From: phreadd AT powerup DOT com DOT au (David Orme)
Newsgroups: comp.os.msdos.djgpp
Subject: Re: newbie doing a port from BC to DJGPP
Date: 15 Apr 1997 08:44:15 GMT
Organization: Power Up
Lines: 53
Message-ID: <5ivf4v$of7$1@grissom.powerup.com.au>
References: <5io1nm$t3c$1 AT grissom DOT powerup DOT com DOT au> <334F9793 DOT 48A7 AT cornell DOT edu>
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To: djgpp AT delorie DOT com
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In article <334F9793 DOT 48A7 AT cornell DOT edu>, asu1 AT cornell DOT edu says...
>
In article <334F9793 DOT 48A7 AT cornell DOT edu>, asu1 AT cornell DOT edu says...
>i would recommend reading the section:
>17.7 What should I do with those "near" and "far" declarations? 
>in the djgpp faq. it should be available in various formats (i prefer
>html) at the site you downloaded djgpp from.

I have, and 18.2, and the surrounding sections. It says to put the variable 
address into di and ignore es. This I did, and successfully caused a 
"SIGSEGV" program halt.

My original code (before alterations, in BC) looks like this:

struct{
  byte buffer[256];
} VESA, *VESA_ptr=VESA;

int CheckVESA()
{
  union REGS r;
  union SREGS s;

  r.h.ah=0x4f;
  r.h.al=0;
  s.es=FP_SEG(VESA_ptr);
  r.x.di=FP_OFF(VESA_ptr);

  int86x(0x10,&r,&r,&s);  /* here's where it "crashes" with */

  if(r.h.ah=0) return 0;

  return 1;
}


Apparently DJGPP handles REGS and SREGS differently to Borland C, which is 
why my program halts. I converted to _dpmi_regs and __dpmi_int, but they 
don't support sending your own buffer (VESA in this case) to the interrupt.

[Actually, this isn't true. You can send your own buffer but it can't be 
less than 2Mb, which defeats the purpose of a 256 byte struct]

Please help, as the information in the FAQ isn't very helpful (in this 
instance at least).

+----------------------------------------+
|   David Orme                     \/\   |
|   phreadd AT powerup DOT com DOT au         /\/   |
+----------------------------------------+
|   "Striving for Excellence"            |
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