192 lines
5.8 KiB
C
192 lines
5.8 KiB
C
/*
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* Copyright (c) 1992 William F. Jolitz, TeleMuse
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This software is a component of "386BSD" developed by
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William F. Jolitz, TeleMuse.
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* 4. Neither the name of the developer nor the name "386BSD"
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS A COMPONENT OF 386BSD DEVELOPED BY WILLIAM F. JOLITZ
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* AND IS INTENDED FOR RESEARCH AND EDUCATIONAL PURPOSES ONLY. THIS
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* SOFTWARE SHOULD NOT BE CONSIDERED TO BE A COMMERCIAL PRODUCT.
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* THE DEVELOPER URGES THAT USERS WHO REQUIRE A COMMERCIAL PRODUCT
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* NOT MAKE USE THIS WORK.
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*
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* FOR USERS WHO WISH TO UNDERSTAND THE 386BSD SYSTEM DEVELOPED
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* BY WILLIAM F. JOLITZ, WE RECOMMEND THE USER STUDY WRITTEN
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* REFERENCES SUCH AS THE "PORTING UNIX TO THE 386" SERIES
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* (BEGINNING JANUARY 1991 "DR. DOBBS JOURNAL", USA AND BEGINNING
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* JUNE 1991 "UNIX MAGAZIN", GERMANY) BY WILLIAM F. JOLITZ AND
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* LYNNE GREER JOLITZ, AS WELL AS OTHER BOOKS ON UNIX AND THE
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* ON-LINE 386BSD USER MANUAL BEFORE USE. A BOOK DISCUSSING THE INTERNALS
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* OF 386BSD ENTITLED "386BSD FROM THE INSIDE OUT" WILL BE AVAILABLE LATE 1992.
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*
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* THIS SOFTWARE IS PROVIDED BY THE DEVELOPER ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE DEVELOPER BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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*/
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static char rcsid[] = "$Header: /usr/bill/working/sys/kern/RCS/subr_rlist.c,v 1.2 92/01/21 21:29:31 william Exp $";
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#include "sys/param.h"
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#include "sys/cdefs.h"
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#include "sys/malloc.h"
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#include "rlist.h"
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/*
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* Resource lists.
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*/
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/*
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* Add space to a resource list. Used to either
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* initialize a list or return free space to it.
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*/
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rlist_free (rlp, start, end)
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register struct rlist **rlp; unsigned start, end; {
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struct rlist *head;
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head = *rlp;
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loop:
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/* if nothing here, insert (tail of list) */
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if (*rlp == 0) {
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*rlp = (struct rlist *)malloc(sizeof(**rlp), M_TEMP, M_NOWAIT);
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(*rlp)->rl_start = start;
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(*rlp)->rl_end = end;
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(*rlp)->rl_next = 0;
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return;
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}
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/* if new region overlaps something currently present, panic */
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if (start >= (*rlp)->rl_start && start <= (*rlp)->rl_end) {
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printf("Frag %d:%d, ent %d:%d ", start, end,
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(*rlp)->rl_start, (*rlp)->rl_end);
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panic("overlapping front rlist_free: freed twice?");
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}
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if (end >= (*rlp)->rl_start && end <= (*rlp)->rl_end) {
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printf("Frag %d:%d, ent %d:%d ", start, end,
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(*rlp)->rl_start, (*rlp)->rl_end);
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panic("overlapping tail rlist_free: freed twice?");
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}
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/* are we adjacent to this element? (in front) */
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if (end+1 == (*rlp)->rl_start) {
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/* coalesce */
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(*rlp)->rl_start = start;
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goto scan;
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}
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/* are we before this element? */
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if (end < (*rlp)->rl_start) {
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register struct rlist *nlp;
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nlp = (struct rlist *)malloc(sizeof(*nlp), M_TEMP, M_NOWAIT);
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nlp->rl_start = start;
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nlp->rl_end = end;
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nlp->rl_next = *rlp;
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*rlp = nlp;
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return;
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}
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/* are we adjacent to this element? (at tail) */
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if ((*rlp)->rl_end + 1 == start) {
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/* coalesce */
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(*rlp)->rl_end = end;
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goto scan;
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}
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/* are we after this element */
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if (start > (*rlp)->rl_end) {
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rlp = &((*rlp)->rl_next);
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goto loop;
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} else
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panic("rlist_free: can't happen");
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scan:
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/* can we coalesce list now that we've filled a void? */
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{
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register struct rlist *lp, *lpn;
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for (lp = head; lp->rl_next ;) {
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lpn = lp->rl_next;
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/* coalesce ? */
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if (lp->rl_end + 1 == lpn->rl_start) {
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lp->rl_end = lpn->rl_end;
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lp->rl_next = lpn->rl_next;
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free(lpn, M_TEMP);
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} else
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lp = lp->rl_next;
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}
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}
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}
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/*
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* Obtain a region of desired size from a resource list.
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* If nothing available of that size, return 0. Otherwise,
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* return a value of 1 and set resource start location with
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* "*loc". (Note: loc can be zero if we don't wish the value)
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*/
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int rlist_alloc (rlp, size, loc)
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struct rlist **rlp; unsigned size, *loc; {
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register struct rlist *lp;
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/* walk list, allocating first thing that's big enough (first fit) */
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for (; *rlp; rlp = &((*rlp)->rl_next))
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if(size <= (*rlp)->rl_end - (*rlp)->rl_start + 1) {
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/* hand it to the caller */
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if (loc) *loc = (*rlp)->rl_start;
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(*rlp)->rl_start += size;
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/* did we eat this element entirely? */
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if ((*rlp)->rl_start > (*rlp)->rl_end) {
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lp = (*rlp)->rl_next;
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free (*rlp, M_TEMP);
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*rlp = lp;
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}
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return (1);
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}
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/* nothing in list that's big enough */
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return (0);
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}
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/*
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* Finished with this resource list, reclaim all space and
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* mark it as being empty.
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*/
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rlist_destroy (rlp)
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struct rlist **rlp; {
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struct rlist *lp, *nlp;
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lp = *rlp;
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*rlp = 0;
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for (; lp; lp = nlp) {
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nlp = lp->rl_next;
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free (lp, M_TEMP);
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}
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}
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