From 999495734b9de597f59590708979902f28ebce61 Mon Sep 17 00:00:00 2001 From: Stefano Sabatini Date: Sun, 15 Jan 2012 22:59:42 +0100 Subject: [PATCH] lavu/eval: add if() and ifnot() eval functions They allow to implement the if/then/else logic, which cannot be implemented otherwise. For example the expression: A*B + not(A)*C always evaluates to NaN if B is NaN, even in the case where A is 0. --- doc/eval.texi | 12 ++++++++++-- libavutil/avutil.h | 2 +- libavutil/eval.c | 8 ++++++++ tests/ref/fate/eval | 9 +++++++++ 4 files changed, 28 insertions(+), 3 deletions(-) diff --git a/doc/eval.texi b/doc/eval.texi index b325b37dff..95e9df5a80 100644 --- a/doc/eval.texi +++ b/doc/eval.texi @@ -98,6 +98,14 @@ point (@var{x}, @var{y}) from the origin. @item gcd(x, y) Return the greatest common divisor of @var{x} and @var{y}. If both @var{x} and @var{y} are 0 or either or both are less than zero then behavior is undefined. + +@item if(x, y) +Evaluate @var{x}, and if the result is non-zero return the result of +the evaluation of @var{y}, return 0 otherwise. + +@item ifnot(x, y) +Evaluate @var{x}, and if the result is zero return the result of the +evaluation of @var{y}, return 0 otherwise. @end table The following constants are available: @@ -116,13 +124,13 @@ Note that: @code{+} works like OR -thus +and the construct: @example if A then B else C @end example is equivalent to @example -A*B + not(A)*C +if(A,B) + ifnot(A,C) @end example In your C code, you can extend the list of unary and binary functions, diff --git a/libavutil/avutil.h b/libavutil/avutil.h index d6855a4020..3f772621e0 100644 --- a/libavutil/avutil.h +++ b/libavutil/avutil.h @@ -155,7 +155,7 @@ #define LIBAVUTIL_VERSION_MAJOR 51 #define LIBAVUTIL_VERSION_MINOR 34 -#define LIBAVUTIL_VERSION_MICRO 100 +#define LIBAVUTIL_VERSION_MICRO 101 #define LIBAVUTIL_VERSION_INT AV_VERSION_INT(LIBAVUTIL_VERSION_MAJOR, \ LIBAVUTIL_VERSION_MINOR, \ diff --git a/libavutil/eval.c b/libavutil/eval.c index 1b8176c505..2ee3965e7c 100644 --- a/libavutil/eval.c +++ b/libavutil/eval.c @@ -136,6 +136,7 @@ struct AVExpr { e_pow, e_mul, e_div, e_add, e_last, e_st, e_while, e_floor, e_ceil, e_trunc, e_sqrt, e_not, e_random, e_hypot, e_gcd, + e_if, e_ifnot, } type; double value; // is sign in other types union { @@ -165,6 +166,8 @@ static double eval_expr(Parser *p, AVExpr *e) case e_trunc: return e->value * trunc(eval_expr(p, e->param[0])); case e_sqrt: return e->value * sqrt (eval_expr(p, e->param[0])); case e_not: return e->value * (eval_expr(p, e->param[0]) == 0); + case e_if: return e->value * ( eval_expr(p, e->param[0]) ? eval_expr(p, e->param[1]) : 0); + case e_ifnot: return e->value * (!eval_expr(p, e->param[0]) ? eval_expr(p, e->param[1]) : 0); case e_random:{ int idx= av_clip(eval_expr(p, e->param[0]), 0, VARS-1); uint64_t r= isnan(p->var[idx]) ? 0 : p->var[idx]; @@ -324,6 +327,8 @@ static int parse_primary(AVExpr **e, Parser *p) else if (strmatch(next, "random")) d->type = e_random; else if (strmatch(next, "hypot" )) d->type = e_hypot; else if (strmatch(next, "gcd" )) d->type = e_gcd; + else if (strmatch(next, "if" )) d->type = e_if; + else if (strmatch(next, "ifnot" )) d->type = e_ifnot; else { for (i=0; p->func1_names && p->func1_names[i]; i++) { if (strmatch(next, p->func1_names[i])) { @@ -690,6 +695,9 @@ int main(int argc, char **argv) "pow(PI,1.23)", "PI^1.23", "pow(-1,1.23)", + "if(1, 2)", + "ifnot(0, 23)", + "ifnot(1, NaN) + if(0, 1)", NULL }; diff --git a/tests/ref/fate/eval b/tests/ref/fate/eval index 88d7e17bee..09e310f25d 100644 --- a/tests/ref/fate/eval +++ b/tests/ref/fate/eval @@ -160,5 +160,14 @@ Evaluating 'PI^1.23' Evaluating 'pow(-1,1.23)' 'pow(-1,1.23)' -> nan +Evaluating 'if(1, 2)' +'if(1, 2)' -> 2.000000 + +Evaluating 'ifnot(0, 23)' +'ifnot(0, 23)' -> 23.000000 + +Evaluating 'ifnot(1, NaN) + if(0, 1)' +'ifnot(1, NaN) + if(0, 1)' -> 0.000000 + 12.700000 == 12.7 0.931323 == 0.931322575