diff options
Diffstat (limited to 'compiler-rt/lib/builtins/popcountti2.c')
| -rw-r--r-- | compiler-rt/lib/builtins/popcountti2.c | 46 |
1 files changed, 25 insertions, 21 deletions
diff --git a/compiler-rt/lib/builtins/popcountti2.c b/compiler-rt/lib/builtins/popcountti2.c index 62309f11ad1..087e3807e46 100644 --- a/compiler-rt/lib/builtins/popcountti2.c +++ b/compiler-rt/lib/builtins/popcountti2.c @@ -17,27 +17,31 @@ /* Returns: count of 1 bits */ -COMPILER_RT_ABI si_int -__popcountti2(ti_int a) -{ - tu_int x3 = (tu_int)a; - x3 = x3 - ((x3 >> 1) & (((tu_int)0x5555555555555555uLL << 64) | - 0x5555555555555555uLL)); - /* Every 2 bits holds the sum of every pair of bits (64) */ - x3 = ((x3 >> 2) & (((tu_int)0x3333333333333333uLL << 64) | 0x3333333333333333uLL)) - + (x3 & (((tu_int)0x3333333333333333uLL << 64) | 0x3333333333333333uLL)); - /* Every 4 bits holds the sum of every 4-set of bits (3 significant bits) (32) */ - x3 = (x3 + (x3 >> 4)) - & (((tu_int)0x0F0F0F0F0F0F0F0FuLL << 64) | 0x0F0F0F0F0F0F0F0FuLL); - /* Every 8 bits holds the sum of every 8-set of bits (4 significant bits) (16) */ - du_int x2 = (du_int)(x3 + (x3 >> 64)); - /* Every 8 bits holds the sum of every 8-set of bits (5 significant bits) (8) */ - su_int x = (su_int)(x2 + (x2 >> 32)); - /* Every 8 bits holds the sum of every 8-set of bits (6 significant bits) (4) */ - x = x + (x >> 16); - /* Every 8 bits holds the sum of every 8-set of bits (7 significant bits) (2) */ - /* Upper 16 bits are garbage */ - return (x + (x >> 8)) & 0xFF; /* (8 significant bits) */ +COMPILER_RT_ABI si_int __popcountti2(ti_int a) { + tu_int x3 = (tu_int)a; + x3 = x3 - ((x3 >> 1) & + (((tu_int)0x5555555555555555uLL << 64) | 0x5555555555555555uLL)); + /* Every 2 bits holds the sum of every pair of bits (64) */ + x3 = ((x3 >> 2) & + (((tu_int)0x3333333333333333uLL << 64) | 0x3333333333333333uLL)) + + (x3 & (((tu_int)0x3333333333333333uLL << 64) | 0x3333333333333333uLL)); + /* Every 4 bits holds the sum of every 4-set of bits (3 significant bits) (32) + */ + x3 = (x3 + (x3 >> 4)) & + (((tu_int)0x0F0F0F0F0F0F0F0FuLL << 64) | 0x0F0F0F0F0F0F0F0FuLL); + /* Every 8 bits holds the sum of every 8-set of bits (4 significant bits) (16) + */ + du_int x2 = (du_int)(x3 + (x3 >> 64)); + /* Every 8 bits holds the sum of every 8-set of bits (5 significant bits) (8) + */ + su_int x = (su_int)(x2 + (x2 >> 32)); + /* Every 8 bits holds the sum of every 8-set of bits (6 significant bits) (4) + */ + x = x + (x >> 16); + /* Every 8 bits holds the sum of every 8-set of bits (7 significant bits) (2) + */ + /* Upper 16 bits are garbage */ + return (x + (x >> 8)) & 0xFF; /* (8 significant bits) */ } #endif /* CRT_HAS_128BIT */ |
