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Mail Archives: djgpp/1997/08/31/01:36:38

From: tim <tim AT h2oent DOT com>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: Linked lists with DJGPP
Date: 31 Aug 1997 01:34:34 GMT
Organization: H2O
Lines: 77
Message-ID: <5uahna$sbv@nr1.calgary.istar.net>
References: <3406E97E DOT 35F6 AT club-internet DOT fr>
Reply-To: No AT delorie DOT com, More AT delorie DOT com, Spam AT delorie DOT com
NNTP-Posting-Host: pm306.spots.ab.ca
Mime-Version: 1.0
CC: ludvig AT club-internet DOT fr
To: djgpp AT delorie DOT com
DJ-Gateway: from newsgroup comp.os.msdos.djgpp

ludvig wrote:
> 
> Hi I'v left my Borland4.52 for DJGPP and I'm not used to protectedmode
> programming so  I have just a little question...
> 
> What I have understood is that one can't allocate as many adress spaces
> as you would wish even if they can be at almost any size, and as I would
> have large (preferably generic) linked list, my question is:
> Is the new/malloc functions being able to alloc for an example 1500
> different structures(they arn't all different, but some differs in size
> and configuration, and the compiler wouldn't know anyway as it i dynamic
> allocation I want) or do I have to allocate a huge memory block and
> store all information by myselve?
> 
> Thank you for reading this Ludvig Larsson
> 
> ps. please send a copy to <ludvig AT club-internet DOT fr>

You could try something like this:

/**************************************************/
struct StrA;
typedef struct StrA
{
	/*
	 * data members
	 */

	void	*data; /* additional data for this element */
	struct
	StrA	*next; /* pointer to the next element */
} StrA;

void LoadStructures(void)
{
	StrA *StrAhead;    /* head of the linked list */
	StrA *StrAcurrent; /* current element pointer */
	StrA *StrAprev;    /* previous element pointer */
	long nBytesTotal;  /* number of bytes to allocate */
	long element;      /* data element index */
	char *d;           /* general purpose pointer */

	/* calculate the total number of bytes required */
	nBytesTotal = CalculateTotalStorageRequirements();

	/* allocate the memory */
	StrAhead = (StrA *)malloc(nBytesTotal);
	if(!StrAhead) return; /* simple error check */

	/* initialize the memory */
	d = (char*)StrA;
	StrAprev = NULL;
	for(element=0;element<NumberOfElements();++element)
	{
		/* initialize the `next' pointer for the previous element */
		if(strAprev)
		{
			StrAprev->next = (StrA *)d;
		}

		/* Initialize the current element */
		StrAcurrent = (StrA*)d;
		StrA->next = NULL;

		/* place the data after the fixed portion of the structure */
		StrA->data = (void*)((int)d + sizeof(StrA);

		/* load the data into the element */
		StoreElementData(element,StrAcurrent->data);

		/* save the current pointer for the previous element */
		StrAprev = StrAcurrent;

		/* advance the data pointer to the next element location */
		d+=sizeof(StrA) + ElementDataSize(element);
	}
}

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