src/common/bmalloc.c

#ifndef lint
static const char       RCSid[] = "$Id$";
#endif
/*
 * Bmalloc provides basic memory allocation without overhead (no free lists).
 * Use only to take the load off of malloc for all those
 * piddling little requests that you never expect to free.
 * Bmalloc defers to malloc for big requests.
 * Bfree should hand memory to bmalloc, but it usually fails here.
 *
 *  External symbols declared in standard.h
 */

#include "copyright.h"

#include <stdlib.h>

#ifndef  MBLKSIZ
#define  MBLKSIZ        16376           /* size of memory allocation block */
#endif
#define  WASTEFRAC      12              /* don't waste more than a fraction */
#ifndef  ALIGNT
#define  ALIGNT         double          /* type for alignment */
#endif
#define  BYTES_WORD     sizeof(ALIGNT)

static char  *bposition = NULL;
static unsigned int  nremain = 0;


char *
bmalloc(n)              /* allocate a block of n bytes */
register unsigned int  n;
{
        if (n > nremain && (n > MBLKSIZ || nremain > MBLKSIZ/WASTEFRAC))
                return(malloc(n));                      /* too big */

        n = (n+(BYTES_WORD-1))&~(BYTES_WORD-1);         /* word align */

        if (n > nremain && (bposition = (char *)malloc(nremain = MBLKSIZ)) == NULL) {
                nremain = 0;
                return(NULL);
        }
        bposition += n;
        nremain -= n;
        return(bposition - n);
}


void
bfree(p, n)                     /* free random memory */
register char   *p;
register unsigned int   n;
{
        register unsigned int   bsiz;
                                        /* check alignment */
        bsiz = BYTES_WORD - ((unsigned int)p&(BYTES_WORD-1));
        if (bsiz < BYTES_WORD) {
                p += bsiz;
                n -= bsiz;
        }
        if (p + n == bposition) {       /* just allocated? */
                bposition = p;
                nremain += n;
                return;
        }
        if (n > nremain) {              /* better than what we've got? */
                bposition = p;
                nremain = n;
                return;
        }
                                /* just throw it away, then */
}
Revision:	2.4
Committed:	Tue Feb 25 02:47:21 2003 UTC (21 years, 2 months ago) by greg
Content type:	text/plain
Branch:	MAIN
CVS Tags:	rad3R5
Changes since 2.3:	+1 -56 lines
Log Message:	Replaced inline copyright notice with #include "copyright.h"
#	User	Rev	Content
1	greg	1.1	#ifndef lint
2	greg	2.3	static const char RCSid[] = "$Id$";
3	greg	1.1	#endif
4			/*
5	greg	1.3	* Bmalloc provides basic memory allocation without overhead (no free lists).
6			* Use only to take the load off of malloc for all those
7			* piddling little requests that you never expect to free.
8			* Bmalloc defers to malloc for big requests.
9			* Bfree should hand memory to bmalloc, but it usually fails here.
10	greg	2.3	*
11			* External symbols declared in standard.h
12	greg	1.1	*/
13
14	greg	2.4	#include "copyright.h"
15	greg	2.3
16			#include <stdlib.h>
17	greg	1.2
18	greg	1.1	#ifndef MBLKSIZ
19			#define MBLKSIZ 16376 /* size of memory allocation block */
20			#endif
21	greg	1.3	#define WASTEFRAC 12 /* don't waste more than a fraction */
22	greg	2.3	#ifndef ALIGNT
23			#define ALIGNT double /* type for alignment */
24	greg	1.1	#endif
25	greg	2.3	#define BYTES_WORD sizeof(ALIGNT)
26	greg	1.1
27	greg	1.3	static char *bposition = NULL;
28	greg	2.3	static unsigned int nremain = 0;
29	greg	1.3
30
31	greg	1.1	char *
32	greg	2.2	bmalloc(n) /* allocate a block of n bytes */
33	greg	2.3	register unsigned int n;
34	greg	1.1	{
35	greg	1.3	if (n > nremain && (n > MBLKSIZ \|\| nremain > MBLKSIZ/WASTEFRAC))
36	greg	1.2	return(malloc(n)); /* too big */
37	greg	1.1
38			n = (n+(BYTES_WORD-1))&~(BYTES_WORD-1); /* word align */
39
40	greg	2.3	if (n > nremain && (bposition = (char *)malloc(nremain = MBLKSIZ)) == NULL) {
41	greg	2.2	nremain = 0;
42			return(NULL);
43	greg	1.1	}
44	greg	1.3	bposition += n;
45			nremain -= n;
46			return(bposition - n);
47	greg	1.1	}
48
49
50	greg	2.3	void
51	greg	1.1	bfree(p, n) /* free random memory */
52	greg	1.3	register char *p;
53	greg	2.3	register unsigned int n;
54	greg	1.1	{
55	greg	2.3	register unsigned int bsiz;
56	greg	1.3	/* check alignment */
57	greg	2.3	bsiz = BYTES_WORD - ((unsigned int)p&(BYTES_WORD-1));
58	greg	1.3	if (bsiz < BYTES_WORD) {
59			p += bsiz;
60			n -= bsiz;
61			}
62			if (p + n == bposition) { /* just allocated? */
63			bposition = p;
64			nremain += n;
65			return;
66			}
67			if (n > nremain) { /* better than what we've got? */
68			bposition = p;
69			nremain = n;
70			return;
71			}
72			/* just throw it away, then */
73	greg	1.1	}