svn commit: r223884 - head/sys/sys

[Ed Schouten]

Hi Kostik,

* Konstantin Belousov <kib at FreeBSD.org>, 20110709 16:29:
> +static __inline uint16_t
> +bitcount16(uint32_t x)

Shouldn't we use uint16_t for the argument here?

When I saw the code, I thought by myself, this could be done more
efficiently:

| static __inline uint16_t
| bitcount16(uint16_t x)
| {
|
| 	x = (x & 0x5555) + ((x >> 1) & 0x5555);
| 	x = (x & 0x3333) + ((x >> 2) & 0x3333);
| 	x *= 0x1111;
| 	return (x >> 12);
| }

But some testing revealed it works for all inputs, except 65536. d'oh!

-- 
 Ed Schouten <ed at 80386.nl>
 WWW: http://80386.nl/
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