/*      $NetBSD: pack.c,v 1.12 2025/01/07 14:21:11 joe Exp $    */

/*
* Copyright (c) 1992, 1993
*      The Regents of the University of California.  All rights reserved.
*
* This software was developed by the Computer Systems Engineering group
* at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
* contributed to Berkeley.
*
* All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
*      This product includes software developed by the University of
*      California, Lawrence Berkeley Laboratories.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
*    notice, this list of conditions and the following disclaimer in the
*    documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
*    may be used to endorse or promote products derived from this software
*    without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
*      from: @(#)pack.c        8.1 (Berkeley) 6/6/93
*/

#if HAVE_NBTOOL_CONFIG_H
#include "nbtool_config.h"
#endif

#include <sys/cdefs.h>
__RCSID("$NetBSD: pack.c,v 1.12 2025/01/07 14:21:11 joe Exp $");

#include <sys/param.h>
#include <stdlib.h>
#include <string.h>
#include <util.h>
#include "defs.h"

/*
* Packing.  We have three separate kinds of packing here.
*
* First, we pack device instances which have identical parent specs.
*
* Second, we pack locators.  Given something like
*
*      hp0 at mba0 drive 0
*      hp* at mba* drive ?
*      ht0 at mba0 drive 0
*      tu0 at ht0 slave 0
*      ht* at mba* drive ?
*      tu* at ht* slave ?
*
* (where the default drive and slave numbers are -1), we have three
* locators whose value is 0 and three whose value is -1.  Rather than
* emitting six integers, we emit just two.
*
* When packing locators, we would like to find sequences such as
*      {1 2 3} {2 3 4} {3} {4 5}
* and turn this into the flat sequence {1 2 3 4 5}, with each subsequence
* given by the appropriate offset (here 0, 1, 2, and 3 respectively).
* Non-overlapping packing is much easier, and so we use that here
* and miss out on the chance to squeeze the locator sequence optimally.
* (So it goes.)
*/

typedef int (*vec_cmp_func)(const void *, int, int);

#define TAILHSIZE       128
#define PVHASH(i)       ((i) & (TAILHSIZE - 1))
#define LOCHASH(l)      (((long)(l) >> 2) & (TAILHSIZE - 1))
struct tails {
       struct  tails *t_next;
       int     t_ends_at;
};

static struct tails *tails[TAILHSIZE];
static int locspace;

static void packdevi(void);
static void packlocs(void);

static int sameas(struct devi *, struct devi *);
static int findvec(const void *, int, int, vec_cmp_func, int);
static int samelocs(const void *, int, int);
static int addlocs(const char **, int);
static int loclencmp(const void *, const void *);
static void resettails(void);

void
pack(void)
{
       struct pspec *p;
       struct devi *i;

       /* Pack instances and make parent vectors. */
       packdevi();

       /*
        * Now that we know what we have, find upper limits on space
        * needed for the loc[] table.  The loc table size is bounded by
        * what we would get if no packing occurred.
        */
       locspace = 0;
       TAILQ_FOREACH(i, &alldevi, i_next) {
               if (i->i_active != DEVI_ACTIVE || i->i_collapsed)
                       continue;
               if ((p = i->i_pspec) == NULL)
                       continue;
               locspace += p->p_iattr->a_loclen;
       }

       /* Allocate and pack loc[]. */
       locators.vec = ecalloc((size_t)locspace, sizeof(*locators.vec));
       locators.used = 0;
       packlocs();
}

/*
* Pack device instances together wherever possible.
*/
static void
packdevi(void)
{
       struct devi *firststar, *i, **ip, *l, *p;
       struct devbase *d;
       u_short j, m, n;

       /*
        * Sort all the cloning units to after the non-cloning units,
        * preserving order of cloning and non-cloning units with
        * respect to other units of the same type.
        *
        * Algorithm: Walk down the list until the first cloning unit is
        * seen for the second time (or until the end of the list, if there
        * are no cloning units on the list), moving starred units to the
        * end of the list.
        */
       TAILQ_FOREACH(d, &allbases, d_next) {
               ip = &d->d_ihead;
               firststar = NULL;

               for (i = *ip; i != firststar; i = *ip) {
                       if (i->i_unit != STAR) {
                               /* try i->i_bsame next */
                               ip = &i->i_bsame;
                       } else {
                               if (firststar == NULL)
                                       firststar = i;

                               *d->d_ipp = i;
                               d->d_ipp = &i->i_bsame;

                               *ip = i->i_bsame;
                               i->i_bsame = NULL;

                               /* leave ip alone; try (old) i->i_bsame next */
                       }
               }
       }

       packed = ecalloc((size_t)ndevi + 1, sizeof *packed);
       n = 0;
       TAILQ_FOREACH(d, &allbases, d_next) {
               /*
                * For each instance of each device, add or collapse
                * all its aliases.
                *
                * Pseudo-devices have a non-empty d_ihead for convenience.
                * Ignore them.
                */
               if (d->d_ispseudo)
                       continue;
               for (i = d->d_ihead; i != NULL; i = i->i_bsame) {
                       m = n;
                       for (l = i; l != NULL; l = l->i_alias) {
                               if (l->i_active != DEVI_ACTIVE
                                   || i->i_pseudoroot)
                                       continue;
                               l->i_locoff = -1;
                               /* try to find an equivalent for l */
                               for (j = m; j < n; j++) {
                                       p = packed[j];
                                       if (sameas(l, p)) {
                                               l->i_collapsed = 1;
                                               l->i_cfindex = p->i_cfindex;
                                               goto nextalias;
                                       }
                               }
                               /* could not find a suitable alias */
                               l->i_collapsed = 0;
                               l->i_cfindex = n;
                               packed[n++] = l;
nextalias:;
                       }
               }
       }
       npacked = n;
       packed[n] = NULL;
}

/*
* Return true if two aliases are "the same".  In this case, they need
* to have the same parent spec, have the same config flags, and have
* the same locators.
*/
static int
sameas(struct devi *i1, struct devi *i2)
{
       const char **p1, **p2;

       if (i1->i_pspec != i2->i_pspec)
               return (0);
       if (i1->i_cfflags != i2->i_cfflags)
               return (0);
       for (p1 = i1->i_locs, p2 = i2->i_locs; *p1 == *p2; p2++)
               if (*p1++ == 0)
                       return (1);
       return (0);
}

static void
packlocs(void)
{
       struct pspec *ps;
       struct devi **p, *i;
       int l,o;
       extern int Pflag;

       qsort(packed, npacked, sizeof *packed, loclencmp);
       for (p = packed; (i = *p) != NULL; p++) {
               if ((ps = i->i_pspec) != NULL &&
                   (l = ps->p_iattr->a_loclen) > 0) {
                       if (Pflag) {
                               o = findvec(i->i_locs,
                                   LOCHASH(i->i_locs[l - 1]), l,
                                   samelocs, locators.used);
                               i->i_locoff = o < 0 ?
                                   addlocs(i->i_locs, l) : o;
                       } else
                               i->i_locoff = addlocs(i->i_locs, l);
               } else
                       i->i_locoff = -1;
       }
       resettails();
}

/*
* Return the index at which the given vector already exists, or -1
* if it is not anywhere in the current set.  If we return -1, we assume
* our caller will add it at the end of the current set, and we make
* sure that next time, we will find it there.
*/
static int
findvec(const void *ptr, int hash, int len, vec_cmp_func cmp, int nextplace)
{
       struct tails *t, **hp;
       int off;

       hp = &tails[hash];
       for (t = *hp; t != NULL; t = t->t_next) {
               off = t->t_ends_at - len;
               if (off >= 0 && (*cmp)(ptr, off, len))
                       return (off);
       }
       t = ecalloc(1, sizeof(*t));
       t->t_next = *hp;
       *hp = t;
       t->t_ends_at = nextplace + len;
       return (-1);
}

/*
* Comparison function for locators.
*/
static int
samelocs(const void *ptr, int off, int len)
{
       const char * const *p, * const *q;

       for (p = &locators.vec[off], q = (const char * const *)ptr; --len >= 0;)
               if (*p++ != *q++)
                       return (0);     /* different */
       return (1);                     /* same */
}

/*
* Add the given locators at the end of the global loc[] table.
*/
static int
addlocs(const char **locs, int len)
{
       const char **p;
       int ret;

       ret = locators.used;
       if ((locators.used = ret + len) > locspace)
               panic("addlocs: overrun");
       for (p = &locators.vec[ret]; --len >= 0;)
               *p++ = *locs++;
       return (ret);
}

/*
* Comparison function for qsort-by-locator-length, longest first.
*
* In the event of equality, break ties by i_cfindex, which should be
* unique, obviating the need for a stable sort.
*/
static int
loclencmp(const void *a, const void *b)
{
       const struct devi *const *d1p = a, *d1 = *d1p;
       const struct devi *const *d2p = b, *d2 = *d2p;
       const struct pspec *p1, *p2;
       int l1, l2;

       p1 = d1->i_pspec;
       l1 = p1 != NULL ? p1->p_iattr->a_loclen : 0;

       p2 = d2->i_pspec;
       l2 = p2 != NULL ? p2->p_iattr->a_loclen : 0;

       /*
        * Longer locators first; among equal locator lengths, earliest
        * index first.
        */
       if (l2 < l1)
               return -1;
       else if (l2 > l1)
               return +1;
       else if (d2->i_cfindex > d1->i_cfindex)
               return -1;
       else if (d2->i_cfindex < d1->i_cfindex)
               return +1;
       else
               abort();        /* no ties possible */
}

static void
resettails(void)
{
       struct tails **p, *t, *next;
       int i;

       for (p = tails, i = TAILHSIZE; --i >= 0; p++) {
               for (t = *p; t != NULL; t = next) {
                       next = t->t_next;
                       free(t);
               }
               *p = NULL;
       }
}

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