freebsd-dev/contrib/gperf/lib/hash.cc
Baptiste Daroussin acca521c82 upgrade gperf to the last GPLv2 version (3.0.3)
Reviewed by:	cognet
Approved by:	cognet
2011-11-28 12:29:16 +00:00

28 lines
584 B
C++

/*
Copyright (C) 1990, 2000, 2002 Free Software Foundation
written by Doug Lea <dl@rocky.oswego.edu>
*/
#include <hash.h>
/*
Some useful hash function.
It's not a particularly good hash function (<< 5 would be better than << 4),
but people believe in it because it comes from Dragon book.
*/
unsigned int
hashpjw (const unsigned char *x, unsigned int len) // From Dragon book, p436
{
unsigned int h = 0;
unsigned int g;
for (; len > 0; len--)
{
h = (h << 4) + *x++;
if ((g = h & 0xf0000000) != 0)
h = (h ^ (g >> 24)) ^ g;
}
return h;
}