[p5sagit/p5-mst-13.2.git] / malloc.c

/* $Header: malloc.c,v 3.0.1.4 90/11/13 15:23:45 lwall Locked $
 *
 * $Log:	malloc.c,v $
 * Revision 3.0.1.4  90/11/13  15:23:45  lwall
 * patch41: added hp malloc union overhead strut (that sounds very blue collar)
 * 
 * Revision 3.0.1.3  90/10/16  15:27:47  lwall
 * patch29: various portability fixes
 * 
 * Revision 3.0.1.2  89/11/11  04:36:37  lwall
 * patch2: malloc pointer corruption check made more portable
 * 
 * Revision 3.0.1.1  89/10/26  23:15:05  lwall
 * patch1: some declarations were missing from malloc.c
 * patch1: sparc machines had alignment problems in malloc.c
 * 
 * Revision 3.0  89/10/18  15:20:39  lwall
 * 3.0 baseline
 * 
 */

#ifndef lint
static char sccsid[] = "@(#)malloc.c	4.3 (Berkeley) 9/16/83";

#ifdef DEBUGGING
#define RCHECK
#endif
/*
 * malloc.c (Caltech) 2/21/82
 * Chris Kingsley, kingsley@cit-20.
 *
 * This is a very fast storage allocator.  It allocates blocks of a small 
 * number of different sizes, and keeps free lists of each size.  Blocks that
 * don't exactly fit are passed up to the next larger size.  In this 
 * implementation, the available sizes are 2^n-4 (or 2^n-12) bytes long.
 * This is designed for use in a program that uses vast quantities of memory,
 * but bombs when it runs out. 
 */

#include "EXTERN.h"
#include "perl.h"

static findbucket(), morecore();

/* I don't much care whether these are defined in sys/types.h--LAW */

#define u_char unsigned char
#define u_int unsigned int
#define u_short unsigned short

/*
 * The overhead on a block is at least 4 bytes.  When free, this space
 * contains a pointer to the next free block, and the bottom two bits must
 * be zero.  When in use, the first byte is set to MAGIC, and the second
 * byte is the size index.  The remaining bytes are for alignment.
 * If range checking is enabled and the size of the block fits
 * in two bytes, then the top two bytes hold the size of the requested block
 * plus the range checking words, and the header word MINUS ONE.
 */
union	overhead {
	union	overhead *ov_next;	/* when free */
#if defined(mips) || defined(sparc) || defined(luna88k) || defined(hp9000s800)
	double  strut;			/* alignment problems */
#endif
	struct {
		u_char	ovu_magic;	/* magic number */
		u_char	ovu_index;	/* bucket # */
#ifdef RCHECK
		u_short	ovu_size;	/* actual block size */
		u_int	ovu_rmagic;	/* range magic number */
#endif
	} ovu;
#define	ov_magic	ovu.ovu_magic
#define	ov_index	ovu.ovu_index
#define	ov_size		ovu.ovu_size
#define	ov_rmagic	ovu.ovu_rmagic
};

#define	MAGIC		0xff		/* magic # on accounting info */
#define OLDMAGIC	0x7f		/* same after a free() */
#define RMAGIC		0x55555555	/* magic # on range info */
#ifdef RCHECK
#define	RSLOP		sizeof (u_int)
#else
#define	RSLOP		0
#endif

/*
 * nextf[i] is the pointer to the next free block of size 2^(i+3).  The
 * smallest allocatable block is 8 bytes.  The overhead information
 * precedes the data area returned to the user.
 */
#define	NBUCKETS 30
static	union overhead *nextf[NBUCKETS];
extern	char *sbrk();

#ifdef MSTATS
/*
 * nmalloc[i] is the difference between the number of mallocs and frees
 * for a given block size.
 */
static	u_int nmalloc[NBUCKETS];
#include <stdio.h>
#endif

#ifdef debug
#define	ASSERT(p)   if (!(p)) botch("p"); else
static
botch(s)
	char *s;
{

	printf("assertion botched: %s\n", s);
	abort();
}
#else
#define	ASSERT(p)
#endif

char *
malloc(nbytes)
	register unsigned nbytes;
{
  	register union overhead *p;
  	register int bucket = 0;
  	register unsigned shiftr;

	/*
	 * Convert amount of memory requested into
	 * closest block size stored in hash buckets
	 * which satisfies request.  Account for
	 * space used per block for accounting.
	 */
  	nbytes += sizeof (union overhead) + RSLOP;
  	nbytes = (nbytes + 3) &~ 3; 
  	shiftr = (nbytes - 1) >> 2;
	/* apart from this loop, this is O(1) */
  	while (shiftr >>= 1)
  		bucket++;
	/*
	 * If nothing in hash bucket right now,
	 * request more memory from the system.
	 */
  	if (nextf[bucket] == NULL)    
  		morecore(bucket);
  	if ((p = (union overhead *)nextf[bucket]) == NULL)
  		return (NULL);
	/* remove from linked list */
#ifdef RCHECK
	if (*((int*)p) & (sizeof(union overhead) - 1))
#ifndef I286
	    fprintf(stderr,"Corrupt malloc ptr 0x%x at 0x%x\n",*((int*)p),p);
#else
	    fprintf(stderr,"Corrupt malloc ptr 0x%lx at 0x%lx\n",*((int*)p),p);
#endif
#endif
  	nextf[bucket] = p->ov_next;
	p->ov_magic = MAGIC;
	p->ov_index= bucket;
#ifdef MSTATS
  	nmalloc[bucket]++;
#endif
#ifdef RCHECK
	/*
	 * Record allocated size of block and
	 * bound space with magic numbers.
	 */
  	if (nbytes <= 0x10000)
		p->ov_size = nbytes - 1;
	p->ov_rmagic = RMAGIC;
  	*((u_int *)((caddr_t)p + nbytes - RSLOP)) = RMAGIC;
#endif
  	return ((char *)(p + 1));
}

/*
 * Allocate more memory to the indicated bucket.
 */
static
morecore(bucket)
	register int bucket;
{
  	register union overhead *op;
  	register int rnu;       /* 2^rnu bytes will be requested */
  	register int nblks;     /* become nblks blocks of the desired size */
	register int siz;

  	if (nextf[bucket])
  		return;
	/*
	 * Insure memory is allocated
	 * on a page boundary.  Should
	 * make getpageize call?
	 */
  	op = (union overhead *)sbrk(0);
#ifndef I286
  	if ((int)op & 0x3ff)
  		(void)sbrk(1024 - ((int)op & 0x3ff));
#else
	/* The sbrk(0) call on the I286 always returns the next segment */
#endif

#ifndef I286
	/* take 2k unless the block is bigger than that */
  	rnu = (bucket <= 8) ? 11 : bucket + 3;
#else
	/* take 16k unless the block is bigger than that 
	   (80286s like large segments!)		*/
  	rnu = (bucket <= 11) ? 14 : bucket + 3;
#endif
  	nblks = 1 << (rnu - (bucket + 3));  /* how many blocks to get */
  	if (rnu < bucket)
		rnu = bucket;
	op = (union overhead *)sbrk(1 << rnu);
	/* no more room! */
  	if ((int)op == -1)
  		return;
	/*
	 * Round up to minimum allocation size boundary
	 * and deduct from block count to reflect.
	 */
#ifndef I286
  	if ((int)op & 7) {
  		op = (union overhead *)(((int)op + 8) &~ 7);
  		nblks--;
  	}
#else
	/* Again, this should always be ok on an 80286 */
#endif
	/*
	 * Add new memory allocated to that on
	 * free list for this hash bucket.
	 */
  	nextf[bucket] = op;
  	siz = 1 << (bucket + 3);
  	while (--nblks > 0) {
		op->ov_next = (union overhead *)((caddr_t)op + siz);
		op = (union overhead *)((caddr_t)op + siz);
  	}
}

free(cp)
	char *cp;
{   
  	register int size;
	register union overhead *op;

  	if (cp == NULL)
  		return;
	op = (union overhead *)((caddr_t)cp - sizeof (union overhead));
#ifdef debug
  	ASSERT(op->ov_magic == MAGIC);		/* make sure it was in use */
#else
	if (op->ov_magic != MAGIC) {
		warn("%s free() ignored",
		    op->ov_magic == OLDMAGIC ? "Duplicate" : "Bad");
		return;				/* sanity */
	}
	op->ov_magic = OLDMAGIC;
#endif
#ifdef RCHECK
  	ASSERT(op->ov_rmagic == RMAGIC);
	if (op->ov_index <= 13)
		ASSERT(*(u_int *)((caddr_t)op + op->ov_size + 1 - RSLOP) == RMAGIC);
#endif
  	ASSERT(op->ov_index < NBUCKETS);
  	size = op->ov_index;
	op->ov_next = nextf[size];
  	nextf[size] = op;
#ifdef MSTATS
  	nmalloc[size]--;
#endif
}

/*
 * When a program attempts "storage compaction" as mentioned in the
 * old malloc man page, it realloc's an already freed block.  Usually
 * this is the last block it freed; occasionally it might be farther
 * back.  We have to search all the free lists for the block in order
 * to determine its bucket: 1st we make one pass thru the lists
 * checking only the first block in each; if that fails we search
 * ``reall_srchlen'' blocks in each list for a match (the variable
 * is extern so the caller can modify it).  If that fails we just copy
 * however many bytes was given to realloc() and hope it's not huge.
 */
int reall_srchlen = 4;	/* 4 should be plenty, -1 =>'s whole list */

char *
realloc(cp, nbytes)
	char *cp; 
	unsigned nbytes;
{   
  	register u_int onb;
	union overhead *op;
  	char *res;
	register int i;
	int was_alloced = 0;

  	if (cp == NULL)
  		return (malloc(nbytes));
	op = (union overhead *)((caddr_t)cp - sizeof (union overhead));
	if (op->ov_magic == MAGIC) {
		was_alloced++;
		i = op->ov_index;
	} else {
		/*
		 * Already free, doing "compaction".
		 *
		 * Search for the old block of memory on the
		 * free list.  First, check the most common
		 * case (last element free'd), then (this failing)
		 * the last ``reall_srchlen'' items free'd.
		 * If all lookups fail, then assume the size of
		 * the memory block being realloc'd is the
		 * smallest possible.
		 */
		if ((i = findbucket(op, 1)) < 0 &&
		    (i = findbucket(op, reall_srchlen)) < 0)
			i = 0;
	}
	onb = (1 << (i + 3)) - sizeof (*op) - RSLOP;
	/* avoid the copy if same size block */
	if (was_alloced &&
	    nbytes <= onb && nbytes > (onb >> 1) - sizeof(*op) - RSLOP) {
#ifdef RCHECK
		/*
		 * Record new allocated size of block and
		 * bound space with magic numbers.
		 */
		if (op->ov_index <= 13) {
			/*
			 * Convert amount of memory requested into
			 * closest block size stored in hash buckets
			 * which satisfies request.  Account for
			 * space used per block for accounting.
			 */
			nbytes += sizeof (union overhead) + RSLOP;
			nbytes = (nbytes + 3) &~ 3; 
			op->ov_size = nbytes - 1;
			*((u_int *)((caddr_t)op + nbytes - RSLOP)) = RMAGIC;
		}
#endif
		return(cp);
	}
  	if ((res = malloc(nbytes)) == NULL)
  		return (NULL);
  	if (cp != res)			/* common optimization */
		(void)bcopy(cp, res, (int)((nbytes < onb) ? nbytes : onb));
  	if (was_alloced)
		free(cp);
  	return (res);
}

/*
 * Search ``srchlen'' elements of each free list for a block whose
 * header starts at ``freep''.  If srchlen is -1 search the whole list.
 * Return bucket number, or -1 if not found.
 */
static
findbucket(freep, srchlen)
	union overhead *freep;
	int srchlen;
{
	register union overhead *p;
	register int i, j;

	for (i = 0; i < NBUCKETS; i++) {
		j = 0;
		for (p = nextf[i]; p && j != srchlen; p = p->ov_next) {
			if (p == freep)
				return (i);
			j++;
		}
	}
	return (-1);
}

#ifdef MSTATS
/*
 * mstats - print out statistics about malloc
 * 
 * Prints two lines of numbers, one showing the length of the free list
 * for each size category, the second showing the number of mallocs -
 * frees for each size category.
 */
mstats(s)
	char *s;
{
  	register int i, j;
  	register union overhead *p;
  	int totfree = 0,
  	totused = 0;

  	fprintf(stderr, "Memory allocation statistics %s\nfree:\t", s);
  	for (i = 0; i < NBUCKETS; i++) {
  		for (j = 0, p = nextf[i]; p; p = p->ov_next, j++)
  			;
  		fprintf(stderr, " %d", j);
  		totfree += j * (1 << (i + 3));
  	}
  	fprintf(stderr, "\nused:\t");
  	for (i = 0; i < NBUCKETS; i++) {
  		fprintf(stderr, " %d", nmalloc[i]);
  		totused += nmalloc[i] * (1 << (i + 3));
  	}
  	fprintf(stderr, "\n\tTotal in use: %d, total free: %d\n",
	    totused, totfree);
}
#endif
#endif /* lint */
Commit	Line	Data
4e8eb4f0	1	/* $Header: malloc.c,v 3.0.1.4 90/11/13 15:23:45 lwall Locked $
8d063cd8	2	*
8d063cd8	3	* $Log: malloc.c,v $
4e8eb4f0	4	* Revision 3.0.1.4 90/11/13 15:23:45 lwall
	5	* patch41: added hp malloc union overhead strut (that sounds very blue collar)
	6	*
d9d8d8de	7	* Revision 3.0.1.3 90/10/16 15:27:47 lwall
	8	* patch29: various portability fixes
	9	*
bf38876a	10	* Revision 3.0.1.2 89/11/11 04:36:37 lwall
	11	* patch2: malloc pointer corruption check made more portable
	12	*
03a14243	13	* Revision 3.0.1.1 89/10/26 23:15:05 lwall
	14	* patch1: some declarations were missing from malloc.c
	15	* patch1: sparc machines had alignment problems in malloc.c
	16	*
a687059c	17	* Revision 3.0 89/10/18 15:20:39 lwall
a687059c	18	* 3.0 baseline
8d063cd8	19	*
	20	*/
	21
	22	#ifndef lint
	23	static char sccsid[] = "@(#)malloc.c 4.3 (Berkeley) 9/16/83";
8d063cd8	24
a687059c	25	#ifdef DEBUGGING
8d063cd8	26	#define RCHECK
a687059c	27	#endif
8d063cd8	28	/*
	29	* malloc.c (Caltech) 2/21/82
	30	* Chris Kingsley, kingsley@cit-20.
	31	*
	32	* This is a very fast storage allocator. It allocates blocks of a small
	33	* number of different sizes, and keeps free lists of each size. Blocks that
	34	* don't exactly fit are passed up to the next larger size. In this
	35	* implementation, the available sizes are 2^n-4 (or 2^n-12) bytes long.
	36	* This is designed for use in a program that uses vast quantities of memory,
	37	* but bombs when it runs out.
	38	*/
	39
135863df	40	#include "EXTERN.h"
135863df	41	#include "perl.h"
135863df	42
03a14243	43	static findbucket(), morecore();
03a14243	44
135863df	45	/* I don't much care whether these are defined in sys/types.h--LAW */
	46
	47	#define u_char unsigned char
	48	#define u_int unsigned int
	49	#define u_short unsigned short
8d063cd8	50
8d063cd8	51	/*
	52	* The overhead on a block is at least 4 bytes. When free, this space
	53	* contains a pointer to the next free block, and the bottom two bits must
	54	* be zero. When in use, the first byte is set to MAGIC, and the second
	55	* byte is the size index. The remaining bytes are for alignment.
	56	* If range checking is enabled and the size of the block fits
	57	* in two bytes, then the top two bytes hold the size of the requested block
	58	* plus the range checking words, and the header word MINUS ONE.
	59	*/
	60	union overhead {
	61	union overhead ov_next; / when free */
4e8eb4f0	62	#if defined(mips) \|\| defined(sparc) \|\| defined(luna88k) \|\| defined(hp9000s800)
a687059c	63	double strut; /* alignment problems */
a687059c	64	#endif
8d063cd8	65	struct {
	66	u_char ovu_magic; /* magic number */
	67	u_char ovu_index; /* bucket # */
	68	#ifdef RCHECK
	69	u_short ovu_size; /* actual block size */
	70	u_int ovu_rmagic; /* range magic number */
	71	#endif
	72	} ovu;
	73	#define ov_magic ovu.ovu_magic
	74	#define ov_index ovu.ovu_index
	75	#define ov_size ovu.ovu_size
	76	#define ov_rmagic ovu.ovu_rmagic
	77	};
	78
	79	#define MAGIC 0xff /* magic # on accounting info */
378cc40b	80	#define OLDMAGIC 0x7f /* same after a free() */
8d063cd8	81	#define RMAGIC 0x55555555 /* magic # on range info */
	82	#ifdef RCHECK
	83	#define RSLOP sizeof (u_int)
	84	#else
	85	#define RSLOP 0
	86	#endif
	87
	88	/*
	89	* nextf[i] is the pointer to the next free block of size 2^(i+3). The
	90	* smallest allocatable block is 8 bytes. The overhead information
	91	* precedes the data area returned to the user.
	92	*/
	93	#define NBUCKETS 30
	94	static union overhead *nextf[NBUCKETS];
	95	extern char *sbrk();
	96
	97	#ifdef MSTATS
	98	/*
	99	* nmalloc[i] is the difference between the number of mallocs and frees
	100	* for a given block size.
	101	*/
	102	static u_int nmalloc[NBUCKETS];
	103	#include <stdio.h>
	104	#endif
	105
	106	#ifdef debug
	107	#define ASSERT(p) if (!(p)) botch("p"); else
	108	static
	109	botch(s)
	110	char *s;
	111	{
	112
	113	printf("assertion botched: %s\n", s);
	114	abort();
	115	}
	116	#else
	117	#define ASSERT(p)
	118	#endif
	119
	120	char *
	121	malloc(nbytes)
	122	register unsigned nbytes;
	123	{
	124	register union overhead *p;
	125	register int bucket = 0;
	126	register unsigned shiftr;
	127
	128	/*
	129	* Convert amount of memory requested into
	130	* closest block size stored in hash buckets
	131	* which satisfies request. Account for
	132	* space used per block for accounting.
	133	*/
	134	nbytes += sizeof (union overhead) + RSLOP;
	135	nbytes = (nbytes + 3) &~ 3;
	136	shiftr = (nbytes - 1) >> 2;
	137	/* apart from this loop, this is O(1) */
	138	while (shiftr >>= 1)
	139	bucket++;
	140	/*
	141	* If nothing in hash bucket right now,
	142	* request more memory from the system.
	143	*/
	144	if (nextf[bucket] == NULL)
145	morecore(bucket);
146	if ((p = (union overhead *)nextf[bucket]) == NULL)
147	return (NULL);
148	/* remove from linked list */
bf38876a	149	#ifdef RCHECK
bf38876a	150	if (((int)p) & (sizeof(union overhead) - 1))
a687059c	151	#ifndef I286
8d063cd8	152	fprintf(stderr,"Corrupt malloc ptr 0x%x at 0x%x\n",((int)p),p);
a687059c	153	#else
	154	fprintf(stderr,"Corrupt malloc ptr 0x%lx at 0x%lx\n",((int)p),p);
	155	#endif
bf38876a	156	#endif
bf38876a	157	nextf[bucket] = p->ov_next;
8d063cd8	158	p->ov_magic = MAGIC;
	159	p->ov_index= bucket;
	160	#ifdef MSTATS
	161	nmalloc[bucket]++;
	162	#endif
	163	#ifdef RCHECK
	164	/*
	165	* Record allocated size of block and
	166	* bound space with magic numbers.
	167	*/
	168	if (nbytes <= 0x10000)
	169	p->ov_size = nbytes - 1;
	170	p->ov_rmagic = RMAGIC;
	171	((u_int )((caddr_t)p + nbytes - RSLOP)) = RMAGIC;
	172	#endif
	173	return ((char *)(p + 1));
	174	}
	175
	176	/*
	177	* Allocate more memory to the indicated bucket.
	178	*/
	179	static
	180	morecore(bucket)
a687059c	181	register int bucket;
8d063cd8	182	{
	183	register union overhead *op;
	184	register int rnu; /* 2^rnu bytes will be requested */
	185	register int nblks; /* become nblks blocks of the desired size */
	186	register int siz;
	187
	188	if (nextf[bucket])
	189	return;
	190	/*
	191	* Insure memory is allocated
	192	* on a page boundary. Should
	193	* make getpageize call?
	194	*/
	195	op = (union overhead *)sbrk(0);
a687059c	196	#ifndef I286
8d063cd8	197	if ((int)op & 0x3ff)
a687059c	198	(void)sbrk(1024 - ((int)op & 0x3ff));
	199	#else
	200	/* The sbrk(0) call on the I286 always returns the next segment */
	201	#endif
	202
	203	#ifndef I286
8d063cd8	204	/* take 2k unless the block is bigger than that */
8d063cd8	205	rnu = (bucket <= 8) ? 11 : bucket + 3;
a687059c	206	#else
	207	/* take 16k unless the block is bigger than that
	208	(80286s like large segments!) */
	209	rnu = (bucket <= 11) ? 14 : bucket + 3;
	210	#endif
8d063cd8	211	nblks = 1 << (rnu - (bucket + 3)); /* how many blocks to get */
	212	if (rnu < bucket)
	213	rnu = bucket;
	214	op = (union overhead *)sbrk(1 << rnu);
	215	/* no more room! */
	216	if ((int)op == -1)
	217	return;
	218	/*
	219	* Round up to minimum allocation size boundary
	220	* and deduct from block count to reflect.
	221	*/
a687059c	222	#ifndef I286
8d063cd8	223	if ((int)op & 7) {
	224	op = (union overhead *)(((int)op + 8) &~ 7);
	225	nblks--;
	226	}
a687059c	227	#else
	228	/* Again, this should always be ok on an 80286 */
	229	#endif
8d063cd8	230	/*
	231	* Add new memory allocated to that on
	232	* free list for this hash bucket.
	233	*/
	234	nextf[bucket] = op;
	235	siz = 1 << (bucket + 3);
	236	while (--nblks > 0) {
	237	op->ov_next = (union overhead *)((caddr_t)op + siz);
	238	op = (union overhead *)((caddr_t)op + siz);
	239	}
	240	}
	241
	242	free(cp)
	243	char *cp;
	244	{
	245	register int size;
	246	register union overhead *op;
	247
	248	if (cp == NULL)
	249	return;
	250	op = (union overhead *)((caddr_t)cp - sizeof (union overhead));
	251	#ifdef debug
	252	ASSERT(op->ov_magic == MAGIC); /* make sure it was in use */
	253	#else
378cc40b	254	if (op->ov_magic != MAGIC) {
a687059c	255	warn("%s free() ignored",
378cc40b	256	op->ov_magic == OLDMAGIC ? "Duplicate" : "Bad");
8d063cd8	257	return; /* sanity */
378cc40b	258	}
378cc40b	259	op->ov_magic = OLDMAGIC;
8d063cd8	260	#endif
	261	#ifdef RCHECK
	262	ASSERT(op->ov_rmagic == RMAGIC);
	263	if (op->ov_index <= 13)
	264	ASSERT((u_int )((caddr_t)op + op->ov_size + 1 - RSLOP) == RMAGIC);
	265	#endif
	266	ASSERT(op->ov_index < NBUCKETS);
	267	size = op->ov_index;
	268	op->ov_next = nextf[size];
	269	nextf[size] = op;
	270	#ifdef MSTATS
	271	nmalloc[size]--;
	272	#endif
	273	}
	274
	275	/*
	276	* When a program attempts "storage compaction" as mentioned in the
	277	* old malloc man page, it realloc's an already freed block. Usually
	278	* this is the last block it freed; occasionally it might be farther
	279	* back. We have to search all the free lists for the block in order
	280	* to determine its bucket: 1st we make one pass thru the lists
	281	* checking only the first block in each; if that fails we search
378cc40b	282	* ``reall_srchlen'' blocks in each list for a match (the variable
8d063cd8	283	* is extern so the caller can modify it). If that fails we just copy
	284	* however many bytes was given to realloc() and hope it's not huge.
	285	*/
378cc40b	286	int reall_srchlen = 4; /* 4 should be plenty, -1 =>'s whole list */
8d063cd8	287
	288	char *
	289	realloc(cp, nbytes)
	290	char *cp;
	291	unsigned nbytes;
	292	{
	293	register u_int onb;
	294	union overhead *op;
	295	char *res;
	296	register int i;
	297	int was_alloced = 0;
	298
	299	if (cp == NULL)
	300	return (malloc(nbytes));
	301	op = (union overhead *)((caddr_t)cp - sizeof (union overhead));
	302	if (op->ov_magic == MAGIC) {
	303	was_alloced++;
	304	i = op->ov_index;
	305	} else {
	306	/*
	307	* Already free, doing "compaction".
	308	*
	309	* Search for the old block of memory on the
	310	* free list. First, check the most common
	311	* case (last element free'd), then (this failing)
378cc40b	312	* the last ``reall_srchlen'' items free'd.
8d063cd8	313	* If all lookups fail, then assume the size of
	314	* the memory block being realloc'd is the
	315	* smallest possible.
	316	*/
	317	if ((i = findbucket(op, 1)) < 0 &&
378cc40b	318	(i = findbucket(op, reall_srchlen)) < 0)
8d063cd8	319	i = 0;
	320	}
	321	onb = (1 << (i + 3)) - sizeof (*op) - RSLOP;
	322	/* avoid the copy if same size block */
	323	if (was_alloced &&
a687059c	324	nbytes <= onb && nbytes > (onb >> 1) - sizeof(*op) - RSLOP) {
	325	#ifdef RCHECK
	326	/*
	327	* Record new allocated size of block and
	328	* bound space with magic numbers.
	329	*/
	330	if (op->ov_index <= 13) {
	331	/*
	332	* Convert amount of memory requested into
	333	* closest block size stored in hash buckets
	334	* which satisfies request. Account for
	335	* space used per block for accounting.
	336	*/
	337	nbytes += sizeof (union overhead) + RSLOP;
	338	nbytes = (nbytes + 3) &~ 3;
	339	op->ov_size = nbytes - 1;
	340	((u_int )((caddr_t)op + nbytes - RSLOP)) = RMAGIC;
	341	}
	342	#endif
8d063cd8	343	return(cp);
a687059c	344	}
8d063cd8	345	if ((res = malloc(nbytes)) == NULL)
	346	return (NULL);
	347	if (cp != res) /* common optimization */
a687059c	348	(void)bcopy(cp, res, (int)((nbytes < onb) ? nbytes : onb));
8d063cd8	349	if (was_alloced)
	350	free(cp);
	351	return (res);
	352	}
	353
	354	/*
	355	* Search ``srchlen'' elements of each free list for a block whose
	356	* header starts at ``freep''. If srchlen is -1 search the whole list.
	357	* Return bucket number, or -1 if not found.
	358	*/
	359	static
	360	findbucket(freep, srchlen)
	361	union overhead *freep;
	362	int srchlen;
	363	{
	364	register union overhead *p;
	365	register int i, j;
	366
	367	for (i = 0; i < NBUCKETS; i++) {
	368	j = 0;
	369	for (p = nextf[i]; p && j != srchlen; p = p->ov_next) {
	370	if (p == freep)
	371	return (i);
	372	j++;
	373	}
	374	}
	375	return (-1);
	376	}
	377
	378	#ifdef MSTATS
	379	/*
	380	* mstats - print out statistics about malloc
	381	*
	382	* Prints two lines of numbers, one showing the length of the free list
	383	* for each size category, the second showing the number of mallocs -
	384	* frees for each size category.
	385	*/
	386	mstats(s)
	387	char *s;
	388	{
	389	register int i, j;
	390	register union overhead *p;
	391	int totfree = 0,
	392	totused = 0;
	393
	394	fprintf(stderr, "Memory allocation statistics %s\nfree:\t", s);
	395	for (i = 0; i < NBUCKETS; i++) {
	396	for (j = 0, p = nextf[i]; p; p = p->ov_next, j++)
	397	;
	398	fprintf(stderr, " %d", j);
	399	totfree += j * (1 << (i + 3));
	400	}
	401	fprintf(stderr, "\nused:\t");
	402	for (i = 0; i < NBUCKETS; i++) {
	403	fprintf(stderr, " %d", nmalloc[i]);
	404	totused += nmalloc[i] * (1 << (i + 3));
	405	}
	406	fprintf(stderr, "\n\tTotal in use: %d, total free: %d\n",
	407	totused, totfree);
	408	}
	409	#endif
a687059c	410	#endif /* lint */