[perl5.git] / malloc.c

/* $Header: malloc.c,v 1.0.1.1 88/01/24 03:53:23 root Exp $
 *
 * $Log:	malloc.c,v $
 * Revision 1.0.1.1  88/01/24  03:53:23  root
 * patch 2: made depend on perl.h.
 * 
 * Revision 1.0  87/12/18  13:05:35  root
 * Initial revision
 * 
 */

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

#define RCHECK
/*
 * 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 "handy.h"
#include "search.h"
#include "perl.h"

/* 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

#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 */
	if (*((int*)p) > 0x10000000)
	    fprintf(stderr,"Corrupt malloc ptr 0x%x at 0x%x\n",*((int*)p),p);
  	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
135863df	1	/* $Header: malloc.c,v 1.0.1.1 88/01/24 03:53:23 root Exp $
8d063cd8 LW	2	*
8d063cd8 LW	3	* $Log: malloc.c,v $
135863df AB	4	* Revision 1.0.1.1 88/01/24 03:53:23 root
	5	* patch 2: made depend on perl.h.
	6	*
8d063cd8 LW	7	* Revision 1.0 87/12/18 13:05:35 root
	8	* Initial revision
	9	*
	10	*/
	11
	12	#ifndef lint
	13	static char sccsid[] = "@(#)malloc.c 4.3 (Berkeley) 9/16/83";
	14	#endif
	15	#include <stdio.h>
	16
	17	#define RCHECK
	18	/*
	19	* malloc.c (Caltech) 2/21/82
	20	* Chris Kingsley, kingsley@cit-20.
	21	*
	22	* This is a very fast storage allocator. It allocates blocks of a small
	23	* number of different sizes, and keeps free lists of each size. Blocks that
	24	* don't exactly fit are passed up to the next larger size. In this
	25	* implementation, the available sizes are 2^n-4 (or 2^n-12) bytes long.
	26	* This is designed for use in a program that uses vast quantities of memory,
	27	* but bombs when it runs out.
	28	*/
	29
135863df AB	30	#include "EXTERN.h"
	31	#include "handy.h"
	32	#include "search.h"
	33	#include "perl.h"
	34
	35	/* I don't much care whether these are defined in sys/types.h--LAW */
	36
	37	#define u_char unsigned char
	38	#define u_int unsigned int
	39	#define u_short unsigned short
8d063cd8 LW	40
	41	#define NULL 0
	42
	43	/*
	44	* The overhead on a block is at least 4 bytes. When free, this space
	45	* contains a pointer to the next free block, and the bottom two bits must
	46	* be zero. When in use, the first byte is set to MAGIC, and the second
	47	* byte is the size index. The remaining bytes are for alignment.
	48	* If range checking is enabled and the size of the block fits
	49	* in two bytes, then the top two bytes hold the size of the requested block
	50	* plus the range checking words, and the header word MINUS ONE.
	51	*/
	52	union overhead {
	53	union overhead ov_next; / when free */
	54	struct {
	55	u_char ovu_magic; /* magic number */
	56	u_char ovu_index; /* bucket # */
	57	#ifdef RCHECK
	58	u_short ovu_size; /* actual block size */
	59	u_int ovu_rmagic; /* range magic number */
	60	#endif
	61	} ovu;
	62	#define ov_magic ovu.ovu_magic
	63	#define ov_index ovu.ovu_index
	64	#define ov_size ovu.ovu_size
	65	#define ov_rmagic ovu.ovu_rmagic
	66	};
	67
	68	#define MAGIC 0xff /* magic # on accounting info */
	69	#define RMAGIC 0x55555555 /* magic # on range info */
	70	#ifdef RCHECK
	71	#define RSLOP sizeof (u_int)
	72	#else
	73	#define RSLOP 0
	74	#endif
	75
	76	/*
	77	* nextf[i] is the pointer to the next free block of size 2^(i+3). The
	78	* smallest allocatable block is 8 bytes. The overhead information
	79	* precedes the data area returned to the user.
	80	*/
	81	#define NBUCKETS 30
	82	static union overhead *nextf[NBUCKETS];
	83	extern char *sbrk();
	84
	85	#ifdef MSTATS
	86	/*
	87	* nmalloc[i] is the difference between the number of mallocs and frees
	88	* for a given block size.
	89	*/
	90	static u_int nmalloc[NBUCKETS];
	91	#include <stdio.h>
	92	#endif
	93
	94	#ifdef debug
	95	#define ASSERT(p) if (!(p)) botch("p"); else
	96	static
	97	botch(s)
	98	char *s;
	99	{
	100
	101	printf("assertion botched: %s\n", s);
	102	abort();
	103	}
104	#else
105	#define ASSERT(p)
106	#endif
107
108	char *
109	malloc(nbytes)
110	register unsigned nbytes;
111	{
112	register union overhead *p;
113	register int bucket = 0;
114	register unsigned shiftr;
115
116	/*
117	* Convert amount of memory requested into
118	* closest block size stored in hash buckets
119	* which satisfies request. Account for
120	* space used per block for accounting.
121	*/
122	nbytes += sizeof (union overhead) + RSLOP;
123	nbytes = (nbytes + 3) &~ 3;
124	shiftr = (nbytes - 1) >> 2;
125	/* apart from this loop, this is O(1) */
126	while (shiftr >>= 1)
127	bucket++;
128	/*
129	* If nothing in hash bucket right now,
130	* request more memory from the system.
131	*/
132	if (nextf[bucket] == NULL)
133	morecore(bucket);
134	if ((p = (union overhead *)nextf[bucket]) == NULL)
135	return (NULL);
136	/* remove from linked list */
137	if (((int)p) > 0x10000000)
138	fprintf(stderr,"Corrupt malloc ptr 0x%x at 0x%x\n",((int)p),p);
139	nextf[bucket] = nextf[bucket]->ov_next;
140	p->ov_magic = MAGIC;
141	p->ov_index= bucket;
142	#ifdef MSTATS
143	nmalloc[bucket]++;
144	#endif
145	#ifdef RCHECK
146	/*
147	* Record allocated size of block and
148	* bound space with magic numbers.
149	*/
150	if (nbytes <= 0x10000)
151	p->ov_size = nbytes - 1;
152	p->ov_rmagic = RMAGIC;
153	((u_int )((caddr_t)p + nbytes - RSLOP)) = RMAGIC;
154	#endif
155	return ((char *)(p + 1));
156	}
157
158	/*
159	* Allocate more memory to the indicated bucket.
160	*/
161	static
162	morecore(bucket)
163	register bucket;
164	{
165	register union overhead *op;
166	register int rnu; /* 2^rnu bytes will be requested */
167	register int nblks; /* become nblks blocks of the desired size */
168	register int siz;
169
170	if (nextf[bucket])
171	return;
172	/*
173	* Insure memory is allocated
174	* on a page boundary. Should
175	* make getpageize call?
176	*/
177	op = (union overhead *)sbrk(0);
178	if ((int)op & 0x3ff)
179	sbrk(1024 - ((int)op & 0x3ff));
180	/* take 2k unless the block is bigger than that */
181	rnu = (bucket <= 8) ? 11 : bucket + 3;
182	nblks = 1 << (rnu - (bucket + 3)); /* how many blocks to get */
183	if (rnu < bucket)
184	rnu = bucket;
185	op = (union overhead *)sbrk(1 << rnu);
186	/* no more room! */
187	if ((int)op == -1)
188	return;
189	/*
190	* Round up to minimum allocation size boundary
191	* and deduct from block count to reflect.
192	*/
193	if ((int)op & 7) {
194	op = (union overhead *)(((int)op + 8) &~ 7);
195	nblks--;
196	}
197	/*
198	* Add new memory allocated to that on
199	* free list for this hash bucket.
200	*/
201	nextf[bucket] = op;
202	siz = 1 << (bucket + 3);
203	while (--nblks > 0) {
204	op->ov_next = (union overhead *)((caddr_t)op + siz);
205	op = (union overhead *)((caddr_t)op + siz);
206	}
207	}
208
209	free(cp)
210	char *cp;
211	{
212	register int size;
213	register union overhead *op;
214
215	if (cp == NULL)
216	return;
217	op = (union overhead *)((caddr_t)cp - sizeof (union overhead));
218	#ifdef debug
219	ASSERT(op->ov_magic == MAGIC); /* make sure it was in use */
220	#else
221	if (op->ov_magic != MAGIC)
222	return; /* sanity */
223	#endif
224	#ifdef RCHECK
225	ASSERT(op->ov_rmagic == RMAGIC);
226	if (op->ov_index <= 13)
227	ASSERT((u_int )((caddr_t)op + op->ov_size + 1 - RSLOP) == RMAGIC);
228	#endif
229	ASSERT(op->ov_index < NBUCKETS);
230	size = op->ov_index;
231	op->ov_next = nextf[size];
232	nextf[size] = op;
233	#ifdef MSTATS
234	nmalloc[size]--;
235	#endif
236	}
237
238	/*
239	* When a program attempts "storage compaction" as mentioned in the
240	* old malloc man page, it realloc's an already freed block. Usually
241	* this is the last block it freed; occasionally it might be farther
242	* back. We have to search all the free lists for the block in order
243	* to determine its bucket: 1st we make one pass thru the lists
244	* checking only the first block in each; if that fails we search
245	* ``realloc_srchlen'' blocks in each list for a match (the variable
246	* is extern so the caller can modify it). If that fails we just copy
247	* however many bytes was given to realloc() and hope it's not huge.
248	*/
249	int realloc_srchlen = 4; /* 4 should be plenty, -1 =>'s whole list */
250
251	char *
252	realloc(cp, nbytes)
253	char *cp;
254	unsigned nbytes;
255	{
256	register u_int onb;
257	union overhead *op;
258	char *res;
259	register int i;
260	int was_alloced = 0;
261
262	if (cp == NULL)
263	return (malloc(nbytes));
264	op = (union overhead *)((caddr_t)cp - sizeof (union overhead));
265	if (op->ov_magic == MAGIC) {
266	was_alloced++;
267	i = op->ov_index;
268	} else {
269	/*
270	* Already free, doing "compaction".
271	*
272	* Search for the old block of memory on the
273	* free list. First, check the most common
274	* case (last element free'd), then (this failing)
275	* the last ``realloc_srchlen'' items free'd.
276	* If all lookups fail, then assume the size of
277	* the memory block being realloc'd is the
278	* smallest possible.
279	*/
280	if ((i = findbucket(op, 1)) < 0 &&
281	(i = findbucket(op, realloc_srchlen)) < 0)
282	i = 0;
283	}
284	onb = (1 << (i + 3)) - sizeof (*op) - RSLOP;
285	/* avoid the copy if same size block */
286	if (was_alloced &&
287	nbytes <= onb && nbytes > (onb >> 1) - sizeof(*op) - RSLOP)
288	return(cp);
289	if ((res = malloc(nbytes)) == NULL)
290	return (NULL);
291	if (cp != res) /* common optimization */
292	bcopy(cp, res, (nbytes < onb) ? nbytes : onb);
293	if (was_alloced)
294	free(cp);
295	return (res);
296	}
297
298	/*
299	* Search ``srchlen'' elements of each free list for a block whose
300	* header starts at ``freep''. If srchlen is -1 search the whole list.
301	* Return bucket number, or -1 if not found.
302	*/
303	static
304	findbucket(freep, srchlen)
305	union overhead *freep;
306	int srchlen;
307	{
308	register union overhead *p;
309	register int i, j;
310
311	for (i = 0; i < NBUCKETS; i++) {
312	j = 0;
313	for (p = nextf[i]; p && j != srchlen; p = p->ov_next) {
314	if (p == freep)
315	return (i);
316	j++;
317	}
318	}
319	return (-1);
320	}
321
322	#ifdef MSTATS
323	/*
324	* mstats - print out statistics about malloc
325	*
326	* Prints two lines of numbers, one showing the length of the free list
327	* for each size category, the second showing the number of mallocs -
328	* frees for each size category.
329	*/
330	mstats(s)
331	char *s;
332	{
333	register int i, j;
334	register union overhead *p;
335	int totfree = 0,
336	totused = 0;
337
338	fprintf(stderr, "Memory allocation statistics %s\nfree:\t", s);
339	for (i = 0; i < NBUCKETS; i++) {
340	for (j = 0, p = nextf[i]; p; p = p->ov_next, j++)
341	;
342	fprintf(stderr, " %d", j);
343	totfree += j * (1 << (i + 3));
344	}
345	fprintf(stderr, "\nused:\t");
346	for (i = 0; i < NBUCKETS; i++) {
347	fprintf(stderr, " %d", nmalloc[i]);
348	totused += nmalloc[i] * (1 << (i + 3));
349	}
350	fprintf(stderr, "\n\tTotal in use: %d, total free: %d\n",
351	totused, totfree);
352	}
353	#endif