Click above to get retro games delivered to your door ever month!

__djgpp_nearptr_enable
======================

Syntax
------

     #include <sys/nearptr.h>
     
     int __djgpp_nearptr_enable(void);

Description
-----------

This function enables "near pointers" to be used to access the DOS
memory arena.  Sort of.  When you call this function, it will return
nonzero if it has successfully enabled near pointers.  If so, you must
add the value `__djgpp_conventional_base' to the linear address of the
physical memory.  For example:

     if (__djgpp_nearptr_enable())
     {
       short *screen = (short *)(__djgpp_conventional_base + 0xb8000);
       for (i=0; i<80*24*2; i++)
         screen[i] = 0x0720;
       __djgpp_nearptr_disable();
     }

The variable `__djgpp_base_address' contains the linear base address of
the application's data segment.  You can subtract this value from other
linear addresses that DPMI functions might return in order to obtain a
near pointer to those linear regions as well.

If using the Unix-like sbrk algorithm, near pointers are only valid
until the next `malloc', `system', `spawn*', or `exec*' function call,
since the linear base address of the application may be changed by
these calls.

WARNING: When you enable near pointers, you disable all the protection
that the system is providing.  If you are not careful, your application
may destroy the data in your computer.  USE AT YOUR OWN RISK!

Return Value
------------

Returns 0 if near pointers are not available, or nonzero if they are.