src/common/malloc.c

/* Copyright (c) 1992 Regents of the University of California */

#ifndef lint
static char SCCSid[] = "$SunId$ LBL";
#endif

/*
 * Fast malloc for memory hogs and VM environments.
 * Performs a minimum of searching through free lists.
 * malloc(), realloc() and free() use buckets
 *      containing blocks in powers of two, similar to CIT routines.
 * bfree() puts memory from any source into malloc free lists.
 * bmalloc() doesn't keep track of free lists -- it's usually
 *      just a buffered call to sbrk(2).  However, bmalloc will
 *      call mscrounge() if sbrk fails.
 * mscrounge() returns whatever free memory it can find to satisfy the
 *      request along with the number of bytes (modified).
 * mcompact() takes the same arguments as mscrounge() (and is in fact
 *      called by mscrounge() under dire circumstances), but it uses
 *      memory compaction to return a larger block.  (MCOMP)
 *
 *      Greg Ward       Lawrence Berkeley Laboratory
 */

#include  <errno.h>

extern int      errno;

#ifdef MSTATS
#include  <stdio.h>
static unsigned b_nsbrked = 0;
static unsigned b_nalloced = 0;
static unsigned b_nfreed = 0;
static unsigned b_nscrounged = 0;
static unsigned b_ncompacted = 0;
static unsigned m_nalloced = 0;
static unsigned m_nfreed = 0;
static unsigned m_nwasted = 0;
#else
#define  NULL           0
#endif

#ifndef ALIGN
#define  ALIGN          int                     /* align type */
#endif
#define  BYTES_WORD     sizeof(ALIGN)

#ifndef  MAXINCR
#define  MAXINCR        (1<<16)                 /* largest sbrk(2) increment */
#endif
                                        /* malloc free lists */
typedef union m_head {
        union m_head    *next;
        struct {
                short           magic;
                short           bucket;
        }       a;
        ALIGN           dummy;
} M_HEAD;

#define MAGIC           0x1a2           /* magic number for allocated memory */

#define FIRSTBUCKET     3
#define NBUCKETS        30

static M_HEAD   *free_list[NBUCKETS];

static ALIGN    dummy_mem;

static char     *memlim[2];

#define DUMMYLOC        ((char *)&dummy_mem)

#define BADPTR(p)       ((p) < memlim[0] | (p) >= memlim[1])

#ifdef  MCOMP                   /* memory compaction routines */
static char     seedtab[1024];          /* seed for compaction table */

static struct mblk {
        char            *ptr;   /* pointer to memory block */
        unsigned        siz;    /* size of memory block */
}       cptab = {seedtab, sizeof(seedtab)};

#define mtab(mb)        ((struct mblk *)(mb)->ptr)
#define mtablen(mb)     ((mb)->siz/sizeof(struct mblk))


static int
mbcmp(m1, m2)           /* compare memory block locations */
register struct mblk    *m1, *m2;
{
                                /* put empty blocks at end */
        if (m1->siz == 0)
                return(m2->siz == 0 ? 0 : 1);
        if (m2->siz == 0)
                return(-1);
                                /* otherwise, ascending order */
        return(m1->ptr - m2->ptr);
}


int
compactfree()           /* compact free lists (moving to table) */
{
        register struct mblk    *tp;
        register int    bucket;
        unsigned        n, bsiz, ncomp;
                                /* fill table from free lists */
        tp = mtab(&cptab); n = mtablen(&cptab);
        bucket = NBUCKETS-1; bsiz = 1<<(NBUCKETS-1);
        ncomp = 0;
        for ( ; ; ) {
                while (tp->siz) {       /* find empty slot */
                        if (--n == 0)
                                goto loopexit;
                        tp++;
                }
                while (free_list[bucket] == NULL) {     /* find block */
                        if (--bucket < FIRSTBUCKET)
                                goto loopexit;
                        bsiz >>= 1;
                }
                tp->ptr = (char *)free_list[bucket];
                ncomp += (tp->siz = bsiz + sizeof(M_HEAD));
                free_list[bucket] = free_list[bucket]->next;
        }
loopexit:
        if (ncomp == 0)
                return(0);              /* nothing new to compact */
#ifdef MSTATS
        b_ncompacted += ncomp;
#endif
        tp = mtab(&cptab); n = mtablen(&cptab);         /* sort table */
        qsort((char *)tp, n, sizeof(struct mblk), mbcmp);
        ncomp = 0;                                      /* collect blocks */
        while (--n && tp[1].siz) {
                if (tp[0].ptr + tp[0].siz == tp[1].ptr) {
                        tp[1].ptr = tp[0].ptr;
                        tp[1].siz += tp[0].siz;
                        ncomp += tp[0].siz;
                        tp[0].siz = 0;
                }
                tp++;
        }
        return(ncomp);
}


char *
mcompact(np)            /* compact free lists to satisfy request */
unsigned        *np;
{
        struct mblk     *tab;
        unsigned        tablen;
        register struct mblk    *bp, *big;

        for ( ; ; ) {
                                        /* compact free lists */
                compactfree();
                                        /* find largest block */
                tab = mtab(&cptab); tablen = mtablen(&cptab);
                big = tab;
                bp = tab + tablen;
                while (--bp > tab)
                        if (bp->siz > big->siz)
                                big = bp;
                if (big->siz >= *np) {          /* big enough? */
                        *np = big->siz;
                        big->siz = 0;           /* remove from table */
                        return(big->ptr);       /* return it */
                }
                if (mtablen(big) < tablen+1) {
                        *np = 0;                /* cannot grow table */
                        return(NULL);           /* report failure */
                }
                                /* enlarge table, free old one */
                mtab(big)[0].ptr = cptab.ptr;
                mtab(big)[0].siz = cptab.siz;
                cptab.ptr = big->ptr;
                cptab.siz = big->siz;
                big->siz = 0;                   /* clear and copy */
#ifdef BSD
                bcopy((char *)tab, (char *)(mtab(&cptab)+1),
                                tablen*sizeof(struct mblk));
                bzero((char *)(mtab(&cptab)+tablen+1),
                        (mtablen(&cptab)-tablen-1)*sizeof(struct mblk));
#else
                (void)memcpy((char *)(mtab(&cptab)+1), (char *)tab,
                                tablen*sizeof(struct mblk));
                memset((char *)(mtab(&cptab)+tablen+1), 0,
                        (mtablen(&cptab)-tablen-1)*sizeof(struct mblk));
#endif
        }                       /* next round */
}
#endif          /* MCOMP */


char *
mscrounge(np)           /* search free lists to satisfy request */
register unsigned       *np;
{
        char    *p;
        register int    bucket;
        register unsigned       bsiz;

        for (bucket = FIRSTBUCKET, bsiz = 1<<FIRSTBUCKET;
                        bucket < NBUCKETS; bucket++, bsiz <<= 1)
                if (free_list[bucket] != NULL && bsiz+sizeof(M_HEAD) >= *np) {
                        *np = bsiz+sizeof(M_HEAD);
                        p = (char *)free_list[bucket];
                        free_list[bucket] = free_list[bucket]->next;
#ifdef MSTATS
                        b_nscrounged += *np;
#endif
                        return(p);
                }
#ifdef MCOMP
        return(mcompact(np));           /* try compaction */
#else
        *np = 0;
        return(NULL);
#endif
}


char *
bmalloc(n)              /* allocate a block of n bytes, sans header */
register unsigned  n;
{
        extern char  *sbrk();
        static unsigned  pagesz = 0;
        static unsigned  amnt;
        static char  *bpos;
        static unsigned  nrem;
        unsigned  thisamnt;
        register char   *p;

        if (pagesz == 0) {                              /* initialize */
                pagesz = amnt = getpagesize();
                nrem = (int)sbrk(0);                    /* page align break */
                nrem = pagesz - (nrem&(pagesz-1));
                bpos = sbrk(nrem);
                if ((int)bpos == -1)
                        return(NULL);
#ifdef MSTATS
                b_nsbrked += nrem;
#endif
                bpos += nrem & (BYTES_WORD-1);          /* align pointer */
                nrem &= ~(BYTES_WORD-1);
                memlim[0] = bpos;
                memlim[1] = bpos + nrem;
        }

        n = (n+(BYTES_WORD-1))&~(BYTES_WORD-1);         /* word align rqst. */

        if (n > nrem) {                                 /* need more core */
                if (n > amnt) {                         /* big chunk */
                        thisamnt = (n+(pagesz-1))&~(pagesz-1);
                        if (thisamnt <= MAXINCR)        /* increase amnt */
                                amnt = thisamnt;
                } else
                        thisamnt = amnt;
                p = sbrk(thisamnt);
                if ((int)p == -1) {                     /* uh-oh, ENOMEM */
                        thisamnt = n;                   /* search free lists */
                        p = mscrounge(&thisamnt);
                        if (p == NULL)                  /* we're really out */
                                return(NULL);
                }
#ifdef MSTATS
                else b_nsbrked += thisamnt;
#endif
                if (p != bpos+nrem) {                   /* not an increment */
                        bfree(bpos, nrem);              /* free what we have */
                        bpos = p;
                        nrem = thisamnt;
                } else                                  /* otherwise tack on */
                        nrem += thisamnt;
                if (bpos < memlim[0])
                        memlim[0] = bpos;
                if (bpos + nrem > memlim[1])
                        memlim[1] = bpos + nrem;
        }
        p = bpos;
        bpos += n;                                      /* advance */
        nrem -= n;
#ifdef MSTATS
        b_nalloced += n;
#endif
        return(p);
}


bfree(p, n)                     /* free n bytes of random memory */
register char  *p;
register unsigned  n;
{
        register int    bucket;
        register unsigned       bsiz;

        if (n < 1<<FIRSTBUCKET)
                return;
#ifdef MSTATS
        b_nfreed += n;
#endif
                                        /* align pointer */
        bsiz = BYTES_WORD - ((unsigned)p&(BYTES_WORD-1));
        if (bsiz < BYTES_WORD) {
                p += bsiz;
                n -= bsiz;
        }
        if (p < memlim[0])
                memlim[0] = p;
        if (p + n > memlim[1])
                memlim[1] = p + n;
                                        /* fill big buckets first */
        for (bucket = NBUCKETS-1, bsiz = 1<<(NBUCKETS-1);
                        bucket >= FIRSTBUCKET; bucket--, bsiz >>= 1)
                if (n >= bsiz+sizeof(M_HEAD)) {
                        ((M_HEAD *)p)->next = free_list[bucket];
                        free_list[bucket] = (M_HEAD *)p;
                        p += bsiz+sizeof(M_HEAD);
                        n -= bsiz+sizeof(M_HEAD);
                }
}


char *
malloc(n)                       /* allocate n bytes of memory */
unsigned        n;
{
        register M_HEAD *mp;
        register int    bucket;
        register unsigned       bsiz;
                                        /* don't return NULL on 0 request */
        if (n == 0)
                return(DUMMYLOC);
                                        /* find first bucket that fits */
        for (bucket = FIRSTBUCKET, bsiz = 1<<FIRSTBUCKET;
                        bucket < NBUCKETS; bucket++, bsiz <<= 1)
                if (bsiz >= n)
                        break;
        if (bucket >= NBUCKETS) {
                errno = EINVAL;
                return(NULL);
        }
        if (free_list[bucket] == NULL) {        /* need more core */
                mp = (M_HEAD *)bmalloc(bsiz+sizeof(M_HEAD));
                if (mp == NULL)
                        return(NULL);
        } else {                                /* got it */
                mp = free_list[bucket];
                free_list[bucket] = mp->next;
        }
#ifdef MSTATS
        m_nalloced += bsiz + sizeof(M_HEAD);
        m_nwasted += bsiz + sizeof(M_HEAD) - n;
#endif
        mp->a.magic = MAGIC;                    /* tag block */
        mp->a.bucket = bucket;
        return((char *)(mp+1));
}


char *
realloc(op, n)                  /* reallocate memory using malloc() */
register char   *op;
unsigned        n;
{
        char    *p;
        register unsigned       on;
                                        /* get old size */
        if (op != DUMMYLOC && !BADPTR(op) &&
                        ((M_HEAD *)op-1)->a.magic == MAGIC)
                on = 1 << ((M_HEAD *)op-1)->a.bucket;
        else
                on = 0;
        if (n <= on && (n > on>>1 || on == 1<<FIRSTBUCKET))
                return(op);             /* same bucket */
        if ((p = malloc(n)) == NULL)
                return(n<=on ? op : NULL);
        if (on) {
#ifdef  BSD
                bcopy(op, p, n>on ? on : n);
#else
                (void)memcpy(p, op, n>on ? on : n);
#endif
                free(op);
        }
        return(p);
}


free(p)                 /* free memory allocated by malloc */
char    *p;
{
        register M_HEAD *mp;
        register int    bucket;

        if (p == DUMMYLOC)
                return(1);
        if (BADPTR(p))
                goto invalid;
        mp = (M_HEAD *)p - 1;
        if (mp->a.magic != MAGIC)               /* sanity check */
                goto invalid;
        bucket = mp->a.bucket;
        if (bucket < FIRSTBUCKET | bucket >= NBUCKETS)
                goto invalid;
        mp->next = free_list[bucket];
        free_list[bucket] = mp;
#ifdef MSTATS
        m_nfreed += (1 << bucket) + sizeof(M_HEAD);
#endif
        return(1);
invalid:
        errno = EINVAL;
        return(0);
}


#ifdef MSTATS
printmemstats(fp)               /* print memory statistics to stream */
FILE    *fp;
{
        register int    i;
        int     n;
        register M_HEAD *mp;
        unsigned int    total = 0;

        fprintf(fp, "Memory statistics:\n");
        fprintf(fp, "\tbmalloc: %d bytes from sbrk\n", b_nsbrked);
        fprintf(fp, "\tbmalloc: %d bytes allocated\n", b_nalloced);
        fprintf(fp, "\tbmalloc: %d bytes freed\n", b_nfreed);
        fprintf(fp, "\tbmalloc: %d bytes scrounged\n", b_nscrounged);
        fprintf(fp, "\tbmalloc: %d bytes compacted\n", b_ncompacted);
        fprintf(fp, "\tmalloc: %d bytes allocated\n", m_nalloced);
        fprintf(fp, "\tmalloc: %d bytes wasted (%.1f%%)\n", m_nwasted,
                        100.0*m_nwasted/m_nalloced);
        fprintf(fp, "\tmalloc: %d bytes freed\n", m_nfreed);
        for (i = NBUCKETS-1; i >= FIRSTBUCKET; i--) {
                n = 0;
                for (mp = free_list[i]; mp != NULL; mp = mp->next)
                        n++;
                if (n) {
                        fprintf(fp, "\t%d * %u\n", n, 1<<i);
                        total += n * ((1<<i) + sizeof(M_HEAD));
                }
        }
        fprintf(fp, "\t %u total bytes in free list\n", total);
}
#endif
Revision:	2.6
Committed:	Fri Sep 4 09:57:43 1992 UTC (31 years, 8 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.5:	+27 -6 lines
Log Message:	additional paranoia -- check pointer bounds before accessing
#	User	Rev	Content
1	greg	2.3	/* Copyright (c) 1992 Regents of the University of California */
2	greg	1.1
3			#ifndef lint
4			static char SCCSid[] = "$SunId$ LBL";
5			#endif
6
7			/*
8			* Fast malloc for memory hogs and VM environments.
9			* Performs a minimum of searching through free lists.
10	greg	1.4	* malloc(), realloc() and free() use buckets
11			* containing blocks in powers of two, similar to CIT routines.
12			* bfree() puts memory from any source into malloc free lists.
13			* bmalloc() doesn't keep track of free lists -- it's usually
14	greg	1.3	* just a buffered call to sbrk(2). However, bmalloc will
15			* call mscrounge() if sbrk fails.
16	greg	1.8	* mscrounge() returns whatever free memory it can find to satisfy the
17	greg	1.3	* request along with the number of bytes (modified).
18	greg	1.14	* mcompact() takes the same arguments as mscrounge() (and is in fact
19			* called by mscrounge() under dire circumstances), but it uses
20			* memory compaction to return a larger block. (MCOMP)
21	greg	1.1	*
22			* Greg Ward Lawrence Berkeley Laboratory
23			*/
24
25	greg	1.6	#include <errno.h>
26
27	greg	2.6	extern int errno;
28
29	greg	1.9	#ifdef MSTATS
30			#include <stdio.h>
31	greg	2.6	static unsigned b_nsbrked = 0;
32	greg	1.9	static unsigned b_nalloced = 0;
33			static unsigned b_nfreed = 0;
34			static unsigned b_nscrounged = 0;
35	greg	1.14	static unsigned b_ncompacted = 0;
36	greg	1.9	static unsigned m_nalloced = 0;
37			static unsigned m_nfreed = 0;
38			static unsigned m_nwasted = 0;
39			#else
40	greg	1.1	#define NULL 0
41	greg	1.9	#endif
42	greg	1.1
43			#ifndef ALIGN
44			#define ALIGN int /* align type */
45			#endif
46			#define BYTES_WORD sizeof(ALIGN)
47
48	greg	1.16	#ifndef MAXINCR
49	greg	1.9	#define MAXINCR (1<<16) /* largest sbrk(2) increment */
50	greg	1.1	#endif
51			/* malloc free lists */
52			typedef union m_head {
53			union m_head *next;
54	greg	1.12	struct {
55			short magic;
56			short bucket;
57			} a;
58	greg	1.1	ALIGN dummy;
59			} M_HEAD;
60
61	greg	1.12	#define MAGIC 0x1a2 /* magic number for allocated memory */
62
63	greg	1.1	#define FIRSTBUCKET 3
64			#define NBUCKETS 30
65
66			static M_HEAD *free_list[NBUCKETS];
67
68	greg	1.12	static ALIGN dummy_mem;
69	greg	1.1
70	greg	2.6	static char *memlim[2];
71
72	greg	1.12	#define DUMMYLOC ((char *)&dummy_mem)
73	greg	1.10
74	greg	2.6	#define BADPTR(p) ((p) < memlim[0] \| (p) >= memlim[1])
75
76	greg	1.14	#ifdef MCOMP /* memory compaction routines */
77			static char seedtab[1024]; /* seed for compaction table */
78	greg	1.12
79	greg	1.14	static struct mblk {
80			char ptr; / pointer to memory block */
81			unsigned siz; /* size of memory block */
82			} cptab = {seedtab, sizeof(seedtab)};
83
84			#define mtab(mb) ((struct mblk *)(mb)->ptr)
85			#define mtablen(mb) ((mb)->siz/sizeof(struct mblk))
86
87
88			static int
89			mbcmp(m1, m2) /* compare memory block locations */
90			register struct mblk m1, m2;
91			{
92			/* put empty blocks at end */
93			if (m1->siz == 0)
94			return(m2->siz == 0 ? 0 : 1);
95			if (m2->siz == 0)
96			return(-1);
97			/* otherwise, ascending order */
98			return(m1->ptr - m2->ptr);
99			}
100
101
102			int
103			compactfree() /* compact free lists (moving to table) */
104			{
105			register struct mblk *tp;
106			register int bucket;
107			unsigned n, bsiz, ncomp;
108			/* fill table from free lists */
109			tp = mtab(&cptab); n = mtablen(&cptab);
110			bucket = NBUCKETS-1; bsiz = 1<<(NBUCKETS-1);
111			ncomp = 0;
112			for ( ; ; ) {
113			while (tp->siz) { /* find empty slot */
114			if (--n == 0)
115			goto loopexit;
116			tp++;
117			}
118			while (free_list[bucket] == NULL) { /* find block */
119			if (--bucket < FIRSTBUCKET)
120			goto loopexit;
121			bsiz >>= 1;
122			}
123			tp->ptr = (char *)free_list[bucket];
124			ncomp += (tp->siz = bsiz + sizeof(M_HEAD));
125			free_list[bucket] = free_list[bucket]->next;
126			}
127			loopexit:
128			if (ncomp == 0)
129			return(0); /* nothing new to compact */
130			#ifdef MSTATS
131			b_ncompacted += ncomp;
132			#endif
133			tp = mtab(&cptab); n = mtablen(&cptab); /* sort table */
134			qsort((char *)tp, n, sizeof(struct mblk), mbcmp);
135			ncomp = 0; /* collect blocks */
136			while (--n && tp[1].siz) {
137			if (tp[0].ptr + tp[0].siz == tp[1].ptr) {
138			tp[1].ptr = tp[0].ptr;
139			tp[1].siz += tp[0].siz;
140			ncomp += tp[0].siz;
141			tp[0].siz = 0;
142			}
143			tp++;
144			}
145			return(ncomp);
146			}
147
148
149	greg	1.1	char *
150	greg	1.14	mcompact(np) /* compact free lists to satisfy request */
151			unsigned *np;
152			{
153			struct mblk *tab;
154			unsigned tablen;
155			register struct mblk bp, big;
156
157			for ( ; ; ) {
158			/* compact free lists */
159			compactfree();
160			/* find largest block */
161			tab = mtab(&cptab); tablen = mtablen(&cptab);
162			big = tab;
163			bp = tab + tablen;
164			while (--bp > tab)
165			if (bp->siz > big->siz)
166			big = bp;
167			if (big->siz >= np) { / big enough? */
168			*np = big->siz;
169			big->siz = 0; /* remove from table */
170			return(big->ptr); /* return it */
171			}
172			if (mtablen(big) < tablen+1) {
173			np = 0; / cannot grow table */
174			return(NULL); /* report failure */
175			}
176			/* enlarge table, free old one */
177			mtab(big)[0].ptr = cptab.ptr;
178			mtab(big)[0].siz = cptab.siz;
179			cptab.ptr = big->ptr;
180			cptab.siz = big->siz;
181			big->siz = 0; /* clear and copy */
182			#ifdef BSD
183			bcopy((char )tab, (char )(mtab(&cptab)+1),
184			tablen*sizeof(struct mblk));
185			bzero((char *)(mtab(&cptab)+tablen+1),
186			(mtablen(&cptab)-tablen-1)*sizeof(struct mblk));
187			#else
188			(void)memcpy((char )(mtab(&cptab)+1), (char )tab,
189			tablen*sizeof(struct mblk));
190			memset((char *)(mtab(&cptab)+tablen+1), 0,
191			(mtablen(&cptab)-tablen-1)*sizeof(struct mblk));
192			#endif
193			} /* next round */
194			}
195			#endif /* MCOMP */
196
197
198			char *
199	greg	1.4	mscrounge(np) /* search free lists to satisfy request */
200	greg	1.3	register unsigned *np;
201			{
202			char *p;
203			register int bucket;
204			register unsigned bsiz;
205
206			for (bucket = FIRSTBUCKET, bsiz = 1<<FIRSTBUCKET;
207			bucket < NBUCKETS; bucket++, bsiz <<= 1)
208			if (free_list[bucket] != NULL && bsiz+sizeof(M_HEAD) >= *np) {
209			*np = bsiz+sizeof(M_HEAD);
210			p = (char *)free_list[bucket];
211			free_list[bucket] = free_list[bucket]->next;
212	greg	1.9	#ifdef MSTATS
213			b_nscrounged += *np;
214			#endif
215	greg	1.3	return(p);
216			}
217	greg	1.14	#ifdef MCOMP
218			return(mcompact(np)); /* try compaction */
219			#else
220	greg	1.3	*np = 0;
221			return(NULL);
222	greg	1.14	#endif
223	greg	1.3	}
224
225
226			char *
227	greg	1.1	bmalloc(n) /* allocate a block of n bytes, sans header */
228			register unsigned n;
229			{
230			extern char *sbrk();
231	greg	1.3	static unsigned pagesz = 0;
232			static unsigned amnt;
233	greg	1.1	static char *bpos;
234	greg	1.3	static unsigned nrem;
235			unsigned thisamnt;
236	greg	1.1	register char *p;
237
238			if (pagesz == 0) { /* initialize */
239	greg	1.2	pagesz = amnt = getpagesize();
240	greg	1.1	nrem = (int)sbrk(0); /* page align break */
241			nrem = pagesz - (nrem&(pagesz-1));
242	greg	2.3	bpos = sbrk(nrem);
243	greg	1.1	if ((int)bpos == -1)
244			return(NULL);
245	greg	1.14	#ifdef MSTATS
246			b_nsbrked += nrem;
247			#endif
248	greg	2.4	bpos += nrem & (BYTES_WORD-1); /* align pointer */
249			nrem &= ~(BYTES_WORD-1);
250	greg	2.6	memlim[0] = bpos;
251			memlim[1] = bpos + nrem;
252	greg	1.1	}
253
254			n = (n+(BYTES_WORD-1))&~(BYTES_WORD-1); /* word align rqst. */
255
256			if (n > nrem) { /* need more core */
257	greg	1.3	if (n > amnt) { /* big chunk */
258			thisamnt = (n+(pagesz-1))&~(pagesz-1);
259			if (thisamnt <= MAXINCR) /* increase amnt */
260			amnt = thisamnt;
261			} else
262			thisamnt = amnt;
263			p = sbrk(thisamnt);
264	greg	1.4	if ((int)p == -1) { /* uh-oh, ENOMEM */
265	greg	1.3	thisamnt = n; /* search free lists */
266			p = mscrounge(&thisamnt);
267			if (p == NULL) /* we're really out */
268			return(NULL);
269			}
270	greg	1.14	#ifdef MSTATS
271			else b_nsbrked += thisamnt;
272			#endif
273	greg	1.3	if (p != bpos+nrem) { /* not an increment */
274	greg	1.4	bfree(bpos, nrem); /* free what we have */
275	greg	1.1	bpos = p;
276	greg	1.3	nrem = thisamnt;
277	greg	1.4	} else /* otherwise tack on */
278	greg	1.3	nrem += thisamnt;
279	greg	2.6	if (bpos < memlim[0])
280			memlim[0] = bpos;
281			if (bpos + nrem > memlim[1])
282			memlim[1] = bpos + nrem;
283	greg	1.1	}
284			p = bpos;
285			bpos += n; /* advance */
286			nrem -= n;
287	greg	1.13	#ifdef MSTATS
288			b_nalloced += n;
289			#endif
290	greg	1.1	return(p);
291			}
292
293
294			bfree(p, n) /* free n bytes of random memory */
295	greg	1.2	register char *p;
296			register unsigned n;
297	greg	1.1	{
298			register int bucket;
299			register unsigned bsiz;
300	greg	1.9
301	greg	1.15	if (n < 1<<FIRSTBUCKET)
302			return;
303	greg	1.9	#ifdef MSTATS
304			b_nfreed += n;
305			#endif
306	greg	1.4	/* align pointer */
307	greg	1.6	bsiz = BYTES_WORD - ((unsigned)p&(BYTES_WORD-1));
308	greg	1.4	if (bsiz < BYTES_WORD) {
309			p += bsiz;
310			n -= bsiz;
311	greg	1.1	}
312	greg	2.6	if (p < memlim[0])
313			memlim[0] = p;
314			if (p + n > memlim[1])
315			memlim[1] = p + n;
316	greg	1.4	/* fill big buckets first */
317			for (bucket = NBUCKETS-1, bsiz = 1<<(NBUCKETS-1);
318			bucket >= FIRSTBUCKET; bucket--, bsiz >>= 1)
319			if (n >= bsiz+sizeof(M_HEAD)) {
320			((M_HEAD *)p)->next = free_list[bucket];
321			free_list[bucket] = (M_HEAD *)p;
322			p += bsiz+sizeof(M_HEAD);
323			n -= bsiz+sizeof(M_HEAD);
324			}
325	greg	1.1	}
326
327
328			char *
329			malloc(n) /* allocate n bytes of memory */
330			unsigned n;
331			{
332			register M_HEAD *mp;
333			register int bucket;
334			register unsigned bsiz;
335	greg	1.10	/* don't return NULL on 0 request */
336			if (n == 0)
337			return(DUMMYLOC);
338	greg	1.2	/* find first bucket that fits */
339	greg	1.6	for (bucket = FIRSTBUCKET, bsiz = 1<<FIRSTBUCKET;
340			bucket < NBUCKETS; bucket++, bsiz <<= 1)
341			if (bsiz >= n)
342			break;
343			if (bucket >= NBUCKETS) {
344			errno = EINVAL;
345			return(NULL);
346			}
347	greg	1.4	if (free_list[bucket] == NULL) { /* need more core */
348	greg	1.1	mp = (M_HEAD *)bmalloc(bsiz+sizeof(M_HEAD));
349			if (mp == NULL)
350			return(NULL);
351	greg	1.4	} else { /* got it */
352	greg	1.1	mp = free_list[bucket];
353			free_list[bucket] = mp->next;
354			}
355	greg	1.13	#ifdef MSTATS
356			m_nalloced += bsiz + sizeof(M_HEAD);
357			m_nwasted += bsiz + sizeof(M_HEAD) - n;
358			#endif
359	greg	1.12	mp->a.magic = MAGIC; /* tag block */
360			mp->a.bucket = bucket;
361	greg	1.1	return((char *)(mp+1));
362			}
363
364
365			char *
366			realloc(op, n) /* reallocate memory using malloc() */
367	greg	1.6	register char *op;
368	greg	1.1	unsigned n;
369			{
370	greg	1.6	char *p;
371	greg	1.1	register unsigned on;
372	greg	1.6	/* get old size */
373	greg	2.6	if (op != DUMMYLOC && !BADPTR(op) &&
374			((M_HEAD *)op-1)->a.magic == MAGIC)
375	greg	1.12	on = 1 << ((M_HEAD *)op-1)->a.bucket;
376	greg	1.5	else
377			on = 0;
378	greg	1.6	if (n <= on && (n > on>>1 \|\| on == 1<<FIRSTBUCKET))
379	greg	1.5	return(op); /* same bucket */
380	greg	1.13	if ((p = malloc(n)) == NULL)
381	greg	2.5	return(n<=on ? op : NULL);
382	greg	1.13	if (on) {
383	greg	1.1	#ifdef BSD
384	greg	1.2	bcopy(op, p, n>on ? on : n);
385	greg	1.1	#else
386	greg	1.2	(void)memcpy(p, op, n>on ? on : n);
387	greg	1.1	#endif
388	greg	1.13	free(op);
389			}
390	greg	1.1	return(p);
391			}
392
393
394			free(p) /* free memory allocated by malloc */
395			char *p;
396			{
397			register M_HEAD *mp;
398			register int bucket;
399
400	greg	2.6	if (p == DUMMYLOC)
401	greg	1.13	return(1);
402	greg	2.6	if (BADPTR(p))
403			goto invalid;
404	greg	1.1	mp = (M_HEAD *)p - 1;
405	greg	1.12	if (mp->a.magic != MAGIC) /* sanity check */
406	greg	2.6	goto invalid;
407	greg	1.12	bucket = mp->a.bucket;
408	greg	2.2	if (bucket < FIRSTBUCKET \| bucket >= NBUCKETS)
409	greg	2.6	goto invalid;
410	greg	1.1	mp->next = free_list[bucket];
411			free_list[bucket] = mp;
412	greg	1.9	#ifdef MSTATS
413			m_nfreed += (1 << bucket) + sizeof(M_HEAD);
414			#endif
415	greg	1.13	return(1);
416	greg	2.6	invalid:
417			errno = EINVAL;
418			return(0);
419	greg	1.1	}
420	greg	1.9
421
422			#ifdef MSTATS
423			printmemstats(fp) /* print memory statistics to stream */
424			FILE *fp;
425			{
426			register int i;
427			int n;
428			register M_HEAD *mp;
429			unsigned int total = 0;
430
431			fprintf(fp, "Memory statistics:\n");
432	greg	1.14	fprintf(fp, "\tbmalloc: %d bytes from sbrk\n", b_nsbrked);
433	greg	1.9	fprintf(fp, "\tbmalloc: %d bytes allocated\n", b_nalloced);
434			fprintf(fp, "\tbmalloc: %d bytes freed\n", b_nfreed);
435			fprintf(fp, "\tbmalloc: %d bytes scrounged\n", b_nscrounged);
436	greg	1.14	fprintf(fp, "\tbmalloc: %d bytes compacted\n", b_ncompacted);
437	greg	1.9	fprintf(fp, "\tmalloc: %d bytes allocated\n", m_nalloced);
438			fprintf(fp, "\tmalloc: %d bytes wasted (%.1f%%)\n", m_nwasted,
439			100.0*m_nwasted/m_nalloced);
440			fprintf(fp, "\tmalloc: %d bytes freed\n", m_nfreed);
441			for (i = NBUCKETS-1; i >= FIRSTBUCKET; i--) {
442			n = 0;
443			for (mp = free_list[i]; mp != NULL; mp = mp->next)
444			n++;
445			if (n) {
446			fprintf(fp, "\t%d * %u\n", n, 1<<i);
447			total += n * ((1<<i) + sizeof(M_HEAD));
448			}
449			}
450			fprintf(fp, "\t %u total bytes in free list\n", total);
451			}
452	greg	1.1	#endif