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#ifndef lint
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static const char RCSid[] = "$Id: bmalloc.c,v 2.6 2003/11/14 17:22:06 schorsch Exp $";
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#endif
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/*
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* Bmalloc provides basic memory allocation without overhead (no free lists).
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* Use only to take the load off of malloc for all those
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* piddling little requests that you never expect to free.
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* Bmalloc defers to malloc for big requests.
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* Bfree should hand memory to bmalloc, but it usually fails here.
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*
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* External symbols declared in standard.h
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*/
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#include "copyright.h"
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#include <stdlib.h>
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#include "rtmisc.h"
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#ifndef MBLKSIZ
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#define MBLKSIZ 16376 /* size of memory allocation block */
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#endif
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#define WASTEFRAC 12 /* don't waste more than a fraction */
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#ifndef ALIGNT
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#define ALIGNT double /* type for alignment */
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#endif
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#define BYTES_WORD sizeof(ALIGNT)
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static void *bposition = NULL;
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static size_t nremain = 0;
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void *
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bmalloc( /* allocate a block of n bytes */
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register size_t n
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)
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{
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if (n > nremain && (n > MBLKSIZ || nremain > MBLKSIZ/WASTEFRAC))
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return(malloc(n)); /* too big */
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n = (n+(BYTES_WORD-1))&~(BYTES_WORD-1); /* word align */
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if (n > nremain && (bposition = malloc(nremain = MBLKSIZ)) == NULL) {
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nremain = 0;
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return(NULL);
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}
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bposition += n;
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nremain -= n;
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return(bposition - n);
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}
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void
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bfree( /* free random memory */
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register void *p,
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register size_t n
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)
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{
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register size_t bsiz;
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/* check alignment */
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bsiz = BYTES_WORD - ((size_t)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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if (p + n == bposition) { /* just allocated? */
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bposition = p;
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nremain += n;
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return;
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}
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if (n > nremain) { /* better than what we've got? */
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bposition = p;
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nremain = n;
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return;
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}
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/* just throw it away, then */
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}
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