mirror of https://github.com/python/cpython
446 lines
12 KiB
C
446 lines
12 KiB
C
/*
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* Attempt at a memory allocator for the Mac, Jack Jansen, CWI, 1995-1997.
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*
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* Code adapted from BSD malloc, which is:
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*
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* Copyright (c) 1983 Regents of the University of California.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#if defined(LIBC_SCCS) && !defined(lint)
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/*static char *sccsid = "from: @(#)malloc.c 5.11 (Berkeley) 2/23/91";*/
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static char *rcsid = "$Id$";
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#endif /* LIBC_SCCS and not lint */
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/*
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* malloc.c (Caltech) 2/21/82
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* Chris Kingsley, kingsley@cit-20. Modified by Jack Jansen, CWI.
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*
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* This is a very fast storage allocator. It allocates blocks of a small
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* number of different sizes, and keeps free lists of each size. Blocks that
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* don't exactly fit are passed up to the next larger size.
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*
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* Blocks over a certain size are directly allocated by calling NewPtr.
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*
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*/
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#ifdef USE_MALLOC_DEBUG
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/* You may also selectively enable some of these (but some are interdependent) */
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#define DEBUG
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#define DEBUG2
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#define MSTATS
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#define RCHECK
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#define VCHECK
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#endif /* USE_MALLOC_DEBUG */
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/*
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* Set the next define if you want to return memory that is aligned to 32-byte
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* boundaries. This allows 604 (and, to a lesser extent, any PPC) programs to
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* make better use of the L1 cache.
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*/
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/* #define USE_CACHE_ALIGNED 8 /* The alignment (in 4-byte words) */
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typedef unsigned char u_char;
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typedef unsigned long u_long;
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typedef unsigned int u_int;
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typedef unsigned short u_short;
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typedef u_long caddr_t;
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#include <Memory.h>
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#include <stdlib.h>
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#include <string.h>
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#define NULL 0
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static void morecore();
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/*
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* The overhead on a block is at least 4 bytes. When free, this space
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* contains a pointer to the next free block, and the bottom two bits must
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* be zero. When in use, the first byte is set to MAGIC, and the second
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* byte is the size index. The remaining bytes are for alignment.
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* If range checking is enabled then a second word holds the size of the
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* requested block, less 1, rounded up to a multiple of sizeof(RMAGIC).
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* The order of elements is critical: ov_magic must overlay the low order
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* bits of ov_next, and ov_magic can not be a valid ov_next bit pattern.
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*/
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union overhead {
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union overhead *ov_next; /* when free */
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struct {
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u_char ovu_magic0; /* magic number */
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u_char ovu_index; /* bucket # */
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u_char ovu_unused; /* unused */
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u_char ovu_magic1; /* other magic number */
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#ifdef RCHECK
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u_short ovu_rmagic; /* range magic number */
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u_long ovu_size; /* actual block size */
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#endif
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} ovu;
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#define ov_magic0 ovu.ovu_magic0
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#define ov_magic1 ovu.ovu_magic1
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#define ov_index ovu.ovu_index
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#define ov_rmagic ovu.ovu_rmagic
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#define ov_size ovu.ovu_size
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#ifdef USE_CACHE_ALIGNED
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struct cachealigner {
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u_long ovalign[USE_CACHE_ALIGNED];
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} ovu_aligner;
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#endif /* USE_CACHE_ALIGN */
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};
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#define MAGIC 0xef /* magic # on accounting info */
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#define RMAGIC 0x5555 /* magic # on range info */
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#ifdef RCHECK
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#define RSLOP sizeof (u_short)
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#else
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#define RSLOP 0
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#endif
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#define OVERHEAD (sizeof(union overhead) + RSLOP)
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/*
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* nextf[i] is the pointer to the next free block of size 2^(i+3). The
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* smallest allocatable block is 8 bytes. The overhead information
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* precedes the data area returned to the user.
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*/
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#define NBUCKETS 11
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#define MAXMALLOC (1<<(NBUCKETS+2))
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static union overhead *nextf[NBUCKETS];
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#ifdef MSTATS
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/*
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* nmalloc[i] is the difference between the number of mallocs and frees
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* for a given block size.
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*/
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static u_int nmalloc[NBUCKETS+1];
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#include <stdio.h>
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#endif
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#if defined(DEBUG) || defined(RCHECK) || defined(DEBUG2)
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#define ASSERT(p) if (!(p)) botch(# p)
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#include <stdio.h>
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static
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botch(s)
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char *s;
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{
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fprintf(stderr, "\r\nmalloc assertion botched: %s\r\n", s);
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(void) fflush(stderr); /* just in case user buffered it */
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abort();
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}
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#else
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#define ASSERT(p)
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#endif
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void *
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malloc(nbytes)
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size_t nbytes;
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{
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register union overhead *op;
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register long bucket;
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register unsigned amt;
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/*
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** First the simple case: we simple allocate big blocks directly
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*/
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if ( nbytes + OVERHEAD >= MAXMALLOC ) {
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op = (union overhead *)NewPtr(nbytes+OVERHEAD);
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if ( op == NULL )
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return NULL;
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op->ov_magic0 = op->ov_magic1 = MAGIC;
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op->ov_index = 0xff;
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#ifdef MSTATS
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nmalloc[NBUCKETS]++;
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#endif
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#ifdef RCHECK
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/*
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* Record allocated size of block and
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* bound space with magic numbers.
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*/
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op->ov_size = (nbytes + RSLOP - 1) & ~(RSLOP - 1);
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op->ov_rmagic = RMAGIC;
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*(u_short *)((caddr_t)(op + 1) + op->ov_size) = RMAGIC;
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#endif
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return (void *)(op+1);
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}
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/*
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* Convert amount of memory requested into closest block size
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* stored in hash buckets which satisfies request.
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* Account for space used per block for accounting.
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*/
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#ifndef RCHECK
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amt = 8; /* size of first bucket */
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bucket = 0;
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#else
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amt = 16; /* size of first bucket */
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bucket = 1;
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#endif
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while (nbytes + OVERHEAD > amt) {
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amt <<= 1;
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if (amt == 0)
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return (NULL);
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bucket++;
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}
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#ifdef DEBUG2
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ASSERT( bucket < NBUCKETS );
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#endif
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/*
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* If nothing in hash bucket right now,
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* request more memory from the system.
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*/
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if ((op = nextf[bucket]) == NULL) {
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morecore(bucket);
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if ((op = nextf[bucket]) == NULL)
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return (NULL);
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}
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/* remove from linked list */
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nextf[bucket] = op->ov_next;
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op->ov_magic0 = op->ov_magic1 = MAGIC;
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op->ov_index = bucket;
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#ifdef MSTATS
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nmalloc[bucket]++;
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#endif
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#ifdef RCHECK
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/*
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* Record allocated size of block and
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* bound space with magic numbers.
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*/
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op->ov_size = (nbytes + RSLOP - 1) & ~(RSLOP - 1);
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op->ov_rmagic = RMAGIC;
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*(u_short *)((caddr_t)(op + 1) + op->ov_size) = RMAGIC;
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#endif
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#ifdef VCHECK
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memset((char *)(op+1), 0x41, nbytes);
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#endif
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return ((char *)(op + 1));
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}
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/*
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* Allocate more memory to the indicated bucket.
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*/
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static void
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morecore(bucket)
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int bucket;
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{
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register union overhead *op;
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register long sz; /* size of desired block */
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long amt; /* amount to allocate */
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int nblks; /* how many blocks we get */
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/*
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* sbrk_size <= 0 only for big, FLUFFY, requests (about
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* 2^30 bytes on a VAX, I think) or for a negative arg.
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*/
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sz = 1 << (bucket + 3);
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#ifdef DEBUG2
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ASSERT(sz > 0);
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#endif
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amt = MAXMALLOC;
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nblks = amt / sz;
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#ifdef DEBUG2
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ASSERT(nblks*sz == amt);
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#endif
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#ifdef USE_CACHE_ALIGNED
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op = (union overhead *)NewPtr(amt+4*USE_CACHE_ALIGNED);
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#else
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op = (union overhead *)NewPtr(amt);
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#endif
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/* no more room! */
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if (op == NULL)
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return;
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#ifdef USE_CACHE_ALIGNED
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#define ALIGN_MASK (4*USE_CACHE_ALIGNED-1)
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while ((long)op & ALIGN_MASK )
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op = (union overhead *)((long)op+1);
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#endif /* USE_CACHE_ALIGNED */
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/*
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* Add new memory allocated to that on
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* free list for this hash bucket.
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*/
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nextf[bucket] = op;
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while (--nblks > 0) {
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op->ov_next = (union overhead *)((caddr_t)op + sz);
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op = (union overhead *)((caddr_t)op + sz);
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}
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op->ov_next = (union overhead *)NULL;
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}
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void
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free(cp)
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void *cp;
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{
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register long size;
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register union overhead *op;
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if (cp == NULL)
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return;
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op = (union overhead *)((caddr_t)cp - sizeof (union overhead));
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#ifdef DEBUG
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ASSERT(op->ov_magic0 == MAGIC); /* make sure it was in use */
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ASSERT(op->ov_magic1 == MAGIC);
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#else
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if (op->ov_magic0 != MAGIC || op->ov_magic1 != MAGIC)
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return; /* sanity */
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#endif
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#ifdef RCHECK
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ASSERT(op->ov_rmagic == RMAGIC);
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ASSERT(*(u_short *)((caddr_t)(op + 1) + op->ov_size) == RMAGIC);
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#endif
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#ifdef VCHECK
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memset(cp, 43, op->ov_size);
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#endif
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size = op->ov_index;
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if ( size == 0xff ) {
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#ifdef MSTATS
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nmalloc[NBUCKETS]--;
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#endif
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DisposePtr((Ptr)op);
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return;
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}
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ASSERT(size < NBUCKETS);
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op->ov_next = nextf[size]; /* also clobbers ov_magic */
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nextf[size] = op;
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#ifdef MSTATS
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nmalloc[size]--;
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#endif
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}
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void *
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realloc(cp, nbytes)
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void *cp;
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size_t nbytes;
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{
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int i;
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union overhead *op;
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int expensive;
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u_long maxsize;
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if (cp == NULL)
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return (malloc(nbytes));
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op = (union overhead *)((caddr_t)cp - sizeof (union overhead));
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#ifdef DEBUG
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ASSERT(op->ov_magic0 == MAGIC); /* make sure it was in use */
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ASSERT(op->ov_magic1 == MAGIC);
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#else
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if (op->ov_magic0 != MAGIC || op->ov_magic1 != MAGIC)
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return NULL; /* sanity */
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#endif
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#ifdef RCHECK
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ASSERT(op->ov_rmagic == RMAGIC);
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ASSERT(*(u_short *)((caddr_t)(op + 1) + op->ov_size) == RMAGIC);
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#endif
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i = op->ov_index;
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/*
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** First the malloc/copy cases
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*/
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expensive = 0;
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if ( i == 0xff ) {
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/* Big block. See if it has to stay big */
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if (nbytes+OVERHEAD > MAXMALLOC) {
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/* Yup, try to resize it first */
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SetPtrSize((Ptr)op, nbytes+OVERHEAD);
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if ( MemError() == 0 ) {
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#ifdef RCHECK
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op->ov_size = (nbytes + RSLOP - 1) & ~(RSLOP - 1);
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*(u_short *)((caddr_t)(op + 1) + op->ov_size) = RMAGIC;
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#endif
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return cp;
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}
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/* Nope, failed. Take the long way */
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}
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maxsize = GetPtrSize((Ptr)op);
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expensive = 1;
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} else {
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maxsize = 1 << (i+3);
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if ( nbytes + OVERHEAD > maxsize )
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expensive = 1;
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else if ( i > 0 && nbytes + OVERHEAD < (maxsize/2) )
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expensive = 1;
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}
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if ( expensive ) {
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void *newp;
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newp = malloc(nbytes);
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if ( newp == NULL ) {
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return NULL;
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}
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maxsize -= OVERHEAD;
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if ( maxsize < nbytes )
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nbytes = maxsize;
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memcpy(newp, cp, nbytes);
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free(cp);
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return newp;
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}
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/*
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** Ok, we don't have to copy, it fits as-is
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*/
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#ifdef RCHECK
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op->ov_size = (nbytes + RSLOP - 1) & ~(RSLOP - 1);
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*(u_short *)((caddr_t)(op + 1) + op->ov_size) = RMAGIC;
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#endif
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return(cp);
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}
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#ifdef MSTATS
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/*
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* mstats - print out statistics about malloc
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*
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* Prints two lines of numbers, one showing the length of the free list
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* for each size category, the second showing the number of mallocs -
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* frees for each size category.
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*/
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mstats(s)
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char *s;
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{
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register int i, j;
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register union overhead *p;
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int totfree = 0,
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totused = 0;
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fprintf(stderr, "Memory allocation statistics %s\nfree:\t", s);
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for (i = 0; i < NBUCKETS; i++) {
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for (j = 0, p = nextf[i]; p; p = p->ov_next, j++)
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;
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fprintf(stderr, " %d", j);
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totfree += j * (1 << (i + 3));
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}
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fprintf(stderr, "\nused:\t");
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for (i = 0; i < NBUCKETS; i++) {
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fprintf(stderr, " %d", nmalloc[i]);
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totused += nmalloc[i] * (1 << (i + 3));
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}
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fprintf(stderr, "\n\tTotal small in use: %d, total free: %d\n",
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totused, totfree);
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fprintf(stderr, "\n\tNumber of big (>%d) blocks in use: %d\n", MAXMALLOC, nmalloc[NBUCKETS]);
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}
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#endif
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