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| author | Kaz Kylheku <kaz@kylheku.com> | 2019-02-19 06:39:02 -0800 |
|---|---|---|
| committer | Kaz Kylheku <kaz@kylheku.com> | 2019-02-19 06:39:02 -0800 |
| commit | 15b7c542dc44899e8db7addfcc2f1c1c4a188b49 (patch) | |
| tree | 3857de5f06aae8f5bf25acebe306920545fc7ee4 /mpi | |
| parent | 2b3179ea5e50778f1f19054b9d6d8aa06d683081 (diff) | |
| download | txr-15b7c542dc44899e8db7addfcc2f1c1c4a188b49.tar.gz txr-15b7c542dc44899e8db7addfcc2f1c1c4a188b49.tar.bz2 txr-15b7c542dc44899e8db7addfcc2f1c1c4a188b49.zip | |
mpi/arith: optimize "highest bit" with GCC builtins.
* arith.c (highest_bit): On GCC, use __builtin_clz.
* mpi/mpi.c (s_highest_bit): Likewise.
Diffstat (limited to 'mpi')
| -rw-r--r-- | mpi/mpi.c | 8 |
1 files changed, 7 insertions, 1 deletions
@@ -2949,7 +2949,13 @@ void s_mp_clamp(mp_int *mp) static mp_size s_highest_bit(mp_digit n) { -#if MP_DIGIT_SIZE == 8 +#if defined __GNUC__ && MP_DIGIT_SIZE == SIZEOF_INT + return (n == 0) ? 0 : (MP_DIGIT_BIT - __builtin_clz(n)); +#elif defined __GNUC__ && MP_DIGIT_SIZE == SIZEOF_LONG + return (n == 0) ? 0 : (MP_DIGIT_BIT - __builtin_clzl(n)); +#elif defined __GNUC__ && MP_DIGIT_SIZE == SIZEOF_LONGLONG_T + return (n == 0) ? 0 : (MP_DIGIT_BIT - __builtin_clzll(n)); +#elif MP_DIGIT_SIZE == 8 if (n & 0xFFFFFFFF00000000) { if (n & 0xFFFF000000000000) { if (n & 0xFF00000000000000) { |