Date: Fri, 28 Dec 2007 13:35:43 +0100 From: Ivan Voras <ivoras@freebsd.org> To: freebsd-hackers@freebsd.org Subject: Re: BSD license compatible hash algorithm? Message-ID: <fl2qiv$qoh$1@ger.gmane.org> In-Reply-To: <B8D4C3C6-B867-4550-9F17-4DC6930D10E2@u.washington.edu> References: <5950EE0C-383D-4D6B-9991-A0DEABD2ADE4@u.washington.edu> <20071228003716.GB48997@lor.one-eyed-alien.net> <B8D4C3C6-B867-4550-9F17-4DC6930D10E2@u.washington.edu>
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Garrett Cooper wrote:
> Looks promising, but how difficult would it be to port the code to
> other platforms (Win32 for instance?).
The hash algorithm itself as implemented in hash.h is pretty much a
text-book hash algorithm (D.J.Bernstein's):
#ifndef HASHINIT
#define HASHINIT 5381
#define HASHSTEP(x,c) (((x << 5) + x) + (c))
#endif
/*
* Return a 32-bit hash of the given buffer. The init
* value should be 0, or the previous hash value to extend
* the previous hash.
*/
static __inline uint32_t
hash32_buf(const void *buf, size_t len, uint32_t hash)
{
const unsigned char *p = buf;
while (len--)
hash = HASHSTEP(hash, *p++);
return hash;
}
It apparently has some weaknesses if used on binary (non-text) data but
I don't see why it wouldn't work on Windows.
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