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>

#ifndef  BSD
#define  bcopy(s,d,n)           (void)memcpy(d,s,n)
#define  bzero(d,n)             (void)memset(d,0,n)
#endif

#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 */
                while (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) {
                        *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 */
                bcopy((char *)tab, (char *)(mtab(&cptab)+1),
                                tablen*sizeof(struct mblk));
                bzero((char *)(mtab(&cptab)+tablen+1),
                        (mtablen(&cptab)-tablen-1)*sizeof(struct mblk));
        }                       /* 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 */
        tryagain:
                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 */
                        errno = 0;                      /* call cavalry */
                        if (thisamnt >= n+pagesz) {
                                amnt = pagesz;          /* minimize request */
                                goto tryagain;
                        }
                        thisamnt = n;
                        p = mscrounge(&thisamnt);       /* search free lists */
                        if (p == NULL) {                /* we're really out */
                                errno = ENOMEM;
                                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 || p == NULL)
                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) {
                bcopy(op, p, n>on ? on : n);
                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:	2.11
Committed:	Mon Aug 24 15:31:29 1998 UTC (25 years, 8 months ago) by gwlarson
Content type:	text/plain
Branch:	MAIN
Changes since 2.10:	+1 -1 lines
Log Message:	added defensive measure to bfree() for NULL pointer
#	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	2.7	#ifndef BSD
28			#define bcopy(s,d,n) (void)memcpy(d,s,n)
29			#define bzero(d,n) (void)memset(d,0,n)
30			#endif
31
32	greg	1.9	#ifdef MSTATS
33			#include <stdio.h>
34	greg	2.6	static unsigned b_nsbrked = 0;
35	greg	1.9	static unsigned b_nalloced = 0;
36			static unsigned b_nfreed = 0;
37			static unsigned b_nscrounged = 0;
38	greg	1.14	static unsigned b_ncompacted = 0;
39	greg	1.9	static unsigned m_nalloced = 0;
40			static unsigned m_nfreed = 0;
41			static unsigned m_nwasted = 0;
42			#else
43	greg	1.1	#define NULL 0
44	greg	1.9	#endif
45	greg	1.1
46			#ifndef ALIGN
47			#define ALIGN int /* align type */
48			#endif
49			#define BYTES_WORD sizeof(ALIGN)
50
51	greg	1.16	#ifndef MAXINCR
52	greg	1.9	#define MAXINCR (1<<16) /* largest sbrk(2) increment */
53	greg	1.1	#endif
54			/* malloc free lists */
55			typedef union m_head {
56			union m_head *next;
57	greg	1.12	struct {
58			short magic;
59			short bucket;
60			} a;
61	greg	1.1	ALIGN dummy;
62			} M_HEAD;
63
64	greg	1.12	#define MAGIC 0x1a2 /* magic number for allocated memory */
65
66	greg	1.1	#define FIRSTBUCKET 3
67			#define NBUCKETS 30
68
69			static M_HEAD *free_list[NBUCKETS];
70
71	greg	1.12	static ALIGN dummy_mem;
72	greg	1.1
73	greg	2.6	static char *memlim[2];
74
75	greg	1.12	#define DUMMYLOC ((char *)&dummy_mem)
76	greg	1.10
77	greg	2.6	#define BADPTR(p) ((p) < memlim[0] \| (p) >= memlim[1])
78
79	greg	1.14	#ifdef MCOMP /* memory compaction routines */
80			static char seedtab[1024]; /* seed for compaction table */
81	greg	1.12
82	greg	1.14	static struct mblk {
83			char ptr; / pointer to memory block */
84			unsigned siz; /* size of memory block */
85			} cptab = {seedtab, sizeof(seedtab)};
86
87			#define mtab(mb) ((struct mblk *)(mb)->ptr)
88			#define mtablen(mb) ((mb)->siz/sizeof(struct mblk))
89
90
91			static int
92			mbcmp(m1, m2) /* compare memory block locations */
93			register struct mblk m1, m2;
94			{
95			/* put empty blocks at end */
96			if (m1->siz == 0)
97			return(m2->siz == 0 ? 0 : 1);
98			if (m2->siz == 0)
99			return(-1);
100			/* otherwise, ascending order */
101			return(m1->ptr - m2->ptr);
102			}
103
104
105			int
106			compactfree() /* compact free lists (moving to table) */
107			{
108			register struct mblk *tp;
109			register int bucket;
110			unsigned n, bsiz, ncomp;
111			/* fill table from free lists */
112			tp = mtab(&cptab); n = mtablen(&cptab);
113			bucket = NBUCKETS-1; bsiz = 1<<(NBUCKETS-1);
114			ncomp = 0;
115			for ( ; ; ) {
116			while (tp->siz) { /* find empty slot */
117			if (--n == 0)
118			goto loopexit;
119			tp++;
120			}
121			while (free_list[bucket] == NULL) { /* find block */
122			if (--bucket < FIRSTBUCKET)
123			goto loopexit;
124			bsiz >>= 1;
125			}
126			tp->ptr = (char *)free_list[bucket];
127			ncomp += (tp->siz = bsiz + sizeof(M_HEAD));
128			free_list[bucket] = free_list[bucket]->next;
129			}
130			loopexit:
131			if (ncomp == 0)
132			return(0); /* nothing new to compact */
133			#ifdef MSTATS
134			b_ncompacted += ncomp;
135			#endif
136			tp = mtab(&cptab); n = mtablen(&cptab); /* sort table */
137			qsort((char *)tp, n, sizeof(struct mblk), mbcmp);
138			ncomp = 0; /* collect blocks */
139			while (--n && tp[1].siz) {
140			if (tp[0].ptr + tp[0].siz == tp[1].ptr) {
141			tp[1].ptr = tp[0].ptr;
142			tp[1].siz += tp[0].siz;
143			ncomp += tp[0].siz;
144			tp[0].siz = 0;
145			}
146			tp++;
147			}
148			return(ncomp);
149			}
150
151
152	greg	1.1	char *
153	greg	1.14	mcompact(np) /* compact free lists to satisfy request */
154			unsigned *np;
155			{
156			struct mblk *tab;
157			unsigned tablen;
158			register struct mblk bp, big;
159
160			for ( ; ; ) {
161			/* compact free lists */
162	greg	2.9	while (compactfree())
163			;
164	greg	1.14	/* find largest block */
165			tab = mtab(&cptab); tablen = mtablen(&cptab);
166			big = tab;
167			bp = tab + tablen;
168			while (--bp > tab)
169			if (bp->siz > big->siz)
170			big = bp;
171			if (big->siz >= np) { / big enough? */
172			*np = big->siz;
173			big->siz = 0; /* remove from table */
174			return(big->ptr); /* return it */
175			}
176	greg	2.7	if (mtablen(big) <= tablen) {
177	greg	1.14	np = 0; / cannot grow table */
178			return(NULL); /* report failure */
179			}
180			/* enlarge table, free old one */
181			mtab(big)[0].ptr = cptab.ptr;
182			mtab(big)[0].siz = cptab.siz;
183			cptab.ptr = big->ptr;
184			cptab.siz = big->siz;
185			big->siz = 0; /* clear and copy */
186			bcopy((char )tab, (char )(mtab(&cptab)+1),
187			tablen*sizeof(struct mblk));
188			bzero((char *)(mtab(&cptab)+tablen+1),
189			(mtablen(&cptab)-tablen-1)*sizeof(struct mblk));
190			} /* next round */
191			}
192			#endif /* MCOMP */
193
194
195			char *
196	greg	1.4	mscrounge(np) /* search free lists to satisfy request */
197	greg	1.3	register unsigned *np;
198			{
199			char *p;
200			register int bucket;
201			register unsigned bsiz;
202
203			for (bucket = FIRSTBUCKET, bsiz = 1<<FIRSTBUCKET;
204			bucket < NBUCKETS; bucket++, bsiz <<= 1)
205			if (free_list[bucket] != NULL && bsiz+sizeof(M_HEAD) >= *np) {
206			*np = bsiz+sizeof(M_HEAD);
207			p = (char *)free_list[bucket];
208			free_list[bucket] = free_list[bucket]->next;
209	greg	1.9	#ifdef MSTATS
210			b_nscrounged += *np;
211			#endif
212	greg	1.3	return(p);
213			}
214	greg	1.14	#ifdef MCOMP
215			return(mcompact(np)); /* try compaction */
216			#else
217	greg	1.3	*np = 0;
218			return(NULL);
219	greg	1.14	#endif
220	greg	1.3	}
221
222
223			char *
224	greg	1.1	bmalloc(n) /* allocate a block of n bytes, sans header */
225			register unsigned n;
226			{
227			extern char *sbrk();
228	greg	1.3	static unsigned pagesz = 0;
229			static unsigned amnt;
230	greg	1.1	static char *bpos;
231	greg	1.3	static unsigned nrem;
232			unsigned thisamnt;
233	greg	1.1	register char *p;
234
235			if (pagesz == 0) { /* initialize */
236	greg	1.2	pagesz = amnt = getpagesize();
237	greg	1.1	nrem = (int)sbrk(0); /* page align break */
238			nrem = pagesz - (nrem&(pagesz-1));
239	greg	2.3	bpos = sbrk(nrem);
240	greg	1.1	if ((int)bpos == -1)
241			return(NULL);
242	greg	1.14	#ifdef MSTATS
243			b_nsbrked += nrem;
244			#endif
245	greg	2.4	bpos += nrem & (BYTES_WORD-1); /* align pointer */
246			nrem &= ~(BYTES_WORD-1);
247	greg	2.6	memlim[0] = bpos;
248			memlim[1] = bpos + nrem;
249	greg	1.1	}
250
251			n = (n+(BYTES_WORD-1))&~(BYTES_WORD-1); /* word align rqst. */
252
253			if (n > nrem) { /* need more core */
254	greg	2.8	tryagain:
255	greg	1.3	if (n > amnt) { /* big chunk */
256			thisamnt = (n+(pagesz-1))&~(pagesz-1);
257			if (thisamnt <= MAXINCR) /* increase amnt */
258			amnt = thisamnt;
259			} else
260			thisamnt = amnt;
261			p = sbrk(thisamnt);
262	greg	1.4	if ((int)p == -1) { /* uh-oh, ENOMEM */
263	greg	2.8	errno = 0; /* call cavalry */
264			if (thisamnt >= n+pagesz) {
265			amnt = pagesz; /* minimize request */
266			goto tryagain;
267			}
268			thisamnt = n;
269			p = mscrounge(&thisamnt); /* search free lists */
270			if (p == NULL) { /* we're really out */
271			errno = ENOMEM;
272	greg	1.3	return(NULL);
273	greg	2.8	}
274	greg	1.3	}
275	greg	1.14	#ifdef MSTATS
276			else b_nsbrked += thisamnt;
277			#endif
278	greg	1.3	if (p != bpos+nrem) { /* not an increment */
279	greg	1.4	bfree(bpos, nrem); /* free what we have */
280	greg	1.1	bpos = p;
281	greg	1.3	nrem = thisamnt;
282	greg	1.4	} else /* otherwise tack on */
283	greg	1.3	nrem += thisamnt;
284	greg	2.6	if (bpos < memlim[0])
285			memlim[0] = bpos;
286			if (bpos + nrem > memlim[1])
287			memlim[1] = bpos + nrem;
288	greg	1.1	}
289			p = bpos;
290			bpos += n; /* advance */
291			nrem -= n;
292	greg	1.13	#ifdef MSTATS
293			b_nalloced += n;
294			#endif
295	greg	1.1	return(p);
296			}
297
298
299			bfree(p, n) /* free n bytes of random memory */
300	greg	1.2	register char *p;
301			register unsigned n;
302	greg	1.1	{
303			register int bucket;
304			register unsigned bsiz;
305	greg	1.9
306	gwlarson	2.11	if (n < 1<<FIRSTBUCKET \|\| p == NULL)
307	greg	1.15	return;
308	greg	1.9	#ifdef MSTATS
309			b_nfreed += n;
310			#endif
311	greg	1.4	/* align pointer */
312	greg	1.6	bsiz = BYTES_WORD - ((unsigned)p&(BYTES_WORD-1));
313	greg	1.4	if (bsiz < BYTES_WORD) {
314			p += bsiz;
315			n -= bsiz;
316	greg	1.1	}
317	greg	2.6	if (p < memlim[0])
318			memlim[0] = p;
319			if (p + n > memlim[1])
320			memlim[1] = p + n;
321	greg	1.4	/* fill big buckets first */
322			for (bucket = NBUCKETS-1, bsiz = 1<<(NBUCKETS-1);
323			bucket >= FIRSTBUCKET; bucket--, bsiz >>= 1)
324			if (n >= bsiz+sizeof(M_HEAD)) {
325			((M_HEAD *)p)->next = free_list[bucket];
326			free_list[bucket] = (M_HEAD *)p;
327			p += bsiz+sizeof(M_HEAD);
328			n -= bsiz+sizeof(M_HEAD);
329			}
330	greg	1.1	}
331
332
333			char *
334			malloc(n) /* allocate n bytes of memory */
335			unsigned n;
336			{
337			register M_HEAD *mp;
338			register int bucket;
339			register unsigned bsiz;
340	greg	1.10	/* don't return NULL on 0 request */
341			if (n == 0)
342			return(DUMMYLOC);
343	greg	1.2	/* find first bucket that fits */
344	greg	1.6	for (bucket = FIRSTBUCKET, bsiz = 1<<FIRSTBUCKET;
345			bucket < NBUCKETS; bucket++, bsiz <<= 1)
346			if (bsiz >= n)
347			break;
348			if (bucket >= NBUCKETS) {
349			errno = EINVAL;
350			return(NULL);
351			}
352	greg	1.4	if (free_list[bucket] == NULL) { /* need more core */
353	greg	1.1	mp = (M_HEAD *)bmalloc(bsiz+sizeof(M_HEAD));
354			if (mp == NULL)
355			return(NULL);
356	greg	1.4	} else { /* got it */
357	greg	1.1	mp = free_list[bucket];
358			free_list[bucket] = mp->next;
359			}
360	greg	1.13	#ifdef MSTATS
361			m_nalloced += bsiz + sizeof(M_HEAD);
362			m_nwasted += bsiz + sizeof(M_HEAD) - n;
363			#endif
364	greg	1.12	mp->a.magic = MAGIC; /* tag block */
365			mp->a.bucket = bucket;
366	greg	1.1	return((char *)(mp+1));
367			}
368
369
370			char *
371			realloc(op, n) /* reallocate memory using malloc() */
372	greg	1.6	register char *op;
373	greg	1.1	unsigned n;
374			{
375	greg	1.6	char *p;
376	greg	1.1	register unsigned on;
377	greg	1.6	/* get old size */
378	greg	2.6	if (op != DUMMYLOC && !BADPTR(op) &&
379			((M_HEAD *)op-1)->a.magic == MAGIC)
380	greg	1.12	on = 1 << ((M_HEAD *)op-1)->a.bucket;
381	greg	1.5	else
382			on = 0;
383	greg	1.6	if (n <= on && (n > on>>1 \|\| on == 1<<FIRSTBUCKET))
384	greg	1.5	return(op); /* same bucket */
385	greg	1.13	if ((p = malloc(n)) == NULL)
386	greg	2.5	return(n<=on ? op : NULL);
387	greg	1.13	if (on) {
388	greg	1.2	bcopy(op, p, n>on ? on : n);
389	greg	1.13	free(op);
390			}
391	greg	1.1	return(p);
392			}
393
394
395			free(p) /* free memory allocated by malloc */
396			char *p;
397			{
398			register M_HEAD *mp;
399			register int bucket;
400
401	greg	2.6	if (p == DUMMYLOC)
402	greg	1.13	return(1);
403	greg	2.6	if (BADPTR(p))
404			goto invalid;
405	greg	1.1	mp = (M_HEAD *)p - 1;
406	greg	1.12	if (mp->a.magic != MAGIC) /* sanity check */
407	greg	2.6	goto invalid;
408	greg	1.12	bucket = mp->a.bucket;
409	greg	2.2	if (bucket < FIRSTBUCKET \| bucket >= NBUCKETS)
410	greg	2.6	goto invalid;
411	greg	1.1	mp->next = free_list[bucket];
412			free_list[bucket] = mp;
413	greg	1.9	#ifdef MSTATS
414			m_nfreed += (1 << bucket) + sizeof(M_HEAD);
415			#endif
416	greg	1.13	return(1);
417	greg	2.6	invalid:
418			errno = EINVAL;
419			return(0);
420	greg	1.1	}
421	greg	1.9
422
423			#ifdef MSTATS
424			printmemstats(fp) /* print memory statistics to stream */
425			FILE *fp;
426			{
427			register int i;
428			int n;
429			register M_HEAD *mp;
430			unsigned int total = 0;
431
432			fprintf(fp, "Memory statistics:\n");
433	greg	1.14	fprintf(fp, "\tbmalloc: %d bytes from sbrk\n", b_nsbrked);
434	greg	1.9	fprintf(fp, "\tbmalloc: %d bytes allocated\n", b_nalloced);
435			fprintf(fp, "\tbmalloc: %d bytes freed\n", b_nfreed);
436			fprintf(fp, "\tbmalloc: %d bytes scrounged\n", b_nscrounged);
437	greg	1.14	fprintf(fp, "\tbmalloc: %d bytes compacted\n", b_ncompacted);
438	greg	1.9	fprintf(fp, "\tmalloc: %d bytes allocated\n", m_nalloced);
439			fprintf(fp, "\tmalloc: %d bytes wasted (%.1f%%)\n", m_nwasted,
440			100.0*m_nwasted/m_nalloced);
441			fprintf(fp, "\tmalloc: %d bytes freed\n", m_nfreed);
442			for (i = NBUCKETS-1; i >= FIRSTBUCKET; i--) {
443			n = 0;
444			for (mp = free_list[i]; mp != NULL; mp = mp->next)
445			n++;
446			if (n) {
447			fprintf(fp, "\t%d * %u\n", n, 1<<i);
448			total += n * ((1<<i) + sizeof(M_HEAD));
449			}
450			}
451			fprintf(fp, "\t %u total bytes in free list\n", total);
452			}
453	greg	1.1	#endif