ack/util/topgen/hash.c

/* $Id$ */
/*
 * (c) copyright 1987 by the Vrije Universiteit, Amsterdam, The Netherlands.
 * See the copyright notice in the ACK home directory, in the file "Copyright".
 */
/* h a s h . c
 *
 * maintains the the lists of hashed patterns
 * Functions : addtohashtable() and printhashtable()
 */

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include "misc.h"
#include "hash.h"

struct hlist
{ /* linear list of pattern numbers */
	int h_patno;
	struct hlist *h_next;
};

static struct hlist *hashtable[129]; /* an array of ptr's to these lists,
 * the index in the array is the
 * result of hashing
 */

static unsigned hash(char* string)
{
	register char *p;
	register unsigned i, sum;

	if (strcmp(string, "ANY") == 0)
		return 128;
	for (sum = i = 0, p = string; *p; i += 3)
		sum += (*p++) << (i & 03);
	return sum % 128;
}

void addtohashtable(char* s, int n)
{
	/*
	 * Add a new pattern number to the hashtable.
	 * s is the key, n the pattern number
	 */
	unsigned hval;
	register struct hlist *p;

	hval = hash(s);
	p = (struct hlist *) malloc(sizeof *p);
	p->h_patno = n;
	/*
	 * Now insert in front of the list
	 * This way, the list will be sorted from high to low, which is the
	 * wrong way around, but easy
	 */
	p->h_next = hashtable[hval];
	hashtable[hval] = p;
}

static void prhlist(struct hlist *p)
{
	/*
	 * Print a list in reversed order (see comment above)
	 */

	if (p)
	{
		prhlist(p->h_next);
		fprintf(genc, "%d, ", p->h_patno - 1);
	}
}

void printhashtable(void)
{
	/*
	 * Print the linear lists, and also output an array of
	 * pointers to them
	 */
	register int i;

	for (i = 1; i <= 128; i++)
	{
		fprintf(genc, "int hash%d[] = { ", i);
		prhlist(hashtable[i - 1]);
		fputs("-1};\n", genc);
	}
	fputs("int hashany[] = { ", genc);
	prhlist(hashtable[128]);
	fputs("-1 };\n", genc);
	fputs("int *hashtab[] = {\n", genc);
	for (i = 1; i <= 128; i++)
		fprintf(genc, "\thash%d,\n", i);
	fputs("\thashany\n};\n", genc);
}