From: kroe AT sbcs DOT sunysb DOT edu (KiYun Roe)
Date: Fri, 31 Jan 92 19:07:11 EST
To: djgpp AT sun DOT soe DOT clarkson DOT edu
Subject: Patches for VPCI/XMS allocation
Status: O

I left for a couple of days and when I returned I found 26 messages
from the mailing list or its participants!  It's active enough for me
now. :-)

Below are my patches for valloc.c in go32 which allow it to allocate
from both XMS/extended memory and VCPI.  I think the changes are
relatively straightforward.  The new version of valloc.c allocates a
large block from DOS memory and another large block from XMS/extended
memory.  After these blocks have run out it allocates from VCPI (EMS)
memory.  The most fundamental assumption is that VCPI pages come from
outside of the two initial blocks, so it is possible to track the VCPI
allocations in map[].  I haven't tested the changes extensively in the
sense of hammering on them, but I've used the modified go32/debug32 to
run gcc, etc., without any problems.

Somebody asked what VCPI is.  It stands for Virtual Control Program
Interface, and it's just a scheme for allowing a 386/486 EMS emulator
to co-exist with other protected mode programs.  386/486 EMS emulators
work by putting the processor into V86 mode and using the memory
mapping hardware to do the trick of putting extended memory pages into
the EMS page frames of a V86 "box".  Without a scheme like VCPI, other
programs couldn't access protected mode.  VCPI also allows protected
mode programs to allocate memory from the extended memory pool reserved
by the EMS emulator.

Finally, on an entirely separate note, I reviewed the DPMI information
in my copy of "Extending DOS" by Duncan et al., and as DJ has explained
DPMI 0.9 won't cut it for djgpp.  There's no way to ask it to do
something like "please put XXX bytes of memory at YYY address (because
my program expects memory to be there)".  That capability is in DPMI 1.0.

				-- KiYun

KiYun Roe					kroe AT sbcs DOT sunysb DOT edu
Department of Computer Science
SUNY at Stony Brook
Stony Brook, NY  11794-4400			(516) 632-7675

-----
Here are the context diffs for valloc.c.  I confess that I normally use
MKS patch instead of the djgpp patch, but I don't think there should be
any problem using either patch program to apply the diffs.

----- CUT HERE -----
*** old\valloc.c Sun Aug 25 17:26:38 1991
--- valloc.c Mon Jan 27 17:26:48 1992
***************
*** 13,18 ****
--- 13,19 ----
  */
  
  /* Modified for VCPI Implement by Y.Shibata Aug 5th 1991 */
+ /* Modified for joint VCPI/extended memory allocation by KiYun Roe 27-Jan-92 */
  /* History:126,1 */
  
  #include <stdio.h>
***************
*** 138,151 ****
    unsigned los, i, lol;
    struct REGPACK r;
    
!   if (vcpi_installed)
!     {
!     pn_hi_first = 32767;
!     pn_hi_last  = DOS_PAGE;
!     }
!   else if(use_xms) {
! 	  xms_alloc_init();	/*  Try XMS allocation  */
! 	  }
    else {
  	/*
  	** int 15/vdisk memory allocation
--- 139,147 ----
    unsigned los, i, lol;
    struct REGPACK r;
    
!   if (use_xms) {
! 	xms_alloc_init();	/*  Try XMS allocation  */
!   }
    else {
  	/*
  	** int 15/vdisk memory allocation
***************
*** 181,205 ****
    r.r_ax = 0x4900;	/* because Turbo Debugger won't if we don't */
    intr(0x21, &r);
  
!   mem_avail = 0;
!   for ( i=0; i<DOS_PAGE/8; i++)
!     map[i] = 0xff;	/* DOS Area  */
!   for (    ; i<4096; i++)
!     map[i] = (vcpi_installed)? 0x00:0xff;	/* Extened Memory Area  */
  
-   for (i=pn_lo_first; i<=pn_lo_last; i++)
-     vset(i, VA_FREE);
-   for (i=pn_hi_first; i<=pn_hi_last; i++)
-     vset(i, VA_FREE);
    vcpi_flush_ok = 1;
  
-   mem_used = 0;
    left_lo  = (pn_lo_last - pn_lo_first + 1)*4;
!   left_hi  = (vcpi_installed)? vcpi_capacity()*4:(pn_hi_last-pn_hi_first+1)*4;
    if (vcpi_installed)
!     mem_avail = left_lo + left_hi;
  
! /*  mem_avail = (pn_lo_last-pn_lo_first+1)*4 + (pn_hi_last-pn_hi_first+1)*4; */
  #if DEBUGGER
    if (debug_mode)
      printf("%d Kb conventional, %d Kb extended - %d Kb total RAM available\n",
--- 177,195 ----
    r.r_ax = 0x4900;	/* because Turbo Debugger won't if we don't */
    intr(0x21, &r);
  
!   for (i=0; i<4096; i++)
!     map[i] = 0;
  
    vcpi_flush_ok = 1;
  
    left_lo  = (pn_lo_last - pn_lo_first + 1)*4;
!   left_hi  = (pn_hi_last - pn_hi_first + 1)*4;
    if (vcpi_installed)
!     left_hi += vcpi_capacity()*4;
  
!   mem_avail= left_lo + left_hi;
!   mem_used = 0;
! 
  #if DEBUGGER
    if (debug_mode)
      printf("%d Kb conventional, %d Kb extended - %d Kb total RAM available\n",
***************
*** 233,261 ****
      case VA_1M:
        more_1m:
        if (vcpi_installed)
  	{
- 	if (pn = vcpi_alloc())
- 	  {
  	  left_hi -= 4;
! 	  if (pn < pn_hi_first)
! 	    pn_hi_first = pn;
! 	  if (pn > pn_hi_last)
! 	    pn_hi_last  = pn;
! 	  vset(pn,VA_USED);
  	  return pn;
- 	  }
  	}
-       else
- 	{
-         for (pn=pn_hi_first; pn<=pn_hi_last; pn++)
-           if (vtest(pn) == VA_FREE)
-             {
-             left_hi -= 4;
-             vset(pn, VA_USED);
-             return pn;
-             }
- 	}
  
        for (pn=pn_lo_first; pn<=pn_lo_last; pn++)
          if (vtest(pn) == VA_FREE)
          {
--- 223,243 ----
      case VA_1M:
        more_1m:
        if (vcpi_installed)
+         if (pn = vcpi_alloc())
  	{
  	  left_hi -= 4;
! 	  vset(pn, VA_USED);
  	  return pn;
  	}
  
+       for (pn=pn_hi_first; pn<=pn_hi_last; pn++)
+         if (vtest(pn) == VA_FREE)
+         {
+           left_hi -= 4;
+           vset(pn, VA_USED);
+           return pn;
+         }
+ 
        for (pn=pn_lo_first; pn<=pn_lo_last; pn++)
          if (vtest(pn) == VA_FREE)
          {
***************
*** 271,278 ****
  
  void vfree(unsigned pn)
  {
!   if ((vcpi_installed)&&(pn >= DOS_PAGE))
!     vcpi_free(pn);
    vset(pn, VA_FREE);
  }
  
--- 253,261 ----
  
  void vfree(unsigned pn)
  {
!   if (vcpi_installed && pn > pn_lo_last)
!     if (pn < pn_hi_first || pn > pn_hi_last)
!       vcpi_free(pn);
    vset(pn, VA_FREE);
  }
  
***************
*** 282,288 ****
  
    if (!vcpi_flush_ok)
      return;			/*  Not Initaialized Map[]  */
!   for(pn = pn_hi_first; pn <= pn_hi_last; pn++)
      if (vtest(pn))
        vcpi_free(pn);
  
--- 265,274 ----
  
    if (!vcpi_flush_ok)
      return;			/*  Not Initaialized Map[]  */
!   for (pn = pn_lo_last + 1; pn < pn_hi_first; pn++)
!     if (vtest(pn))
!       vcpi_free(pn);
!   for (pn = pn_hi_last + 1; pn <= 32767; pn++)
      if (vtest(pn))
        vcpi_free(pn);