diff options
Diffstat (limited to 'libavutil/internal.h')
-rw-r--r-- | libavutil/internal.h | 37 |
1 files changed, 37 insertions, 0 deletions
diff --git a/libavutil/internal.h b/libavutil/internal.h index 5c2cd99dcc..8d2d8759bf 100644 --- a/libavutil/internal.h +++ b/libavutil/internal.h @@ -257,6 +257,43 @@ void avpriv_request_sample(void *avc, #endif /** + * Clip and convert a double value into the long long amin-amax range. + * This function is needed because conversion of floating point to integers when + * it does not fit in the integer's representation does not necessarily saturate + * correctly (usually converted to a cvttsd2si on x86) which saturates numbers + * > INT64_MAX to INT64_MIN. The standard marks such conversions as undefined + * behavior, allowing this sort of mathematically bogus conversions. This provides + * a safe alternative that is slower obviously but assures safety and better + * mathematical behavior. + * @param a value to clip + * @param amin minimum value of the clip range + * @param amax maximum value of the clip range + * @return clipped value + */ +static av_always_inline av_const int64_t ff_rint64_clip(double a, int64_t amin, int64_t amax) +{ + int64_t res; +#if defined(HAVE_AV_CONFIG_H) && defined(ASSERT_LEVEL) && ASSERT_LEVEL >= 2 + if (amin > amax) abort(); +#endif + // INT64_MAX+1,INT64_MIN are exactly representable as IEEE doubles + // do range checks first + if (a >= 9223372036854775808.0) + return amax; + if (a <= -9223372036854775808.0) + return amin; + + // safe to call llrint and clip accordingly + res = llrint(a); + if (res > amax) + return amax; + if (res < amin) + return amin; + return res; +} + + +/** * A wrapper for open() setting O_CLOEXEC. */ av_warn_unused_result |