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From: dkb@bistromath.mitre.org (Daryl K. Baker)
Newsgroups: comp.windows.ms.programmer
Subject: Re: GlobalDosAlloc not exported in libs?
Message-ID: <1991Mar12.183804.19190@linus.mitre.org>
Date: 12 Mar 91 18:38:04 GMT
References: <1991Feb13.165724.18629@linus.mitre.org> <1991Mar10.143402.12577@siesoft.co.uk> <1991Mar12.081711.8270@Informatik.TU-Muenchen.DE>
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I posted the orignal querry and thanks to all who responded with
the "correct" answer (no included in windows.h add defintions).

Now for the why.  I am trying to call a tsr.

In article <1991Mar12.081711.8270@Informatik.TU-Muenchen.DE> rommel@Informatik.TU-Muenchen.DE (Kai-Uwe Rommel) writes:
>In article <1991Mar10.143402.12577@siesoft.co.uk> mjc@siesoft.co.uk (Mark Carlin) writes:
>>I would hazard a guess and suggest that if your intention is to
>>communicate with a a DOS program, such as a TSR, then you may have another
>>problem to follow; altering segment registers and issuing a software
>>interrupt in in enhanced mode will cause a protection violation.
>>To overcome this you may have to mess around with DPMI (DOS Protected
>>Mode Interface).
>You *can* issue software interrupts in 386 enhanced mode, at least to
>the most often used vectors, such as 2F, the multiplex interrupt. I use

Unfortunately the interupt rouinte already exists and I can't change it.
What I did was to write a little routine called dpmi_int86x ();  with
the same calling parameters as the microsoft routine int86x.  This
routine calls the dpmi handler to do a "call real mode interupt"
(this routine is based on a recent article in PC Magazine)

The thing you must make sure of is that all pointers point to dos
memory.

=== dpmi_int86x ===
#include <windows.h>
#include <dos.h>

struct DPMI_REGS {
   WORD   di;   WORD  xdi;
   WORD   si;   WORD  xsi;
   WORD   bp;   WORD  xbp;

   DWORD reserved;

   WORD   bx;   WORD  xbx;
   WORD   dx;   WORD  xdx;
   WORD   cx;   WORD  xcx;
   WORD   ax;   WORD  xax;
   WORD  flags;
   WORD  es;
   WORD  ds;
   WORD  fs;
   WORD  gs;
   WORD  ip;    WORD  cs;
   WORD  sp;    WORD  ss;
   WORD  protdx;
   WORD  protsi;
   WORD  protes;
};

int dpmi_int86x ( int int_num, union REGS *inregs, union REGS *outregs,
                  struct SREGS *segregs)
{

   struct DPMI_REGS far * dos_dpmi_regs;
   struct DPMI_REGS       dpmi_regs;
   WORD regs_seg, regs_off;

   dos_dpmi_regs = &dpmi_regs;
   dos_dpmi_regs->ax = inregs->x.ax;
   dos_dpmi_regs->bx = inregs->x.bx;
   dos_dpmi_regs->cx = inregs->x.cx;
   dos_dpmi_regs->dx = inregs->x.dx;
   dos_dpmi_regs->si = inregs->x.si;
   dos_dpmi_regs->di = inregs->x.di;
   dos_dpmi_regs->es = segregs->es;
   dos_dpmi_regs->ds = segregs->ds;

   dos_dpmi_regs->protdx = inregs->x.dx;
   dos_dpmi_regs->protsi = inregs->x.si;
   dos_dpmi_regs->protes = segregs->es;


   dos_dpmi_regs->ss = 0;
   dos_dpmi_regs->sp = 0;              /* Uses dpmi server stack */

   regs_seg = FP_SEG (dos_dpmi_regs);
   regs_off = FP_OFF (dos_dpmi_regs);

   _asm {
      push  es
      mov   ax, regs_seg
      mov   es, ax

      mov   ax, 0300h
      mov   bx, int_num
      mov   bh, 0
      mov   cx, 0
      mov   di, regs_off
      int   31h
      pop   es
   }

   outregs->x.ax = dos_dpmi_regs->ax;
   outregs->x.bx = dos_dpmi_regs->bx;
   outregs->x.cx = dos_dpmi_regs->cx;
   outregs->x.dx = dos_dpmi_regs->dx;
   outregs->x.si = dos_dpmi_regs->si;
   outregs->x.di = dos_dpmi_regs->di;
   outregs->x.cflag = dos_dpmi_regs->flags & 1;

   return outregs->x.ax;
}

=== sample caller ===

   char far * dos_char_ptr;

   DWORD hDosMemory;
   HANDLE hProt, hReal;

   hDosMemory = GlobalDosAlloc ( (long) maxlen );
   hProt      = LOWORD (hDosMemory);
   hReal      = HIWORD (hDosMemory);
   dos_char_ptr = GlobalLock ( hProt );
   lstrcpy ( dos_char_ptr, name);

   inregs.h.ah = _nm_res_name;
   
   inregs.x.cx = maxlen;

   inregs.x.dx = FP_OFF(dos_char_ptr);
   inregs.x.di = FP_OFF(dos_char_ptr);

   segregs.ds = hReal;
   segregs.es = hReal;

   result = dpmi_int86x ( pctcp_int, &inregs, &outregs, &segregs);


   GlobalUnlock ( hProt);
   GlobalDosFree (hProt);


Daryl Baker
dkb@bistromath.mitre.org