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/*
Clif - A C-like Interpreter Framework
Copyright (C) 1992, 1993, 1994, 1995, 1996, 1997 T. Hruz, L. Koren
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
/*
symbols.c
saving a copy of each string
*/
#include <string.h>
#include "allocx.h"
#ifndef PROTO
#if defined (USE_PROTOTYPES) ? USE_PROTOTYPES : defined(__STDC__)
#define PROTO(ARGS) ARGS
#else
#define PROTO(ARGS) ()
#endif
#endif
#define SIZE_HAS 1999
#define PAGE 1024
#define K 4
static unsigned int hash PROTO((char *));
char *string PROTO((char *));
static struct string
{
char *str;
int len;
struct string *next;
} *buckets[SIZE_HAS + 1];
static unsigned int
hash (s)
char *s;
{
int c = 0;
while (*s)
{
c = c << 1 ^ (*s);
s++;
}
if (0 > c)
c = (-c);
return (c % SIZE_HAS);
}
char *
string (s)
char *s;
{
int len = strlen (s);
unsigned int h;
struct string *p;
char *end = s + len;
h = hash (s);
for (p = buckets[h]; p; p = p->next)
if (p->len == len)
{
char *s1 = s, *s2 = p->str;
do
{
if (s1 == end)
return p->str;
} while (*s1++ == *s2++);
}
{
static char *next, *limit;
if (next + len + 1 >= limit)
{
int n = len + K * PAGE;
next = allocate (n, PERM);
limit = next + n;
}
p = (struct string *)allocate (sizeof (*p), PERM);
p->len = len;
for (p->str = next; s < end;)
*next++ = *s++;
*next++ = '\0';
p->next = buckets[h];
buckets[h] = p;
return p->str;
}
}
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