Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!usc!elroy.jpl.nasa.gov!swrinde!mips!spool.mu.edu!uunet!proto!joe
From: joe@proto.com (Joe Huffman)
Newsgroups: comp.os.msdos.programmer
Subject: Re: Memory allocation error
Message-ID: <1991May28.203501.24420@proto.com>
Date: 28 May 91 20:35:01 GMT
References: <1991May20.055124.24741@ariel.unm.edu> <1991May23.092728.440@sc2a.unige.ch> <1991May24.235640.17077@proto.com> <43736@netnews.upenn.edu>
Organization: Prototronics @ Sandpoint, Idaho
Lines: 36

theall@rm105serve.sas.upenn.edu (George A. Theall) writes:

>In article <1991May24.235640.17077@proto.com> joe@proto.com (Joe Huffman) writes:
>>--------- high memory -------\
>>			   	\
>>                               ---      Resident portion
>>      --magic position--      /
>>----- not so high memory ----/

>   How does one determine where this portion begins in high memory?

Rough outline:

long unsigned int mask = 1L << 20;
long unsigned int M;

do	/* A binary search. */
{
  mask >>= 1;
  M |= mask;
  Allocate all of DOS memory.
  if(M < bytes_allocated)
  {
    Set the top 'M' bytes to 0.
    Free all allocated DOS memory.
    Exit program.
    if(no_crash)
      M ^= mask;
  }
  else
    M ^= mask;
} while(mask != 0);

Answer = 'Magic position' is M bytes from top of memory.
-- 
joe@proto.com