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From: tanner@ki4pv.UUCP (Tanner Andrews)
Newsgroups: net.unix,net.unix-wizards,net.arch,net.lang.c
Subject: Re: get size of malloc'd object
Message-ID: <6922@ki4pv.UUCP>
Date: Tue, 24-Jun-86 10:21:15 EDT
Article-I.D.: ki4pv.6922
Posted: Tue Jun 24 10:21:15 1986
Date-Received: Thu, 26-Jun-86 04:30:08 EDT
References: <165@daisy.UUCP> <334@valid.UUCP> <2206@peora.UUCP>, <718@wjvax.wjvax.UUCP>
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Xref: watmath net.unix:8387 net.unix-wizards:18600 net.arch:3572 net.lang.c:9577

The problem with alignments, it would appear to me, would be easily
solved by allowing for the largest machine type, which should be
double.  Thus (cast the routine type as needed when you call it):

 /*  allocate core -- must free using my_free()
  */
char *my_malloc(sz)
short int sz;
	{
	register char
		*p;

	if  (p = malloc(sz+sizeof(double)))  {
		*((short int *)p) = sz;
		p += sizeof(double);
		}
	return(p);
	}

 /*  size of allocated object -- works for any p such that p is return
  *  value from my_malloc
  *  which has not been my_free'd
  */
short int my_sizeof(p)
char *p;
	{

	return(*((short int *)(p - sizeof(double)))

	}

-- 
<std dsclm, copies upon request>	   Tanner Andrews