr_state_alloc, av_expr_state_free > >>+ > >> 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..86fb634fd8 100644 > >>--- a/libavutil/eval.c > >>+++ b/libavutil/eval.c > >>@@ -173,7 +173,11 @@ struct AVExpr { > >> double (*func2)(void *, double, double); > >> } a; > >> struct AVExpr *param[3]; > >>- double *var; > >>+ AVExprState *state; > >>+}; > >>+ > >>+struct AVExprState { > >>+ double vars[VARS]; > >> }; > >> > >> static double etime(double v) > >>@@ -333,13 +337,23 @@ 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 +738,8 @@ 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 +777,21 @@ 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..8bd1592f6c 100644 > >>--- a/libavutil/eval.h > >>+++ b/libavutil/eval.h > >>@@ -29,6 +29,7 @@ > >> #include "avutil.h" > >> > >> typedef struct AVExpr AVExpr; > >>+typedef struct AVExprState AVExprState; > >> > >> /** > >> * Parse and evaluate an expression. > >>@@ -86,6 +87,22 @@ int av_expr_parse(AVExpr **expr, const char *s, > >> */ > >> double av_expr_eval(AVExpr *e, const double *const_values, void *opaque); > >> > >>+/** > >>+ * Evaluate a previously parsed expression using a custom state. > >>+ * > >>+ * Some expressions can use stateful functions, like random(), st() and > >>ld(). > >>+ * With this function you can provide your own state to the evaluator > >>instead > >>+ * of using the internal state of the AVExpr. This makes it possible to > >>use the > >>+ * same AVExpr in multiple threads each with their own AVExprState avoiding > >>+ * unprotected concurrent access of the internal AVExpr state. > >>+ * > >>+ * @param s the state of the expression, if NULL, the internal state of > >>AVExpr will be used > >>+ * @param const_values a zero terminated array of values for the > >>identifiers from av_expr_parse() const_names > >>+ * @param opaque a pointer which will be passed to all functions from > >>funcs1 and funcs2 > >>+ * @return the value of the expression > >>+ */ > >>+double av_expr_eval2(AVExpr *e, AVExprState *s, const double > >>*const_values, void *opaque); > >>+ > >> /** > >> * Track the presence of variables and their number of occurrences in a > >> parsed expression > >> * > >>@@ -134,4 +151,14 @@ void av_expr_free(AVExpr *e); > >> */ > >> double av_strtod(const char *numstr, char **tail); > >> > >>+/** > >>+ * Allocate a new AVExprState struct > >>+ */ > >>+AVExprState *av_expr_state_alloc(void); > > > >maybe this should have a double [] argument so the caller can set the > >initial variables (or pass NULL if not) > > Maybe it is better to simply make the AVExprState struct public if > setting/getting state manually is something we want to support. What do you > think?
if its still extendible, then it may be a good idea, yes thx [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB "I am not trying to be anyone's saviour, I'm trying to think about the future and not be sad" - Elon Musk
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