mirror of https://github.com/FDOS/kernel.git
New file by Tom Ehlert for HMA initialization.
git-svn-id: https://svn.code.sf.net/p/freedos/svn/kernel/trunk@168 6ac86273-5f31-0410-b378-82cca8765d1b
This commit is contained in:
Bart Oldeman
parent
f2184025da
commit
8dff303fda
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@ -0,0 +1,534 @@
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/****************************************************************/
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/* */
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/* initHMA.c */
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/* DOS-C */
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/* */
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/* move kernel to HMA area */
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/* */
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/* Copyright (c) 2001 */
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/* tom ehlert */
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/* All Rights Reserved */
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/* */
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/* This file is part of DOS-C. */
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/* */
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/* DOS-C is free software; you can redistribute it and/or */
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/* modify it under the terms of the GNU General Public License */
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/* as published by the Free Software Foundation; either version */
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/* 2, or (at your option) any later version. */
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/* */
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/* DOS-C is distributed in the hope that it will be useful, but */
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/* WITHOUT ANY WARRANTY; without even the implied warranty of */
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/* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See */
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/* the GNU General Public License for more details. */
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/* */
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/* You should have received a copy of the GNU General Public */
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/* License along with DOS-C; see the file COPYING. If not, */
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/* write to the Free Software Foundation, 675 Mass Ave, */
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/* Cambridge, MA 02139, USA. */
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/****************************************************************/
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/*
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current status:
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load FreeDOS high, if DOS=HIGH detected
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suppress High Loading, if any SHIFT status detected (for debugging)
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if no XMS driver (HIMEM,FDXMS,...) loaded, should work
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cooperation with XMS drivers as follows:
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copy HMA_TEXT segment up.
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after each loaded DEVICE=SOMETHING.SYS, try to request the HMA
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(XMS function 0x01).
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if no XMS driver detected, during ONFIG.SYS processing,
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create a dummy VDISK entry in high memory
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this works with
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FD FDXMS - no problems detected
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MS HIMEM.SYS (from DOS 6.2, 9-30-93)
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works if and only if
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/TESTMEM:OFF
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is given
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otherwise HIMEM will TEST AND ZERO THE HIGH MEMORY+HMA.
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so, in CONFIG.C, if "HIMEM.SYS" is detected, a "/TESTMEM:OFF"
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parameter is forced.
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*/
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#include "init-mod.h"
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#include "portab.h"
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#include "globals.h"
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#ifdef VERSION_STRINGS
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static BYTE *RcsId = "$Id$";
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#endif
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/*
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* $Log$
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* Revision 1.1 2001/03/21 03:01:45 bartoldeman
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* New file by Tom Ehlert for HMA initialization.
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*
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* Revision 0.1 2001/03/16 12:00:00 tom ehlert
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* initial creation
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*/
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BYTE DosLoadedInHMA; /* set to TRUE if loaded HIGH */
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BYTE HMAclaimed; /* set to TRUE if claimed from HIMEM */
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WORD HMAFree; /* first byte in HMA not yet used */
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extern BYTE FAR * FAR XMSDriverAddress;
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extern FAR _EnableA20();
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extern FAR _DisableA20();
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void FAR *DetectXMSDriver();
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#ifdef DEBUG
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#define int3() __int__(3);
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#else
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#define int3()
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#endif
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#if defined( DEBUG ) || 1 /* experimental kernel !! */
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#define HMAInitPrintf(x) printf x
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#else
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#define HMAInitPrintf(x)
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#endif
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#ifdef DEBUG
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hdump(BYTE FAR *p)
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{
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int loop;
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HMAInitPrintf(("%p", p));
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for (loop = 0; loop < 16; loop++)
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HMAInitPrintf(("%02x ", p[loop]));
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printf("\n");
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}
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#else
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#define hdump(ptr)
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#endif
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#ifdef __TURBOC__
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void __int__(int); /* TC 2.01 requires this. :( -- ror4 */
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unsigned char __inportb__(int portid);
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void __outportb__ (int portid, unsigned char value);
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#endif
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#define KeyboardShiftState() (*(BYTE FAR *)(MK_FP(0x40,0x17)))
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/* of course, this should go to ASMSUPT */
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fmemcmp(BYTE far *s1, BYTE FAR *s2, unsigned len)
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{
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for ( ; len ; s1++,s2++,--len)
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{
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if (*s1 - *s2)
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return *s1-*s2;
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}
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return 0;
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}
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/* Enable / Disable borrowed without understanding from FDXMS. Thanks.
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gone done to KERNEL.ASM
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OutportWithDelay(WORD port, BYTE val)
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{
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int loop;
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__outportb__(port,val);
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for (loop = 100; --loop && __inportb__(0x64) & 0x02;)
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;
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}
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void _EnableHMA()
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{
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OutportWithDelay(0x64, 0xd1);
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OutportWithDelay(0x60, 0xdf);
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OutportWithDelay(0x64, 0xff);
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}
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void _DisableHMA()
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{
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OutportWithDelay(0x64, 0xd1);
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OutportWithDelay(0x60, 0xdd);
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OutportWithDelay(0x64, 0xff);
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}
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*/
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/*
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this tests, if the HMA area can be enabled.
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if so, it simply leaves it on
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*/
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int EnableHMA()
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{
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_EnableA20();
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if (fmemcmp(MK_FP(0x0000,0x0000), MK_FP(0xffff,0x0010),128) == 0)
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{
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printf("HMA can't be enabled\n");
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return FALSE;
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}
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_DisableA20();
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if (fmemcmp(MK_FP(0x0000,0x0000), MK_FP(0xffff,0x0010),128) != 0)
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{
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printf("HMA can't be disabled - no problem for us\n");
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}
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_EnableA20();
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if (fmemcmp(MK_FP(0x0000,0x0000), MK_FP(0xffff,0x0010),128) == 0)
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{
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printf("HMA can't be enabled second time\n");
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return FALSE;
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}
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HMAInitPrintf(("HMA success - leaving enabled\n"));
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return TRUE;
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}
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/*
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move the kernel up to high memory
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this is very unportable
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if we thin we succeeded, we return TRUE, else FALSE
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*/
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#define HMAOFFSET 0x20
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#define HMASEGMENT 0xffff
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int MoveKernelToHMA()
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{
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UBYTE FAR *HMASource;
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unsigned len;
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int3();
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if (DosLoadedInHMA)
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{
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return TRUE;
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}
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{ /* is very improbable - we are just booting - but
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there might already a XMS handler installed
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this is the case for DOSEMU
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*/
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void FAR *pXMS = DetectXMSDriver();
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if (pXMS != NULL)
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{
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XMSDriverAddress = pXMS;
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printf("DOSEMU ? detected XMS driver at %p\n", XMSDriverAddress);
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}
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}
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/* A) for debugging purpose, suppress this,
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if any shift key is pressed
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*/
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if (KeyboardShiftState() & 0x0f)
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{
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printf("Keyboard state is %0x, NOT moving to HMA\n",KeyboardShiftState());
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return FALSE;
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}
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/* B) check out, if we can have HMA */
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if (!EnableHMA())
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{
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printf("Can't enable HMA area (the famous A20), NOT moving to HMA\n");
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return FALSE;
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}
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/* C) we have HMA, copy HMA_TEXT up to 0xffff:0..ffff */
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{
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UBYTE FAR *HMADest = MK_FP(HMASEGMENT,0x0000);
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len = FP_OFF(_HMATextEnd) - FP_OFF(_HMATextStart);
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HMASource = _HMATextStart;
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len += FP_OFF(HMASource) & 0x000f;
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FP_OFF(HMASource) &= 0xfff0;
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HMASource += HMAOFFSET;
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HMADest += HMAOFFSET;
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len -= HMAOFFSET;
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HMAInitPrintf(("HMA moving %p up to %p for %04x bytes\n",
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HMASource, HMADest, len));
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fmemcpy(HMADest, HMASource, len);
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HMAFree = FP_OFF(HMADest)+len; /* first free byte after HMA_TEXT */
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int3();
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}
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{
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/* D) but it only makes sense, if we can relocate
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all our entries to make use of HMA
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*/
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/* this is for a
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call near enableA20
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jmp far kernelentry
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style table
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*/
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struct RelocationTable {
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UBYTE jmpFar;
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UWORD jmpOffset;
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UWORD jmpSegment;
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UBYTE callNear;
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UWORD callOffset;
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};
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struct RelocatedEntry {
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UBYTE callNear;
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UWORD callOffset;
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UBYTE jmpFar;
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UWORD jmpOffset;
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UWORD jmpSegment;
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};
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extern struct RelocationTable
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FAR _HMARelocationTableStart[],
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FAR _HMARelocationTableEnd[];
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struct RelocationTable FAR *rp, rtemp ;
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UWORD HMATextSegment = FP_SEG( _HMATextStart );
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/* verify, that all entries are valid */
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for (rp = _HMARelocationTableStart; rp < _HMARelocationTableEnd; rp++)
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{
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if (rp->jmpFar != 0xea || /* jmp FAR */
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rp->jmpSegment != HMATextSegment || /* will only relocate HMA_TEXT */
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rp->callNear != 0xe8 || /* call NEAR */
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0)
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{
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printf("illegal relocation entry # %d\n",rp - _HMARelocationTableStart);
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goto errorReturn;
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}
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}
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/* OK, all valid, go to relocate*/
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for (rp = _HMARelocationTableStart; rp < _HMARelocationTableEnd; rp++)
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{
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struct RelocatedEntry FAR *rel = (struct RelocatedEntry FAR *)rp;
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fmemcpy(&rtemp, rp, sizeof(rtemp));
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rel->jmpFar = rtemp.jmpFar;
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rel->jmpSegment = HMASEGMENT;
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rel->jmpOffset = rtemp.jmpOffset;
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rel->callNear = rtemp.callNear;
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rel->callOffset = rtemp.callOffset+5; /* near calls are relative */
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}
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}
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{
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/* E) up to now, nothing really bad was done.
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but now, we reuse the HMA area. bad things will happen
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to find bugs early,
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cause INT 3 on all accesses to this area
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*/
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fmemset(HMASource, 0xcc, len);
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HMAInitPrintf(("HMA text segment filled with INT 3\n"));
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DosLoadedInHMA = TRUE;
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}
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int3();
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return TRUE;
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errorReturn:
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printf("HMA errors, not doing HMA\n");
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int3();
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return FALSE;
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}
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/*
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/*
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now protect against HIMEM/FDXMS/... by simulating a VDISK
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FDXMS should detect us and not give HMA access to ohers
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unfortunately this also disables HIMEM completely
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so: we install this after all drivers have been loaded
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*/
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void InstallVDISK()
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{
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static struct { /* Boot-Sektor of a RAM-Disk */
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BYTE dummy1[3]; /* HIMEM.SYS uses 3, but FDXMS uses 2 */
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char Name[5];
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BYTE dummy2[3];
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WORD BpS;
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BYTE dummy3[6];
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WORD Sektoren;
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BYTE dummy4;
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} VDISK_BOOT_SEKTOR =
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{
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{ 0xcf, ' ', ' '},
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{ 'V', 'D', 'I', 'S', 'K'},
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{ ' ', ' ', ' '},
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512,
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{ 'F', 'D', 'O', 'S', ' ', ' '},
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128, /* 128*512 = 64K */
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' '
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};
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if (!DosLoadedInHMA) return;
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if (HMAclaimed) return;
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fmemcpy(MK_FP(0xffff,0x0010), &VDISK_BOOT_SEKTOR, sizeof(VDISK_BOOT_SEKTOR));
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setvec(0x19, MK_FP(0xffff,0x0010)); /* let INT 19 point to VDISK */
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}
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int init_call_XMScall( void FAR * driverAddress, UWORD ax, UWORD dx);
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void init_call_intr(int intrnr, iregs *rp);
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/*
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after each driver, we try to allocate the HMA.
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it might be HIMEM.SYS we just loaded.
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*/
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void ClaimHMA()
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{
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void FAR *pXMS;
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if (!DosLoadedInHMA) return;
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if (HMAclaimed) return;
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pXMS = DetectXMSDriver();
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if (pXMS != NULL)
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{
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XMSDriverAddress = pXMS;
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if (init_call_XMScall( pXMS, 0x0100, 0xffff))
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{
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printf("HMA area successfully claimed\n");
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HMAclaimed = TRUE;
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}
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}
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}
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void FAR *DetectXMSDriver()
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{
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iregs regs;
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regs.a.x = 0x4300; /* XMS installation check */
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init_call_intr(0x2f, ®s);
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if ((regs.a.x & 0xff) != 0x80) return NULL;
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regs.a.x = 0x4310; /* XMS get driver address */
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init_call_intr(0x2f, ®s);
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return MK_FP(regs.es, regs.b.x);
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}
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/*
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this should be called, after each device driver
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has been loaded with FALSE
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and on finished CONFIG processing with TRUE.
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will try to grab HMA;
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on finalize, will install a VDISK
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*/
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void HMAconfig(int finalize)
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{
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ClaimHMA();
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if (finalize)
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InstallVDISK();
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}
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/*
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this allocates some bytes from the HMA area
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only available if DOS=HIGH was successful
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*/
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VOID FAR *HMAalloc(COUNT bytesToAllocate)
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{
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VOID FAR *HMAptr;
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if (!DosLoadedInHMA) return NULL;
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if (HMAFree >= 0xfff0 - bytesToAllocate) return NULL;
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HMAptr = MK_FP(0xffff, HMAFree);
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HMAFree += bytesToAllocate;
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/*printf("HMA allocated %d byte at %x\n", bytesToAllocate, HMAptr); */
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return HMAptr;
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}
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