[Ffmpeg-devel] clip_uint8

[Panagiotis Issaris]

Hi,

The clip function clips between the amin and amax values given as parameters, 
the clip_uint8 function, actually behaves a bit differently. The lower bound
is indeed 0 as the uint8 postfix in the name implies, but upper values (values 
higher then 255) are returned as -1. This works if the value which stores the 
returned value is uint8, but in other cases will cause strange behavior imho.

libavutil/common.h:
430 static inline int clip(int a, int amin, int amax)
431 {
432     if (a < amin)
433         return amin;
434     else if (a > amax)
435         return amax;
436     else
437         return a;
438 }
439
440 static inline int clip_uint8(int a)
441 {
442     if (a&(~255)) return (-a)>>31;
443     else          return a;
444 }

Changing the return type to uint8_t fixes this, or was the -1 
return value intentional?

diff --git a/libavutil/common.h b/libavutil/common.h
index d8f2c40..92c0d08 100644
--- a/libavutil/common.h
+++ b/libavutil/common.h
@@ -437,7 +437,7 @@ static inline int clip(int a, int amin,
         return a;
 }

-static inline int clip_uint8(int a)
+static inline uint8_t clip_uint8(int a)
 {
     if (a&(~255)) return (-a)>>31;
     else          return a;



With friendly regards,
Takis