From: jonslaughter AT my-dejanews DOT com
Newsgroups: comp.os.msdos.djgpp
Subject: __dpmi_resize_dos_memory problem(not working?)
Date: Mon, 17 Aug 1998 08:33:29 GMT
Organization: Deja News - The Leader in Internet Discussion
Lines: 103
Message-ID: <6r8psp$qmm$1@nnrp1.dejanews.com>
NNTP-Posting-Host: 38.11.206.18
To: djgpp AT delorie DOT com
DJ-Gateway: from newsgroup comp.os.msdos.djgpp
Precedence: bulk

sorry if I have already posted this(having problems with news servers)...



    I'm having a HUGE problem trying to get __dpmi_resize_dos_memory to
work...
it always fails and I don't understand why... since I'm only shrinking the
memory block I don't see why it should fail(jus has to lower the segment
limit in the descriptor?).

    Anyways, I've done alittle test program to show you what I'm trying to
do. just allocate, resize, and free a dos block.  From what I understand
this should work, so what am I missing?? please help me ;) I'm desprate.
when I run it, I get a very low free dos memory(like 3k).

    What I'm trying to do is create a function that allocate a dos memory
that doesn't cross a 64k segment boundry... they way I'm doing this is
explained at the bottom.

if you can help me, please email me at 1jjs5206 AT csunix DOT mcc DOT cc DOT tx DOT us , since
I do not know if I can get back on the new group.... Thanks.


#include <stdio.h>
#include <dpmi.h>
#include <go32.h>
#include <memory.h>


void main (void)
{

int sel, seg, memsize, new_memsize, total_mem, retval;

memsize = 0x100;
new_memsize = 0x90;

printf("Allocating %d bytes of dos memory...\n\n",memsize);
seg = __dpmi_allocate_dos_memory(memsize >> 4,&sel);
        if (seg == -1)
                {
                printf("Error allocating dos memory\n");
                exit(1);
                }


printf("Resizing %d bytes to %d bytes of dos
memory...\n\n",memsize,new_memsize);
retval = __dpmi_resize_dos_memory(sel, new_memsize >> 4,&total_mem);
printf("Total Memory avaliable = %d\n",total_mem << 4);
if (retval == -1)
        {
        __dpmi_free_dos_memory(sel);
        printf("Error resizing dos memory block");
        exit(1);
        }


__dpmi_free_dos_memory(sel);
printf("Dos memory successfully allocated, resized, and freed\n");



}




to allocate a block of mem that doesn't cross a 64k seg boundry, I do the
following pseudo code:

memsize < 64k

allocate memory.

do {

if (dosmemseg < (int)(dosmemseg/0xFFF+1)*0xFFF) && ((16*dosmemory + memsize)
< (int)(dosmemseg/0xFFF+1)*0xFFF)
    {
    dosmemseg does not cross 64k bound, mem ok. return dosmemseg;
    }

resize dosmemseg to end just at end of 64k bound... ***** problem occurs
here, just as in sample code above *****

allocate new_dosmemseg hoping that it would start right after dosmemseg

free dosmemseg

dosmemseg = new_dosmemseg;

while (retry count == ok)








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