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 <[email protected]> --- 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); + +/** + * Free an allocated AVExprState struct and set its pointer to NULL + */ +void av_expr_state_free(AVExprState **ps); + #endif /* AVUTIL_EVAL_H */ diff --git a/libavutil/version.h b/libavutil/version.h index af8f614aff..2bc1b98615 100644 --- a/libavutil/version.h +++ b/libavutil/version.h @@ -79,7 +79,7 @@ */ #define LIBAVUTIL_VERSION_MAJOR 56 -#define LIBAVUTIL_VERSION_MINOR 38 +#define LIBAVUTIL_VERSION_MINOR 39 #define LIBAVUTIL_VERSION_MICRO 100 #define LIBAVUTIL_VERSION_INT AV_VERSION_INT(LIBAVUTIL_VERSION_MAJOR, \ -- 2.16.4 _______________________________________________ ffmpeg-devel mailing list [email protected] https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email [email protected] with subject "unsubscribe".
