diff options
Diffstat (limited to 'libavutil/intmath.h')
| -rw-r--r-- | libavutil/intmath.h | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/libavutil/intmath.h b/libavutil/intmath.h index 08d54a64ad..b412385e53 100644 --- a/libavutil/intmath.h +++ b/libavutil/intmath.h @@ -114,6 +114,9 @@ static av_always_inline av_const int ff_log2_16bit_c(unsigned int v) #ifndef ff_ctz #define ff_ctz(v) __builtin_ctz(v) #endif +#ifndef ff_ctzll +#define ff_ctzll(v) __builtin_ctzll(v) +#endif #endif #endif @@ -158,6 +161,22 @@ static av_always_inline av_const int ff_ctz_c( int v ) #endif #endif +#ifndef ff_ctzll +#define ff_ctzll ff_ctzll_c +/* We use the De-Bruijn method outlined in: + * http://supertech.csail.mit.edu/papers/debruijn.pdf. */ +static av_always_inline av_const int ff_ctzll_c(long long v) +{ + static const int debruijn_ctz64[64] = { + 0, 1, 2, 53, 3, 7, 54, 27, 4, 38, 41, 8, 34, 55, 48, 28, + 62, 5, 39, 46, 44, 42, 22, 9, 24, 35, 59, 56, 49, 18, 29, 11, + 63, 52, 6, 26, 37, 40, 33, 47, 61, 45, 43, 21, 23, 58, 17, 10, + 51, 25, 36, 32, 60, 20, 57, 16, 50, 31, 19, 15, 30, 14, 13, 12 + }; + return debruijn_ctz64[(uint64_t)((v & -v) * 0x022FDD63CC95386D) >> 58]; +} +#endif + /** * Trailing zero bit count. * |