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/* Copyright (c) 1990 Regents of the University of California */ |
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|
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#ifndef lint |
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static char SCCSid[] = "$SunId$ LBL"; |
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#endif |
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|
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/* |
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* Fast malloc for memory hogs and VM environments. |
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* Performs a minimum of searching through free lists. |
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* malloc(), realloc() and free() use buckets |
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* containing blocks in powers of two, similar to CIT routines. |
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* bfree() puts memory from any source into malloc free lists. |
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* bmalloc() doesn't keep track of free lists -- it's usually |
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* just a buffered call to sbrk(2). However, bmalloc will |
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* call mscrounge() if sbrk fails. |
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* mscrounge() returns whatever memory it can find to satisfy the |
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* request along with the number of bytes (modified). |
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* |
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* Greg Ward Lawrence Berkeley Laboratory |
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*/ |
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|
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#include <errno.h> |
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|
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#define NULL 0 |
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|
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#ifndef ALIGN |
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#define ALIGN int /* align type */ |
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#endif |
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#define BYTES_WORD sizeof(ALIGN) |
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|
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#define MAXINCR (1<<18) /* largest sbrk(2) increment */ |
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|
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#ifdef NOVMEM |
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#define getpagesize() BYTES_WORD |
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#endif |
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/* malloc free lists */ |
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typedef union m_head { |
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union m_head *next; |
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int bucket; |
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ALIGN dummy; |
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} M_HEAD; |
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|
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#define FIRSTBUCKET 3 |
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#define NBUCKETS 30 |
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|
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static M_HEAD *free_list[NBUCKETS]; |
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|
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|
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char * |
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mscrounge(np) /* search free lists to satisfy request */ |
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register unsigned *np; |
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{ |
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char *p; |
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register int bucket; |
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register unsigned bsiz; |
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|
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for (bucket = FIRSTBUCKET, bsiz = 1<<FIRSTBUCKET; |
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bucket < NBUCKETS; bucket++, bsiz <<= 1) |
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if (free_list[bucket] != NULL && bsiz+sizeof(M_HEAD) >= *np) { |
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*np = bsiz+sizeof(M_HEAD); |
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p = (char *)free_list[bucket]; |
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free_list[bucket] = free_list[bucket]->next; |
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return(p); |
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} |
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*np = 0; |
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return(NULL); |
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} |
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|
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|
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char * |
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bmalloc(n) /* allocate a block of n bytes, sans header */ |
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register unsigned n; |
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{ |
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extern char *sbrk(); |
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static unsigned pagesz = 0; |
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static unsigned amnt; |
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static char *bpos; |
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static unsigned nrem; |
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unsigned thisamnt; |
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register char *p; |
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|
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if (pagesz == 0) { /* initialize */ |
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pagesz = amnt = getpagesize(); |
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nrem = (int)sbrk(0); /* page align break */ |
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nrem = pagesz - (nrem&(pagesz-1)); |
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bpos = sbrk(nrem); /* word aligned! */ |
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if ((int)bpos == -1) |
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return(NULL); |
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} |
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|
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n = (n+(BYTES_WORD-1))&~(BYTES_WORD-1); /* word align rqst. */ |
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|
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if (n > nrem) { /* need more core */ |
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if (n > amnt) { /* big chunk */ |
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thisamnt = (n+(pagesz-1))&~(pagesz-1); |
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if (thisamnt <= MAXINCR) /* increase amnt */ |
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amnt = thisamnt; |
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} else |
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thisamnt = amnt; |
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p = sbrk(thisamnt); |
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if ((int)p == -1) { /* uh-oh, ENOMEM */ |
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thisamnt = n; /* search free lists */ |
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p = mscrounge(&thisamnt); |
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if (p == NULL) /* we're really out */ |
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return(NULL); |
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} |
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if (p != bpos+nrem) { /* not an increment */ |
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bfree(bpos, nrem); /* free what we have */ |
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bpos = p; |
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nrem = thisamnt; |
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} else /* otherwise tack on */ |
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nrem += thisamnt; |
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} |
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p = bpos; |
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bpos += n; /* advance */ |
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nrem -= n; |
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return(p); |
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} |
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|
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|
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bfree(p, n) /* free n bytes of random memory */ |
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register char *p; |
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register unsigned n; |
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{ |
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register int bucket; |
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register unsigned bsiz; |
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/* align pointer */ |
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bsiz = BYTES_WORD - ((unsigned)p&(BYTES_WORD-1)); |
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if (bsiz < BYTES_WORD) { |
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p += bsiz; |
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n -= bsiz; |
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} |
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/* fill big buckets first */ |
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for (bucket = NBUCKETS-1, bsiz = 1<<(NBUCKETS-1); |
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bucket >= FIRSTBUCKET; bucket--, bsiz >>= 1) |
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if (n >= bsiz+sizeof(M_HEAD)) { |
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((M_HEAD *)p)->next = free_list[bucket]; |
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free_list[bucket] = (M_HEAD *)p; |
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p += bsiz+sizeof(M_HEAD); |
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n -= bsiz+sizeof(M_HEAD); |
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} |
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} |
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|
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|
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char * |
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malloc(n) /* allocate n bytes of memory */ |
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unsigned n; |
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{ |
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extern int errno; |
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register M_HEAD *mp; |
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register int bucket; |
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register unsigned bsiz; |
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/* find first bucket that fits */ |
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for (bucket = FIRSTBUCKET, bsiz = 1<<FIRSTBUCKET; |
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bucket < NBUCKETS; bucket++, bsiz <<= 1) |
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if (bsiz >= n) |
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break; |
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if (bucket >= NBUCKETS) { |
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errno = EINVAL; |
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return(NULL); |
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} |
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if (free_list[bucket] == NULL) { /* need more core */ |
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mp = (M_HEAD *)bmalloc(bsiz+sizeof(M_HEAD)); |
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if (mp == NULL) |
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return(NULL); |
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} else { /* got it */ |
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mp = free_list[bucket]; |
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free_list[bucket] = mp->next; |
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} |
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mp->bucket = bucket; /* tag block */ |
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return((char *)(mp+1)); |
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} |
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|
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|
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char * |
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realloc(op, n) /* reallocate memory using malloc() */ |
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register char *op; |
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unsigned n; |
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{ |
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char *p; |
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register unsigned on; |
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/* get old size */ |
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if (op != NULL) |
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on = 1 << ((M_HEAD *)op-1)->bucket; |
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else |
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on = 0; |
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if (n <= on && (n > on>>1 || on == 1<<FIRSTBUCKET)) |
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return(op); /* same bucket */ |
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p = malloc(n); |
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if (p != NULL) |
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#ifdef BSD |
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bcopy(op, p, n>on ? on : n); |
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#else |
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(void)memcpy(p, op, n>on ? on : n); |
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#endif |
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free(op); |
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return(p); |
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} |
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|
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|
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free(p) /* free memory allocated by malloc */ |
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char *p; |
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{ |
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register M_HEAD *mp; |
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register int bucket; |
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|
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if (p == NULL) |
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return; |
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mp = (M_HEAD *)p - 1; |
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bucket = mp->bucket; |
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mp->next = free_list[bucket]; |
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free_list[bucket] = mp; |
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} |
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|
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|
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#ifndef NOVMEM |
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#ifndef BSD |
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#include <sys/var.h> |
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int |
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getpagesize() /* use SYSV var structure to get page size */ |
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{ |
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static int pagesz = 0; |
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struct var v; |
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|
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if (pagesz == 0) { |
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uvar(&v); |
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pagesz = 1 << v.v_pageshift; |
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} |
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return(pagesz); |
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} |
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#endif |
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#endif |
