distrib/x2p/hash.c

/* $RCSfile: hash.c,v $$Revision: 4.1 $$Date: 92/08/07 18:29:20 $
 *
 *    Copyright (C) 1991, 1992, 1993, 1994, 1995, 1999, 2000, 2001, 2002,
 *    by Larry Wall and others
 *
 *    You may distribute under the terms of either the GNU General Public
 *    License or the Artistic License, as specified in the README file.
 *
 * $Log:    hash.c,v $
 */

#include <stdio.h>
#include "EXTERN.h"
#include "a2p.h"
#include "util.h"

#ifdef NETWARE
char *savestr(char *str);
#endif

STR *
hfetch(register HASH *tb, char *key)
{
    register char *s;
    register int i;
    register int hash;
    register HENT *entry;

    if (!tb)
    return Nullstr;
    for (s=key,     i=0,    hash = 0;
      /* while */ *s;
     s++,       i++,    hash *= 5) {
    hash += *s * coeff[i];
    }
    entry = tb->tbl_array[hash & tb->tbl_max];
    for (; entry; entry = entry->hent_next) {
    if (entry->hent_hash != hash)       /* strings can't be equal */
        continue;
    if (strNE(entry->hent_key,key)) /* is this it? */
        continue;
    return entry->hent_val;
    }
    return Nullstr;
}

bool
hstore(register HASH *tb, char *key, STR *val)
{
    register char *s;
    register int i;
    register int hash;
    register HENT *entry;
    register HENT **oentry;

    if (!tb)
    return FALSE;
    for (s=key,     i=0,    hash = 0;
      /* while */ *s;
     s++,       i++,    hash *= 5) {
    hash += *s * coeff[i];
    }

    oentry = &(tb->tbl_array[hash & tb->tbl_max]);
    i = 1;

    for (entry = *oentry; entry; i=0, entry = entry->hent_next) {
    if (entry->hent_hash != hash)       /* strings can't be equal */
        continue;
    if (strNE(entry->hent_key,key)) /* is this it? */
        continue;
    /*NOSTRICT*/
    safefree(entry->hent_val);
    entry->hent_val = val;
    return TRUE;
    }
    /*NOSTRICT*/
    entry = (HENT*) safemalloc(sizeof(HENT));

    entry->hent_key = savestr(key);
    entry->hent_val = val;
    entry->hent_hash = hash;
    entry->hent_next = *oentry;
    *oentry = entry;

    if (i) {                /* initial entry? */
    tb->tbl_fill++;
    if ((tb->tbl_fill * 100 / (tb->tbl_max + 1)) > FILLPCT)
        hsplit(tb);
    }

    return FALSE;
}

#ifdef NOTUSED
bool
hdelete(register HASH *tb, char *key)
{
    register char *s;
    register int i;
    register int hash;
    register HENT *entry;
    register HENT **oentry;

    if (!tb)
    return FALSE;
    for (s=key,     i=0,    hash = 0;
      /* while */ *s;
     s++,       i++,    hash *= 5) {
    hash += *s * coeff[i];
    }

    oentry = &(tb->tbl_array[hash & tb->tbl_max]);
    entry = *oentry;
    i = 1;
    for (; entry; i=0, oentry = &entry->hent_next, entry = entry->hent_next) {
    if (entry->hent_hash != hash)       /* strings can't be equal */
        continue;
    if (strNE(entry->hent_key,key)) /* is this it? */
        continue;
    safefree((char*)entry->hent_val);
    safefree(entry->hent_key);
    *oentry = entry->hent_next;
    safefree((char*)entry);
    if (i)
        tb->tbl_fill--;
    return TRUE;
    }
    return FALSE;
}
#endif

void
hsplit(HASH *tb)
{
    int oldsize = tb->tbl_max + 1;
    register int newsize = oldsize * 2;
    register int i;
    register HENT **a;
    register HENT **b;
    register HENT *entry;
    register HENT **oentry;

    a = (HENT**) saferealloc((char*)tb->tbl_array, newsize * sizeof(HENT*));
    memset(&a[oldsize], 0, oldsize * sizeof(HENT*)); /* zero second half */
    tb->tbl_max = --newsize;
    tb->tbl_array = a;

    for (i=0; i<oldsize; i++,a++) {
    if (!*a)                /* non-existent */
        continue;
    b = a+oldsize;
    for (oentry = a, entry = *a; entry; entry = *oentry) {
        if ((entry->hent_hash & newsize) != i) {
        *oentry = entry->hent_next;
        entry->hent_next = *b;
        if (!*b)
            tb->tbl_fill++;
        *b = entry;
        continue;
        }
        else
        oentry = &entry->hent_next;
    }
    if (!*a)                /* everything moved */
        tb->tbl_fill--;
    }
}

HASH *
hnew(void)
{
    register HASH *tb = (HASH*)safemalloc(sizeof(HASH));

    tb->tbl_array = (HENT**) safemalloc(8 * sizeof(HENT*));
    tb->tbl_fill = 0;
    tb->tbl_max = 7;
    hiterinit(tb);  /* so each() will start off right */
    memset(tb->tbl_array, 0, 8 * sizeof(HENT*));
    return tb;
}

#ifdef NOTUSED
hshow(register HASH *tb)
{
    fprintf(stderr,"%5d %4d (%2d%%)\n",
    tb->tbl_max+1,
    tb->tbl_fill,
    tb->tbl_fill * 100 / (tb->tbl_max+1));
}
#endif

int
hiterinit(register HASH *tb)
{
    tb->tbl_riter = -1;
    tb->tbl_eiter = Null(HENT*);
    return tb->tbl_fill;
}

HENT *
hiternext(register HASH *tb)
{
    register HENT *entry;

    entry = tb->tbl_eiter;
    do {
    if (entry)
        entry = entry->hent_next;
    if (!entry) {
        tb->tbl_riter++;
        if (tb->tbl_riter > tb->tbl_max) {
        tb->tbl_riter = -1;
        break;
        }
        entry = tb->tbl_array[tb->tbl_riter];
    }
    } while (!entry);

    tb->tbl_eiter = entry;
    return entry;
}

char *
hiterkey(register HENT *entry)
{
    return entry->hent_key;
}

STR *
hiterval(register HENT *entry)
{
    return entry->hent_val;
}