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)
extern char  *memcpy(), *memset();
#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)
                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:	2.9
Committed:	Tue Oct 24 09:45:07 1995 UTC (30 years, 1 month ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.8:	+2 -1 lines
Log Message:	modest improvement in compaction algorithm
#	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			extern char memcpy(), memset();
31			#endif
32
33	greg	1.9	#ifdef MSTATS
34			#include <stdio.h>
35	greg	2.6	static unsigned b_nsbrked = 0;
36	greg	1.9	static unsigned b_nalloced = 0;
37			static unsigned b_nfreed = 0;
38			static unsigned b_nscrounged = 0;
39	greg	1.14	static unsigned b_ncompacted = 0;
40	greg	1.9	static unsigned m_nalloced = 0;
41			static unsigned m_nfreed = 0;
42			static unsigned m_nwasted = 0;
43			#else
44	greg	1.1	#define NULL 0
45	greg	1.9	#endif
46	greg	1.1
47			#ifndef ALIGN
48			#define ALIGN int /* align type */
49			#endif
50			#define BYTES_WORD sizeof(ALIGN)
51
52	greg	1.16	#ifndef MAXINCR
53	greg	1.9	#define MAXINCR (1<<16) /* largest sbrk(2) increment */
54	greg	1.1	#endif
55			/* malloc free lists */
56			typedef union m_head {
57			union m_head *next;
58	greg	1.12	struct {
59			short magic;
60			short bucket;
61			} a;
62	greg	1.1	ALIGN dummy;
63			} M_HEAD;
64
65	greg	1.12	#define MAGIC 0x1a2 /* magic number for allocated memory */
66
67	greg	1.1	#define FIRSTBUCKET 3
68			#define NBUCKETS 30
69
70			static M_HEAD *free_list[NBUCKETS];
71
72	greg	1.12	static ALIGN dummy_mem;
73	greg	1.1
74	greg	2.6	static char *memlim[2];
75
76	greg	1.12	#define DUMMYLOC ((char *)&dummy_mem)
77	greg	1.10
78	greg	2.6	#define BADPTR(p) ((p) < memlim[0] \| (p) >= memlim[1])
79
80	greg	1.14	#ifdef MCOMP /* memory compaction routines */
81			static char seedtab[1024]; /* seed for compaction table */
82	greg	1.12
83	greg	1.14	static struct mblk {
84			char ptr; / pointer to memory block */
85			unsigned siz; /* size of memory block */
86			} cptab = {seedtab, sizeof(seedtab)};
87
88			#define mtab(mb) ((struct mblk *)(mb)->ptr)
89			#define mtablen(mb) ((mb)->siz/sizeof(struct mblk))
90
91
92			static int
93			mbcmp(m1, m2) /* compare memory block locations */
94			register struct mblk m1, m2;
95			{
96			/* put empty blocks at end */
97			if (m1->siz == 0)
98			return(m2->siz == 0 ? 0 : 1);
99			if (m2->siz == 0)
100			return(-1);
101			/* otherwise, ascending order */
102			return(m1->ptr - m2->ptr);
103			}
104
105
106			int
107			compactfree() /* compact free lists (moving to table) */
108			{
109			register struct mblk *tp;
110			register int bucket;
111			unsigned n, bsiz, ncomp;
112			/* fill table from free lists */
113			tp = mtab(&cptab); n = mtablen(&cptab);
114			bucket = NBUCKETS-1; bsiz = 1<<(NBUCKETS-1);
115			ncomp = 0;
116			for ( ; ; ) {
117			while (tp->siz) { /* find empty slot */
118			if (--n == 0)
119			goto loopexit;
120			tp++;
121			}
122			while (free_list[bucket] == NULL) { /* find block */
123			if (--bucket < FIRSTBUCKET)
124			goto loopexit;
125			bsiz >>= 1;
126			}
127			tp->ptr = (char *)free_list[bucket];
128			ncomp += (tp->siz = bsiz + sizeof(M_HEAD));
129			free_list[bucket] = free_list[bucket]->next;
130			}
131			loopexit:
132			if (ncomp == 0)
133			return(0); /* nothing new to compact */
134			#ifdef MSTATS
135			b_ncompacted += ncomp;
136			#endif
137			tp = mtab(&cptab); n = mtablen(&cptab); /* sort table */
138			qsort((char *)tp, n, sizeof(struct mblk), mbcmp);
139			ncomp = 0; /* collect blocks */
140			while (--n && tp[1].siz) {
141			if (tp[0].ptr + tp[0].siz == tp[1].ptr) {
142			tp[1].ptr = tp[0].ptr;
143			tp[1].siz += tp[0].siz;
144			ncomp += tp[0].siz;
145			tp[0].siz = 0;
146			}
147			tp++;
148			}
149			return(ncomp);
150			}
151
152
153	greg	1.1	char *
154	greg	1.14	mcompact(np) /* compact free lists to satisfy request */
155			unsigned *np;
156			{
157			struct mblk *tab;
158			unsigned tablen;
159			register struct mblk bp, big;
160
161			for ( ; ; ) {
162			/* compact free lists */
163	greg	2.9	while (compactfree())
164			;
165	greg	1.14	/* find largest block */
166			tab = mtab(&cptab); tablen = mtablen(&cptab);
167			big = tab;
168			bp = tab + tablen;
169			while (--bp > tab)
170			if (bp->siz > big->siz)
171			big = bp;
172			if (big->siz >= np) { / big enough? */
173			*np = big->siz;
174			big->siz = 0; /* remove from table */
175			return(big->ptr); /* return it */
176			}
177	greg	2.7	if (mtablen(big) <= tablen) {
178	greg	1.14	np = 0; / cannot grow table */
179			return(NULL); /* report failure */
180			}
181			/* enlarge table, free old one */
182			mtab(big)[0].ptr = cptab.ptr;
183			mtab(big)[0].siz = cptab.siz;
184			cptab.ptr = big->ptr;
185			cptab.siz = big->siz;
186			big->siz = 0; /* clear and copy */
187			bcopy((char )tab, (char )(mtab(&cptab)+1),
188			tablen*sizeof(struct mblk));
189			bzero((char *)(mtab(&cptab)+tablen+1),
190			(mtablen(&cptab)-tablen-1)*sizeof(struct mblk));
191			} /* next round */
192			}
193			#endif /* MCOMP */
194
195
196			char *
197	greg	1.4	mscrounge(np) /* search free lists to satisfy request */
198	greg	1.3	register unsigned *np;
199			{
200			char *p;
201			register int bucket;
202			register unsigned bsiz;
203
204			for (bucket = FIRSTBUCKET, bsiz = 1<<FIRSTBUCKET;
205			bucket < NBUCKETS; bucket++, bsiz <<= 1)
206			if (free_list[bucket] != NULL && bsiz+sizeof(M_HEAD) >= *np) {
207			*np = bsiz+sizeof(M_HEAD);
208			p = (char *)free_list[bucket];
209			free_list[bucket] = free_list[bucket]->next;
210	greg	1.9	#ifdef MSTATS
211			b_nscrounged += *np;
212			#endif
213	greg	1.3	return(p);
214			}
215	greg	1.14	#ifdef MCOMP
216			return(mcompact(np)); /* try compaction */
217			#else
218	greg	1.3	*np = 0;
219			return(NULL);
220	greg	1.14	#endif
221	greg	1.3	}
222
223
224			char *
225	greg	1.1	bmalloc(n) /* allocate a block of n bytes, sans header */
226			register unsigned n;
227			{
228			extern char *sbrk();
229	greg	1.3	static unsigned pagesz = 0;
230			static unsigned amnt;
231	greg	1.1	static char *bpos;
232	greg	1.3	static unsigned nrem;
233			unsigned thisamnt;
234	greg	1.1	register char *p;
235
236			if (pagesz == 0) { /* initialize */
237	greg	1.2	pagesz = amnt = getpagesize();
238	greg	1.1	nrem = (int)sbrk(0); /* page align break */
239			nrem = pagesz - (nrem&(pagesz-1));
240	greg	2.3	bpos = sbrk(nrem);
241	greg	1.1	if ((int)bpos == -1)
242			return(NULL);
243	greg	1.14	#ifdef MSTATS
244			b_nsbrked += nrem;
245			#endif
246	greg	2.4	bpos += nrem & (BYTES_WORD-1); /* align pointer */
247			nrem &= ~(BYTES_WORD-1);
248	greg	2.6	memlim[0] = bpos;
249			memlim[1] = bpos + nrem;
250	greg	1.1	}
251
252			n = (n+(BYTES_WORD-1))&~(BYTES_WORD-1); /* word align rqst. */
253
254			if (n > nrem) { /* need more core */
255	greg	2.8	tryagain:
256	greg	1.3	if (n > amnt) { /* big chunk */
257			thisamnt = (n+(pagesz-1))&~(pagesz-1);
258			if (thisamnt <= MAXINCR) /* increase amnt */
259			amnt = thisamnt;
260			} else
261			thisamnt = amnt;
262			p = sbrk(thisamnt);
263	greg	1.4	if ((int)p == -1) { /* uh-oh, ENOMEM */
264	greg	2.8	errno = 0; /* call cavalry */
265			if (thisamnt >= n+pagesz) {
266			amnt = pagesz; /* minimize request */
267			goto tryagain;
268			}
269			thisamnt = n;
270			p = mscrounge(&thisamnt); /* search free lists */
271			if (p == NULL) { /* we're really out */
272			errno = ENOMEM;
273	greg	1.3	return(NULL);
274	greg	2.8	}
275	greg	1.3	}
276	greg	1.14	#ifdef MSTATS
277			else b_nsbrked += thisamnt;
278			#endif
279	greg	1.3	if (p != bpos+nrem) { /* not an increment */
280	greg	1.4	bfree(bpos, nrem); /* free what we have */
281	greg	1.1	bpos = p;
282	greg	1.3	nrem = thisamnt;
283	greg	1.4	} else /* otherwise tack on */
284	greg	1.3	nrem += thisamnt;
285	greg	2.6	if (bpos < memlim[0])
286			memlim[0] = bpos;
287			if (bpos + nrem > memlim[1])
288			memlim[1] = bpos + nrem;
289	greg	1.1	}
290			p = bpos;
291			bpos += n; /* advance */
292			nrem -= n;
293	greg	1.13	#ifdef MSTATS
294			b_nalloced += n;
295			#endif
296	greg	1.1	return(p);
297			}
298
299
300			bfree(p, n) /* free n bytes of random memory */
301	greg	1.2	register char *p;
302			register unsigned n;
303	greg	1.1	{
304			register int bucket;
305			register unsigned bsiz;
306	greg	1.9
307	greg	1.15	if (n < 1<<FIRSTBUCKET)
308			return;
309	greg	1.9	#ifdef MSTATS
310			b_nfreed += n;
311			#endif
312	greg	1.4	/* align pointer */
313	greg	1.6	bsiz = BYTES_WORD - ((unsigned)p&(BYTES_WORD-1));
314	greg	1.4	if (bsiz < BYTES_WORD) {
315			p += bsiz;
316			n -= bsiz;
317	greg	1.1	}
318	greg	2.6	if (p < memlim[0])
319			memlim[0] = p;
320			if (p + n > memlim[1])
321			memlim[1] = p + n;
322	greg	1.4	/* fill big buckets first */
323			for (bucket = NBUCKETS-1, bsiz = 1<<(NBUCKETS-1);
324			bucket >= FIRSTBUCKET; bucket--, bsiz >>= 1)
325			if (n >= bsiz+sizeof(M_HEAD)) {
326			((M_HEAD *)p)->next = free_list[bucket];
327			free_list[bucket] = (M_HEAD *)p;
328			p += bsiz+sizeof(M_HEAD);
329			n -= bsiz+sizeof(M_HEAD);
330			}
331	greg	1.1	}
332
333
334			char *
335			malloc(n) /* allocate n bytes of memory */
336			unsigned n;
337			{
338			register M_HEAD *mp;
339			register int bucket;
340			register unsigned bsiz;
341	greg	1.10	/* don't return NULL on 0 request */
342			if (n == 0)
343			return(DUMMYLOC);
344	greg	1.2	/* find first bucket that fits */
345	greg	1.6	for (bucket = FIRSTBUCKET, bsiz = 1<<FIRSTBUCKET;
346			bucket < NBUCKETS; bucket++, bsiz <<= 1)
347			if (bsiz >= n)
348			break;
349			if (bucket >= NBUCKETS) {
350			errno = EINVAL;
351			return(NULL);
352			}
353	greg	1.4	if (free_list[bucket] == NULL) { /* need more core */
354	greg	1.1	mp = (M_HEAD *)bmalloc(bsiz+sizeof(M_HEAD));
355			if (mp == NULL)
356			return(NULL);
357	greg	1.4	} else { /* got it */
358	greg	1.1	mp = free_list[bucket];
359			free_list[bucket] = mp->next;
360			}
361	greg	1.13	#ifdef MSTATS
362			m_nalloced += bsiz + sizeof(M_HEAD);
363			m_nwasted += bsiz + sizeof(M_HEAD) - n;
364			#endif
365	greg	1.12	mp->a.magic = MAGIC; /* tag block */
366			mp->a.bucket = bucket;
367	greg	1.1	return((char *)(mp+1));
368			}
369
370
371			char *
372			realloc(op, n) /* reallocate memory using malloc() */
373	greg	1.6	register char *op;
374	greg	1.1	unsigned n;
375			{
376	greg	1.6	char *p;
377	greg	1.1	register unsigned on;
378	greg	1.6	/* get old size */
379	greg	2.6	if (op != DUMMYLOC && !BADPTR(op) &&
380			((M_HEAD *)op-1)->a.magic == MAGIC)
381	greg	1.12	on = 1 << ((M_HEAD *)op-1)->a.bucket;
382	greg	1.5	else
383			on = 0;
384	greg	1.6	if (n <= on && (n > on>>1 \|\| on == 1<<FIRSTBUCKET))
385	greg	1.5	return(op); /* same bucket */
386	greg	1.13	if ((p = malloc(n)) == NULL)
387	greg	2.5	return(n<=on ? op : NULL);
388	greg	1.13	if (on) {
389	greg	1.2	bcopy(op, p, n>on ? on : n);
390	greg	1.13	free(op);
391			}
392	greg	1.1	return(p);
393			}
394
395
396			free(p) /* free memory allocated by malloc */
397			char *p;
398			{
399			register M_HEAD *mp;
400			register int bucket;
401
402	greg	2.6	if (p == DUMMYLOC)
403	greg	1.13	return(1);
404	greg	2.6	if (BADPTR(p))
405			goto invalid;
406	greg	1.1	mp = (M_HEAD *)p - 1;
407	greg	1.12	if (mp->a.magic != MAGIC) /* sanity check */
408	greg	2.6	goto invalid;
409	greg	1.12	bucket = mp->a.bucket;
410	greg	2.2	if (bucket < FIRSTBUCKET \| bucket >= NBUCKETS)
411	greg	2.6	goto invalid;
412	greg	1.1	mp->next = free_list[bucket];
413			free_list[bucket] = mp;
414	greg	1.9	#ifdef MSTATS
415			m_nfreed += (1 << bucket) + sizeof(M_HEAD);
416			#endif
417	greg	1.13	return(1);
418	greg	2.6	invalid:
419			errno = EINVAL;
420			return(0);
421	greg	1.1	}
422	greg	1.9
423
424			#ifdef MSTATS
425			printmemstats(fp) /* print memory statistics to stream */
426			FILE *fp;
427			{
428			register int i;
429			int n;
430			register M_HEAD *mp;
431			unsigned int total = 0;
432
433			fprintf(fp, "Memory statistics:\n");
434	greg	1.14	fprintf(fp, "\tbmalloc: %d bytes from sbrk\n", b_nsbrked);
435	greg	1.9	fprintf(fp, "\tbmalloc: %d bytes allocated\n", b_nalloced);
436			fprintf(fp, "\tbmalloc: %d bytes freed\n", b_nfreed);
437			fprintf(fp, "\tbmalloc: %d bytes scrounged\n", b_nscrounged);
438	greg	1.14	fprintf(fp, "\tbmalloc: %d bytes compacted\n", b_ncompacted);
439	greg	1.9	fprintf(fp, "\tmalloc: %d bytes allocated\n", m_nalloced);
440			fprintf(fp, "\tmalloc: %d bytes wasted (%.1f%%)\n", m_nwasted,
441			100.0*m_nwasted/m_nalloced);
442			fprintf(fp, "\tmalloc: %d bytes freed\n", m_nfreed);
443			for (i = NBUCKETS-1; i >= FIRSTBUCKET; i--) {
444			n = 0;
445			for (mp = free_list[i]; mp != NULL; mp = mp->next)
446			n++;
447			if (n) {
448			fprintf(fp, "\t%d * %u\n", n, 1<<i);
449			total += n * ((1<<i) + sizeof(M_HEAD));
450			}
451			}
452			fprintf(fp, "\t %u total bytes in free list\n", total);
453			}
454	greg	1.1	#endif