Function sign_extend

libavcodec/mathops.h:135–140

#ifndef sign_extend
static inline av_const int sign_extend(int val, unsigned bits)
{
    unsigned shift = 8 * sizeof(int) - bits;
    union { unsigned u; int s; } v = { (unsigned) val << shift };
    return v.s >> shift;
}
#endif

#ifndef sign_extend64