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#ifndef lint |
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static const char RCSid[] = "$Id: bmalloc.c,v 2.7 2004/03/28 20:33:12 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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|
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#include "copyright.h" |
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|
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#include <stdlib.h> |
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|
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#include "rtmisc.h" |
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|
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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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|
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static char *bposition = NULL; |
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static size_t nremain = 0; |
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|
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|
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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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|
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n = (n+(BYTES_WORD-1))&~(BYTES_WORD-1); /* word align */ |
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|
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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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|
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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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} |
