RE: [Dev-C++] new is a wrapper around malloc so...

[Daniel G. <sp...@ho...>]

Thanks. I'm trying to use the large memory model at the moment but it hasn't 
gotten rid of the need for FAR. Maybe I've done something wrong somewhere, I 
need to check.

Windows 9x has 16 bit code in it in places, such as Printer Drivers and 
other bits.


>From: "Abhijit Shylanath" <mu...@gm...>
>To: "Ioannis Vranos" 
><iv...@em...>,<dev...@li...>,<sp...@ho...>
>Subject: RE: [Dev-C++] new is a wrapper around malloc so...
>Date: Wed, 16 Jul 2003 00:07:20 +0530
>
>
>Hello, Ioannis and Daniel.
>
> > I do not know what a Far pointer, but I do know that they exist. Can you
> > tell us what does it mean?
>
>Well, you must know that we have four basic segments (on the 8086) - the 
>CS,
>DS, SS and ES... by default, when a data pointer is defined, it is assumed
>that the pointer resides in the data segment, and when a function pointer 
>is
>defined, that it resides in the code segment. However, when a pointer is
>flagged as `far', it means that the segment is also stored explicitly along
>with the offset. So, basically, far pointers allow you to access the whole
>(and overwhelmingly huge) 1M of the 8086. Basically, far means residing in 
>a
>different segment, while near means residing in the same (the default)
>segment.
>
>Daniel, in response to your original question:
>
>Assuming you code in Turbo-C++, you have three options:
>
>1. Use a memory-model in which the required pointer's type is far by
>default. If you need far data (the most common), use compact (in which the
>data pointers are still near). If you need far code, use (umm, not sure,
>really) large or huge (check the docs). You'll need to say something like
>this:
>	char *foo = (char *)malloc(WHATEVER);
>
>2. Use the farmalloc() function (in TC - in M$C, I've heard that it's named
>halloc()). Corresponding frees should be done by farfree() (dunno about
>M$C).
>
>	char far *foo = (char far *)farmalloc(WHATEVER);
>	// ...
>	farfree(foo);
>
>3. The easiest - simply call `new'. AFAIK, you don't need to overload new:
>
>	char far *big_one = new char far[200];
>       //                           ^?
>	// Play around a bit with the syntax, I'm not sure that this works...
>
>    I remember doing something like this sometime back.
>
>However, why do you need to use different segments at all? You should try
>porting it to 32-bit protected-mode DOS (or even Windows console-mode), if
>your application allows it. Sad as it is for me to say it, DOS is dead.
>Anyway, here are a few links you might find interesting:
>
>* http://www.delorie.com/djgpp
>   DJGPP - A DOS protected-mode C/++ compiler based on GCC
>
>* http://sunsite.lanet.lv/ftp/mirror/x2ftp/msdos/programming/
>   The X2FTP - hordes of information on related topics.
>
>HTH.
>
>--
>Abhijit Shylanath
>Homepage: http://mudeth.tripod.com/
>
>
>
>
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