Message-ID:	<3776881A.E1420D39@unb.ca>
From:	Endlisnis <s257m AT unb DOT ca>
Organization:	Nortel Networks
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Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: Linear addressing using brk() and sbrk()
References:	<ehYc3.1130$Dl DOT 33483 AT news DOT clear DOT net DOT nz>
Lines:	34
Date:	Sun, 27 Jun 1999 20:22:19 GMT
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NNTP-Posting-Date:	Sun, 27 Jun 1999 16:22:19 EDT
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp
Reply-To:	djgpp AT delorie DOT com

Bruce Hoyt wrote:

> Question 3: Is it very bad to do the following?
>
>     unsigned desired_address = 0x100000;
>     unsigned desired_size = 0x80000;
>     if(sbrk((void *)desired_address - sbrk(0)) == (void *)-1) {
>        printf("Can't adjust brk to %X\n", desired_address);
>        return memory_error1;
>     }
>     if(sbrk(desired_size) == (void *)-1) {
>         printf("Can't allocate %X bytes for image\n",
> desired_size);
>         return memory_error2;
>     }

    Is it bad... I don't know, but it wastes upwards of 1Meg of RAM.  And it
wouldn't work if you had already allocated more than 1Meg of RAM for your
current program.

> And what happens when I malloc some more memory? How do I keep
> the heap from overlapping desired_address ?

    The malloced memory will be AFTER the block you've allocated (it will not
overlap).


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     (\/) Endlisnis (\/)
          s257m AT unb DOT ca
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