Path: utzoo!attcan!uunet!aplcen!haven!umd5!brianf
From: brianf@umd5.umd.edu (Brian Farmer)
Newsgroups: comp.windows.ms
Subject: Re: __ahincr
Message-ID: <6908@umd5.umd.edu>
Date: 18 Jul 90 14:35:20 GMT
References: <6887@umd5.umd.edu> <118500044@uxa.cso.uiuc.edu>
Reply-To: brianf@umd5.umd.edu (Brian Farmer)
Organization: University of Maryland, College Park
Lines: 72

In article <118500044@uxa.cso.uiuc.edu> mms00786@uxa.cso.uiuc.edu writes:

>Under enhanced and standard mode, I am now allowed to GlobalAlloc chunks greater
>than 64K. I assume I am also able to GlobalLock these large chunks. Question is,
>how do I access this memory? For example, suppose I wanted to create a memory
>chunk filled with letter 'a', would the following work?
>
>  hMem = GlobalAlloc (GMEM_MOVEABLE | GMEM_ZEROINIT, 70000);
>  lpStr = GlobalLock (hMem);
>  for (i=0; i < 70000; i++)
>      *lpStr++ = 'a';
>

Only if lpStr is a huge pointer.


>Or would I have to worry about segment boundaries etc, possibly through
>the use of this mysterious _ahincr?

Only if lpStr is just a long pointer.  I wanted to know about is because
we have a routine needs to be as quick as possible so was written in 
in-line assembly.  Here is a routine that I wrote to test __ahincr that
should do what you want.  A huge pointer is easier for C.

/*  __ahincr needs to be define like:       */

extern	int	_ahincr;



void AhincrTest (HWND hWnd)

{
        HANDLE  foo;
        char    far *foo2;
        int     incr, *ptr;
        LONG    i;


	incr = &_incr;

        foo = GlobalAlloc (GMEM_MOVEABLE, 70000);
        foo2 = (char far *)GlobalLock (foo);

        incr = &_ahincr;

        ptr = (int *)&foo2;

        while (i<70000)
        {
                foo2[(int)i] = 'a';  /* (int)i or LOWORD (i) should work here */
                i++;
                if (!LOWORD (i))
                        ptr[1] += incr;  /* update the segment pointer. 
					    you can also use __ahincr for
					    subtraction to go backward in 
					    array.		       */
			

        }

	GlobalUnlock (foo);

        MessageBox (hWnd, "finished looping", "Generic.C", MB_OK);
}


Thanks to Microsoft for posting there earlier responses, they really helped.


Brian Farmer 
brianf@umd5.umd.edu