[unix-history] / usr / src / ucb / lisp / franz / vax / malloc.c

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

#define	NULL 0

/*
 * 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 */
	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 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 */
  	nextf[bucket] = nextf[bucket]->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 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);
  	if ((int)op & 0x3ff)
  		sbrk(1024 - ((int)op & 0x3ff));
	/* take 2k unless the block is bigger than that */
  	rnu = (bucket <= 8) ? 11 : bucket + 3;
  	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.
	 */
  	if ((int)op & 7) {
  		op = (union overhead *)(((int)op + 8) &~ 7);
  		nblks--;
  	}
	/*
	 * 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)
		return;				/* sanity */
#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
 * ``realloc_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 realloc_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 ``realloc_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, realloc_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)
		return(cp);
  	if ((res = malloc(nbytes)) == NULL)
  		return (NULL);
  	if (cp != res)			/* common optimization */
		bcopy(cp, res, (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
Commit	Line	Data
ad9153b8	1	#ifndef lint
0f4556f1	2	static char sccsid[] = "@(#)malloc.c 4.3 (Berkeley) 9/16/83";
ad9153b8	3	#endif
ef8bf40a MK	4
	5	/*
	6	* malloc.c (Caltech) 2/21/82
	7	* Chris Kingsley, kingsley@cit-20.
	8	*
	9	* This is a very fast storage allocator. It allocates blocks of a small
	10	* number of different sizes, and keeps free lists of each size. Blocks that
	11	* don't exactly fit are passed up to the next larger size. In this
	12	* implementation, the available sizes are 2^n-4 (or 2^n-12) bytes long.
	13	* This is designed for use in a program that uses vast quantities of memory,
	14	* but bombs when it runs out.
	15	*/
	16
	17	#include <sys/types.h>
	18
	19	#define NULL 0
	20
	21	/*
	22	* The overhead on a block is at least 4 bytes. When free, this space
	23	* contains a pointer to the next free block, and the bottom two bits must
	24	* be zero. When in use, the first byte is set to MAGIC, and the second
	25	* byte is the size index. The remaining bytes are for alignment.
	26	* If range checking is enabled and the size of the block fits
	27	* in two bytes, then the top two bytes hold the size of the requested block
	28	* plus the range checking words, and the header word MINUS ONE.
	29	*/
	30	union overhead {
	31	union overhead ov_next; / when free */
	32	struct {
	33	u_char ovu_magic; /* magic number */
	34	u_char ovu_index; /* bucket # */
	35	#ifdef RCHECK
	36	u_short ovu_size; /* actual block size */
	37	u_int ovu_rmagic; /* range magic number */
	38	#endif
	39	} ovu;
	40	#define ov_magic ovu.ovu_magic
	41	#define ov_index ovu.ovu_index
	42	#define ov_size ovu.ovu_size
	43	#define ov_rmagic ovu.ovu_rmagic
	44	};
	45
	46	#define MAGIC 0xff /* magic # on accounting info */
	47	#define RMAGIC 0x55555555 /* magic # on range info */
	48	#ifdef RCHECK
	49	#define RSLOP sizeof (u_int)
	50	#else
	51	#define RSLOP 0
	52	#endif
	53
	54	/*
	55	* nextf[i] is the pointer to the next free block of size 2^(i+3). The
	56	* smallest allocatable block is 8 bytes. The overhead information
	57	* precedes the data area returned to the user.
	58	*/
	59	#define NBUCKETS 30
	60	static union overhead *nextf[NBUCKETS];
	61	extern char *sbrk();
	62
	63	#ifdef MSTATS
	64	/*
	65	* nmalloc[i] is the difference between the number of mallocs and frees
	66	* for a given block size.
	67	*/
68	static u_int nmalloc[NBUCKETS];
69	#include <stdio.h>
70	#endif
71
ad9153b8	72	#ifdef debug
ef8bf40a MK	73	#define ASSERT(p) if (!(p)) botch("p"); else
ef8bf40a MK	74	static
ad9153b8	75	botch(s)
6cfec127	76	char *s;
ad9153b8	77	{
6cfec127 SL	78
6cfec127 SL	79	printf("assertion botched: %s\n", s);
ad9153b8 BJ	80	abort();
	81	}
	82	#else
ef8bf40a	83	#define ASSERT(p)
ad9153b8 BJ	84	#endif
ad9153b8 BJ	85
ad9153b8 BJ	86	char *
ad9153b8 BJ	87	malloc(nbytes)
ef8bf40a	88	register unsigned nbytes;
ad9153b8	89	{
ef8bf40a MK	90	register union overhead *p;
	91	register int bucket = 0;
	92	register unsigned shiftr;
	93
	94	/*
	95	* Convert amount of memory requested into
	96	* closest block size stored in hash buckets
	97	* which satisfies request. Account for
	98	* space used per block for accounting.
	99	*/
	100	nbytes += sizeof (union overhead) + RSLOP;
	101	nbytes = (nbytes + 3) &~ 3;
	102	shiftr = (nbytes - 1) >> 2;
	103	/* apart from this loop, this is O(1) */
	104	while (shiftr >>= 1)
	105	bucket++;
	106	/*
	107	* If nothing in hash bucket right now,
	108	* request more memory from the system.
	109	*/
	110	if (nextf[bucket] == NULL)
	111	morecore(bucket);
	112	if ((p = (union overhead *)nextf[bucket]) == NULL)
	113	return (NULL);
	114	/* remove from linked list */
	115	nextf[bucket] = nextf[bucket]->ov_next;
	116	p->ov_magic = MAGIC;
	117	p->ov_index= bucket;
	118	#ifdef MSTATS
	119	nmalloc[bucket]++;
	120	#endif
	121	#ifdef RCHECK
	122	/*
	123	* Record allocated size of block and
	124	* bound space with magic numbers.
	125	*/
	126	if (nbytes <= 0x10000)
	127	p->ov_size = nbytes - 1;
	128	p->ov_rmagic = RMAGIC;
	129	((u_int )((caddr_t)p + nbytes - RSLOP)) = RMAGIC;
	130	#endif
	131	return ((char *)(p + 1));
ad9153b8 BJ	132	}
ad9153b8 BJ	133
ef8bf40a MK	134	/*
	135	* Allocate more memory to the indicated bucket.
	136	*/
	137	static
	138	morecore(bucket)
	139	register bucket;
ad9153b8	140	{
ef8bf40a MK	141	register union overhead *op;
	142	register int rnu; /* 2^rnu bytes will be requested */
	143	register int nblks; /* become nblks blocks of the desired size */
	144	register int siz;
	145
	146	if (nextf[bucket])
	147	return;
	148	/*
	149	* Insure memory is allocated
	150	* on a page boundary. Should
	151	* make getpageize call?
	152	*/
	153	op = (union overhead *)sbrk(0);
	154	if ((int)op & 0x3ff)
	155	sbrk(1024 - ((int)op & 0x3ff));
	156	/* take 2k unless the block is bigger than that */
	157	rnu = (bucket <= 8) ? 11 : bucket + 3;
	158	nblks = 1 << (rnu - (bucket + 3)); /* how many blocks to get */
	159	if (rnu < bucket)
	160	rnu = bucket;
	161	op = (union overhead *)sbrk(1 << rnu);
	162	/* no more room! */
	163	if ((int)op == -1)
	164	return;
	165	/*
	166	* Round up to minimum allocation size boundary
	167	* and deduct from block count to reflect.
	168	*/
	169	if ((int)op & 7) {
	170	op = (union overhead *)(((int)op + 8) &~ 7);
	171	nblks--;
	172	}
	173	/*
	174	* Add new memory allocated to that on
	175	* free list for this hash bucket.
	176	*/
	177	nextf[bucket] = op;
	178	siz = 1 << (bucket + 3);
	179	while (--nblks > 0) {
	180	op->ov_next = (union overhead *)((caddr_t)op + siz);
	181	op = (union overhead *)((caddr_t)op + siz);
	182	}
	183	}
	184
	185	free(cp)
	186	char *cp;
	187	{
	188	register int size;
	189	register union overhead *op;
	190
	191	if (cp == NULL)
	192	return;
	193	op = (union overhead *)((caddr_t)cp - sizeof (union overhead));
	194	#ifdef debug
	195	ASSERT(op->ov_magic == MAGIC); /* make sure it was in use */
	196	#else
	197	if (op->ov_magic != MAGIC)
	198	return; /* sanity */
	199	#endif
	200	#ifdef RCHECK
	201	ASSERT(op->ov_rmagic == RMAGIC);
	202	if (op->ov_index <= 13)
	203	ASSERT((u_int )((caddr_t)op + op->ov_size + 1 - RSLOP) == RMAGIC);
	204	#endif
205	ASSERT(op->ov_index < NBUCKETS);
206	size = op->ov_index;
207	op->ov_next = nextf[size];
208	nextf[size] = op;
209	#ifdef MSTATS
210	nmalloc[size]--;
211	#endif
ad9153b8 BJ	212	}
ad9153b8 BJ	213
ef8bf40a MK	214	/*
	215	* When a program attempts "storage compaction" as mentioned in the
	216	* old malloc man page, it realloc's an already freed block. Usually
	217	* this is the last block it freed; occasionally it might be farther
	218	* back. We have to search all the free lists for the block in order
	219	* to determine its bucket: 1st we make one pass thru the lists
	220	* checking only the first block in each; if that fails we search
	221	* ``realloc_srchlen'' blocks in each list for a match (the variable
	222	* is extern so the caller can modify it). If that fails we just copy
	223	* however many bytes was given to realloc() and hope it's not huge.
	224	*/
6cfec127	225	int realloc_srchlen = 4; /* 4 should be plenty, -1 =>'s whole list */
ad9153b8 BJ	226
ad9153b8 BJ	227	char *
ef8bf40a MK	228	realloc(cp, nbytes)
	229	char *cp;
	230	unsigned nbytes;
	231	{
	232	register u_int onb;
	233	union overhead *op;
	234	char *res;
	235	register int i;
	236	int was_alloced = 0;
	237
	238	if (cp == NULL)
	239	return (malloc(nbytes));
	240	op = (union overhead *)((caddr_t)cp - sizeof (union overhead));
	241	if (op->ov_magic == MAGIC) {
	242	was_alloced++;
	243	i = op->ov_index;
6cfec127 SL	244	} else {
	245	/*
	246	* Already free, doing "compaction".
	247	*
	248	* Search for the old block of memory on the
	249	* free list. First, check the most common
	250	* case (last element free'd), then (this failing)
	251	* the last ``realloc_srchlen'' items free'd.
	252	* If all lookups fail, then assume the size of
	253	* the memory block being realloc'd is the
	254	* smallest possible.
	255	*/
ef8bf40a MK	256	if ((i = findbucket(op, 1)) < 0 &&
ef8bf40a MK	257	(i = findbucket(op, realloc_srchlen)) < 0)
6cfec127	258	i = 0;
ef8bf40a MK	259	}
ef8bf40a MK	260	onb = (1 << (i + 3)) - sizeof (*op) - RSLOP;
6cfec127 SL	261	/* avoid the copy if same size block */
6cfec127 SL	262	if (was_alloced &&
ef8bf40a MK	263	nbytes <= onb && nbytes > (onb >> 1) - sizeof(*op) - RSLOP)
	264	return(cp);
	265	if ((res = malloc(nbytes)) == NULL)
	266	return (NULL);
	267	if (cp != res) /* common optimization */
	268	bcopy(cp, res, (nbytes < onb) ? nbytes : onb);
	269	if (was_alloced)
	270	free(cp);
	271	return (res);
	272	}
	273
	274	/*
	275	* Search ``srchlen'' elements of each free list for a block whose
	276	* header starts at ``freep''. If srchlen is -1 search the whole list.
	277	* Return bucket number, or -1 if not found.
	278	*/
	279	static
	280	findbucket(freep, srchlen)
6cfec127 SL	281	union overhead *freep;
6cfec127 SL	282	int srchlen;
ad9153b8	283	{
ef8bf40a MK	284	register union overhead *p;
	285	register int i, j;
	286
6cfec127 SL	287	for (i = 0; i < NBUCKETS; i++) {
	288	j = 0;
	289	for (p = nextf[i]; p && j != srchlen; p = p->ov_next) {
ef8bf40a MK	290	if (p == freep)
ef8bf40a MK	291	return (i);
6cfec127 SL	292	j++;
	293	}
	294	}
ef8bf40a	295	return (-1);
ad9153b8 BJ	296	}
ad9153b8 BJ	297
ef8bf40a MK	298	#ifdef MSTATS
	299	/*
	300	* mstats - print out statistics about malloc
	301	*
	302	* Prints two lines of numbers, one showing the length of the free list
	303	* for each size category, the second showing the number of mallocs -
	304	* frees for each size category.
	305	*/
	306	mstats(s)
	307	char *s;
ad9153b8	308	{
ef8bf40a MK	309	register int i, j;
	310	register union overhead *p;
	311	int totfree = 0,
	312	totused = 0;
	313
	314	fprintf(stderr, "Memory allocation statistics %s\nfree:\t", s);
	315	for (i = 0; i < NBUCKETS; i++) {
	316	for (j = 0, p = nextf[i]; p; p = p->ov_next, j++)
	317	;
	318	fprintf(stderr, " %d", j);
	319	totfree += j * (1 << (i + 3));
	320	}
	321	fprintf(stderr, "\nused:\t");
	322	for (i = 0; i < NBUCKETS; i++) {
	323	fprintf(stderr, " %d", nmalloc[i]);
	324	totused += nmalloc[i] * (1 << (i + 3));
	325	}
6cfec127 SL	326	fprintf(stderr, "\n\tTotal in use: %d, total free: %d\n",
6cfec127 SL	327	totused, totfree);
ad9153b8 BJ	328	}
ad9153b8 BJ	329	#endif