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avutil/common: Add saturated add/sub operations for int64_t.

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Many places are using their own custom code for handling overflow
around timestamps or other int64_t values. There are enough of these
now that having some common saturated math functions seems sound.

Signed-off-by: Dale Curtis <dalecurtis@chromium.org>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
This commit is contained in:
Dale Curtis 2020-04-30 15:16:31 -07:00 committed by Michael Niedermayer
parent 2d8d554f15
commit a7e1af3cb1
1 changed files with 36 additions and 0 deletions
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36
libavutil/common.h
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@ -291,6 +291,36 @@ static av_always_inline int av_sat_dsub32_c(int a, int b)
return av_sat_sub32(a, av_sat_add32(b, b));
}
/**
* Add two signed 64-bit values with saturation.
*
* @param a one value
* @param b another value
* @return sum with signed saturation
*/
static av_always_inline int64_t av_sat_add64_c(int64_t a, int64_t b) {
if (b >= 0 && a >= INT64_MAX - b)
return INT64_MAX;
if (b <= 0 && a <= INT64_MIN - b)
return INT64_MIN;
return a + b;
}
/**
* Subtract two signed 64-bit values with saturation.
*
* @param a one value
* @param b another value
* @return difference with signed saturation
*/
static av_always_inline int64_t av_sat_sub64_c(int64_t a, int64_t b) {
if (b <= 0 && a >= INT64_MAX + b)
return INT64_MAX;
if (b >= 0 && a <= INT64_MIN + b)
return INT64_MIN;
return a - b;
}
/**
* Clip a float value into the amin-amax range.
* @param a value to clip
@ -545,6 +575,12 @@ static av_always_inline av_const int av_parity_c(uint32_t v)
#ifndef av_sat_dsub32
# define av_sat_dsub32 av_sat_dsub32_c
#endif
#ifndef av_sat_add64
# define av_sat_add64 av_sat_add64_c
#endif
#ifndef av_sat_sub64
# define av_sat_sub64 av_sat_sub64_c
#endif
#ifndef av_clipf
# define av_clipf av_clipf_c
#endif