From d6cd614dac579850076ae312c29c4188f8659e46 Mon Sep 17 00:00:00 2001 From: Michael Niedermayer Date: Thu, 3 Sep 2015 02:17:24 +0200 Subject: [PATCH] avutil/common: Add FFNABS() This macro avoids the undefined corner case with the *_MIN values Previous version Reviewed-by: Ganesh Ajjanagadde Signed-off-by: Michael Niedermayer --- libavutil/common.h | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/libavutil/common.h b/libavutil/common.h index 14343d977b..38eae28d2a 100644 --- a/libavutil/common.h +++ b/libavutil/common.h @@ -63,10 +63,19 @@ * Absolute value, Note, INT_MIN / INT64_MIN result in undefined behavior as they * are not representable as absolute values of their type. This is the same * as with *abs() + * @see FFNABS() */ #define FFABS(a) ((a) >= 0 ? (a) : (-(a))) #define FFSIGN(a) ((a) > 0 ? 1 : -1) +/** + * Negative Absolute value. + * this works for all integers of all types. + * As with many macros, this evaluates its argument twice, it thus must not have + * a sideeffect, that is FFNABS(x++) has undefined behavior. + */ +#define FFNABS(a) ((a) <= 0 ? (a) : (-(a))) + #define FFMAX(a,b) ((a) > (b) ? (a) : (b)) #define FFMAX3(a,b,c) FFMAX(FFMAX(a,b),c) #define FFMIN(a,b) ((a) > (b) ? (b) : (a)) -- GitLab