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/* $NetBSD: subr_rmap.c,v 1.9 1994/06/29 06:33:02 cgd Exp $ */
/*
* Copyright (C) 1992, 1994 Wolfgang Solfrank.
* Copyright (C) 1992, 1994 TooLs GmbH.
* All rights reserved.
*
* 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. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by TooLs GmbH.
* 4. The name of TooLs GmbH may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY TOOLS GMBH ``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 TOOLS GMBH 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.
*/
#include <sys/param.h>
#include <sys/map.h>
/*
* Resource allocation map handling.
*
* Code derived from usage in ../vm/swap_pager.c and ../vm/vm_swap.c
* and the (corrected due to the above) comments in ../sys/map.h.
*
* Assume small maps. Keep it sorted by addr with free mapents last.
*/
/*
* Initialize a resource map.
* The map is called "name", and has nelem-1
* slots (the first one is reused to describe the map).
* Initially it manages the address range starting at
* addr with size size.
*/
void
rminit(mp, size, addr, name, nelem)
struct map *mp;
long size, addr;
char *name;
int nelem;
{
struct mapent *ep;
/* mapsize had better be at least 2 */
if (nelem < 2 || addr <= 0 || size < 0)
panic("rminit %s",name);
mp->m_name = name;
mp->m_limit = (struct mapent *)mp + nelem;
/* initially the first entry describes all free space */
ep = (struct mapent *)mp + 1;
ep->m_size = size;
ep->m_addr = addr;
/* the remaining slots are unused (indicated by m_addr == 0) */
while (++ep < mp->m_limit)
ep->m_addr = 0;
}
/*
* Allocate space out of a resource map.
* Try to find an exact match. Otherwise get the space from
* the smallest slot.
*/
long
rmalloc(mp, size)
struct map *mp;
long size;
{
struct mapent *ep, *fp;
long addr;
/* first check arguments */
if (size < 0)
panic("rmalloc %s", mp->m_name);
if (!size)
return 0;
fp = 0;
/* try to find the smallest fit */
for (ep = (struct mapent *)mp + 1; ep < mp->m_limit; ep++) {
if (!ep->m_addr) {
/* unused slots terminate the list */
break;
}
if (ep->m_size == size) {
/* found exact match, use it, ... */
addr = ep->m_addr;
/* copy over the remaining slots ... */
ovbcopy(ep + 1,ep,(char *)mp->m_limit - (char *)(ep + 1));
/* and mark the last slot as unused */
mp->m_limit[-1].m_addr = 0;
return addr;
}
if (ep->m_size > size
&& (!fp
|| fp->m_size > ep->m_size)) {
/* found a larger slot, remember the smallest of these */
fp = ep;
}
}
if (fp) {
/* steal requested size from a larger slot */
addr = fp->m_addr;
fp->m_addr += size;
fp->m_size -= size;
return addr;
}
return 0;
}
/*
* Free (or add) space to a resource map.
* If there aren't enough slots in the map to describe the free space,
* drop the smallest slot.
*/
void
rmfree(mp, size, addr)
struct map *mp;
long size, addr;
{
struct mapent *ep, *fp;
/* first check arguments */
if (size <= 0 || addr <= 0)
panic("rmfree %s", mp->m_name);
while (1) {
fp = 0;
for (ep = (struct mapent *)mp + 1; ep < mp->m_limit; ep++) {
if (!ep->m_addr) {
/* unused slots terminate the list */
break;
}
if (ep->m_addr + ep->m_size == addr) {
/* this slot ends just with the address to free */
ep->m_size += size; /* increase size of slot */
if (ep < mp->m_limit
&& ep[1].m_addr
&& (addr += size) >= ep[1].m_addr) {
if (addr > ep[1].m_addr) /* overlapping frees? */
panic("rmfree %s", mp->m_name);
/* the next slot is now contiguous, so join ... */
ep->m_size += ep[1].m_size;
ovbcopy(ep + 2, ep + 1,
(char *)mp->m_limit - (char *)(ep + 2));
/* and mark the last slot as unused */
mp->m_limit[-1].m_addr = 0;
}
return;
}
if (addr + size == ep->m_addr) {
/* range to free is contiguous to this slot */
ep->m_addr = addr;
ep->m_size += size;
return;
}
if (addr < ep->m_addr
&& !mp->m_limit[-1].m_addr) {
/* insert entry into list keeping it sorted on m_addr */
ovbcopy(ep,ep + 1,(char *)(mp->m_limit - 1) - (char *)ep);
ep->m_addr = addr;
ep->m_size = size;
return;
}
if (!fp || fp->m_size > ep->m_size) {
/* find the slot with the smallest size to drop */
fp = ep;
}
}
if (ep != (struct mapent *)mp + 1
&& ep[-1].m_addr + ep[-1].m_size == addr) {
/* range to free is contiguous to the last used slot */
(--ep)->m_size += size;
return;
}
if (ep != mp->m_limit) {
/* use empty slot for range to free */
ep->m_addr = addr;
ep->m_size = size;
return;
}
/*
* The range to free isn't contiguous to any free space,
* and there is no free slot available, so we are sorry,
* but we have to loose some space.
* fp points to the slot with the smallest size
*/
if (fp->m_size > size) {
/* range to free is smaller, so drop that */
printf("rmfree: map '%s' loses space (%d)\n", mp->m_name,
size);
return;
} else {
/* drop the smallest slot in the list */
printf("rmfree: map '%s' loses space (%d)\n", mp->m_name,
fp->m_size);
ovbcopy(fp + 1,fp,(char *)(mp->m_limit - 1) - (char *)fp);
mp->m_limit[-1].m_addr = 0;
/* now retry */
}
}
}
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