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avutil/common: Fix underflow for ROUNDED_DIV with unsigned integer

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When used ROUNDED_DIV(a,b), if a is unsigned integer zero, it's
will lead to an underflow issue(it called unsigned integer
wrapping).

Fixes #8062

Reviewed-by: Michael Niedermayer <michael@niedermayer.cc>
Signed-off-by: Mengye Lv <mengyelv@tencent.com>
Signed-off-by: Jun Zhao <barryjzhao@tencent.com>
This commit is contained in:
Mengye Lv 2019-10-02 10:30:45 +08:00 committed by Jun Zhao
parent 3b4e9a31ea
commit 9f353e376b
1 changed files with 1 additions and 1 deletions
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2
libavutil/common.h
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@ -53,7 +53,7 @@
//rounded division & shift
#define RSHIFT(a,b) ((a) > 0 ? ((a) + ((1<<(b))>>1))>>(b) : ((a) + ((1<<(b))>>1)-1)>>(b))
/* assume b>0 */
#define ROUNDED_DIV(a,b) (((a)>0 ? (a) + ((b)>>1) : (a) - ((b)>>1))/(b))
#define ROUNDED_DIV(a,b) (((a)>=0 ? (a) + ((b)>>1) : (a) - ((b)>>1))/(b))
/* Fast a/(1<<b) rounded toward +inf. Assume a>=0 and b>=0 */
#define AV_CEIL_RSHIFT(a,b) (!av_builtin_constant_p(b) ? -((-(a)) >> (b)) \
: ((a) + (1<<(b)) - 1) >> (b))