Imported Upstream version 93u+upstream

1 files changed, 61 insertions, 0 deletions

diff --git a/src/lib/libast/cdt/dtstrhash.c b/src/lib/libast/cdt/dtstrhash.c
new file mode 100644
index 0000000..7eaac89
--- /dev/null
+++ b/src/lib/libast/cdt/dtstrhash.c
@@ -0,0 +1,61 @@
+/***********************************************************************
+*                                                                      *
+*               This software is part of the ast package               *
+*          Copyright (c) 1985-2011 AT&T Intellectual Property          *
+*                      and is licensed under the                       *
+*                 Eclipse Public License, Version 1.0                  *
+*                    by AT&T Intellectual Property                     *
+*                                                                      *
+*                A copy of the License is available at                 *
+*          http://www.eclipse.org/org/documents/epl-v10.html           *
+*         (with md5 checksum b35adb5213ca9657e911e9befb180842)         *
+*                                                                      *
+*              Information and Software Systems Research               *
+*                            AT&T Research                             *
+*                           Florham Park NJ                            *
+*                                                                      *
+*                 Glenn Fowler <gsf@research.att.com>                  *
+*                  David Korn <dgk@research.att.com>                   *
+*                   Phong Vo <kpv@research.att.com>                    *
+*                                                                      *
+***********************************************************************/
+#include	"dthdr.h"
+
+/* Hashing a string into an unsigned integer.
+** The basic method is to continuingly accumulate bytes and multiply
+** with some given prime. The length n of the string is added last.
+** The recurrent equation is like this:
+**	h[k] = (h[k-1] + bytes)*prime	for 0 <= k < n
+**	h[n] = (h[n-1] + n)*prime
+** The prime is chosen to have a good distribution of 1-bits so that
+** the multiplication will distribute the bits in the accumulator well.
+** The below code accumulates 2 bytes at a time for speed.
+**
+** Written by Kiem-Phong Vo (02/28/03)
+*/
+
+#if __STD_C
+uint dtstrhash(uint h, Void_t* args, ssize_t n)
+#else
+uint dtstrhash(h,args,n)
+reg uint	h;
+Void_t*		args;
+ssize_t		n;
+#endif
+{
+	unsigned char	*s = (unsigned char*)args;
+
+	if(n <= 0)
+	{	for(; *s != 0; s += s[1] ? 2 : 1)
+			h = (h + (s[0]<<8) + s[1])*DT_PRIME;
+		n = s - (unsigned char*)args;
+	}
+	else
+	{	unsigned char*	ends;
+		for(ends = s+n-1; s < ends; s += 2)
+			h = (h + (s[0]<<8) + s[1])*DT_PRIME;
+		if(s <= ends)
+			h = (h + (s[0]<<8))*DT_PRIME;
+	}
+	return (h+n)*DT_PRIME;
+}