diff options
Diffstat (limited to 'lib/hweight.c')
| -rw-r--r-- | lib/hweight.c | 29 |
1 files changed, 14 insertions, 15 deletions
diff --git a/lib/hweight.c b/lib/hweight.c index 721a4b8b4fb8..438257671708 100644 --- a/lib/hweight.c +++ b/lib/hweight.c @@ -10,28 +10,28 @@ unsigned int hweight32(unsigned int w) { - unsigned int res = (w & 0x55555555) + ((w >> 1) & 0x55555555); + unsigned int res = w - ((w >> 1) & 0x55555555); res = (res & 0x33333333) + ((res >> 2) & 0x33333333); - res = (res & 0x0F0F0F0F) + ((res >> 4) & 0x0F0F0F0F); - res = (res & 0x00FF00FF) + ((res >> 8) & 0x00FF00FF); - return (res & 0x0000FFFF) + ((res >> 16) & 0x0000FFFF); + res = (res + (res >> 4)) & 0x0F0F0F0F; + res = res + (res >> 8); + return (res + (res >> 16)) & 0x000000FF; } EXPORT_SYMBOL(hweight32); unsigned int hweight16(unsigned int w) { - unsigned int res = (w & 0x5555) + ((w >> 1) & 0x5555); + unsigned int res = w - ((w >> 1) & 0x5555); res = (res & 0x3333) + ((res >> 2) & 0x3333); - res = (res & 0x0F0F) + ((res >> 4) & 0x0F0F); - return (res & 0x00FF) + ((res >> 8) & 0x00FF); + res = (res + (res >> 4)) & 0x0F0F; + return (res + (res >> 8)) & 0x00FF; } EXPORT_SYMBOL(hweight16); unsigned int hweight8(unsigned int w) { - unsigned int res = (w & 0x55) + ((w >> 1) & 0x55); + unsigned int res = w - ((w >> 1) & 0x55); res = (res & 0x33) + ((res >> 2) & 0x33); - return (res & 0x0F) + ((res >> 4) & 0x0F); + return (res + (res >> 4)) & 0x0F; } EXPORT_SYMBOL(hweight8); @@ -40,13 +40,12 @@ unsigned long hweight64(__u64 w) #if BITS_PER_LONG == 32 return hweight32((unsigned int)(w >> 32)) + hweight32((unsigned int)w); #elif BITS_PER_LONG == 64 - u64 res; - res = (w & 0x5555555555555555ul) + ((w >> 1) & 0x5555555555555555ul); + __u64 res = w - ((w >> 1) & 0x5555555555555555ul); res = (res & 0x3333333333333333ul) + ((res >> 2) & 0x3333333333333333ul); - res = (res & 0x0F0F0F0F0F0F0F0Ful) + ((res >> 4) & 0x0F0F0F0F0F0F0F0Ful); - res = (res & 0x00FF00FF00FF00FFul) + ((res >> 8) & 0x00FF00FF00FF00FFul); - res = (res & 0x0000FFFF0000FFFFul) + ((res >> 16) & 0x0000FFFF0000FFFFul); - return (res & 0x00000000FFFFFFFFul) + ((res >> 32) & 0x00000000FFFFFFFFul); + res = (res + (res >> 4)) & 0x0F0F0F0F0F0F0F0Ful; + res = res + (res >> 8); + res = res + (res >> 16); + return (res + (res >> 32)) & 0x00000000000000FFul; #else #error BITS_PER_LONG not defined #endif |