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/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License, Version 1.0 only
* (the "License"). You may not use this file except in compliance
* with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/* Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
/* All Rights Reserved */
#ident "%Z%%M% %I% %E% SMI" /* SVr4.0 1.3 */
#ifdef debug
#define ASSERT(p) if(!(p))botch("p");else
botch(s)
char *s;
{
printf("assertion botched: %s\n",s);
abort();
}
#else
#define ASSERT(p)
#endif
/* C storage allocator
* circular first-fit strategy
* works with noncontiguous, but monotonically linked, arena
* each block is preceded by a ptr to the (pointer of)
* the next following block
* blocks are exact number of words long
* aligned to the data type requirements of ALIGN
* pointers to blocks must have BUSY bit 0
* bit in ptr is 1 for busy, 0 for idle
* gaps in arena are merely noted as busy blocks
* last block of arena is empty and
* has a pointer to first
* idle blocks are coalesced during space search
*
* a different implementation may need to redefine
* ALIGN, NALIGN, BLOCK, BUSY, INT
* where INT is integer type to which a pointer can be cast
*/
#define INT int
#define ALIGN int
#define NALIGN 1
#define WORD sizeof(union store)
#define BLOCK 1024
#define BUSY 1
#define NULL 0
#define testbusy(p) ((INT)(p)&BUSY)
#define setbusy(p) (union store *)((INT)(p)|BUSY)
#define clearbusy(p) (union store *)((INT)(p)&~BUSY)
union store {
union store *ptr;
ALIGN dummy[NALIGN];
int calloc; /*calloc clears an array of integers*/
};
static union store alloca; /* initial arena */
static union store *allocb = &alloca; /*arena base*/
static union store *allocp = &alloca; /*search ptr*/
static union store *allocx; /*for benefit of realloc*/
extern char *sbrk();
char *
malloc(nbytes)
unsigned nbytes;
{
register union store *p, *q;
register nw;
register temp;
register union store *r = 0;
nw = (nbytes+WORD+WORD-1)/WORD + 1; /*need one more than asked for*/
ASSERT(allock(allocp));
for(; ; ) { /* done at most twice */
p = allocp;
if(alloca.ptr!=0) /*C can't initialize union*/
for(temp=0; ; ) {
if(!testbusy(p->ptr)) {
while(!testbusy((q=p->ptr)->ptr)) {
ASSERT(q>p);
p->ptr = q->ptr;
allocp = p;
}
if(q>=p+nw && p+nw>=p)
goto found;
r = p;
}
q = p;
p = clearbusy(p->ptr);
if(p <= q) {
ASSERT(p==allocb);
if(p != allocb)
return(NULL);
if(++temp>1)
break;
}
}
temp = nw;
p = (union store *)sbrk(0);
if (r && !testbusy(r->ptr) && r->ptr + 1 == p)
temp -= p - r - 1;
temp = ((temp+BLOCK/WORD)/(BLOCK/WORD))*(BLOCK/WORD);
if(p+temp <= p)
return(NULL);
for(; ; ) {
q = (union store *)sbrk(temp*WORD);
if((INT)q != -1)
break;
temp -= (temp-nw+1)/2;
if(temp <= nw)
return(NULL);
}
ialloc((char *)q, (unsigned)temp*WORD);
}
found:
allocp = p + nw;
if(q>allocp) {
allocx = allocp->ptr;
allocp->ptr = p->ptr;
}
p->ptr = setbusy(allocp);
return((char *)(p+1));
}
/* freeing strategy tuned for LIFO allocation
*/
free(ap)
char *ap;
{
register union store *p = (union store *)ap;
allocp = --p;
ASSERT(allock(allocp));
ASSERT(testbusy(p->ptr));
p->ptr = clearbusy(p->ptr);
ASSERT(p->ptr > allocp);
}
/* ialloc(q, nbytes) inserts a block that did not come
* from malloc into the arena
*
* q points to new block
* r points to last of new block
* p points to last cell of arena before new block
* s points to first cell of arena after new block
*/
ialloc(qq, nbytes)
char *qq;
unsigned nbytes;
{
register union store *p, *q, *s;
union store *r;
q = (union store *)qq;
r = q + (nbytes/WORD) - 1;
q->ptr = r;
if(alloca.ptr==0) /*C can't initialize union*/
alloca.ptr = &alloca;
for(p=allocb; ; p=s) {
s = clearbusy(p->ptr);
if(s==allocb)
break;
ASSERT(s>p);
if(s>r) {
if(p<q)
break;
else
ASSERT(p>r);
}
}
p->ptr = q==p+1? q: setbusy(q);
r->ptr = s==r+1? s: setbusy(s);
if(allocb > q)
allocb = q;
allocp = allocb;
}
/* realloc(p, nbytes) reallocates a block obtained from malloc()
* and freed since last call of malloc()
* to have new size nbytes, and old content
* returns new location, or 0 on failure
*/
char *
realloc(pp, nbytes)
char *pp;
unsigned nbytes;
{
register union store *q;
register union store *p = (union store *)pp;
union store *s, *t;
register unsigned nw;
unsigned onw;
ASSERT(allock(p-1));
if(testbusy(p[-1].ptr))
free((char *)p);
onw = p[-1].ptr - p;
q = (union store *)malloc(nbytes);
if(q==NULL || q==p)
return((char *)q);
ASSERT(q<p||q>p[-1].ptr);
s = p;
t = q;
nw = (nbytes+WORD-1)/WORD;
if(nw<onw)
onw = nw;
while(onw--!=0)
*t++ = *s++;
ASSERT(clearbusy(q[-1].ptr)-q==nw);
if(q<p && q+nw>=p)
(q+(q+nw-p))->ptr = allocx;
ASSERT(allock(q-1));
return((char *)q);
}
#ifdef debug
allock(q)
union store *q;
{
#ifdef longdebug
register union store *p, *r;
int x;
x = 0;
p = allocb;
if(alloca.ptr==0)
return(1);
for( ; (r=clearbusy(p->ptr)) > p; p=r) {
if(p==q)
x++;
}
return(r==allocb&(x==1|p==q));
#else
return(q>=allocb);
#endif
}
#endif
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